Climate Change Impacts on Forests | US EPA – U.S.

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Forests and woodlands cover more than 822 million acres of land in the United States—about 36% of the country’s total land.1 There are many types of forests, including tropical forests, pine forests, and deciduous forests, with trees that shed their leaves annually. Forests are found on coasts, in wetlands, in dry inland regions, in areas with cold and warm climates, and even in cities.2
Forest structure changes. In the U.S. Southeast, sea level rise and warmer weather could cause mangrove forests to spread into salt marshes along the coast.38 This could change the balance of other species living in these ecosystems.39
Economic impacts. Outdoor activities can be a key source of income for rural areas. In northwest Massachusetts, communities banded together to create the Mohawk Trail Woodlands Partnerships to help keep the region’s forests—and economy—healthy.40
Forest losses from wildfires. In 2020, wildfires burned over 10 million acres of U.S. lands, the highest-ever amount on record.41 Wildfires are expected to become more frequent and intense as the climate warms.42
Insect damage to trees. Bark beetles eat away at trees.43 As the climate changes, warmer temperatures can lead to bark beetle population growth.44 Since 2000, bark beetles are thought to have damaged as much forest area as wildfires.45
More invasive species in forests. In the northeastern and midwestern United States, invasive garlic mustard plants can take nutrients away from native species.46 As climate change leads to changes in forest health, invasive species may spread more easily.47
Forests provide clean air and water, recreational opportunities, food, goods, and (ecosystem) services. Forests also connect people with nature and play an important role in the culture and survival of some Indigenous peoples.
Climate plays an important role in the makeup, function, and health of forests. Therefore, changes in climate, such as in temperature and precipitation, can have direct impacts on forests. These impacts vary by region and forest type. Some impacts may be beneficial while others could be damaging. For example, a warmer climate may increase tree growth in some forests but decrease it in others.3
Some forests may be able to respond to climate changes more successfully than others. For instance, forests that are fragmented into smaller patches may be less able to adapt than those that are well connected.4 Fortunately, forests are long-lived and naturally resistant to some climate variation.5 In addition, people can take many steps to help make forests more resilient to climate change.
Explore the sections on this page to learn more about climate impacts on forests:
Forests are a critical part of the carbon cycle and can help to lessen the impacts of climate change worldwide. Forests absorb carbon as they grow, acting as a carbon storage “bank” that helps to offset fossil fuel emissions. If trees are cut or burned, a forest temporarily releases part of this stored carbon to the atmosphere. When forests are converted to other uses, such as farming or development, they permanently release nearly all their carbon.6 
Climate change may affect forests at both local and regional scales. The impacts can vary even within a single forest. Three key impacts are described in this section.
Climate change will influence a number of natural disturbances that threaten forest health. These include insect outbreaks, invasive species, wildfires, and storms.7 Some disturbances, like a wildfire, take place quickly. Others, like changes in animal or plant populations, happen over decades to centuries.8 Some of their effects may be temporary, allowing a forest to recover. In other cases, a forest may suffer lasting impacts.9
Some forests may benefit from certain climate impacts. For instance, warmer temperatures can lead to more tree and plant growth in regions where cold weather limits the growing season.10 However, in other forests, warmer temperatures may allow invasive species to thrive.11,12 Warmer weather can also encourage insect survivial and growth. Over the past decade, climate change has led to an increase in bark beetle damage to mountain pines in parts of the West.13
Disturbances can also interact with one another to increase risks to forests. For example, drought can weaken trees and make a forest more vulnerable to wildfire or insect outbreaks. Similarly, wildfires can make a forest more vulnerable to pests.14 Climate impacts can also interact with other stressors, like land development, that decrease a forest’s ability to adapt.15
Climate change is expected to affect forests’ ability to provide key ecosystem services, including carbon storage, clean air, water supply, recreation, and wildlife habitat.16 One of the most important ecosystem services forests provide is absorbing carbon dioxide from the atmosphere and storing it in roots, soil, aboveground tree growth, and the forest floor.17 
Climate change can affect carbon storage in several ways. For example, it may bring more frequent and intense rainfall to some regions.18 Heavy precipitation and flooding can erode forest soils and cause stored carbon to be released back into the atmosphere. Damage to forests from more wildfires, insects, and disease outbreaks can also release stored carbon.19
Another key ecosystem service that forests provide is water for drinking, irrigation, recreation, and other uses. Forest watersheds also moderate extreme weather impacts, such as flooding from heavy rainfall, on downstream communities and ecosystems.20
Droughts, wildfires, rising temperatures, and reduced snowfall and snowpack due to climate change can all limit a watershed’s ability to provide these services.21 For example, more frequent or severe droughts could reduce streamflow in some forests. Less streamflow means less water may be available for people to use. Reduced streamflow can also affect some plants and animals, such as fish that migrate to certain streams to reproduce.22
For more specific examples of climate change impacts in your region, please see the National Climate Assessment.
Every day, Americans use a wide array of forest products including paper and packaging materials, lumber, and construction materials.24 The forest-products industry employs over 900,000 people in the United States.25  It also generates over $200 billion a year in sales and makes up about 6% of the U.S. manufacturing gross domestic product.26
In addition, forests provide important ecosystem services, such as clean air and water, climate regulation, wildlife habitat, and carbon storage. These services are often perceived as “free,” but they have great value. Some forests also provide opportunities for outdoor recreation, a source of revenue and economic growth for many regions.27
Certain communities may be more affected by climate change impacts on forests than others. For example, some Indigenous peoples rely on forests for medicine, food, or ceremonial practices.28 If they cannot access these resources, their diet, mental health, and cultural identity may be impacted.29,30 Tribes in remote or rural areas may already lack access to wastewater-treatment services and safe drinking water supplies. Climate impacts on the forest watershed can worsen these Tribes’ water security.31
Many rural communities benefit from their location near scenic forests.32 Climate change impacts on these forests may disrupt tourism and outdoor activities that are key sources of revenue for these communities.
Urban forests—such as parks, gardens, and nature preserves—provide important benefits to neighborhoods within cities.33 As the climate changes, impacts like extreme weather, heat, and soil and air quality changes can stress urban forests. This may affect their ability to provide cooling and other key services, particularly for those people most in need.34 For example, low-income households may be less able to afford air conditioning.35 People with certain medical conditions can also be more sensitive to heat, putting them at greater risk.36
We can reduce climate change’s impacts on forests and improve the resiliency of forested areas in many ways, including the following:
See additional actions you can take, as well as steps that companies can take, on EPA’s What You Can Do About Climate Change page.
Learn more about some of the key indicators of climate change related to this sector from EPA’s Climate Change Indicators in the United States:
Oswalt, S.N., et al. (2019). Forest resources of the United States, 2017: A technical document supporting the Forest Service 2020 RPA assessment. U.S. Department of Agriculture (USDA), Forest Service, Washington, DC, p. 4. 
Tidwell, T. (2016). State of forests and forestry in the United States. USDA, Forest Service. Retrieved 3/21/2021. 
Vose, J.M., et al. (2018). Ch. 6: Forests. In: Impacts, risks, and adaptation in the United States: Fourth national climate assessment, volume II. U.S. Global Change Research Program, Washington, DC, p. 243.  
Butler-Leopold, P.R., et al. (2018). Mid-Atlantic forest ecosystem vulnerability assessment and synthesis: A report from the Mid-Atlantic Climate Change Response Framework project. USDA, Forest Service, Newtown Square, PA, pp. 142–143. 
Vose, J.M., et al. (2018). Ch. 6: Forests. In: Impacts, risks, and adaptation in the United States: Fourth national climate assessment, volume II. U.S. Global Change Research Program, Washington, DC, p. 251.
Hines, S., and A. Daniels. (N.D.). Private forestland stewardship. USDA, Forest Service. Retrieved 3/21/2022. 
Vose, J.M., et al. (2018). Ch. 6: Forests. In: Impacts, risks, and adaptation in the United States: Fourth national climate assessment, volume II. U.S. Global Change Research Program, Washington, DC, p. 234.  
Vose, J.M., et al. (2018). Ch. 6: Forests. In: Impacts, risks, and adaptation in the United States: Fourth national climate assessment, volume II. U.S. Global Change Research Program, Washington, DC, p. 240.  
Butler-Leopold, P.R., et al. (2018). Mid-Atlantic forest ecosystem vulnerability assessment and synthesis: A report from the Mid-Atlantic Climate Change Response Framework project. USDA, Forest Service, Newtown Square, PA, p. 137. 
10 Vose, J.M., et al. (2018). Ch. 6: Forests. In: Impacts, risks, and adaptation in the United States: Fourth national climate assessment, volume II. U.S. Global Change Research Program, Washington, DC, p. 243.  
11 Butler-Leopold, P.R., et al. (2018). Mid-Atlantic forest ecosystem vulnerability assessment and synthesis: A report from the Mid-Atlantic Climate Change Response Framework project. USDA, Forest Service, Newtown Square, PA, p. 135. 
12 Butler-Leopold, P.R., et al. (2018). Mid-Atlantic forest ecosystem vulnerability assessment and synthesis: A report from the Mid-Atlantic Climate Change Response Framework project. USDA, Forest Service, Newtown Square, PA, p. 129.
13 USDA, U.S. Forest Service. (2019). Bark beetles. Retrieved 10/30/2022.
14 Vose, J.M., et al. (2018). Ch. 6: Forests. In: Impacts, risks, and adaptation in the United States: Fourth national climate assessment, volume II. U.S. Global Change Research Program, Washington, DC, p. 234.  
15 Butler-Leopold, P.R., et al. (2018). Mid-Atlantic forest ecosystem vulnerability assessment and synthesis: A report from the Mid-Atlantic Climate Change Response Framework project. USDA, Forest Service, Newtown Square, PA, p. 148.
16 Vose, J.M., et al. (2018). Ch. 6: Forests. In: Impacts, risks, and adaptation in the United States: Fourth national climate assessment, volume II. U.S. Global Change Research Program, Washington, DC, p. 244.  
17 Vose, J.M., et al. (2018). Ch. 6: Forests. In: Impacts, risks, and adaptation in the United States: Fourth national climate assessment, volume II. U.S. Global Change Research Program, Washington, DC, p. 244.  
18 Vose, J.M., et al. (2018). Ch. 6: Forests. In: Impacts, risks, and adaptation in the United States: Fourth national climate assessment, volume II. U.S. Global Change Research Program, Washington, DC, p. 244.  
19 Vose, J.M., et al. (2018). Ch. 6: Forests. In: Impacts, risks, and adaptation in the United States: Fourth national climate assessment, volume II. U.S. Global Change Research Program, Washington, DC, p. 244.  
20 Vose, J.M., et al. (2018). Ch. 6: Forests. In: Impacts, risks, and adaptation in the United States: Fourth national climate assessment, volume II. U.S. Global Change Research Program, Washington, DC, p. 246.  
21 Vose, J.M., et al. (2018). Ch. 6: Forests. In: Impacts, risks, and adaptation in the United States: Fourth national climate assessment, volume II. U.S. Global Change Research Program, Washington, DC, p. 246.  
22 EPA. (2021). Climate change indicators: Streamflow. Retrieved 3/21/2022. 
23 Vose, J.M., et al. (2018). Ch. 6: Forests. In: Impacts, risks, and adaptation in the United States: Fourth national climate assessment, volume II. U.S. Global Change Research Program, Washington, DC, p. 253.  
24 USDA, Forest Service. (N.D.). Forest products. Retrieved 3/21/2021. 
25 USDA, Forest Service. (N.D.). Energy & forest products. Retrieved 3/21/2022. 
26 USDA, Forest Service. (N.D.). Forest products. Retrieved 3/21/2021. 
27 U.S. Environmental Protection Agency (EPA). (2021). Recreation economy for rural communities. Retrieved 3/21/2022. 
28  Vose, J.M., et al. (2018). Ch. 6: Forests. In: Impacts, risks, and adaptation in the United States: Fourth national climate assessment, volume II. U.S. Global Change Research Program, Washington, DC, p. 247. 
29 Gamble, J.L., et al. (2016). Ch. 9: Populations of concern. In: The impacts of climate change on human health in the United States: A scientific assessment. U.S. Global Change Research Program, Washington, DC, p. 254. 
30 Keener, V., et al. (2018). Ch. 27: Hawai’i and U.S.-Affiliated Pacific Islands. In: Impacts, risks, and adaptation in the United States: Fourth national climate assessment, volume II. U.S. Global Change Research Program, Washington, DC, p. 1269. 
31 Vose, J.M., et al. (2018). Ch. 6: Forests. In: Impacts, risks, and adaptation in the United States: Fourth national climate assessment, volume II. U.S. Global Change Research Program, Washington, DC, p. 246.  
32 EPA. (2021). Recreation economy for rural communities. Retrieved 3/21/2021. 
33 USDA, Forest Service. (N.D.). Urban forests. Retrieved 3/21/2021.
34 Janowiak, M.K., et al. (2021). Climate adaptation actions for urban forests and human health. USDA, Forest Service, Madison, WI, p. 2. 
35 EPA. (2022). Heat islands and equity. Retrieved 3/21/2022. 
36 EPA. (2022). Heat islands and equity. Retrieved 3/21/2022. 
37 Vose, J.M., et al. (2018). Ch. 6: Forests. In: Impacts, risks, and adaptation in the United States: Fourth national climate assessment, volume II. U.S. Global Change Research Program, Washington, DC, p. 248.  
38 Vose, J.M., et al. (2018). Ch. 6: Forests. In: Impacts, risks, and adaptation in the United States: Fourth national climate assessment, volume II. U.S. Global Change Research Program, Washington, DC, p. 243.  
39 Smee, D.L., et al. (2017). Mangrove expansion into salt marshes alters associated faunal communities. In: Estuarine, Coastal and Shelf Science. USDA, Southern Research Station. p. 306. 
40 USDA, Forest Service. (N.D.). Mohawk Trail Woodlands Partnership. Retrieved 3/21/2022. 
41 National Centers for Environmental Information. (2020). Wildfires—annual 2020. Retrieved 3/21/2021. 
42 EPA. (2021). Climate change indicators: Wildfires. Retrieved 3/21/2022. 
43 USDA, Forest Service. (2014). Bark beetles and climate change in the United States. Retrieved 3/21/2022. 
44 Vose, J.M., et al. (2018). Ch. 6: Forests. In: Impacts, risks, and adaptation in the United States: Fourth national climate assessment, volume II. U.S. Global Change Research Program, Washington, DC, p. 251.  
45 USDA, Forest Service. (2021). Forest disturbances and drought. Retrieved 3/21/2022. 
46 Jenkins, M. (2017). A new way to stop invasive pests—clean recreation. USDA, Forest Service. Retrieved 3/21/2022. 
47 USDA, National Invasive Species Information Center. (N.D.). Climate change. Retrieved 10/30/2022. 


Everglades Forever Act (EFA) – Florida Department of Environmental Protection

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The Office of Ecosystem Projects is the lead office responsible for implementation of the following Florida Department of Environmental Protection’s (DEP) responsibilities under the Everglades Forever Act (EFA) pursuant to Chapter 373.4592 of the Florida Statutes:
The Everglades Forever Act was passed in 1994. The long-term water quality objective for the Everglades is to implement the optimal combination of source controls, stormwater treatment areas, advanced treatment technologies and regulatory programs to ensure that all waters discharged to the Everglades Protection Area achieve water quality standards consistent with the EFA.
The Restoration Planning and Permitting Section of the Bureau of Assessment and Restoration Support is responsible for coordinating with DEP staff, state and federal agencies, industry representatives and other groups on permitting activities required under the EFA.
The Everglades Forever Act requires the state of Florida to:
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The Florida Department of Environmental Protection is the state’s lead agency for environmental management and stewardship – protecting our air, water and land. The vision of the Florida Department of Environmental Protection is to create strong community partnerships, safeguard Florida’s natural resources and enhance its ecosystems.
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Climate change mitigation: reducing emissions – European Environment Agency

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Our climate is changing because of greenhouse gases released into the atmosphere. Despite notable emission reductions over the last decades, the EU must transform production and consumption systems to achieve climate neutrality by 2050.
Mitigating climate change means reducing the flow of heat-trapping greenhouse gases into the atmosphere. This involves cutting greenhouse gases from main sources such as power plants, factories, cars, and farms. Forests, oceans, and soil also absorb and store these gases, and are an important part of the solution. Reducing and avoiding our emissions requires us to reshape everything we do — from how we power our economy and grow our food, to how we travel and live, and the products we consume. It is a problem felt locally and globally
In the past decades, the EU took firm action against climate change, resulting in a more than 31% drop in EU emissions in 2022 compared with 1990 levels. This is mainly a result of a growing use of renewable energy and decreased use of carbon-intensive fossil fuels. Improvements in energy efficiency and structural changes in the economy also contributed to meeting these goals.
Now, more ambitious goals are set that include a net 55% or greater reduction below 1990 levels by 2030 and a climate-neutrality objective by 2050. Reaching these goals will require even higher emission cuts through transitioning from fossil fuels to clean, renewable energy. It also means halting deforestation, using land sustainably and restoring nature until we reach the point where the release of greenhouse gases into the atmosphere is balanced with the capture and storage of these gases in our forests, oceans and soil.
The EU emits 6% of global emissions and cannot act alone. Global cooperation is essential for all climate change mitigation. The United Nations Framework Convention on Climate Change (UNFCCC) and the Paris Agreement ensure cooperation across borders to tackle climate change and ensure a sustainable future.
EU Member States have put in place 3,000 policies and measures to prevent the worst impacts of climate change. National climate change mitigation strategies, policies and other accompanying measures are also in development. These include targets for greenhouse gas emissions in key sectors of the economy, promoting the use of renewable energy and low carbon fuels, energy efficiency improvements in buildings, and many more.
They project that measures already in place across Europe would lead to a reduction of 43% in 2030 for total net greenhouse gas emissions including international aviation, while further measures that are currently being planned would boost reductions to 48%. 
Achievements in emission reductions vary across sectors too. Most EU sectors reduced greenhouse gas emissions over the past three decades, with the highest reductions in the energy supply sector. Still, agriculture and transport struggle to reduce emissions:
The EU also achieved its target for renewable energy. By 2022, 22.5% of our energy consumed came from renewable sources, and 40% was energy production. For energy efficiency, the EU-27 overachieved the target in its final year, after an initial slow start.
The European Green Deal sets the overall roadmap for achieving EU climate neutrality by 2050 by tackling the threat of climate change while also growing economically and protecting people’s well-being. With the European Climate Law, the EU made climate neutrality by 2050 a legally binding goal, set an interim target of a net 55% emission reduction by 2030 and is working on setting the 2040 target. The Fit for 55 proposal aims to bring EU legislation in line with the 2030 goal.
The impacts of the 2022 gas and energy security crisis highlighted the importance of transitioning faster towards a clean and secure EU energy system.
Under the wider umbrella of the European Green Deal, Europe's 2030 policy ambitions include:
To accelerate this transition, Europe must ensure that investments and finance support sustainability. Energy and mobility sectors especially must distance themselves from unsustainable technologies.

of global emissions
are released by the EU: 4th largest emitter
reduction in EU emissions achieved
in 2022 compared to 1990 levels
is the EU reduction target by 2030
compared to 1990 levels
Greenhouse gas emissions dropped by 2% in 2022 across the European Union, compared to 2021 levels according to estimates our latest ‘Trends and Projections’ report. However, despite gains made in emissions reductions, renewable energy and energy efficiency, the report cautions that accelerated action is urgently needed to meet the EU’s ambitious climate and energy targets. 
The EU has reduced net greenhouse gas emissions including international aviation, by 31% compared to 1990 levels, while simultaneously fostering economic growth. Against the backdrop of soaring natural gas prices, 2022 witnessed a 2% reduction in greenhouse gas emissions, driven by substantial decreases in the buildings and industrial sectors, while emissions from energy supply and transport saw an increase. 
While emissions of methane across the European Union have decreased over past years, the overall reduction in emissions needs to accelerate to meet 2030 and 2050 EU climate objectives. Increased global efforts to reduce methane emissions would also be needed to mitigate global warming in the short term.
According to the latest available official data, emissions of methane were down by 36% in the EU in 2020 compared with 1990 levels. The largest reductions in emissions occurred in energy supply, which includes energy industries and fugitive (leaked or uncaptured) emissions (-65%), waste (-37%) and agriculture (-21%).
A robust reporting system is required to monitor progress toward EU climate change mitigation targets. The EEA is a key player in setting up these reporting systems, providing guidance to Member States on how to report and quality check the input. The EEA collects and provides access to the following types of data:
Much of the data comes from datasets collected by the EEA. This data is then used to fulfil the EU's own targets and to allow the European Commission to assess whether the Union is on track to meet its international pledges made in the United Nations setting.

In simple terms, photosynthesis is the process through which trees and plants capture carbon from the atmosphere and release oxygen. This natural process happens to be one of our best allies and the most efficient technology to reduce the amount of carbon in the atmosphere. With the Copernicus Land Monitoring Service, we get detailed information on what grows on the ground.
Knowing where vegetated areas are and what type of vegetation is growing there is crucial for calculating net greenhouse gas emissions. The CLMS has a suite of vegetation-related data products—such as the High-Resolution Vegetation Productivity Parameters and its trio of high resolution forest monitoring products—that provide information on living land cover and land use across Europe. This data can assist local, regional, and national governments in achieving their Nationally Determined Contributions.


Submitting an ERP – Florida Department of Environmental Protection (.gov)

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Environmental Resource Program (ERP) Permits are processed through the DEP district offices, water management districts and delegated local governments.  Some activities are exempt. Please contact a local office for information on permit requirements for your specific project or location. If you want to submit by paper mail, please send the forms to the local DEP district office. If you are mailing large files, please include a CD with an electronic copy of the application
Statewide ERP allows users to submit any type of ERP verification of exemption or permit online. Users can upload supporting documents and pay processing fees online. Options also include submitting payment after and follow up information after the initial application has been submitted online. The applications are submitted through the department’s Business Portal. There is a $100 discount to apply using the DEP business portal for an individual/conceptual permit. Please note, the $100 discount for individual/conceptual permit applications does not apply if you do not submit your application through the DEP Business Portal. If your project is regulated by a delegated local program (Broward or Hillsborough county), please contact your delegated local program.
The self-certification process allows the user to enter information and certify that the project is exempt from requiring a DEP permit. There is no fee for using ESSA self-cert. To apply for a self-certification, exemption, general permit, or individual/conceptual permit online, please use the DEP Business Portal.
ERP Online Help provides helpful information and tools to assist applicants in completing the ERP Joint Application for many activities. The links by subject below will directly link you to the applicable ERP Online Help.
Map Direct 5.0 (DEP’s Web Mapping Tool)

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The Florida Department of Environmental Protection is the state’s lead agency for environmental management and stewardship – protecting our air, water and land. The vision of the Florida Department of Environmental Protection is to create strong community partnerships, safeguard Florida’s natural resources and enhance its ecosystems.
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The Effects of Climate Change – Science@NASA

The effects of human-caused global warming are happening now, are irreversible for people alive today, and will worsen as long as humans add greenhouse gases to the atmosphere.
Global climate change is not a future problem. Changes to Earth’s climate driven by increased human emissions of heat-trapping greenhouse gases are already having widespread effects on the environment: glaciers and ice sheets are shrinking, river and lake ice is breaking up earlier, plant and animal geographic ranges are shifting, and plants and trees are blooming sooner.
Effects that scientists had long predicted would result from global climate change are now occurring, such as sea ice loss, accelerated sea level rise, and longer, more intense heat waves.
Intergovernmental Panel on Climate Change

Some changes (such as droughts, wildfires, and extreme rainfall) are happening faster than scientists previously assessed. In fact, according to the Intergovernmental Panel on Climate Change (IPCC) — the United Nations body established to assess the science related to climate change — modern humans have never before seen the observed changes in our global climate, and some of these changes are irreversible over the next hundreds to thousands of years.
Scientists have high confidence that global temperatures will continue to rise for many decades, mainly due to greenhouse gases produced by human activities.
The IPCC’s Sixth Assessment report, published in 2021, found that human emissions of heat-trapping gases have already warmed the climate by nearly 2 degrees Fahrenheit (1.1 degrees Celsius) since 1850-1900.1 The global average temperature is expected to reach or exceed 1.5 degrees C (about 3 degrees F) within the next few decades. These changes will affect all regions of Earth.
The severity of effects caused by climate change will depend on the path of future human activities. More greenhouse gas emissions will lead to more climate extremes and widespread damaging effects across our planet. However, those future effects depend on the total amount of carbon dioxide we emit. So, if we can reduce emissions, we may avoid some of the worst effects.
Intergovernmental Panel on Climate Change

Here are some of the expected effects of global climate change on the United States, according to the Third and Fourth National Climate Assessment Reports:
Global sea level has risen about 8 inches (0.2 meters) since reliable record-keeping began in 1880. By 2100, scientists project that it will rise at least another foot (0.3 meters), but possibly as high as 6.6 feet (2 meters) in a high-emissions scenario. Sea level is rising because of added water from melting land ice and the expansion of seawater as it warms.

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Global climate is projected to continue warming over this century and beyond.

Image credit: Khagani Hasanov, Creative Commons Attribution-Share Alike 3.0
Scientists project that hurricane-associated storm intensity and rainfall rates will increase as the climate continues to warm.

Image credit: NASA
Droughts in the Southwest and heat waves (periods of abnormally hot weather lasting days to weeks) are projected to become more intense, and cold waves less intense and less frequent.

Image credit: NOAA
Warming temperatures have extended and intensified wildfire season in the West, where long-term drought in the region has heightened the risk of fires. Scientists estimate that human-caused climate change has already doubled the area of forest burned in recent decades. By around 2050, the amount of land consumed by wildfires in Western states is projected to further increase by two to six times. Even in traditionally rainy regions like the Southeast, wildfires are projected to increase by about 30%.
Climate change is having an uneven effect on precipitation (rain and snow) in the United States, with some locations experiencing increased precipitation and flooding, while others suffer from drought. On average, more winter and spring precipitation is projected for the northern United States, and less for the Southwest, over this century.

Image credit: Marvin Nauman/FEMA
The length of the frost-free season, and the corresponding growing season, has been increasing since the 1980s, with the largest increases occurring in the western United States. Across the United States, the growing season is projected to continue to lengthen, which will affect ecosystems and agriculture.
Summer of 2023 was Earth’s hottest summer on record, 0.41 degrees Fahrenheit (F) (0.23 degrees Celsius (C)) warmer than any other summer in NASA’s record and 2.1 degrees F (1.2 C) warmer than the average summer between 1951 and 1980.

Image credit: NASA
Sea ice cover in the Arctic Ocean is expected to continue decreasing, and the Arctic Ocean will very likely become essentially ice-free in late summer if current projections hold. This change is expected to occur before mid-century.
Climate change is bringing different types of challenges to each region of the country. Some of the current and future impacts are summarized below. These findings are from the Third3 and Fourth4 National Climate Assessment Reports, released by the U.S. Global Change Research Program.
1. IPCC 2021, Climate Change 2021: The Physical Science Basis, the Working Group I contribution to the Sixth Assessment Report, Cambridge University Press, Cambridge, UK.
2. IPCC, 2013: Summary for Policymakers. In: Climate Change 2013: The Physical Science Basis. Contribution of Working Group I to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change [Stocker, T.F., D. Qin, G.-K. Plattner, M. Tignor, S.K. Allen, J. Boschung, A. Nauels, Y. Xia, V. Bex and P.M. Midgley (eds.)]. Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA.
3. USGCRP 2014, Third Climate Assessment.
4. USGCRP 2017, Fourth Climate Assessment.
So, the Earth’s average temperature has increased about 2 degrees Fahrenheit during the 20th century. What’s the big deal?
“Global warming” refers to the long-term warming of the planet. “Climate change” encompasses global warming, but refers to the broader range of changes that are happening to our planet, including rising sea levels; shrinking mountain glaciers; accelerating ice melt in Greenland, Antarctica and the Arctic; and shifts in flower/plant blooming times.
Humans have caused major climate changes to happen already, and we have set in motion more changes still. However, if we stopped emitting greenhouse gases today, the rise in global temperatures would begin to flatten within a few years. Temperatures would then plateau but remain well-elevated for many, many centuries.
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Recycling Basics and Benefits | US EPA – U.S.

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Recycling is the process of collecting and processing materials that would otherwise be thrown away as trash and turning them into new products. Recycling can benefit your community, the economy, and the environment. Products should only be recycled if they cannot be reduced or reused. EPA promotes the waste management hierarchy, which ranks various waste management strategies from most to least environmentally preferred. The hierarchy prioritizes source reduction and the reuse of waste materials over recycling.
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Recycling provides many benefits to our environment. By recycling our materials, we create a healthier planet for ourselves and future generations. 
Conserve natural resources: Recycling reduces the need to extract resources such as timber, water, and minerals for new products.
Climate change: According to the most recent EPA data, the recycling and composting of municipal solid waste (MSW or trash) saved over 193 million metric tons of carbon dioxide equivalent in 2018. 
Energy savings: Recycling conserves energy. For example, recycling just 10 plastic bottles saves enough energy to power a laptop for more than 25 hours. To estimate how much energy you can save by recycling certain products, EPA developed the individual Waste Reduction Model (iWARM). 
Waste and pollution reduction: Recycling diverts waste away from landfills and incinerators, which reduces the harmful effects of pollution and emissions. 
EPA released significant findings on the economic benefits of the recycling industry with an update to the national Recycling Economic Information (REI) Study in 2020. This study analyzes the numbers of jobs, wages and tax revenues attributed to recycling. The study found that in a single year, recycling and reuse activities in the United States accounted for:
This equates to 1.17 jobs per 1,000 tons of materials recycled and $65.23 in wages and $9.42 in tax revenue for every ton of materials recycled. For more information, check out the full report.
Environmental Justice: Across the country, waste management facilities are concentrated in underserved communities, and they can have negative impacts on human health, property values, aesthetic and recreation values, and land productivity. Recycling provides these areas with a healthier and more sustainable alternative.
International: Waste generated in the United States also affects communities in other countries. Recycled materials are exported to some countries that are not able to manage those materials in an environmentally sound manner.  
The recycling process is made up of three steps that are repeated over and over again. This creates a continuous loop which is represented by the familiar chasing arrows recycling symbol. The three steps of the recycling process are described below.  
Businesses and consumers generate recyclables that are then collected by either a private hauler or government entity. There are several methods for collecting recyclables, including curbside collection, drop-off centers, and deposit or refund programs. Visit How do I recycle… Common Recyclables for information on specific materials. 
After collection, recyclables are sent to a recovery facility to be sorted, cleaned, and processed into materials that can be used in manufacturing. Recyclables are bought and sold just like raw materials would be, and prices go up and down depending on supply and demand in the United States and around the world.
After processing, recyclables are made into new products at a recycling plant or similar facility. More and more of today’s products are being manufactured with recycled content.
Recycled materials are also used in new ways such as recovered glass in asphalt to pave roads or recovered plastic in carpeting and park benches.
You help close the recycling loop by buying new products made from recycled materials. There are thousands of products that contain recycled content. When you go shopping, look for the following:
Below are some of the terms used:
Some common products you can find that are made with recycled content include the following:
While the benefits of recycling are clear, the current system still faces many challenges. 
The Bipartisan Infrastructure Law: Transforming U.S. Recycling and Waste Management: The Bipartisan Infrastructure Law is a historic investment in the health, equity, and resilience of American communities. With unprecedented funding to support state and local waste management infrastructure and recycling programs, EPA will improve health and safety and help establish and increase recycling programs nationwide. 
National Recycling Strategy: EPA developed the National Recycling Strategy with a focus on advancing the national municipal solid waste recycling system. It identifies strategic objectives and actions to create a stronger, more resilient, and cost-effective recycling system.  
Draft Strategy to Prevent Plastics Pollution: This strategy builds upon EPA’s National Recycling Strategy and focuses on actions to reduce, reuse, collect, and capture plastic waste.
America Recycles Day: Every year on November 15, EPA reminds everyone of the importance and impact of recycling through education and outreach.
Basel Convention: The United States is a signatory to the Basel Convention, but has not yet become a Party to the Convention. The Basel Convention establishes standards for the transboundary movement of various types of waste. 


OR&R Receives Marine Environmental Protection Award from the North American Marine Environment Protection … – NOAA Office of Response and Restoration

NOV. 15, 2023 — On November 2, 2023, NOAA’s OR&R Director Scott Lundgren joined maritime and environmental protection colleagues at State University of New York (SUNY) Maritime College at Fort Schuyler for the North American Marine Environmental Protection Association (NAMEPA) conference and Marine Environmental Protection awards dinner.
On behalf of the work of OR&R, Director Lundgren received NAMEPA’s Government Award. This Marine Environmental Protection award recognized OR&R’s comprehensive program of work within the award criteria, including specific objectives set for environmental performance and improvement; a program of work that is innovative and goes beyond minimum compliance; the impact of the program efforts is long-term and substantial; efforts are aligned with NAMEPA goals; the work provides educational and environmental benefits; and, it has measurable successes in improving protection of the marine environment.
NAMEPA is a marine industry-led organization of environmental stewards preserving the marine environment by promoting sustainable marine industry best practices and educating seafarers, students, and the public about the need and strategies for protecting global ocean, lake, and river resources.
In announcing the award, NAMEPA stated: “NOAA’s Office of Response and Restoration has been proactive in protecting the health of our seas. … Your work and continued efforts were ranked first by our board.”
Participation in the conference and awards program allowed for OR&R to celebrate other Marine Environmental Protection award recipients in other categories, as well as hear informational presentations and panels on current topics in the field including:
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America Recycles Day | US EPA – U.S.

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On America Recycles Day (November 15), EPA recognizes the importance and impact of recycling, which has contributed to American prosperity and the protection of our environment. The recycling rate has increased from less than seven percent in 1960 to the current rate of 32 percent. Help us reach our current National Recycling Goal to increase the U.S. recycling rate to 50 percent by 2030.
The White House and EPA encourage you to celebrate America Recycles Day.
On America Recycles Day, EPA announces the winners of over $90 million in grants for Tribes to expand recycling infrastructure and waste management systems and for recycling education and outreach.
Learn how you can safely recycle used household batteries and lithium ion batteries.
The recycling efforts of communities and business throughout the United States help with this success and growth. To build on our progress, EPA encourages every American to contribute by recycling right, not only on America Recycles Day, but all year long. This means checking with your local recycling provider to know what they will accept in your recycling bin. Items like cardboard, metal cans, and paper are commonly accepted by local curbside programs, and items like plastic bags, electronics and batteries do NOT go in the curbside recycling bin. Visit our How Do I Recycle?: Common Recyclables to learn how and where to recycle these and other items.
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Find out what you can do to make a difference in our environment every day. Whether you’re at home, on the go, in the office or at school, there are many opportunities to go green by reducing, reusing, and recycling. Visit the links below:
Also, check out our Think Green Before You Shop poster for questions you can ask yourself before shopping to reduce, reuse, and recycle more.
In 2016, EPA published significant findings on the economic benefits of the recycling industry with an update to the national Recycling Economic Information REI study. This study analyzes the numbers of jobs, wages, and tax revenues attributed to recycling. The study found that in a single year, recycling and reuse activities in the United States accounted for:
This equates to 1.17 jobs for every 1,000 tons of materials recycled.
The ferrous metals industry provides the largest contribution to all three categories (job, wage, and tax revenue), followed by construction and demolition,  and non-ferrous metals such as aluminum.
How often do you ask yourself what’s right to put in your recycling bin? Next time you go to throw something away, get creative and think of ways to reduce waste in the first place!  There are many ways to improve the recycling rate.  Check out our What You Can Do to Improve the Recycling Rate fact sheet for ideas on how you can improve your recycling. Additionally, check out our poster to the right and our How Do I Recycle?: Common Recyclables webpage to learn how to recycle more and recycle right.
Check out our Frequent Questions on Recycling page for more information on ways you can contribute.
Recycling everyday objects, such as paper, bottles and magazines, saves energy. The materials that you recycle are used to create the products you buy. This means less virgin material needs to be mined or harvested, processed, manufactured, and transported – all of which consumes energy. The iWARM tool is based on EPA’s Waste Reduction Model (WARM) for solid waste planners and organizations. iWARM can be used to calculate how much energy organizations can save and how much greenhouse gases they can avoid by recycling versus landfilling their waste.

Educators: Our Reduce, Reuse, Recycle Resources for Students and Educators webpage has resources and activities for America Recycles Day. 


EPA Administrator | US EPA – U.S.

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Contact Administrator Regan:
(202) 564-4700
Michael S. Regan was sworn in as the 16th Administrator of the United States Environmental Protection Agency on March 11, 2021, becoming the first Black man and second person of color to lead the U.S. EPA.
Administrator Regan is a native of Goldsboro, North Carolina, where he developed a passion for the environment while hunting and fishing with his father and grandfather, and exploring the vast lands, waters, and inner Coastal Plain of North Carolina.
As the son of two public servants – his mother, a nurse for nearly 30 years, and his father, a retired Colonel with the North Carolina National Guard, Vietnam veteran, and former agricultural extension agent – Michael Regan went on to follow in his parents’ footsteps and pursue a life of public service.
Prior to his nomination as EPA Administrator, Michael Regan served as the Secretary of the North Carolina Department of Environmental Quality (DEQ).
As Secretary, he spearheaded the development and implementation of North Carolina’s seminal plan to address climate change and transition the state to a clean energy economy. Under his leadership, he secured the largest coal ash clean-up in United States history. He led complex negotiations regarding the clean-up of the Cape Fear River, which had been contaminated for years by the toxic chemicals per- and polyfluoroalkyl substance (PFAS). In addition, he established North Carolina’s first-of-its-kind Environmental Justice and Equity Advisory board to better align social inequities, environmental protection, and community empowerment.
Previously, Administrator Regan served as Associate Vice President of U.S. Climate and Energy, and as Southeast Regional Director of the Environmental Defense Fund where he convened energy companies, business leaders, environmental and industry groups, and elected officials across the country to achieve pragmatic solutions to the climate crisis.
He began his career with the U.S. Environmental Protection Agency, eventually becoming a national program manager responsible for designing strategic solutions with industry and corporate stakeholders to reduce air pollution, improve energy efficiency and address climate change.
Throughout his career, he has been guided by a belief in forming consensus, fostering an open dialogue rooted in respect for science and the law, and an understanding that environmental protection and economic prosperity go hand in hand.
Administrator Regan is a graduate of the North Carolina Agricultural & Technical State University, making him the first EPA Administrator to have graduated from a Historically Black College and University. He earned a master’s degree in Public Administration from The George Washington University.
He and his wife Melvina are proud parents to their son, Matthew.


EVENT: How is the Environment Protected During Armed Conflict? – ICRC

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How is the Environment Protected During Armed Conflict? (Event Highlights) from ICRC on Vimeo.
In 2021, the UN International Law Commission (ILC) finalized its Principles on the protection of the environment in armed conflict. Two years earlier, the ICRC released its own Guidelines on the Protection of the Natural Environment in Armed Conflict. These two significant legal initiatives are part and parcel to a flurry of interest in the topic. In response to these initiatives and in reaction to this vibrant interest, the International Review of the Red Cross has compiled a special edition on the protection of the environment in armed conflict, featuring more than two dozen articles exploring the topic from a variety of angles. At this event, authors whose work is featured in that edition engaged in a lively conversation, followed by closing remarks by former ILC Special Rapporteur Marja Lehto.
Want to take a deep dive? Find the full event recording here to unpack all the substance from this report launch event!
– International sign language interpretation was provided at this event. –

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S(no)w pain, S(no)w gain: How does El Niño affect snowfall over North America? –

Note: The primary writer of this post is Michelle L’Heureux, but it is inspired by and reviewed by Brian Brettschneider, who is the NWS Climate Service Program manager for the Alaska region.
The last several winters have been depressingly bleak for snow lovers in the Washington, D.C. area, where we at the Climate Prediction Center (CPC) are located. Needless to say, when Brian Brettschneider (@Climatologist49) showed me that the D.C. area historically sees above-average snowfall during El Niño winters, I excitedly dusted off our sleds and ordered new mittens because we’re expecting an El Niño this winter 2023–24. With that said, longtime ENSO blog readers will know that I’m wish-casting a bit and there’s S(no)w guarantee in this business! [And, yes, this blog post will include a painful number of snow puns]. El Niño nudges the odds in favor of certain climate outcomes, but never ensures them. There have been some D.C. area snow droughts during past El Niño winters, and climate change is not our friend. 
Sad children trying to scrape together enough snow to make a snowball in the D.C. area last winter. Even worse, they didn’t get a snow day. Photo credit: Michelle L’Heureux.
My next question to Brian was “What exactly is this snowfall dataset you are using?” As Deke Arndt (NCEI) has noted, collecting historical measurements of snow is a tricky endeavor, fraught with measurement errors, so creating a dataset of sufficient quality for climate studies is hard. But, Brian, who is a clever, outside-the-box thinker, realized that the new ECMWF ERA5 reanalysis dataset may be the ticket (footnote #1). About five years ago, my colleague at CPC, Stephen Baxter, published this wildly popular blog post on snow and La Niña winters. The only problem is the dataset he used stopped updating in 2009. Thus, we’ve been adrift, snow-wise, until Brian pointed us to this new snowfall analysis. So, what does it look like?
Who are the snowfall winners (or losers) during El Niño? As Emily shared with us last month, the jet stream tends to extend eastward and shift southward during El Niño winters. You can think of the jet stream as a river of air, which carries more moisture and precipitation along the southern tier of the United States during El Niño. As a result, it is not surprising to see a stripe of increased snowfall (blue shading) over the southern half of the country. Obviously, snowfall is limited in its southernmost reaches because it needs to be cold enough to snow, so the effects are strongest in the higher and colder elevations of the West. To the north, however, there is a reduction in snowfall (brown shading), especially around the Great Lakes, interior New England, the northern Rockies and Pacific Northwest, extending through far western Canada, and over most of Alaska. In fact, El Niño appears to be the great snowfall suppressor over most of North America. 
Snowfall during all El Niño winters (January-March) compared to the 1991-2020 average (after the long-term trend has been removed). Blue colors show more snow than average; brown shows less snow than average. NOAA map, based on ERA5 data from 1959-2023 analyzed by Michelle L’Heureux.
How about snowfall during moderate-to-strong El Niño events like the one expected in winter 2023-24? In the map below, over many regions, the anomalies become stronger (anomaly = difference from the long-term average), which makes sense because El Niño affects the climate. Stronger El Niño events tend to land a larger punch on our atmosphere, thus increasing the chance of seeing expected El Niño impacts. 
Snowfall during moderate-to-strong El Niño winters (January-March) compared to the 1991-2020 average (after the long-term trend has been removed). Blue colors show more snow than average; brown shows less snow than average. NOAA map, based on ERA5 data from 1959-2023 analyzed by Michelle L’Heureux.
While the maps we’ve shown above may excite or depress you depending on your situation and snow preferences, it is very important to recognize that the map is the showing the average of all winters with El Niño (footnote #2). Relying on the average is a bit dangerous because a few heavy snowfall winters can give the impression that most winters are above average. Which is why it’s important to recognize there can be large variation from winter-to-winter.
Below is a map showing a count of El Niño winters: Here, we ask how many of the 13 moderate-to-strong El Niño winters had below-average snowfall? If it is in red shading, that means most winters had below-average snowfall. The deepest reds mean almost all past winters had below-average snowfall (black indicates no snowfall at all, which makes sense if you’re sitting on a beach in South Florida). If it is in grey shading, that means most moderate-to-strong winters had above-average snowfall.
Number of years with below-average snowfall during the 13 moderate-to-strong El Niño winters (January-March average) since 1959. Red shows locations where more than half the years had below-average snowfall; gray areas below-average snowfall less than half the time. NOAA map, based on ERA5 data from 1959-2023 analyzed by Michelle L’Heureux.
Another major caveat related to these maps is they are just based on snowfall during El Niño, and I have removed long-term trends. There is also a trend in snowfall, and it looks like this over North America during January-March.
Changes in snowfall (in inches per decade) between 1959 and 2023. Across most of the United States—Alaska being the major exception—snowfall has declined (brown colors). NOAA map, based on ERA5 data from 1959-2023 analyzed by Michelle L’Heureux.
Unsurprisingly, because of climate change, over most of the contiguous United States we have trended toward less snowy winters. This doesn’t mean that it never snows, or we cannot get big snowstorms (footnote #3), but that snowfall has gradually trended downward over time. In contrast, wintertime snowfall may have actually increased somewhat over time over the colder northern latitudes of Alaska and parts of Canada (this trend reverses in the spring; see footnote #4). Why would that be the case? Well, if you think about it, the warming of our planet allows the air to hold more moisture. If the atmospheric circulation allows for it, then that moisture can be wrung out of the air and precipitate. Snowfall also depends on the air temperature remaining below the freezing point. At more northern latitudes, despite warming air temperatures, it still remains cold enough in the winter to fall as snow. But there is no such luck in more southern locations which are often closer to the freezing point. There, the tendency toward warmer winters is a snow killer. 
So, will the expected pattern of El Ni-S(ño)W pan out for us this winter? Time will tell, but in the meantime, it is fun to imagine the possibilities.
(1) We have to be careful to not take any one dataset literally, but this ECMWF ERA5 data seems to pass a few sniff tests. Sniff test #1 was “Does ERA5 snowfall reproduce the winter pattern of snowfall made with other datasets?” The answer, at least when comparing with winter 2022-23, is yes. Sniff test #2 was “Does ERA5 snowfall reproduce the historical ENSO pattern that is found within other datasets?” Here again, the answer is yes, we were able to reproduce ENSO composite maps that were made with the Rutgers gridded snow data in this older ENSO blog post. Sniff test #3 was comparing with our old ENSO snowfall composites made from an even older (not quality controlled) station-based dataset that has been discontinued. With that said, ERA5 is a newer dataset, it is “reanalysis,” which means that a very short-range weather model is used to produce snowfall from in situ observations (from the ECMWF website, it outputs the “mass of snow that has fallen to the earth’s surface”). Essentially a reanalysis is predicting what observed snowfall would have looked like based on past observational inputs from satellites, stations, buoys, and other observing systems. Therefore, we recommend you treat some of the finer details with a healthy degree of suspicion and try to corroborate them in other datasets. Hopefully this blog post will motivate the creation of additional snowfall datasets and scientists will explore how well ERA5 compares with these other snowfall measurements.
(2) Brian emphasizes that composites (average historical maps during El Niño) are retrospectives and they are not a forecast. A forecast takes in account conditions beyond just El Niño, such as long-term climate trends, soil moisture, sea ice, and other global boundary forcings.
(3) In fact, because a warmer atmosphere carries more moisture, there is published evidence that extreme snowfall events can intensify as a response to global warming (e.g. O’Gorman, P., 2014: Contrasting responses of mean and extreme snowfall to climate change. Nature512, 416–418).
(4) This pattern of snow trends drastically changes if you look at the shoulder seasons, say April-June, which is warmer even in those northern latitudes. Rebecca took a look at this in this article on spring snow cover in the Northern Hemisphere. In this season, trends are toward less snow cover over Alaska and western Canada. The ERA5 snowfall trends in April-June also reproduce the same features.
There is no statistically significant difference in DCA’s season-total snowfall between +ENSO states.
Submitted by NEWxSFC on Thu, 10/26/2023 – 13:33
So, one thing I would caution folks is to not compare this dataset to point-based “man measuring with a ruler” type measurements.  This is a different quantity (snowfall toward Earth’s surface) and therefore not subjected to influence from pavement, canopy, surface winds, etc. which tend to reduce amounts actually measured at the surface.  Overall the pattern and strength of the relationship is consistent with what we find in other datasets (see footnote #1).  
I should add that the counts map also tends to suggest there is a slight lean among the 13 El Ninos, but it is not strong in the DC area.  It won’t stop me from wishing for more snow this winter though!
Submitted by michelle.lheureux on Thu, 10/26/2023 – 14:20
In reply to by NEWxSFC
THANKS for this article. As a forecaster who spent 4 decades tracking the dreaded rain-snow line along I-95, DC,PHL and NYC your maps show the wide ranges of El Niño conditions, from very quite 4am-shift cross-country ski trip to work down NYC’s 5th Ave, to two-hands-on blown-out umbrellas with raging rain.
While in the West the effect of El Nino’s change in the subtropical storm track steers Pacific moisture further south. In the East the GALE Experiment Design Panel, chaired by my former UW Prof. Peter Hobbs, of the mid-1980s investigated the many factors of East Coast snow storm development. wide range of meteorological and oceanographic phenomena  are numerous, including: 1. cyclogenesis, 2. rainbands, 3. cold fronts, 4. coastal fronts, 5. cold-air damming, 6. jet streaks, 6. tropopause folding, 7. low-level jets, 8. cold-air outbreaks, 9. lightning and 10. Gulf Stream.
It is a 4-dimensional Chinese jig-saw puzzle for sure. 
Submitted by Joe Witte on Fri, 10/27/2023 – 00:33
In reply to by michelle.lheureux
Thank you for sharing this, Joe. As a current and long-time resident of central New Jersey, I’m no stranger to that dreaded rain-snow line whenever a potential major snowstorm is brewing. 
Submitted by Nathaniel.Johnson on Fri, 10/27/2023 – 09:43
In reply to by Joe Witte
What is tropopause folding?  And, what does it have to do with storm formation?
I had never heard about it until I read your comment, so I’m curious.  
Submitted by Matt on Mon, 11/06/2023 – 13:41
In reply to by Joe Witte
It would take an MIT scientist to figure out these maps.  I’ll go back to just looking out the window daily during the winter.
Talk about  making a mountain out of a molehill!
Submitted by elaine m. knapp on Fri, 11/03/2023 – 09:12
In reply to by michelle.lheureux
Speak simply …
Submitted by Maureen on Sat, 11/11/2023 – 14:41
In reply to by elaine m. knapp
Lol it’s not that hard.
Submitted by Edward on Sat, 11/11/2023 – 17:55
In reply to by elaine m. knapp
Interesting and amusing post. Thanks!
But I’d add that the color scheme or the key seem to have a difficulty. Much of the maps look white, but no white appears on the key. (As reproduced on my screen anyhow.)
That is most obvious on the number of years graph, where I’ll guess white might be 7 years??
Submitted by Paul on Sat, 11/25/2023 – 08:36
In reply to by Edward
The number of years map does have some pale shades in the middle–6 years is a very pale gray, with 7 years a pale pink. It’s hard to see on my monitor, too!
Submitted by emily.becker on Mon, 11/27/2023 – 13:39
In reply to by Paul
Meteorologists are great at making mountains out of molehills!  I would be willing to bet that not even an MIT Scientist could figure out the weather. “A meteorologist is the only job you can be wrong 99.99% of the time and still keep your job!” As they keep repeating in their article it’s allll “PREDICTIONS”! I agree with you, the only 100% percent accurate forecast is day to day looking out the window or stepping outside to see if it’s cold or hot. 
Submitted by Douglas McTasney on Sun, 11/19/2023 – 06:08
In reply to by elaine m. knapp
Nov 4 Fr Minnesota 
We read all the data and warm weather charts
El Niño winter means nothing here. There is no such effect. 
We always have  the cold northern winds from the Canadian prairies and effects fr arctic and north territories and being a cold weather state is a barrier to any El Niño.
Submitted by Stacy Jenkins on Sat, 11/04/2023 – 17:26
In reply to by NEWxSFC
Article is about snowfall…not temps.
Submitted by Chris on Fri, 11/24/2023 – 16:51
In reply to by Stacy Jenkins
What are the odds of a sudden stratospheric warming event during an El Niño winter?  It seems like one of those happening would increase the odds of measurable snowfall across most of the U.S. (depending, of course, on when it happened).
Submitted by Matt on Sun, 10/29/2023 – 19:47
Good question!  I’ll quote Amy Butler’s ENSO blog post on this very subject: 
El Niño, with its modified planetary waves, tends to promote the breakdown of the polar vortex, especially in late winter, which in turn modifies the atmospheric circulation pattern associated with the El Niño.
All the details here:ño-and-stratospheric-polar-vortex
Submitted by michelle.lheureux on Mon, 10/30/2023 – 08:47
In reply to by Matt
I just read the post that you included a link to.  It was interesting, and it helped to answer my question.  Thanks for posting it.
Submitted by Matt on Wed, 11/01/2023 – 19:30
In reply to by michelle.lheureux
Great post, thanks! I thought it was really interesting to see the map showing the number of moderate-strong El Nino winters that had below normal snowfall. It gives some nice context for the snowfall departure map. I love the maps, by the way. Nicely done.
Submitted by Roger Martin on Wed, 11/01/2023 – 19:27
Where can I get similar information on European weather this coming winter? 
Submitted by Susan m on Fri, 11/03/2023 – 09:13
The data used in this post is from the European Centre for Medium-Range Weather Forecasts.  They have a climate page here that is useful, but I’m not sure if they have snowfall readily available:
Submitted by michelle.lheureux on Fri, 11/03/2023 – 12:49
In reply to by Susan m
Whether the weather be good or whether the weather be bad. We’ll weather the weather, whatever the weather, whether we like it or not! Listen! I’m tired of you guys just making stuff up. Your control of the weather is poor and your predictions are worse. Please improve your performance! 
Submitted by JE Martinez on Fri, 11/03/2023 – 14:51
1. I don’t think they can really control the weather; if they could, I suspect that they would prevent land falling hurricanes, droughts, heat waves, cold waves, human-caused global warming, and billion dollar disasters, among other nasty and unpleasant events. (As well, if they could control it, I would bet that they would ensure crappy weather in Washington, DC, when budget negotiations were going on, so as to ensure that they got more money.) 
2. Their forecasting has gotten better since the early 1990s (when I started watching the Weather Channel every day); while their forecasts were generally good for no more than 3 to 4 days back then (the 5th day forecast was fairly correct maybe 50 to 60% of the time), the National Weather Service can now make accurate forecasts for a week in advance–and the forecast for day 7 seems to be fairly correct more often than not.  And, my father has told me that, in the 1950s, weather forecasts were only made for the next day or two, and that they really could not make accurate predictions beyond that.  So, their forecasts have been getting better over the years, and are continuing to improve.
3. As I have learned, there are a lot of elements that go into predicting what the weather for the next 3 months will be like.  El Niño is one factor (and it is an important one), but there are a lot of other ones as well, plus there are some things that cannot be predicted more than a few days or weeks in advance (such as sudden stratospheric warming events during the winter). 
On top of that, as I have noticed, they merely talk about probabilities rather than certainties when dealing with forecasts over the next few months.  As an example, the forecast for the Southern Plains (where I live) for this winter calls for a greater probability of above normal precipitation and average temperatures, though it says absolutely nothing about the odds of things like cold snaps or warm spells.  The weather here this winter may or may not turn out like that; it just means that the odds are that it will be that way.  So, I bear it in mind while understanding that it might be at least somewhat wrong, and that we will have both warm and cold days this winter.
I agree that it would be nice if they could make better long-term predictions.  However, I am sure that they will improve in the future, as they get more and better instruments for collecting weather data (such as more ocean buoys, weather balloons in more places, more weather stations on land, better satellites, etc.), and as they learn more about different weather phenomena, such as ENSO, sudden stratospheric warming events, the Arctic oscillation, atmospheric gravity waves, and the like.  In the meantime, they seem to be doing a pretty good job; more importantly, they seem like they are trying to get even better.
Submitted by Matt on Sat, 11/04/2023 – 02:09
In reply to by JE Martinez
Beautifully put. Thanks!
Submitted by michelle.lheureux on Sat, 11/04/2023 – 16:58
In reply to by Matt
Loved your comment!  LOL!
Submitted by Steve TGAP on Sat, 11/18/2023 – 16:57
In reply to by JE Martinez
Should post some easier to understand maps that are a little less confusing. Instead of -10 to 10, ranging for different time periods and abating that snow will be less likely there’s no clear direction here.  None of these maps indicate any forecast this just proves to be complicated to read and not really showing any real forecast here. 
Submitted by Winter love ❄️ on Fri, 11/03/2023 – 22:33
Rather than absolute inch difference, it could have been more informative to see percentage increase and decrease. In areas that get a lot of snow, you are going to see more variance in the absolute inch change, and the opposite in areas that get less snow. In an area that gets 3 inches of snow average, a difference of +3 inches means double the snow.
Submitted by Let it Snow on Sat, 11/04/2023 – 09:53
I completely agree, but my significant other (non-scientist) still understands snow in inches more than in percentages.  But we’ll keep this in mind in the future!  
Submitted by michelle.lheureux on Sat, 11/04/2023 – 16:57
In reply to by Let it Snow
Weather is controlled by humans. They create hurricane,  flooding,  earthquakes,  droughts,  snow storms and anything else to push the climate change agenda. Fires , flooding, hurricane, tornadoes, train derailment, earthquake whatever it takes to take your land home and ownership of anything away. We will be put in smart cities. Have no cars, no privacy and no freedom if the people do not wake up and realize everything is a lie to control the masses! I beg my fellow people around the world to consider everything we are told and shown is all just a big lie. 
Submitted by Michael Gordon on Sat, 11/04/2023 – 17:24
…is screwed in a little too tight.
Submitted by Captain Coocoo on Sat, 11/25/2023 – 01:21
In reply to by Michael Gordon
You people are still the best at what you do. I will keep in touch weekly as you are MOST INTERESTING on the subjects that control or nearly control the weather. SNOW, storms, winter rain events all effect my health as I am approaching EIGHTY, El NINO, the JET STREAM and your moving maps keep me occupied. THANK YOU…Margaret O’Brien HOBOKEN NEW JERSEY USA
Submitted by Anonymous on Mon, 11/06/2023 – 02:37
MINOR HEAT WAVES have an impact also from the BACK OF THE SUN
How does this interfere with EL NINO this year?????
Submitted by MARGARET OBRIEN on Mon, 11/06/2023 – 03:17
I am sad to see this analysis after last year’s very disappointing winter which was still a moderate La Niña. Now we are looking at a moderate to strong El Niño and it may be an even less snowy winter (if possible after Central Park recorded their latest measurable snowfall on record). Of course, one big storm can make all the difference (much like one hurricane can make a season a bad one even if the recent of it is quiet) so it remains to see what this year brings. Still, it’s rather impressive when 10-13 of 13 El Niños have had less snow from interior New England into the Midwest 
Submitted by Daniel Linek on Tue, 11/07/2023 – 14:19
Interesting to contrast this with the Farmers Almanac prediction. I recently moved to NE Ohio from the Pacific NW. Sometimes decisions are made based on the odds, and to me the data further supports my recent transition into ice skating.  Time to sell the skis and invest in a better pair of skates.
Submitted by Mica on Sun, 11/19/2023 – 09:31
In reply to by Daniel Linek
This is a most informative article.  Yet may I invite the nay-sayers to come to Oklahoma.  Just wait 15 minutes and the weather will change.  The home of Thunder Snow (preceded by lightening of course).  We do have some very diverse weather here.  Most people are amateur meteorologists by age 15.  Understanding the dynamics of weather cycles is quite fascinating.
Submitted by Darrell Chesnut on Tue, 11/07/2023 – 21:33
NOAA, you do great work in predicting the weather.  You have a lot of variables to consider. Remember the old saying: no such thing as bad weather —-only different kinds of good weather.  I don’t like ice on the roads
Submitted by Ken woods on Sat, 11/11/2023 – 11:49
Even politicians could learn something about double talk from weather forcasters. Most people dont want to know How or Why—-we just want to know ” Is it going to snow more this winter-period” The answer always to be the same—-“Maybe”
Submitted by steve on Sat, 11/11/2023 – 13:11
So is it going to snow in the southern United States or what?
Submitted by Stacey on Sat, 11/11/2023 – 14:48
Seriously? Because of climate change we’re gonna have less snowy winters? Guess who’s changing the climate? And it isn’t man. Good grief.
Submitted by JD on Sat, 11/11/2023 – 20:55
Dear Michelle and Rebecca and everyone 
Thank you so much for the very informative article . Is there a re-analysis database that allows multi-year re-analysis of snowfall or water equivalence of snowfall that permits multi-year re-analysis simultaneously for the rest of the world other than the USA, Like southern Europe and the Mediterranean region . For example I used your below valuable service at to reconstruct flood risks using the multi-year list which exceeded 30 analogous months and it worked well but snow water equivalence of snow is not active for re-analysis under any of ( ERA5, ERA5-interim, JRA5, MERRA..) .
I am simply looking for any database that permits snowfall re-analysis if you kindly have an advice . 
To explain my methods employed : The list of analogous approximate years/months ( n=35) were suggested by an ANN and cluster analysis as possible analogs for 2023-2024 autumn-winter that I have conducted personally , this list was yielded using multivariable analogous years analyses utilizing Long time-series metric values of  ( MEI and ON1 ENSO, QBO, MJO, PDO, AMO, AO, NAO, EA-WR , MOi and WeMOi oscillation, LOD, IOD, SST nino regions,  and some other relevant physical phenomena forcing factors) . The list of years was very efficient at predicting severe weather and flood risks for the last three seasons me trying to assess the skill of the method . 
Do you kindly have any suggested service/advice allowing multiyear analysis for snowfall or water equivalence of snow ? I am lost with databases that did not work to be honest .
NB: I am approaching these data statistically and my work is a statistical programmer .Also Any theoretical /climatic relevance or suggestions on my approach is highly appreciated. 
Thank you so much by all results and outcomes
Mohammad Alkhateeb
The Hashemite Kingdom of Jordan 
Submitted by Statisticizer on Sat, 11/18/2023 – 04:39
“Reanalysis” is a type of dataset, rather than a service like the PSL site. I think you’d need to obtain the dataset and then subset it yourself. You might also check out the IRI’s Climate Predictability Tool, here: .
Submitted by emily.becker on Mon, 11/27/2023 – 14:10
In reply to by Statisticizer
mankind is not in control of the weather in any shape or form.  Global warming has been going on for a very long time..much longer than man has been around, at least this time.  No one was around when the ice age was in full effect 
Submitted by Western John on Sat, 11/18/2023 – 20:41
Not kidding here or trying to sound sarcastic.  If you’re having any difficulty in understanding these truly excellent maps (Top Notch work by the way), ask a kid for help.  Kids today are just as smart as they have always been.  So just ask a kid.  Hand them the information and let them show you.  You’ll be surprised.
Submitted by Max on Sat, 11/18/2023 – 20:45
Are the results in inches of snow or inches of SWE?
I also have questions about the detrending but the question may be difficult for me to describe. But here is a try.
Usually when comparing things you try to move them to the same year often the present time or the past time but it does not matter as long as it is the same year. But doing that for this analysis (using climate models) would defeat the purpose of the analysis except that for some purposes you are working with the average of all years and for other purposes just El Nino years and also a subset of El Nino Years to Moderate to Strong El Nino years.
So can you clarify what you mean by detrending and how you did it?
By the way I just published an article on your post at…  All corrections to what I said would be appreciated and probably should be posted as comments to my article but could be published here.
I thought you wrote a great post. So thank you.
Submitted by Sigmund Silber on Thu, 11/23/2023 – 06:02
Whether it’s sunny or whether it’s hot, there’s gonna be weather, whether or not! 😁
Submitted by Rhonda on Fri, 11/24/2023 – 07:28


A decrease in radiative forcing and equivalent effective chlorine from hydrochlorofluorocarbons –

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Nature Climate Change (2024)
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The Montreal Protocol and its successive amendments have been successful in curbing emissions of ozone-depleting substances and potent greenhouse gases via production/consumption controls. Here we show that the radiative forcing and equivalent effective chlorine from hydrochlorofluorocarbons has decreased from 61.75 mW m2 and 321.69 ppt, respectively, since 2021, 5 years before the most recent projected decrease. This important milestone demonstrates the benefits of the Protocol for mitigating climate change and stratospheric ozone layer loss.
Following evidence that chlorofluorocarbons (CFCs) released to the atmosphere cause the depletion of stratospheric ozone1, the Montreal Protocol on Substances that Deplete the Ozone Layer was enacted to control the production and consumption of CFCs and other ozone-depleting substances (ODSs). With numerous amendments and adjustments to the Protocol, which was first adopted in 1987, the global phase out of the production of CFCs was completed in 2010. Because of these controls, and other anticipated reductions in future ODS emissions, Antarctic ozone (a common measure for ozone layer recovery) is estimated to return to 1980 levels shortly after the middle of the current century2.
CFCs were initially replaced by hydrochlorofluorocarbons (HCFCs), primarily for refrigeration, air conditioning and blowing of foam insulation where non-ozone-depleting alternatives, for example, propane in domestic refrigeration, could not be found. While HCFCs have much lower ozone depletion potentials than the CFCs they replaced, they are still ODSs and potent greenhouse gases; HCFC-22, the most abundant HCFC in the atmosphere, has a global warming potential 1,910 times that of carbon dioxide on a 100 year time horizon3. Since non-ozone-depleting alternatives became available, for example hydrofluorocarbons (HFCs), a phaseout of the production and consumption of HCFCs was mandated by the Copenhagen (1992) and Beijing (1999) Amendments to the Montreal Protocol and will be completed globally by 2040.
While the Montreal Protocol was introduced to safeguard stratospheric ozone through the phaseout of consumption and production of long-lived CFCs, which have high global warming potentials, it has also avoided substantial global warming4,5. The total direct radiative forcing due to CFCs in the atmosphere peaked in 2000 (ref. 6). Despite exceptional cases where emissions or atmospheric abundances of certain CFCs have increased, either through illicit production, emissions from processes allowed under the Montreal Protocol, or unknown reasons7,8,9, the overall trajectory for global radiative forcing from CFCs has declined since its peak. CFCs have atmospheric lifetimes of decades to centuries, while those of HCFCs are generally less than 20 years.
In this Brief Communication, we show that the global direct radiative forcing and equivalent effective chlorine (EECl) of HCFCs have fallen between 2021 and 2023 (EECl represents the globally averaged chlorine content of ODSs in the troposphere). Using measurements from the Advanced Global Atmospheric Gases Experiment (AGAGE) and the National Atmospheric and Oceanic Administration (NOAA), the global direct radiative forcing from HCFCs peaked in 2021 at 61.75 ± 0.056 mW m2 (all errors are 1 standard deviation due only to measurement errors and global averaging; Methods) and EECl peaked at 321.69 ± 0.27 ppt. In 2022, these values dropped to 61.67 ± 0.058 mW m2 and 321.35 ± 0.28 ppt and in 2023 to 61.28 ± 0.069 mW m2 and 319.33 ± 0.33 ppt. Given the errors, there is an 84% (81%) probability that the global radiative forcing (EECl) peak occurred in 2021 not 2022. These trends are shown in Fig. 1 and are the averaged AGAGE and NOAA measurements. The results from each network, treated independently, also confirm this peak. The fall was most rapid in the northern hemisphere, reflecting emission changes. In the northern hemisphere, radiative forcing (EECl) has fallen from 63.76 ± 0.16 mW m2 (332.59 ± 0.74 ppt) in 2021 to 63.11 ± 0.19 mW m2 (329.35 ± 0.91 ppt) in 2023. The drop in radiative forcing and EECl was largely due to the atmospheric decline of the most abundant HCFC, HCFC-22, from its peak abundance of 248.96 ± 0.26 ppt in 2021 to 247.33 ± 0.32 ppt in 2023 (Extended Data Fig. 1). The second most abundant HCFC, HCFC-141b, showed a small decrease for the first time from 24.63 ± 0.026 ppt in 2022 to 24.51 ± 0.037 ppt in 2023. There was a renewed increase in emissions of HCFC-141b in 2017–2021, which was most probably due to HCFC-141b being released into the atmosphere when appliance foams containing HCFC-141b reached the end of their life10 and potentially from its release during its use as a feedstock in the production of polymers11. The third most abundant HCFC, HCFC-142b, has fallen monotonically from 22.35 ± 0.017 ppt since 2017. The timing of the apparent peak in HCFC radiative forcing and EECl is 5 years earlier than a previously projected maximum radiative forcing of 62.90 mW m2 and EECl of 328.08 ppt in 2026 (based on HCFC-22, HCFC-141b and HCFC-142b only)11.
a, The total direct global radiative forcing from HCFCs until 2023 and the projected radiative forcing until 2100. b, The EECl from HCFCs until 2023 and the projected EECl until 2100. The projection is for HCFC-22, HCFC-141b and HCFC-142b only (Methods), which are shown to the right of the white dotted line. The category ‘other HCFCs’ contains HCFC-124, HCFC-132b, HCFC-31 and HCFC-133a. We assume all other HCFCs have a negligible contribution to radiative forcing and EECl. Thin black lines indicate the return to 1980 levels.
Several minor HCFCs, with abundances less than 1 ppt, show a mixed picture, with HCFC-124 abundances declining, but HCFC-31, HCFC-133a and HCFC-132b abundances either being relatively constant or increasing in recent years12. Emissions of these minor HCFCs are probably dominated by their leakage during the production of other chemicals12. Production of HCFCs and other ODSs during the manufacture of other chemicals—either as feedstocks, intermediates or by-products—is not controlled under the Montreal Protocol, since it had been assumed that emissions from such processes were negligible; yet recent studies suggest that ODS emissions from these sources are not9,13.
The radiative forcing from HCFCs in 2021 is around a fifth of that from CFCs at their peak of 286 mW m2 in 2000 (ref. 6), an additional success of the Montreal Protocol. The Kigali Amendment to the Montreal Protocol initiated controls on production and consumption of HFCs, which have widely replaced HCFCs for many applications. Additional commitments have been made to reduce emissions of HFCs under the Paris Agreement and the Global Cooling Pledge14. However, despite the controls, the radiative forcing due to HFCs is still increasing.
The reduction in total radiative forcing of HCFCs further demonstrates the benefits of the Montreal Protocol in minimizing global temperature increases and its success in reducing stratospheric ozone loss. However, it remains to be seen how rapidly total radiative forcing and EECl from HCFCs will fall. Our projections show that HCFCs will return to their 1980 values in 2082 for radiative forcing and in 2087 for EECl (these projections are based on the dominant three HCFCs; Methods). Production and consumption of HCFCs are being phased out under the Montreal Protocol, whereas their emissions to the atmosphere are not directly controlled. Therefore, leakage of HCFCs from appliances and foams will continue over the product lifetimes, contributing to radiative forcing and EECl, as shown in Fig. 1, unless efforts are made to reclaim the HCFCs before their eventual release to the atmosphere. Furthermore, the use of HCFCs as feedstock for the production of other chemicals, such as HFCs and polytetrafluoroethylene15,16, is expected to continue long into the future. HCFC-22 is the dominant HCFC used as feedstock, and emissions from such use accounted for 4–8% (14.3–28.5 Gg yr1) of total HCFC-22 emissions in 2019 (ref. 11). Global emissions of HCFC-22 have fallen since 2010 and are the main driver behind the decrease in radiative forcing and EECl from HCFCs. If the future global abundance of HCFC-22 is to exceed that observed in 2021, emissions of HCFC-22 from feedstock usage must be large enough for total emissions to return to or exceed their 2021 levels (around 347 Gg yr1) for a sustained period. Avoidance of additional radiative forcing and EECl from emissions of HCFCs during the manufacture of other chemicals would require changes to the Protocol. Controls on by-product emissions of HFC-23 during HCFC and HFC production have recently been implemented as part of the Kigali Amendment to the Montreal Protocol, where the emissions of HFC-23 should be avoided to the extent practicable. Any future increase in radiative forcing and EECl of HCFCs would be contrary to the goals of the Montreal Protocol.
Our latest observations show that the total radiative forcing and EECl from HCFCs has fallen for the first time. This demonstrates the success of the controls of the Montreal Protocol in mitigating loss of stratospheric ozone and its additional benefits to the climate. In the absence of future increases in ODS production, it was anticipated that Antarctic ozone recovery will occur later this century. The observed reduction in HCFC abundance is sooner than anticipated and may move forward this date for recovery when considered in future projections. The total radiative impact of all synthetic halogenated gases is still increasing, due to increasing abundances of HFCs and other fluorinated greenhouse gases. Adherence to the Kigali Amendment, Paris Agreement and Global Cooling Pledge should ensure that, in time, the radiative impact of HFCs will follow a similar decline to that observed for HCFCs.
The compounds considered here in calculating total global HCFC radiative forcing and EECl are HCFC-22, HCFC-141b, HCFC-142b, HCFC-124, HCFC-132b, HCFC-133a and HCFC-31. Other HCFCs that have been detected in the atmosphere are not included on the basis of their low abundance, short lifetimes and radiative efficiencies3 and will have a negligible impact on the reported quantities. Atmospheric measurements are from the AGAGE and NOAA networks through 2023.
A general overview of the measurement approach in the AGAGE network is outlined in ref. 17, and in more detail for HCFC-22, HCFC-142b, HCFC-124 and HCFC-141b in ref. 18. The measurements of HCFC-132b, HCFC-31 and HCFC-133a are outlined in ref. 12, which were updated until 2023 for this work. The measurement record in this work began in 1978 for HCFC-22, 1973 for HCFC-141b, 1978 for HCFC-142b and 2003 for HCFC-124. The AGAGE measurement record consists of results from the analysis of archived air collected periodically at Trinidad Head and Kennaook/Cape Grim (Extended Data Table 1) before 1998 for HCFC-22 and HCFC-141b and before 1994 for HCFC-142b; high-frequency measurements at multiple sites were added in more recent years (Extended Data Table 1). Measurements of HCFC-133a began in 1973 and are taken from previous literature12 until 2014, after which measurements from the AGAGE network were used. The same applies to HCFC-132b, whose record started in 1978. Measurements of HCFC-31 were updated from a previous record12 through August 2023. All other AGAGE data used were through 2023. Details on the measurement locations of HCFC-132b and HCFC-133a before 2014, and locations of measurements of HCFC-31, are given in ref. 12. The NOAA measurements of HCFC-22, HCFC-142b and HCFC-141b from a globally distributed sampling network are outlined in ref. 19 and updated until 2023 in this work. The sampling locations are shown in Extended Data Table 1. NOAA measurements of HCFC-22 used in this work began in 1991, for HCFC-141b in 1990 and for HCFC-142b in 1992.
The global mean well-mixed background surface mole fractions are estimated using background surface measurements from each network, which are assimilated into the AGAGE 12-box model20,21, using an approach described previously10,18. Measurements of HCFC-133a and HCFC-132b through 2014, and HCFC-31, were reanalysed using the same approach.
A single estimate of abundance is made using the mean of the global averages of the two global networks, at times when measurements from both networks are available. The global total radiative forcing of HCFCs in 2023 is 61.78, 61.71 or 61.75 mW m2 using measurements from AGAGE, NOAA or both networks, where measurements from both networks are used for Fig. 1. Global total EECl in 2023 is 321.81, 321.56 or 321.69 ppt using AGAGE, NOAA or both measurement networks. All global mean mole fractions used to derive the global totals from all measurements are shown in Extended Data Fig. 1, for each network independently. Extended Data Fig. 1 shows that abundances measured by AGAGE and NOAA agree very well, albeit with some small differences for HCFC-142b, but very similar trends. The agreement in trends, over absolute values, is of particular importance in this work given that it is the timing of increases and decreases abundances that is of focus.
For clarity, uncertainties in the main text are reported assuming no error in the radiative efficiency (see next paragraph) and no error from the measurement calibration scales used by either network. Errors in calibration scales are additive or multiplicative adjustments to the measurements, and therefore, trends remain robust even in the presence of calibration differences. In the main text, the uncertainty is given as the 1 standard deviation uncertainty of the mean derived value from both networks (that have independent calibration), assuming that the measurement errors are fully correlated due to the similar approach to the measurements and derived quantities. This can be thought of as the random error in the reported quantities. The calibration error is included in the supplement for each network and gas alongside the respective mole fractions. When including the calibration error, the uncertainty in the maximum radiative forcing from HCFCs is 61.75 ± 0.55 mW m2 and the EECl is 321.69 ± 2.71 ppt.
The total effective direct radiative forcing is calculated using the annual global mean surface mole fraction output from the 12-box model and the recommended adjusted effective radiative efficiency for each gas3. Uncertainties in the radiative efficiencies are ~14% for each HCFC with an atmospheric lifetime 5 years and ~24% for those with lifetimes 5 years22, and are added in quadrature to calculate the total uncertainty due to radiative efficiencies for HCFCs. These uncertainties are not included in the radiative forcing quoted in the main text, and therefore should be added in quadrature to other sources of uncertainty for an absolute uncertainty on radiative forcing. The peak HCFC radiative forcing including both calibration error and uncertainties in the radiative efficiencies is 61.75 ± 7.93 mW m2. The uncertainty in the radiative efficiency does not impact the timing of the peak as this uncertainty will introduce a systematic rather than random error to the radiative forcing.
Projections of HCFCs are made following the approach in ref. 11, using the baseline scenario, but with updated production data of HCFCs reported to the United Nations Environment Programme through 2022 and updated surface mixing ratios for HCFC-22, HCFC-141b and HCFC-142b through 2023. The lifecycle and emissions of the other HCFCs are currently not sufficiently understood to make projections. We assume no production in non-Article 5 (developed) countries since 2020, following the Montreal Protocol phase-out schedule, and therefore all production is assumed to come from Article 5 (developing) countries. Bank estimates through 2023 were updated using the previously reported approach, with revised annual bank release fractions calculated. Because reported production over 2020–2022 was lower than that assumed in ref. 11 for 2023 and 2024, projected production in these two years is assumed to remain at the 2022 reported levels. The projected production in 2023 and 2024 is below what is required under the Montreal Protocol but still above the phase-down requirements starting in 2025. After 2024, projected production is taken from ref. 11. From 2025 to 2029, production is scaled proportionally, so that the total ozone depletion-weighted production was equal to 30% of the Protocol’s baseline HCFC production in Article 5 countries. Production is then scaled to reach 2.3% of the baseline production in 2030–2039. This assumes that the full allocation under the Montreal Protocol is not used, in line with the latest available production data. The approach taken in ref. 11 and here assumes that all of an ODS that is produced goes directly into the bank and then is released in the future with a constant bank release rate. This rate is assumed to be the bank release rate averaged over the final 7 years when emissions estimates are available. For these reasons the scenarios are probably high-end estimates of the future projections of these HCFCs, providing even more robustness to the main conclusion presented here.
Monthly mean data used as input to derive the global mean quantities, projected mole fractions for HCFC-22, HCFC-141b and HCFC-142b, and estimated global mole fractions are available from ref. 23. AGAGE data, used to derive the monthly mean values, are available at (last accessed 20 February 2024) and (current dataset ref. 24). The most recent NOAA atmospheric observations are available at (last accessed 20 February 2024).
The 12-box model and the method used to quantify global mean mole fractions are available via GitHub at (last accessed 05 March 2024) and (last accessed 05 March 2024) and refs. 25,26.
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We are indebted to those making measurements for their dedication to producing high-quality atmospheric trace gas measurements foremost the station manager and station operators. The AGAGE Medusa GC–MS system development, calibrations and measurements at the Scripps Institution of Oceanography, La Jolla and Trinidad Head, CA, USA; Mace Head, Ireland; Ragged Point, Barbados; Cape Matatula, American Samoa; and Kennaook/Cape Grim, Australia were supported by the NASA Upper Atmospheric Research Program in the United States with grants NNX07AE89G, NNX16AC98G and 80NSSC21K1369 to MIT and NNX07AF09G, NNX07AE87G, NNX16AC96G, NNX16AC97G, 80NSSC21K1210 and 80NSSC21K1201 to SIO (and earlier grants). The Department for Energy Security and Net Zero (DESNZ) in the United Kingdom supported the University of Bristol for operations at Mace Head, Ireland (contracts 1028/06/2015, 1537/06/2018 and 5488/11/2021) and through the NASA award to MIT with the subaward to University of Bristol for Mace Head and Barbados (80NSSC21K1369). The National Oceanic and Atmospheric Administration (NOAA) in the United States supported the University of Bristol for operations at Ragged Point, Barbados (contract 1305M319CNRMJ0028) and operations at Cape Matatula, American Samoa. In Australia, the Kennaook/Cape Grim operations were supported by the Commonwealth Scientific and Industrial Research Organization (CSIRO), the Bureau of Meteorology (Australia), the Department of Climate Change, Energy, the Environment and Water (Australia), Refrigerant Reclaim Australia and through the NASA award to MIT with subaward to CSIRO for Cape Grim (80NSSC21K1369). Measurements at Jungfraujoch are supported by the Swiss National Programs HALCLIM (Swiss Federal Office for the Environment, FOEN), by the International Foundation High Altitude Research Stations Jungfraujoch and Gornergrat (HFSJG), and by the European infrastructure projects ICOS and ACTRIS. NOAA measurements were supported in part through the NOAA Cooperative Agreement with CIRES (NA17OAR4320101). This work received funding from the European Union’s Horizon 2020 research and innovation programme under the Marie Słodowska–Curie grant agreement no. 101030750 (L.M.W.). M.R. received funding from the Natural Environment Research Council Highlight Topic Investigating HALocabon impacts on the global Environment (InHALE, NE/X00452X/1).
School of Chemistry, University of Bristol, Bristol, UK
Luke M. Western, Simon O’Doherty, Kieran M. Stanley, Dickon Young & Matt Rigby
NOAA Global Monitoring Laboratory, Boulder, CO, USA
Luke M. Western, Scott Clingan, Molly Crotwell, Brad Hall, Isaac Vimont & Stephen A. Montzka
NOAA Chemical Sciences Laboratory, Boulder, CO, USA
John S. Daniel
Empa—Swiss Federal Laboratories for Materials Science and Technology, Laboratory for Air Pollution/Environmental Technology, Dübendorf, Switzerland
Martin K. Vollmer & Stefan Reimann
Cooperative Institute for Research in Environmental Sciences, University of Colorado, Boulder, CO, USA
Scott Clingan & Molly Crotwell
CSIRO Environment, Aspendale, Victoria, Australia
Paul J. Fraser & Paul B. Krummel
School of Geographical Sciences, University of Bristol, Bristol, UK
Anita L. Ganesan
Scripps Institution of Oceanography, University of California San Diego, La Jolla, CA, USA
Christina M. Harth, Jens Mühle & Ray F. Weiss
GC Soft Inc., Carlsbad, CA, USA
Peter K. Salameh
Center for Global Change Science, Massachusetts Institute of Technology, Cambridge, MA, USA
Anita L. Ganesan, Matt Rigby & Ronald G. Prinn
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L.M.W. conceived the project and led the analysis. J.S.D. created the projections of HCFCs. M.K.V., S.C., M.C., P.J.F., A.L.G., C.M.H., P.B.K., J.M., S.O.’D., K.M.S., S.R., I.V., D.Y., R.F.W. and S.A.M. made and provided measurement data, including its quality control and analysis. B.H., C.M.H. and P.K.S. provided calibration, quality control and analysis tools to make the measurements. L.M.W. and M.R. produced the globally averaged mole fractions using the 12-box model. R.G.P. provided oversight and management of the AGAGE network. L.M.W. led the writing of the article, with contributions from J.S.D., M.K.V., P.B.K., J.M., S.R., M.R., R.G.P. and S.A.M. All authors have read and approved the manuscript.
Correspondence to Luke M. Western.
The authors declare no competing interests.
Nature Climate Change thanks Nicole Miranda, Gunnar Myhre and Hua Zhang for their contribution to the peer review of this work.
Publisher’s note Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
Global mean mole fractions from each network and other available measurements to derive the reported quantities in the main text. Measurements other than those made by the AGAGE and NOAA networks are reported in Vollmer et al.12 and are updated here.
Open Access This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article’s Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit
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Western, L.M., Daniel, J.S., Vollmer, M.K. et al. A decrease in radiative forcing and equivalent effective chlorine from hydrochlorofluorocarbons. Nat. Clim. Chang. (2024).
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Water and Food: How, When, and Why Water Imperils Global Food Security – CSIS | Center for Strategic and International Studies

Photo: MUNIR UZ ZAMAN/AFP via Getty Images
Critical Questions by David Michel
Published October 16, 2023
Every October, World Food Day calls attention to global food security and the actions needed to combat hunger and malnutrition. This year, the Food and Agriculture Organization of the United Nations (FAO) is highlighting sustainable water management as key to the future of food. The United Nations anticipates agricultural production will have to grow 50 percent to meet rising demands in 2050, prospectively requiring global water withdrawals 30 percent higher than today. Yet an estimated 2.4 billion people now live in countries confronting water stress and almost 40 percent of global croplands already experience water scarcity, fueling concerns that mounting needs risk colliding with increasingly strained supplies.
Q1:What is the connection between water resources and food production?
A1: Every person needs 50 to 100 liters of water per day to meet basic drinking, cooking, and hygiene requirements. By comparison, it takes 2,000 to 5,000 liters of water per person per day to grow the food to support diets of 2,800 kilocalories daily, the benchmark for food security used by the FAO. To harvest a kilogram of wheat, for example, necessitates over 1,800 liters of water. Raising a kilogram of beef takes over 15,000 liters (mostly to grow the feed consumed by the cattle). All told, agriculture accounts for 72 percent of global freshwater withdrawals—amounting to nearly 3,000 cubic kilometers of water—taken from the world’s rivers, lakes, and groundwater aquifers each year. In many developing countries from India to Ethiopia, agriculture’s share of water withdrawals tops 90 percent. Healthy freshwater systems and cycles also sustain other important food resources such as livestock pasturage, freshwater fisheries, and aquaculture.
Humanity’s agricultural water use has grown so significant that it shapes global climate mechanisms and even shifts the planet on its axis. South Asian irrigation systems redirect so much water from rivers and aquifers to farmers’ fields that agriculture on the subcontinent substantially influences the Indian Ocean monsoon, impacting precipitation patterns from East Africa to East Asia. Worldwide, relentless pumping from underground reservoirs has removed enough water to measurably tilt the Earth’s axis of rotation.
Q2: What is the relationship between water scarcity and food security?
A2: Water and food security are inextricably interlinked. Food security is defined in terms of food availability, access, utilization, and stability, such that all people at all times have physical and economic access to sufficient quantities of safe and nutritious food that meets their dietary needs and food preferences. Water scarcity, in turn, affects not just the quantities, but also the quality, variety, and seasonal availability of foods that can be produced and consumed. Thus, at the global level, water resource stresses, such as droughts in cereal-producing nations, can contribute to grain supply shortfalls jeopardizing food security for hundreds of millions of people. From 2007–2008, for example, a confluence of low global grain reserves, rising energy prices, reduced harvests, international trade restrictions, and other factors precipitated a global food price crisis that plunged an additional 75 million people into chronic hunger. As world wheat prices surged by 72 percent, one study calculated that the recurrent droughts that then parched Australia—a major exporter—were responsible for over a fifth of the global price shock at the time. At local and farm levels, water constraints can push producers to employ polluted water sources that may then compromise or contaminate food supplies.
Similarly, household water insecurity can undermine household food security via multiple pathways. Scarce or polluted water supplies can hamper people’s ability to grow a garden, raise livestock, or safely prepare available foods. Water shortages can force families to spend more financial resources and effort to obtain water, obliging choices among other necessities and detracting from time devoted to work or school. And limited water supplies can push families to alter the foods they cook and consume, shifting their diets to less water-intensive but also less nutritious foods.
Q3: How does increasing water stress put global food systems at risk?
A3: In the coming decades, the world’s population will grow by close to 2 billion people, climbing from 8 billion people in 2022 to 9.7 billion in 2050. Nearly all of this growth will occur in Africa and Asia. Global GDP is anticipated to more than double by mid-century, expanding from $101 trillion in 2020 to $205 trillion (2015 USD) in 2050. Likewise, global GDP per capita is projected to rise from $16,784 in 2020 to $42,304 per person in 2060 (2005 USD). With higher incomes, dietary preferences and possibilities shift, boosting demand for more water-intensive foods such as dairy, eggs, and meat. Larger, richer populations typically demand and can afford greater water use overall. The Organization for Economic Cooperation and Development projects that global water use will jump 55 percent from 2000 levels by 2050, including a 400 percent spike in demand from manufacturing, a 140 percent rise in withdrawals for electricity production, and a 130 percent increase in domestic needs. Growing claims from other sectors could come to squeeze agricultural requirements. As water demands expand and evolve, the World Bank considers some 25 to 40 percent of global water withdrawals will need to be reallocated to higher-value uses, shifting from relatively lower-value applications such as agriculture.
Parts of the world are already bumping up against the limits of their renewable water resources. For several major river systems supplying key agricultural regions —including the Colorado, Ganges, Indus, Nile, Tigris-Euphrates, and Yellow River—yearly water withdrawals nearly equal or even exceed long-term flow balances and ecosystem needs. Hydrologists consider these rivers “closed,” meaning that, under prevailing practices, almost all of their annually available renewable waters are already committed to various human or environmental requirements, with little if any buffer remaining to accommodate new demands. Underground aquifers currently supply one third of all water use, providing half of global irrigation needs. But withdrawals in many major aquifers surpass natural rates of replenishment, progressively lowering water tables and exhausting groundwater reserves. Considering both surface and groundwater sources together, one recent global assessment found that two to three billion people live in areas where total net water withdrawals outstrip locally available renewable supplies for four to six months of the year. For half a billion people, net demand outpaces supply all year round. Without substantial changes to present policies and practices, over 80 percent of global croplands could face water scarcity by mid-century.
Q4: How will climate change impact world water and food resources?
A4: Global climate change threatens to exacerbate pressures on water resources and food production. As temperatures rise, crop water productivity will largely fall, all else being equal, necessitating larger water inputs to realize the same yields. Consequently, the FAO estimates that meeting growing agricultural demand under climate change will require an additional 40 to 100 percent more water than would have been needed absent its impacts. Climate change is projected to upset elemental patterns and processes such as the El Niño-Southern Oscillation and the onset of the monsoon. Such impacts could scramble the seasonal availability or shuffle the geographical distribution of crucial water supplies for agriculture worldwide. Shifts in the volume, timing, location, and form of precipitation could particularly disrupt the majority of global agricultural production that is rain-fed and unsupported by managed irrigation.
Climate change will also affect the occurrence of water-related disasters. Climate models project that heavy precipitation, floods, and droughts will strike more frequently and severely. Warming of 2 degrees Celsius above preindustrial averages could double the global population annually exposed to significant river flooding and increase the population exposed to drought threefold or more. Agri-food systems often bear the brunt of such catastrophes, absorbing 63 percent of loss and damages compared to other sectors. Extreme storms, floods, and droughts can wipe out crops and livestock and damage or destroy agricultural equipment and infrastructure. For 8 of the 15 years from 2000 to 2014, global grain consumption exceeded production, primarily due to harvest-diminishing droughts in key breadbasket regions. Absent robust adaptations to global warming, climate impacts could reduce major crop yields by 11 percent in the coming decades.
Q5: What kinds of policy solutions can help address these challenges?
A5: Several changes in policy, technology, and consumer behavior can help improve water and food security.
Reduce food wastage. Perhaps a third of global food production is lost or wasted from field to fork along the food supply chain. Lost and wasted food means wasted water. While supply chain inefficiencies exist worldwide, in more developed countries, significant amounts of food are also discarded for cosmetic reasons, such as bruises, scars, or blemishes on products. In developing countries, more food is lost in processing and transport phases due to inadequate infrastructure to store foods and move them to market without spoilage. Cutting food waste by 25 percent would curb the associated water demands and provide food to feed 900 million people.
Reform subsidies. Governments worldwide devote $817 billion a year to subsidizing agriculture and $320 billion to water (and sanitation) subsidies. Subsidies can be important tools promoting water and food security when they are effectively designed and targeted. Too often, however, subsidies are distortionary, encouraging overexploitation of resources and generating environmental damage while failing to benefit the poorest and most vulnerable. Worldwide, the most water-intensive commodities, like beef and dairy, receive the most subsidy support—while also producing comparatively more climate-warming greenhouse gas emissions than other agricultural sectors. Meanwhile, more than half of global water subsidies go to the wealthiest 20 percent of the population, while just 6 percent of subsidies reach the poorest 20 percent.
Reuse and recycle. Planned recovery and reuse of wastewater for agricultural purposes is common in countries around the Middle East and Mediterranean, as well as parts of Australia, China, Mexico, and the United States. Wastewater streams are typically rich in dissolved nutrients, making them attractive irrigation sources, especially in peri-urban areas and where conventional surface and groundwater supplies are increasingly stressed. Between 2 to 7 percent of the world’s total irrigated land is irrigated with raw or diluted wastewater, though much of this use may be unsafe if the reclaimed waters are inadequately treated for agricultural application. With appropriate treatment, however, the 330 cubic kilometers of municipal wastewater generated annually could potentially cover the needs of 15 percent of all irrigated croplands.
Promote information innovation. Effective water management depends on accurate, timely, and consistent information. Advances in remote sensing technologies increasingly allow systematic data collection on important indicators such as crop water use, land use changes, groundwater depletion, and water quality. Drone-based sensors can supply data on individual fields and streams. Innovation in “big data” analytics can enable water managers to integrate multiple data streams, from rainfall patterns to demand trends, to formulate predictive models to guide decisionmaking—and inform early warning systems for risks to water and food security.
Promote infrastructure innovation. Too many agricultural communities labor without adequate infrastructure for effectively storing, treating, moving, and utilizing water. Common irrigation methods, for example, can be highly wasteful, applying considerably more water than necessary. Precision irrigation techniques, in contrast, integrating system-scale irrigation infrastructure with “on-farm” water delivery equipment and data-driven management tools, can allocate irrigation water down to the individual field plot and plant-level, achieving far greater crop per drop. Not all innovative practices, though, rely on the latest technologies. Managed aquifer recharge, sometimes called “groundwater banking,” capitalizes on existing natural infrastructure, collecting excess surface waters when available—by capturing stormwater runoff, floodwater flows, reservoir releases, etc.—to strategically replenish underground aquifers for later use.
David Michel is the senior fellow for water security with the Global Food and Water Security Program at the Center for Strategic and International Studies in Washington, D.C. 
Critical Questions is produced by the Center for Strategic and International Studies (CSIS), a private, tax-exempt institution focusing on international public policy issues. Its research is nonpartisan and nonproprietary. CSIS does not take specific policy positions. Accordingly, all views, positions, and conclusions expressed in this publication should be understood to be solely those of the author(s).
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Composting | US EPA – U.S.

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Source ReductionFeed Hungry PeopleFeed AnimalsIndustrial UsesComposting

Composting is nature’s way of recycling and is one of the most powerful actions we can take to reduce trash in landfills, address climate change, and build healthy soil. Composting is in the fourth tier of EPA’s Wasted Food Scale.
In 2019, 66.2 million tons of wasted food were generated in the food retail, food service and residential sectors in the United States. Only 5% of that wasted food was composted.1
In the U.S., food is the single most common material sent to landfills, comprising 24.1 percent of municipal solid waste. When yard trimmings, wood and paper/paperboard are added to food, these organic materials comprise 51.4 percent of municipal solid waste in landfills.2
When food and other organic materials decompose in a landfill where anaerobic (without oxygen) conditions are present, bacteria break down the materials and generate methane, a powerful greenhouse gas. Municipal solid waste landfills are the third largest source of human-related methane emissions in the U.S, accounting for approximately 14% of methane emissions in 2021.3 Wasted food is responsible for 58% of landfill methane emissions.4
When we send food and other organic materials to landfills or combustion facilities, we throw away the valuable nutrients and carbon contained in those materials. By composting our food scraps and yard trimmings instead and using the compost produced, we can return those nutrients and carbon to the soil to improve soil quality, support plant growth and build resilience in our local ecosystems and communities.
Composting is a fundamentally local process. Organic materials are typically collected and processed into compost near where they are generated, often in the same county, city or even neighborhood. In this way, composting also supports local jobs and economies.
Learn more about the connection between food waste and methane in this fact sheet from USDA and EPA (pdf)(2.1 MB).
Composting is the controlled, aerobic (oxygen-required) biological decomposition of organic materials by microorganisms. Organic (carbon-based) materials include grass clippings, leaves, yard and tree trimmings, food scraps, crop residues, animal manure and biosolids.
Compost is a dark, crumbly, earthy-smelling, biologically-stable soil amendment produced by the aerobic decomposition of organic materials. 
Regardless of size or scale, the basic principles of composting are generally the same. The composting process requires a proper ratio of carbon-rich materials (such as dry leaves or wood chips) to nitrogen-rich materials (such as food scraps or grass clippings). Maintaining adequate moisture level, oxygen flow, particle size, and temperature ensures microorganisms effectively break down organic materials into quality compost. 
The method of composting used, as well as the equipment, is often determined by the scale or size of the site and the volume and type of materials, or feedstocks, being composted. The feedstocks accepted vary by composting facility and should always be free of contaminants such as herbicides, non-compostable packaging, and produce stickers.
Composting can take place at many scales/sizes – backyard, community, on-farm, municipal and regional – and at a range of locations in urban to rural areas. A small-scale system can be as simple as a backyard compost pile or vermicomposting (worm composting) bin, whereas a large-scale system may be a centralized, commercial composting facility processing organic materials from around the region. 
Learn more about the composting process as well as composting at home and community composting.
Check out these EPA fact sheets on stormwater and erosion control with compost:
In the United States, our soils suffer from topsoil loss and erosion, which can lead to water quality issues and reduce the productivity of agricultural land. Compost adds much-needed organic matter to soil to enhance soil health. Compost has other uses as well in green infrastructure and stormwater management. Additionally, the use of compost sustains green jobs throughout the organics recovery cycle.
Markets and applications for compost include agricultural and horticultural, landscape and nursery, vegetable and flower gardens, sod production and roadside projects, wetlands creation, green infrastructure, soil remediation and land reclamation, sports fields and golf courses, sediment and erosion control, and stormwater management.
Learn about the different uses for compost through fact sheets from the Compost Research and Education Foundation (pdf)(2.6 MB).
Composting policies and regulations are set at the state and local government level.
Some states ban or restrict landfill disposal of organic materials such as yard and tree trimmings and wasted food. Some bans only affect large generators of organic materials, whereas others affect all generators of wasted food, down to the household level. 
Below are some composting and compost use policy resources:
Visit the other EPA composting webpages for more information and resources:
Mention of or referral to commercial products or services or links to non-EPA sites does not imply official EPA endorsement of or responsibility for the opinions, ideas, data, or products presented at those locations or guarantee the validity of the information provided. Mention of commercial products/services on non-EPA websites is provided solely as a pointer to information on topics related to environmental protection that may be useful to EPA staff and the public.
Visit the webpages below for more composting information:


What is El Niño? – University of California San Diego

El Niño and La Niña are natural climate phenomena that alter weather patterns around the world. El Niño occurs irregularly but shows up roughly every three to seven years and typically lasts between nine and 12 months with occasional exceptions that linger for multiple years. 
After three successive years of La Niña (2020-2023), the National Oceanic and Atmospheric Administration (NOAA) and the National Weather Service (NWS) have officially declared an El Niño event that is expected to continue and intensify into winter. The forecast predicts this year’s El Niño is likely to be a "strong" event with a 30 percent chance to rival the 2015-2016 and 1997-98 events. 
El Niño’s effects are powerful. Its ocean warming is enough to drive average global temperatures higher, and to temporarily raise sea levels along the California coast via thermal expansion – offering humanity a glimpse of conditions that are projected to become the norm in coming decades as climate change accelerates.  
To learn more, we asked experts from UC San Diego’s Scripps Institution of Oceanography to answer some common questions about El Niño and its impacts.
Shang-Ping Xie (Professor of Climate Science and Physical Oceanography, Roger Revelle Chair in Environmental Science): El Niño refers to anomalously warm waters in the central and eastern Pacific Ocean near the equator. La Niña is the opposite–colder than average water temperatures in the equatorial Pacific. 
The tropics are like the engine room of the Pacific. Heat in the tropics drives global atmospheric circulation. In that sense, variations in the tropical Pacific like El Niño can have huge impacts on global weather patterns. 
Shang-Ping XieEl Niño and La Niña are the result of complex interactions between the ocean and the atmosphere. 
The trade winds that normally blow from east to west across the tropical Pacific relax in response to El Niño’s warmer water conditions. The trade winds normally push warm water from east to west in the tropical Pacific and cause cold, nutrient-rich water upwelling in the eastern equatorial Pacific. Without the trade winds, warm water builds up in the central and eastern equatorial Pacific. 
Anomalously warm water can cause the trade winds to weaken but weaker trade winds can cause ocean warming. It’s somewhat of a chicken-egg problem: “Do we see the ocean side of El Niño or the atmospheric side first?” But really it’s a chicken-egg coupled problem, because the atmosphere and the ocean are in contact and influence each other. 
Once an El Niño gets established these atmospheric and oceanic effects can reinforce each other. 
Shang-Ping XieIn a typical El Niño year, India’s monsoon rainfall from June to September will decrease and may cause drought conditions. The second stop would be around Australia and Indonesia. They’re also likely to get dry conditions, and perhaps wildfires during North America’s fall months. 
Then the third stop would be North America. El Niño often causes California and the southwestern states to experience more storms and increased rainfall in the winter months. That said, every El Niño is different and you can have a dry El Niño winter just like you can have a wet La Niña winter the way we just did. 
The fourth stop – if the El Niño grows in magnitude – is the Pacific coast of South America during North American springtime. Countries like Peru can get heavy rainfall. The final stop would be China and Japan. In that part of the world, research shows that the last echo of a typical El Niño is heavy rains and flooding along the Yangtze River in China and across Japan. 
At the global scale, the ocean warming that occurs during an El Niño year is enough to drive average global temperatures higher by heating the atmosphere around the equator. Layering El Niño on top of warming due to human-caused climate change could push global temperatures to new highs, including past the Paris Agreement threshold of 1.5 degrees Celsius [2.7 degrees Fahrenheit] of warming above pre-industrial levels. 
Dan Cayan (Climate Science Researcher): For California, the North Pacific storm track is often highly active during the winter months, and those storms can be shunted a bit farther southward, which can deliver a more direct hit to Southern California. So California, especially Southern California, can get larger storms in the winter which can mean more rainfall and larger waves along the coast. It can also be somewhat drier in the Pacific Northwest, with Northern California sort of being a fulcrum that can go either way.
Julie Kalansky (Climate scientist and deputy director for operations at the Center for Western Weather and Water Extremes): It’s important to stress that even though we see these general patterns during El Niño and La Niña years, there is still a lot of variability and not every event is going to follow the general pattern. Last year’s La Niña was a perfect example. We’d normally expect dry winter conditions from a La Niña in Southern California but it was wetter than normal. So, the declaration of an El Niño doesn’t guarantee that Southern California is going to have a wet, stormy winter, but it does stack the deck in that direction. 
Laura Engeman (Coastal resilience specialist with the Center for Climate Change Impacts and Adaptation): Often during El Niño years California sees elevated sea levels. This is because El Ninos are associated with warmer sea surface waters in the equatorial eastern Pacific. When large swaths of the Pacific surface waters warm, there is a short-term thermal expansion of the ocean that raises sea levels along California’s coast. For example, in the 2015-2016 El Nino, California sea levels were elevated as much as 11 inches
Adam Young (Integrative Oceanography Researcher): El Niño conditions can generate a triple threat for coastal hazards in California. Increased rainfall triggers landslides; powerful waves can accelerate erosion of beaches, sea cliffs, and bluffs, and cause coastal flooding; and strong El Niño conditions can raise sea level on the California coast by 15 to 30 centimeters (6-13 inches). Combined, these factors increase coastal erosion and flooding during El Niño events, which can threaten public parks, beaches, critical infrastructure, highways, and homes.
Some of what determines the severity of impacts is related to the timing of winter storms. For example, if large waves arrive during a very high tide, the potential for coastal flooding and other types of damage increases significantly. Multiple sequential storms can also be a factor. The first storm may strip all the sand off a beach, and without the natural sand buffer, the next storm can deliver a stronger punch. Every El Niño is different but these conditions increase the possibility for significant coastal impacts.
It’s important for us to monitor this year’s El Niño by mapping the coastline before and after the event so we can measure how the coast responds. The elevated sea levels associated with El Niño also provide a snapshot of how future sea level rise might impact our coast. Collecting these data is essential to improve our ability to predict hazards and plan for the future.
Dan CayanIt’s hard to directly attribute individual storms to a seasonal phenomenon. At the time scale of a season, if we get lots of storms and lots of precipitation I think it makes sense to at least partially attribute what happened with those storms to El Niño. But just like not all El Niño years follow the typical pattern, storms can also be atypical. So El Niño doesn’t dictate every storm but every storm is affected by El Niño. Individual weather patterns can be shifted or enhanced or reinforced by this seasonal phenomenon. 
Daniel Rudnick (Professor of Physical Oceanography): El Niños are detected using measurements from a combination of instruments including moored buoys, the Argo network of floats, and satellite measurements. Sea surface temperatures in the equatorial Pacific from those different sources are the measurements that NOAA uses to officially declare an El Niño.
Locally, I’ve been monitoring the effects of El Niño off California’s coast using underwater gliders since 2005. These autonomous gliders can cover about 15 miles underwater each day during a series of dives from the surface down to about 500 meters. This network of gliders gives us continuous measurements of temperature not just at the surface but at depth, as well as various other measurements related to oxygen concentration, salinity, and ocean currents. The glider data let us see how California’s waters are responding to changes caused by El Niño in real time. Taking all these measurements down to 500 meters helps screen out local factors that might only be altering conditions at the surface.
With the help of new funding from the Bipartisan Infrastructure Law and the Southern California Coastal Ocean Observing System, we are updating our fleet of gliders so they can go farther and carry more sensors. The new gliders will include sensors that detect nitrate, an important nutrient for phytoplankton, and pH, which will help us measure ocean acidification in local waters.
El Niño typically reduces the coastal upwelling that brings cold water full of nutrients like nitrate to the surface off California’s coast, and so having nitrate sensors on the gliders will help us to monitor the status of upwelling along the coast before, after, and during El Niño events.
Mark Ohman (Professor of Biological Oceanography): There are different effects for different organisms, but El Niño often reduces coastal upwelling in the eastern Pacific, which is an important source of nutrients for the plankton at the base of the food web. So, the broadest impact is that overall biological productivity in the eastern Pacific tends to decrease. 
At the same time, the warmer waters off the coast of North America can also lead to an influx of subtropical and tropical species of plankton and fish. In San Diego, we sometimes see major influxes of swimming red crabs (Pleuroncodes planipes) that normally breed off the coast of Baja. When I first came to Scripps, a marine technician told me about a guano index for El Niño. If the guano stains from the seabirds on the Scripps pier turned from white to pink to red this indicated there was a strong El Niño, because the birds were feasting on the red crabs that had come north from Baja waters.
Seabirds and marine mammals may also alter the timing of their migrations if their major food sources diminish because of reduced upwelling. Blue whales, for instance, usually migrate into Southern California waters between May and September and presumably they might delay their arrival if reduced upwelling meant less krill were available.
Colleen Petrik (Assistant Professor of Biological Oceanography): Warmer waters in the eastern Pacific can allow for big open ocean fish like tuna to expand their range closer to the California coast. This range expansion also occurs vertically in the water column. Normally, deeper waters that are high in nutrients can be low in oxygen. But when upwelling is reduced by El Niño, oxygen levels in the middle depths can increase which allows species like tuna that need a lot of oxygen to move into those depths and find more food. Tuna often do quite well during El Niño years because they can expand their range horizontally into the eastern Pacific and vertically into these deeper waters that normally don’t have enough oxygen.
Ed Parnell (Associate Researcher in Integrative Oceanography Division): El Niño can be devastating for giant kelp forests in Southern California and Baja. Reduced coastal upwelling means fewer nutrients to fuel kelp growth and the altered storm track can mean more violent waves that rip out kelp. 
Some recovery occurs during these colder water periods of La Nina conditions, but there hasn’t been a full recovery and now another El Niño is coming that will damage the system again. The whole system is being stressed more frequently and harder. 
Kelp forests provide vital food and habitat for lots of marine species. Giant kelp grows fast but when it gets ripped out various understory algae species can move in that then make it even harder for the kelp forest to come back.
I’m very worried that with the ocean warming we are seeing and the increased likelihood of severe and frequent El Niños, that much of Southern California’s kelp canopy could disappear within my kids’ lifetime. 
Jennifer Smith (Professor of Marine Biology): The impacts of El Niño depend on the specific event – its severity and duration – but an increase in ocean temperatures is ubiquitous, and that can make coral bleaching more likely. Corals are susceptible to changes in temperature and they will bleach if temperatures go above a certain threshold for too long. 
The 2015-2016 El Niño is a clear example of how severe and how widespread the impact on coral reefs can be. During that event we saw massive bleaching in Hawaii, Australia’s Great Barrier Reef, the Caribbean, and places like Fiji in the South Pacific.
I was in the Hawaiian Islands in early August and there was no sign of bleaching, but the predictions suggest warming will continue or accelerate into winter. My lab is keeping a close eye on it and we are definitely worried about potential impacts.
We are hoping these ecosystems are adapting over time and can maybe show more resilience in the future because these heat waves are such a strong selective pressure for heat tolerant individuals. But we don’t know. My lab is actively researching this – looking for corals with more thermal tolerance and hopefully one day using that information to help reefs survive.
Shang-Ping XieThe short answer is we don’t know. It’s the subject of an ongoing and intense debate. Right now the models are telling us different things. This means our physical understanding isn’t yet precise enough to pin down how El Niño changes in a warmer climate. Really, it tells us we need more research into El Niño.
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Opinion | The Stench of Climate Change Denial – The New York Times

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Paul Krugman

Opinion Columnist
This may sound a bit weird, but when I think about my adolescent years, I sometimes associate them with the faint smell of sewage.
You see, when I was in high school, my family lived on the South Shore of Long Island, where few homes had sewer connections. Most had septic tanks, and there always seemed to be an overflowing tank somewhere upwind.
Most of Nassau County eventually got sewered. But many American homes, especially in the Southeast, aren’t connected to sewer lines, and more and more septic tanks are overflowing, on a scale vastly greater than what I remember from my vaguely smelly hometown — which is both disgusting and a threat to public health.
The cause? Climate change. Along the Gulf and South Atlantic coasts, The Washington Post reported last week, “sea levels have risen at least six inches since 2010.” This may not sound like much, but it leads to rising groundwater and elevated risks of overflowing tanks.
The emerging sewage crisis is only one of many disasters we can expect as the planet continues to warm, and nowhere near the top of the list. But it seems to me to offer an especially graphic illustration of two points. First, the damage from climate change is likely to be more severe than even pessimists have tended to believe. Second, mitigation and adjustment — which are going to be necessary, because we’d still be headed for major effects of climate change even if we took immediate action to greatly reduce greenhouse gas emissions — will probably be far more difficult, as a political matter, than it should be.
On the first point: Estimating the costs of climate change and, relatedly, the costs polluters impose every time they emit another ton of carbon dioxide requires fusing results from two disciplines. On one side, we need physical scientists to figure out how much greenhouse gas emissions will warm the planet, how this will change weather patterns and so on. On the other, we need economists to estimate how these physical changes will affect productivity, health care costs and more.
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Gaza taps are running dry as water shortage reaches crisis point – NBC News

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The taps in the besieged Gaza Strip are running dry, and residents are scrambling to save every last drop of water as the shortage reaches a crisis point. 
Dunia Aburahma said her family has rationed supplies, allowing her only a quart of drinking water per day. 
“I haven’t taken a shower for four days now,” said Aburahma, 22, an architecture student who fled northern Gaza with her family last week ahead of Israel’s threatened ground invasion and is now living with relatives in Zawaida in central Gaza. 
After Hamas’ Oct. 7 attack on Israel left at least 1,400 people dead and about 200 people taken hostage, Israel announced a full blockade of Gaza, preventing food, water and fuel from entering the area, which is home to 2 million people. More than 2,800 people have been killed in Gaza, and about 12,000 more have been wounded. 
The lack of water is so dire that surgeons at Gaza City’s Al-Shifa Hospital have reverted to chemical disinfectants.
“Water pressure down in hospital to the point we can’t sterilize instruments,” Dr. Ghassan Abu-Sittah, a surgeon at the hospital, said in a message over WhatsApp.
At the heart of the water supply issue is the lack of fuel and electricity, which powers water pumps to treatment centers. Only about 10% of Gaza’s water comes from Israel; most of what residents drink is drilled locally, and it then needs to be treated to remove salt and contamination, said Elai Rettig, an assistant professor at Bar-Ilan University who studies environmental policy.
But about 50% of Gaza’s electricity comes from Israel, while the rest is generated in Gaza with diesel-powered generators. Much of Gaza’s fuel is trucked in from a refinery in Haifa, and Hamas has rapidly diminished Gaza’s supplies for its own use. Without enough fuel and electricity to run the desalination and water treatment plants, there’s no clean water to flow through the pipes, Rettig said in an interview Monday.  
“And so the major consequence of cutting electricity supply is not necessarily electricity but water supply to the population,” Rettig said. “And that’s where things can become a humanitarian crisis.” 
The United Nations Relief and Works Agency for Palestine Refugees in the Near East, or UNRWA, warned in a situation report Tuesday that “concerns over dehydration and waterborne diseases are high given the collapse of water and sanitation services.”
“Water remains a key issue as people will start dying without water,” the group said. 
U.S. Secretary of State Antony Blinken announced Monday that the U.S. and Israel “have agreed to develop a plan that will enable humanitarian aid” to reach civilians in Gaza. 
Even before the current conflict, 97% of the population of Gaza had to “rely on informal and unregulated private water tankers and small-scale informal desalination plants for drinking water,” according to a 2021 report by the United Nations High Commissioner for Human Rights. Direct pipelines were a luxury, and the risk of waterborne diseases was rampant. 
The private water tankers would load up at the nearest water stations and then go around to neighborhoods. Those who were in need of water could fill their tanks, which were usually placed on the roofs of their homes. 
But those tankers run on fuel, which is now in short supply. And water pulled directly from the ground, which would require electricity and then treatment, is unsafe to drink. 
“The situation is near-catastrophic,” Imene Trabelsi, a spokesperson for the International Committee of the Red Cross, said Tuesday, adding that there were already reports of water contamination, which can pose serious health risks.
Trabelsi said the two main water desalination stations in Gaza were no longer functioning. 
Aburahma’s family was among the approximately 1 million people who have been displaced in Gaza since the conflict began, according to the UNRWA. Many of them moved from northern Gaza to the south over the past several days after Israeli authorities said they would resume supplying water in the south as a way to make people leave the north amid an anticipated ground offensive against Hamas in Gaza City. 
Israel’s bombardments and the displacement of hundreds of thousands of people to the south have put pressure on Gaza’s infrastructure, and water hasn’t arrived in places where people need it. The UNRWA said Israel had supplied water for only three hours in parts of southern Gaza on Monday.
“We can’t get our clothes cleaned,” said Aburahma, who is staying at a relative’s house with 53 other people. “Whenever I need to clean some of the laundry, I fill a bottle of the water we keep and a bit of soap to clean them on my hands.” 
Jonathan Conricus, the international spokesman for Israel Defense Forces, blamed Hamas for using goods, including fuel, that could support civilians in Gaza. 
“The people in Gaza are not our enemies,” Conricus told NBC News’ Tom Llamas. “We are not targeting them.” 
Palestinian authorities say that even if Israel were to resume supplying more water, without power, it can’t be pumped to homes.
“For us as a water authority, if Israel pumps water, it cannot be supplied to the population due to the interruption of the electricity required to pump it,” the Palestinian Water Authority told NBC News in a Facebook message.
In the southern city of Khan Younis, where hundreds of thousands have fled after the evacuation order, the water pressure was so low that Rahaf Abuzarifa was using cups and buckets to collect any drops that would fall.
“We gave each a 2-liter bottle, and each one is managing his own bottle,” said Abuzarifa, 21, who is living in a house with 17 other people. 
Those 2 liters must last for three days, she said, adding that everyone in the family had taken a bath only once since the war broke out this month.
Mithil Aggarwal is a Hong Kong-based reporter/producer for NBC News.
Anna Schecter is a senior producer in the NBC News Investigations Unit.


Winter Outlook 2023-24: Awaiting Wetter Weather With El Niño's Return – North Carolina State Climate Office – North Carolina State Climate Office

Following a snow-free year in many areas and with drought now gripping more than half of the state, a pattern change – both from what we’ve seen in recent winters and in recent weeks – would be welcome.
So could the newly emerging El Niño be the answer? In our twelfth annual winter outlook, we’ll have a closer look at this year’s El Niño, some statistics among similar historical years, and our expectations for the winter ahead.
For the bottom line up front, here are some key takeaways from this year’s outlook:
We spent the past three winters in a La Niña pattern, which favors warm and dry weather for North Carolina. While the first of those events in 2020-21 was unusually wet with few signs of La Niña’s typical atmospheric impacts in our region, that was followed by more typical La Niña winters in 2021-22 and 2022-23.
But that once-unflinching La Niña faded fast this spring, clearing the way for the opposite end of ENSO: its namesake El Niño phase, characterized by warmer water in the equatorial Pacific Ocean and the atmospheric changes it induces.
This El Niño has been gaining strength all summer, with sea surface temperature anomalies over the past three months sitting at 1.5°C above average according to the Oceanic Nino Index, and 1.6°C above average in the so-called Nino 3.4 region – defined by a particular bounding box in the central Pacific that tends to best reflect changes in the tropical atmosphere.
That means a moderate to strong El Niño is already in place, with a classic “tongue” of warmer water extending from the west coast of South America across the Pacific.
The ocean is only half the story, though. ENSO is a coupled system between the ocean and atmosphere, particularly with wind patterns that extend around the world. And at least over the Pacific, NOAA’s ENSO Blog notes that the large-scale circulations, including the easterly trade winds, have been weakening, as is typical in an El Niño event.
One wrinkle is that some indicators don’t show such a strong atmospheric signal at the moment. The Multivariate ENSO Index, or MEI – which considers not just sea surface temperatures, but also air pressure, winds, and radiation changes across the Pacific – came in at just +0.6 (barely above the El Niño threshold of +0.5) in August and September, and actually decreased to +0.3 for the two-month period in September and October.
The large-scale wind and weather patterns extending beyond the Pacific and over North America also have yet to fully take shape. One way of viewing this is via the upper-level velocity potential. Simply put, it shows areas of convergence (or sinking air aloft, often associated with surface-level high pressure) and divergence (or rising air aloft, and commonly surface-level low pressure).
Entering our last strong El Niño winter in 2015-16, much of the continental United States was beneath a broad area of divergence, which certainly matches our weather pattern from that time. October 2015 was wet for most of North Carolina, and that wet pattern continued into the winter that followed.
This October, the eastern US was under an area of convergence, matching our observed dry weather pattern. While that doesn’t mean such a pattern will last through the winter, it does at least confirm that we haven’t seen El Niño’s expected local impacts just yet.
At the moment, most forecast models are showing a wintertime Nino 3.4 sea surface temperature anomaly of between 1.0°C and 2.5°C above normal, which would keep this event in the moderate to strong range. For comparison, the 2015-16 event was at the upper end of this range at 2.4°C above normal, and our last El Niño in 2018-19 was weaker, with an average Nino 3.4 anomaly of 0.7°C.
Accurate records of historical ENSO events begin in 1950, and in the 74 winters since then, 25 have reached the El Niño threshold per the ONI. Of those, 12 were in the same moderate to strong range we’re expecting this year.
On average across those dozen winters, we can see El Niño’s signature wetter-than-normal conditions along the Gulf of Mexico and up the east coast through the mid-Atlantic, including in North Carolina.
That tends to happen because a strong subtropical jet stream anchored to our south carries weather systems through the Gulf and up our coastline, where they pick up moisture and drop it as precipitation across our region.
Statewide, in these past moderate to strong El Niño events, 9 of the 12 were wetter than normal for the climatological winter, from December through February. Each of the past three such winters – in 1997-98, 2009-10, and 2015-16 – ranks among our top ten wettest on record. All of that gives us fairly high confidence in having wetter weather during an El Niño winter.
On a month-by-month basis, November was also wetter than average 9 of 12 times, December and January were each wetter in 7 cases, and 10 of 12 Februarys were on the wet side. But if we’re still awaiting drought-relieving rains by March, then El Niño is no guarantee of that. Just 5 of the 12 moderate to strong El Niño winters were followed by a wet March.
In terms of temperatures, we often used to say that El Niños tend to be both wetter and cooler for North Carolina, but that has not been the case in recent years. While 5 of the 7 El Niño events prior to 1990 were cooler than the 20th-century average, the five events since then have each been warmer than average, including our 10th-warmest winter on record in 2015-16.
Climate change is one cause, since winter is when we’ve seen the most pronounced warming trend, as the North Carolina Climate Science Report notes. In addition, during recent strong El Niños in 1997-98 and 2015-16, the supercharged jet stream has pumped in almost-tropical air at times and prevented any sustained blasts of cold air from setting up this far south.
That 2015-16 winter began with our warmest December on record, and only 3 of the 12 moderate to strong El Niño winters have been cooler in December. However, January and February were each cooler than average in nine of those years, which offers some hope of an eventual cooldown this season.
While warming temperatures have cut down on our average snowfall, El Niño events generally remain one of our best opportunities for wintry weather thanks to the storm systems that frequent our state.
In moderate to strong El Niño winters like we’re expecting this year, we’ve seen above-average snowfall in most areas, including 10.3 inches in Greensboro (vs. an average of 8.4 inches), 6.3 inches in Charlotte (vs. 4.9 inches) and 7.0 inches in Raleigh (vs. 6.4 inches).
Take note, though, that snow is rarely a safe bet especially the farther east you go, and more than half of the moderate to strong El Niño winters have had below-average snowfall across the Coastal Plain, offset by a few years with sizable accumulations.
Finally, a look at these past winters shows that a stronger El Niño tends to have more pronounced impacts in North Carolina. During the six strongest events – with a wintertime ONI greater than 1.5 – we averaged half an inch more precipitation, as compared against all moderate to strong events.
In those strongest El Niño winters, our average temperatures were also more than a degree warmer, and accordingly, we’ve seen a reduction in snowfall across the Mountains and Piedmont. So if this year’s El Niño is on the stronger side, then that could spell better news for drought relief, but perhaps worse odds of snow.
Based on the current average of ENSO forecast models, we expect a relatively strong El Niño event in place this winter, with the ONI and Nino 3.4 anomalies peaking at about 2.0°C.
However, we don’t expect the immediate arrival of El Niño’s typical impacts. Given our recent dryness and the slower emergence of an El Niño-like jet stream pattern over North America this fall, it may take a bit more time before wetter weather kicks in.
That was the case in 1965-66, when we slipped into a fall drought that developed under a similar pattern of upper-level convergence and surface high pressure over the eastern US. By that November, the state Secretary of Agriculture declared a drought emergency in parts of the Mountains while wildfire activity picked up at the coast. However, by the middle of January in 1966, the winter had arrived, to the relief of drought-weary farmers and children eager to play in the snow.
We likewise expect an eventual shift to wetter-than-normal conditions in January or February – if not both. This matches the historical odds during moderate to strong El Niño winters. Only one of those events, in 1991-92, had all three winter months finish with below-average precipitation statewide, and in that case, each month was within an inch of the long-term average.
With that said, we don’t expect a totally clear drought map by the end of winter. Given the current seasonal precipitation deficits of 5 to 10 inches, it would take an almost historically wet winter to fully overcome those in just three months.
For instance, Wilmington is 9.76 inches below normal so far this fall, and only two times – during the strong El Niños of 1982-83 and 1997-98 – has the Port City finished winter more than 10 inches above normal.
Fortunately, even average precipitation this winter could still make a dent in the drought and the impacts we’re currently feeling, particularly tamping down the wildfire activity and boosting reservoir levels and groundwater storage.
Our overall winter temperatures may hinge on how strong this El Niño ends up getting, with a stronger event making warmer-than-normal weather more likely. Consistent with NOAA’s winter outlook, which gives most of North Carolina slightly elevated odds of being warmer than normal, we expect near- to above-normal temperatures on average this winter, but with the potential for at least brief cooler stretches by January or February.
If that happens, then it may be because of help from large-scale patterns besides ENSO that can also shape our weather. While they’re tough to predict this far ahead of time, it’s worth watching for a potentially weakening polar vortex or high pressure parked to our north in a classic “cold air damming” setup, since both of those could send shots of chilly air in our direction.
And yes, a timely combination of cold air and moisture, with just the right amounts of each, could mean frozen precipitation. The historical odds favor at least one measurable snowfall for most of the state this winter. Among the 12 moderate to strong El Niño events, only once has central and eastern North Carolina gone the entire season without snow. That happened in 1991-92, which was also a below-average year in the Mountains, with only 2.5 inches in Asheville.
Of course, whether we meet or exceed our normal snowfall often comes down to whether we get one or two big events. That was the case during our last El Niño winter in 2018, which started with a significant winter storm in early December that brought more than a foot of snow to parts of the Mountains and northern Piedmont.
After that, we saw little to no snow for the remainder of the winter, but many areas still finished above average thanks to that one event. That was also the last 6”+ snow event for parts of the Piedmont, while there has been an even longer wait for areas farther south and east.
Whether it’s frozen or liquid, any precipitation would help at this point, so whether you dream of a White Christmas or a wet one, let’s hope this winter – and the El Niño pattern that is usually one of our most reliable bets for wet weather – delivers much moisture in any form.
Published in Climate Blog, Seasonal Outlook.
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