Global Warming / Climate Change Frequently Asked Questions (FAQ)

1. What is global warming?
2. What causes global warming?
3. What is climate change? Is it different from global warming?
4. What is a climate change impact?
5. What does global warming have to do with severe weather, like storms, heat waves, droughts, and hurricanes?
6. If global warming is real, why is it so cold and snowy this winter? (The difference between climate and weather.)
7. What does global warming have to do with rising sea levels?
8. What is ocean acidification?
9. What does production of meat and dairy products have to do with climate change?
10. What does climate change have to do with health?
11. How does climate change affect the food supply?
12. What is a carbon footprint, and how can I reduce my carbon footprint?
13. What are renewable sources of energy?
14. What is energy efficiency?
15. What is climate change adaptation?
16. What is climate change mitigation?
17. What is climate change resilience?
18. What is the United States doing to address climate change?
19. What are corporations doing to combat climate change?
20. What is the United Nations doing to combat climate change?
21. What is climate finance?
22. Is there hope that we will be able to address climate change before it is too late?
Other recommended climate change FAQs elsewhere on the web

This FAQ was last updated in September 2026

Download this FAQ (PDF with endnotes)

1. What is global warming?

Global warming refers to the increase in average global temperature since the Industrial Revolution. The average global temperature has increased by about one degree Celsius (1.8 degrees Fahrenheit) since 1880, when measurements were first taken. The year 2024 was the hottest year on record. Global warming is an ongoing process. Looking ahead, the World Meteorological Organization projects that average global temperatures will continue to rise through 2030, running between 1.3°C and 1.9°C (2.3–3.4°F) above average pre-industrial levels each year.

Land and ocean temperature index from 1880 to 2025, using 1951-1980 as the base period. Source: NASA Goddard Institute for Space Studies

2. What causes global warming?

Certain gases, such as carbon dioxide and methane, trap the sun's heat in Earth’s atmosphere. These greenhouse gases (GHGs) exist naturally in the atmosphere and help keep the Earth’s surface warm enough to sustain life. Without greenhouse gases, the average temperature on Earth would be would be 0°F, instead of today's roughly 59°F.

Human activities, notably the burning of fossil fuels (i.e., coal, natural gas, and oil) to power vehicles, factories, and homes, release carbon dioxide and other greenhouse gases into the atmosphere. Other activities, including deforestation (cutting down trees) and raising livestock, also emit greenhouse gases.

Higher concentrations of these greenhouse gases in the atmosphere trap more heat on Earth, causing an anthropogenic (i.e., human-caused) rise in global temperatures. Climate scientists agree that human activity is the main driver behind the global warming we are experiencing.

3. What is climate change? Is it different from global warming?

The terms climate change and global warming are often used interchangeably, but climate change broadly refers to persistent changes in average weather (e.g., temperature, precipitation, humidity, wind, atmospheric pressure, ocean temperature, etc.) while global warming narrowly refers to a rise in the Earth’s average global temperature.

Climate change can refer to natural fluctuations in the Earth’s average temperature throughout geologic time, between cold periods (glacial periods, known as ice ages) and warm periods (interglacial periods).

The climate change we are currently experiencing, however, is caused by human activity (see question 2). Scientists have concluded that, over the last 50 years, the Earth’s surface should have been cooling slightly based on natural factors, like solar intensity and volcano activity; instead, the increased burning of fossil fuels has led to global warming—and at a significantly faster rate than at any time over the last 800,000 years.

4. What is a climate change impact?

The rise in average global temperatures because of human activities has many impacts on the planet, including more intense and frequent droughts and storms, melting glaciers and ice sheets, rising sea levels, warming oceans, and ocean acidification (see question 8). People around the world are already feeling the impact of climate change on the environment. Changing weather patterns can ruin crops and cause serious water shortages. Rising sea levels are threatening low-lying islands and coastal cities. Tropical and insect-borne diseases are spreading as their hosts move into new habitats that were previously too cold for them to survive.

Climate change represents a significant threat to the health and well-being of human societies, especially in communities that lack resources and are therefore ill-equipped to deal with the effects of a warmer climate.

5. What does global warming have to do with severe weather, like storms, heat waves, droughts, and hurricanes?

A rise in global temperatures increases the severity and likelihood of storms, floods, wildfires, droughts, and heat waves. In a warmer climate, the atmosphere can collect, retain, and drop more water, leading to changing precipitation patterns. Increased precipitation can help support agriculture, but precipitation is increasingly coming in the form of more intense single-day storms, which damage property, infrastructure, and lead to loss of life in impacted areas. Over the past few decades, the United States has experienced more heat waves and fewer cold waves. Since the 1960s, the number of heat waves per year has tripled from two to six and the average length of the heat wave season in major U.S. cities has increased by 46 days. Global warming also results in warmer sea surface temperatures because the majority of the heat trapped in the Earth’s atmosphere is absorbed by the ocean. Warmer sea surface temperatures make it easier for hurricanes to form. Because of human-caused global warming, it is expected that the rainfall rates from hurricanes will increase, the intensity of hurricanes will increase, and more storms will reach Category 4 or 5 intensity on the Saffir-Simpson Hurricane Wind Scale.

It is difficult for researchers to attribute a specific weather event to global warming. Nevertheless, climate scientists are confident that higher average global temperatures are making extreme weather more likely and severe. The United States is seeing a clear increase in the number of destructive weather and climate disasters at the same time that more people are living in vulnerable coastal and river floodplains. The table below, based on National Oceanic and Atmospheric Administration (NOAA) and Climate Central data, shows the number and impact of billion-dollar disasters by decade from 1980 to 2025.

Source: National Centers for Environmental Information, National Oceanic and Atmospheric Administration (NOAA) and Climate Central

6. If global warming is real, why is it so cold and snowy this winter? (Or: What is the difference between climate and weather?)

The key to understanding the answer to this question is the difference between weather and climate. Weather is what is happening outside today, while climate is an area's typical weather. For example, there might be a very rainy day in Los Angeles, but typically the city's climate is dry. As the average global temperature increases, winters are more likely to be shorter and less snowy. However, there are still cold days and colder than average years due to changes in atmospheric circulation associated with weather patterns.

For snow to occur, moisture and freezing air temperatures must be present. These conditions are still likely in the winter, especially in areas that experience temperatures well below freezing. Therefore, global warming does not prevent snowy winters. In fact, in some areas, global warming may result in more intense winter storms. For example, it is likely that the Northeast United States will see more intense winter storms (although they may be more infrequent) because the increase in sea surface temperature feeds more intense storms.

7. What does global warming have to do with rising sea levels?

This graph shows the change in global sea level from1993 to mid-2026, as observed by satellites. Source: NASA

Global warming contributes to rising sea levels in two main ways. First, warmer temperatures cause glaciers and land-based ice sheets to rapidly melt, which moves water from land to the ocean. Areas experiencing significant ice melt include Greenland, the Antarctic, and mountain glaciers around the world.

Second, thermal expansion, the process by which warmer water takes up more space, is causing the ocean to increase in volume, which leads to rising sea levels.

Other factors affect sea levels, and the combination of all these factors leads to different rates of sea level rise across the planet. Local factors that can cause the sea level to rise faster in certain areas include ocean currents and sinking ground surfaces (known as subsidence).

Since 1880, global average sea level has increased by almost 10 inches. Under a low-emissions scenario, models project that sea level rise will increase about one foot above 2000 levels by the end of the century. Under a high-emissions scenario, sea level could rise more than six feet above 2000 levels by 2100. In either case, this would increase the risk of coastal flooding and endanger millions of people living in low-lying coastal areas like New York, Los Angeles, and Miami.

8. What is ocean acidification?

The ocean is a central component of the carbon cycle. Carbon constantly cycles between the ocean, land, and atmosphere (this is called the carbon flux). Sea water absorbs 25–30% of carbon dioxide emissions. As humans introduce more carbon dioxide into the atmosphere (see question 2), the ocean is absorbing a greater volume of carbon dioxide. This changes the ocean's chemical composition and is referred to as ocean acidification, which is measured in pH (lower pH values are more acidic). The pH value of the ocean has decreased by 0.1 pH units, which is about a 30% increase in acidity. This change is enough to affect many marine organisms. For example, acidification stunts shellfish shell formation and can even cause shells to dissolve.

9. What does production of meat and dairy products have to do with climate change?

Livestock contribute to climate change both directly, through their digestive processes, and indirectly, because of the vegetation that is cleared to make room for animal agriculture.

Agriculture as a whole is responsible for 10% of U.S. greenhouse gas emissions. Global agricultural emissions mostly come from the digestive process of ruminant animals (such as cows, sheep, and goats), which represents 39% of the total, but also from manure left on pastures, synthetic fertilizers, rice cultivation, manure management, burning to clear land, and soil and crop residue management.

Livestock, especially cattle, produce methane through their digestion. Livestock manure also emits methane. Taken together, livestock and manure emissions are responsible for 38% of total U.S. methane emissions. Methane is a potent greenhouse gas that has 25 times the heat trapping impact of carbon dioxide over a 100-year time period.

Forests have often been cut down or burned to obtain land for livestock production, which releases carbon dioxide into the atmosphere and destroys a natural carbon absorber. Economic development and population growth are leading to greater meat and dairy consumption worldwide, making livestock a rising contributor to climate change. There are ways to reduce greenhouse gas emissions from livestock operations, including capturing methane from manure and changing animal feeding practices.

10. What does climate change have to do with health?

Rising global temperatures exacerbate heat-related diseases, such as heat exhaustion and heatstroke, as well as cardiovascular, respiratory, and kidney diseases. Extreme heat kills about 700 people in the United State every year. Since 1990, more people have died of extreme heat in the United States than from cold snaps, floods, hurricanes, or tornadoes.

Climate change also impacts food-borne diseases because higher temperatures can increase the abundance and range of many pathogens, as well as their growth rates and survivability.

Water availability and water-borne or associated illnesses are also impacted by climate change. Regions that depend on snow melt for drinking water may have less available water, because less snow is accumulating during the winter. Increased flooding caused by extreme weather events can intensify water-borne and associated diseases by providing standing water that acts as a breeding ground for insects, like mosquitoes, that spread diseases. Flooding can also result in water unsafe to drink or bathe in because of contamination from bacteria that causes cholera or typhoid fever). Warmer temperatures have caused increased toxic algae blooms in lakes in some parts of the country.

Changes in climate will also affect where disease vectors (such as insects, snails, and other cold-blooded animals) can live by extending or shifting their ranges and the length of the transmission season.

11. How does climate change affect the food supply?

By increasing the frequency and intensity of droughts, floods, and storms, climate change can impact farmers’ ability to grow crops and the infrastructure necessary to transport and store food supplies. Changes in seasonal weather patterns that farmers are accustomed to also make it more difficult for them to plan their plantings and harvests. Warming ocean temperatures are causing range shifts for fish and shellfish species, which affects fisheries.

Though plants need carbon dioxide to grow, higher levels of carbon dioxide in the atmosphere are not necessarily beneficial for agriculture. Researchers have found that higher levels of carbon dioxide result in crops with lower nutritional value.

12. What is a carbon footprint, and how can I reduce my carbon footprint?

A carbon footprint is the amount of carbon emitted by the actions of a person, group, household, organization, or activity over a given time period, primarily due to the consumption of fossil fuels. The more fossil fuels are consumed during an activity, the larger the carbon footprint (for example, flying in a passenger jet results in a larger carbon footprint than taking a train to cover the same distance). Activities that are part of the natural carbon cycle, such as breathing, are not counted. A carbon footprint can also include emissions of methane and other greenhouse gases based on calculations to determine their carbon equivalent).

Reducing or offsetting greenhouse gas emissions by improving energy efficiency, using renewable energy, and adopting sustainable practices is the best way to reduce a carbon footprint. Taking public transportation, using light-emitting diode (LED) light bulbs, and reducing food waste are just a few of the many ways you can reduce your carbon footprint and fight climate change. For more easy ways to reduce your carbon footprint, see EESI's Get Involved page.

13. What are renewable sources of energy?

Share of U.S. renewable energy generation by source. Data Source: EIA (2026)

Renewable sources of energy come from natural resources—like sunlight, plant matter (biomass), geothermal activity, water, and wind—that are not depleted when used (or can be regrown, in the case of plant matter) and emit zero or low levels of carbon dioxide. Increasing global investment in renewable energy technologies has been acknowledged by the overwhelming majority of climate change experts and world leaders to be an essential strategy for reducing greenhouse gas emissions.

In contrast, nonrenewable sources of energy—like fossil fuels—are finite resources that cannot be easily replenished when consumed. Nonrenewable sources like coal, natural gas, and oil emit greenhouse gases when burned.

Common sources of renewable energy are solar, wind, geothermal, and hydropower as well as certain forms of biomass. Renewable technologies like wind turbines and solar panels have become increasingly cost-competitive as their production costs continue to fall. Renewable energy accounted for 26% of the electricity generated in the United States in 2025.

14. What is energy efficiency?

Energy efficiency involves using less energy to perform the same task. For example, a typical incandescent light bulb used about 60 watts (a measurement of energy) to provide about 800 lumens (a measurement of brightness of a light source). In comparison, a compact fluorescent bulb could deliver the same light output for 15 watts. A modern, high-efficiency light-emitting diode (LED) bulb can illuminate the same space for nine watts or less.  

Energy efficiency brings a variety of benefits. Improving energy efficiency is the cheapest—and among the most immediate—ways to reduce the use of fossil fuels to generate electricity. Lowering energy consumption can effectively reduce stress and strain on the electric grid, especially during heat waves and other times of unusually high demand, which helps utilities manage maintenance and ensure system resilience and reliability.  Energy efficiency is also an important opportunity to reduce costs for homeowners, renters, small businesses, and other consumers when utility rates are increasing. Energy efficiency represents an enormous opportunity to cut costs and emissions in residential and commercial buildings, industrial facilities, transportation, energy and water infrastructure, and across all other sectors of the economy.

15. What is climate change adaptation?

Climate adaptation means adjusting to the current and expected impacts of climate change. It can apply to habitats, but also to societies and economies. Adaptation usually involves preparing for harmful effects (such as rising sea levels and more frequent and intense extreme weather), but it can also prepare communities to benefit from climate change opportunities. Examples of climate adaptations include planting salt-tolerant crops or adding gypsum to soil to counteract saltwater intrusion, moving homes away from a coastline or putting those homes on stilts to reduce flood and storm surge risk, and planting trees or using reflective roofing materials in cities to decrease intense heat made worse by the urban heat island effect. Nature-based solutions are an important form of climate adaptation. Examples of nature-based solutions include the tree example above, green roofs which absorb storm water and reduce temperatures, and living shorelines that can absorb storm surge during extreme weather events.

16. What is climate change mitigation?

Climate change mitigation means reducing or stabilizing the level of greenhouse gases in the atmosphere. This can be done by removing carbon from the atmosphere, for example by expanding forested land, or by emitting fewer greenhouse gases.

17. What is climate change resilience?

Resilience is the ability of a system to absorb, withstand, and bounce back after an adverse event. In an environmental context, it is the collection of policies, infrastructure, services, transportation, energy systems, and planning that positions communities to prepare for and respond to the impacts of climate change.

Communities that plan with resilience in mind are better able to adapt and thrive in the face of a changing climate. For the communities that are most vulnerable to climate impacts, planning for resilience can prevent displacement or facilitate planned relocation and reduce devastating financial losses and fatalities.

18. What is the United States doing to address climate change?

The United States has taken steps (at both the federal and state levels) to address climate change by increasing the nation’s use of renewable energy and curbing greenhouse gas emissions through energy efficiency initiatives and carbon pollution standards. But U.S. federal climate policy has ebbed and flowed across successive administrations, even as state-level initiatives and economic momentum have continued to drive U.S. greenhouse gas emissions lower.

The Trump Administration has reversed climate policies enacted by previous administrations. In some cases, Congress is continuing to work on the issue of climate change by holding 180 hearings on relevant topics in 2025 and maintaining tax credits for geothermal, nuclear, and hydropower projects.

In 2016, the United States signed and ratified the Paris Agreement on climate change, joining with almost every country in the world to limit global warming to “well below 2 degrees Celsius” (3.6 Fahrenheit) in the 21st century. The United States withdrew from the Paris Agreement under the first Trump Administration, rejoined under the subsequent Biden Administration, and has withdrawn again under the second Trump Administration (effective January 27, 2026).

Much of tangible climate policy action is now happening at the state level. Members of the U.S. Climate Alliance, which consists of 24 governors representing roughly 60% of the U.S. economy and 55% of its population, have pledged to cut the collective net greenhouse gas emissions of their states by 61–66% by 2035 compared to 2005, with a goal of net-zero emissions by 2050. The Alliance has already cut net emissions by 24% while still growing its collective GDP by 34%. As of August 2025, 22 states and the District of Columbia have set their own greenhouse gas reduction targets.

Economic trends have also contributed to lower carbon emissions. Natural gas and renewable energy are cheaper than coal for electricity generation, so coal-fired power, which is particularly harmful for the climate, continues to decline. As dependence on coal has decreased the power sector has been replaced by the transportation sector as the largest source of U.S. greenhouse gas emissions. The transportation sector now represents about 28% of total U.S. emissions compared to 25% for the power sector.

19. What are corporations doing to combat climate change?

Investors and companies across the globe are embracing the shift from fossil fuels to cleaner energy. Many large corporations have stepped up to show their public support for U.S. carbon cutting efforts and have invested in projects combating climate change. 

Thousands of businesses and investors are part of the America Is All In network in support of climate action and 82% of corporate leaders are in favor of transitioning to renewable energy. Moody's, whose ratings play an essential role in financial markets, includes climate risk in its corporate ratings.

A February 2026 study found that half of U.S. publicly traded companies in climate-relevant industries are still developing climate solutions even though federal incentives have been scaled back. New coalitions have also formed to fill funding gaps left by reduced federal support, including the All Aboard Coalition, a venture-capital collaborative launched in 2026 that aims to mobilize at least $300 million for climate technology startups.

20. What is the United Nations doing to combat climate change?

The United Nations has been instrumental in facilitating international negotiations on efforts to combat climate change through the United Nations Framework Convention on Climate Change (UNFCCC) and the Intergovernmental Panel on Climate Change (IPCC). The UNFCCC brings together 198 members for work sessions throughout the year. During the annual Conference of the Parties (COP), nations share information on emissions, policies, and practices, and attempt to develop strategies for addressing climate change. The IPCC consults experts to assess climate change science and presents policy-relevant information outlining how nations can mitigate greenhouse gas emissions and adapt to the impact and risks of this global threat.

In 1997, the members of the UNFCCC negotiated the Kyoto Protocol, a legally binding agreement that compelled developed nations to reduce greenhouse emissions over the course of two commitment periods (2008-2012 and 2013-2020). At the 2015 Conference of the Parties, countries adopted the Paris Agreement on climate change. The Paris Agreement entered into force in November 2016, less than a year after it was adopted. As of July 2026, 194 parties (193 countries plus the European Union) have ratified the Paris Agreement. The United States initially joined the Paris Agreement but is in the process of withdrawing from it under the Trump Administration. The parties agree to limit global warming to “well below 2 degrees Celsius” (3.6 Fahrenheit) this century. Participating countries are expected to submit their own country-specific emission reduction targets, known as Nationally Determined Contributions.

In 2015, the United Nations adopted 17 Sustainable Development Goals (SDGs) that are meant to serve as a blueprint for action on critical development issues, such as ending poverty and hunger. Goal number 13 (SDG 13) is "Climate Action," which calls on nations to reduce their greenhouse gas emissions and to prepare their communities for the impacts of climate change. The need to address climate change is also woven throughout the other goals.

In 2025, the International Court of Justice, the United Nations’ judicial branch, issued an advisory opinion concluding that states have an obligation to prevent significant harm to the climate under international law. The UN General Assembly passed a resolution in May 2026 backing the court’s ruling.

21. What is climate finance?

Climate finance facilitates the deployment of the large-scale investments in energy efficiency and renewable energy needed to reduce emissions, as well as the investments in climate adaptation and resilience needed to help communities prepare for the harmful impacts of climate change. Different entities exist at the international, national, and local levels to facilitate the mobilization and deployment of climate finance. For example, the Global Environment Facility and the Green Climate Fund are two major climate finance vehicles at the international level. State green banks and infrastructure authorities play a similar role in states across the United States. These entities receive their funding from a variety of sources, including grants from governments, private organizations, public benefit funds, bonds, and carbon pricing mechanisms (e.g., the Regional Greenhouse Gas Initiative (RGGI) in the Northeast United States or California’s cap and trade program). Climate finance facilities use a variety of financing mechanisms to invest their funds, including loans, public-private partnerships, power purchasing agreements, and on-bill financing.

22. Is there hope that we will be able to address climate change before it is too late?

Even though climate change is a pressing threat that is not going away, we can have a significant impact on how it affects us in the near future. By investing in renewable energy and energy efficiency, people, communities, businesses, and governments can reduce the amount of greenhouse gas emissions reaching the atmosphere and slow global warming. This will help minimize the consequences of climate change in the present and for future generations.

In addition, through adaptation and resilience efforts, we can and must prepare an infrastructure built to withstand the impacts of climate change, protecting the lives of millions of people currently living in vulnerable areas. Such investments will also greatly reduce the costs of extreme weather events and other disasters. We know what needs to be done, and that is a critical step in the right direction!

Authors: Hannah Wilson-Black, Jasmyn Mirsepahi, Anna McGinn, Ethan Anabel, Carol Werner, and Brian La Shier

Editors: Daniel Bresette and Amaury Laporte