Is climate change real?

Yes, climate change is real. It refers to long-term shifts in temperatures and weather patterns, and the current rapid warming of Earth’s climate system is unequivocally happening and is primarily driven by human activities.[1]

Scientific Consensus

There is overwhelming agreement among climate scientists and in the peer-reviewed literature:

•Multiple studies of scientific papers find greater than 99% consensus that humans are the main cause of recent climate change (e.g., a 2021 analysis concluded the consensus exceeds 99%).[2]

•Earlier widely cited figures were around 97%, and the consensus has strengthened over time.[3]

•Major scientific organizations—including NASA, NOAA, the IPCC, the American Meteorological Society, the American Association for the Advancement of Science, and numerous national academies of science—endorse this view. There is no credible scientific body that broadly rejects it.[4]

The Intergovernmental Panel on Climate Change (IPCC), which assesses the full body of climate science, states it is “unequivocal” that human influence has warmed the atmosphere, ocean, and land.[5]

Key Evidence That the Climate Is Changing

Multiple independent lines of evidence from observations, paleoclimate records (ice cores, tree rings, sediments), satellites, and instruments confirm rapid change:

•Global temperatures are rising: Earth’s average surface temperature has increased by about 1.1°C (roughly 2°F) since the pre-industrial period (1850–1900). Each of the last several decades has been successively warmer. 2023 and 2024 were the warmest years on record.[6]

•Oceans are warming and absorbing heat: About 90% of excess heat is stored in the oceans, leading to record ocean heat content, marine heatwaves, and thermal expansion.[7]

•Ice loss: Arctic sea ice extent has declined dramatically (nearly 40% at summer minimum since 1979); glaciers and ice sheets (Greenland, Antarctica) are melting; spring snow cover is shrinking.[8]

•Sea levels are rising: Global mean sea level has risen 8–9 inches (20–23 cm) since 1880, with the rate accelerating due to ice melt and thermal expansion.[8]

•Other indicators: Changes in extreme weather (more intense heatwaves, heavy precipitation in some areas, droughts), shifts in species ranges and phenology (e.g., earlier blooming/migrations), and rising atmospheric greenhouse gas concentrations.[9]

These changes are occurring at rates unprecedented in thousands of years in many cases.[10]

Primary Cause: Human Activities

The main driver is the enhanced greenhouse effect from increased atmospheric concentrations of carbon dioxide (CO₂), methane, nitrous oxide, and other gases, primarily from burning fossil fuels, deforestation, and industrial processes.[11]

•CO₂ levels have risen from ~280 ppm pre-industrially to over 410–420+ ppm recently—higher than at any time in at least the last 800,000 years (and likely much longer), with a distinctive isotopic fingerprint matching fossil fuels.[12]

•Natural factors (solar variability, volcanoes, orbital cycles) cannot explain the observed warming pattern. For example, the upper atmosphere is cooling while the lower atmosphere and surface warm—a fingerprint of greenhouse gases—and solar output has been stable or slightly declining.[11]

•IPCC attribution: Human-caused warming accounts for essentially all of the observed ~1.1°C rise (best estimate of human-induced warming ~1.07°C), with natural contributions near zero.[5]

Climate has always varied naturally over Earth’s history, but the current rate and magnitude of change, combined with the well-understood physics of greenhouse gases and direct observations of human emissions, make human influence the dominant cause of recent (post-Industrial Revolution) warming.[13]

In short, the evidence from physics, observations, and models is robust and has only strengthened over decades of research. For the latest details, see reports from the IPCC (AR6), NASA, and NOAA.

Citations (13)

1ipcc.chGovernment
https://report.ipcc.ch/ar6syr/headline.html
Backs: “It refers to long-term shifts in temperatures and weather patterns, and the current rapid warming of Earth’s climate system is unequivocally happening and is primarily driven by human activities.”
2iop.orgAcademic
https://iopscience.iop.org/article/10.1088/1748-9326/ac2966
Backs: “Multiple studies of scientific papers find greater than 99% consensus that humans are the main cause of recent climate change (e.g., a 2021 analysis concluded the consensus exceeds 99%).”
3nasa.govGovernment
https://science.nasa.gov/climate-change/scientific-consensus/
Backs: “Earlier widely cited figures were around 97%, and the consensus has strengthened over time.”
4climate.govGovernment
https://www.climate.gov/news-features/climate-qa/isnt-there-lot-disagreement-among-climate-scientists-about-global-warming
Backs: “There is no credible scientific body that broadly rejects it.”
5ipcc.chGovernment
https://www.ipcc.ch/report/ar6/wg1/chapter/chapter-3
Backs: “The Intergovernmental Panel on Climate Change (IPCC), which assesses the full body of climate science, states it is “unequivocal” that human influence has warmed the atmosphere, ocean, and land.”
6nasa.govGovernment
https://science.nasa.gov/earth/earth-observatory/2024-was-the-warmest-year-on-record-153806/
Backs: “Each of the last several decades has been successively warmer. 2023 and 2024 were the warmest years on record.”
7nasa.govGovernment
https://science.nasa.gov/earth/explore/the-ocean-and-climate-change/
Backs: “About 90% of excess heat is stored in the oceans, leading to record ocean heat content, marine heatwaves, and thermal expansion.”
8climate.govGovernment
https://www.climate.gov/climatedashboard
Backs: “Arctic sea ice extent has declined dramatically (nearly 40% at summer minimum since 1979); glaciers and ice sheets (Greenland, Antarctica) are melting; spring snow cover is shrinking.”
9nasa.govGovernment
https://science.nasa.gov/climate-change/evidence/
Backs: “Changes in extreme weather (more intense heatwaves, heavy precipitation in some areas, droughts), shifts in species ranges and phenology (e.g., earlier blooming/migrations), and rising atmospheric greenhouse gas concentrations.”
10ipcc.chGovernment
https://www.ipcc.ch/report/ar6/syr/longer-report/
Backs: “These changes are occurring at rates unprecedented in thousands of years in many cases.”
11nasa.govGovernment
https://science.nasa.gov/climate-change/causes/
Backs: “The main driver is the enhanced greenhouse effect from increased atmospheric concentrations of carbon dioxide (CO₂), methane, nitrous oxide, and other gases, primarily from burning fossil fuels, deforestation, and industrial processes.”
12archive.mdData and tools
https://archive.md/2024.11.07-200429/https://www.climate.gov/news-features/climate-qa/what-evidence-exists-earth-warming-and-humans-are-main-cause
Backs: “CO₂ levels have risen from ~280 ppm pre-industrially to over 410–420+ ppm recently—higher than at any time in at least the last 800,000 years (and likely much longer), with a distinctive isotopic fingerprint matching fossil fuels.”
13royalsociety.orgAcademic
https://royalsociety.org/news-resources/projects/climate-change-evidence-causes/
Backs: “Climate has always varied naturally over Earth’s history, but the current rate and magnitude of change, combined with the well-understood physics of greenhouse gases and direct observations of human emissions, make human influence the dominant cause of recent (post-Industrial Revolution) warming.”