Are humans responsible for climate change?

Yes

Yes, humans are the primary cause of the current rapid climate change (global warming). This is the overwhelming scientific consensus, based on multiple independent lines of evidence from observations, physics, paleoclimate records, and climate models.[1]

Scientific Consensus

The Intergovernmental Panel on Climate Change (IPCC), which synthesizes the work of thousands of climate scientists worldwide and whose summaries are approved by governments, states in its Sixth Assessment Report (AR6, 2021):
> “It is unequivocal that human influence has warmed the atmosphere, ocean and land.”

Observed increases in well-mixed greenhouse gases (GHGs) since around 1750 are unequivocally caused by human activities. The likely range of human-caused global surface temperature increase from 1850–1900 to 2010–2019 is 0.8–1.3°C (best estimate 1.07°C), which accounts for essentially all the observed warming of ~1.1°C. Natural drivers (solar and volcanic) contributed roughly –0.1 to +0.1°C, and internal variability ±0.2°C.[2]

Surveys of the scientific literature and experts show extremely high agreement:

•Multiple studies find 97%+ of climate scientists and peer-reviewed papers agree that humans are the main cause; more recent analyses put it above 99% (e.g., >99.9% in a 2021 review of ~88,000 papers).[3]

•Leading scientific organizations (NASA, NOAA, AAAS, National Academies, Royal Society, and many others) endorse this position.[1]

Key Evidence

1.Greenhouse gas increases from human activities: Atmospheric CO₂ has risen ~50% since pre-industrial times (to over 410–420 ppm), with methane and nitrous oxide also rising sharply. These levels are unprecedented in at least 800,000 years. The isotopic “fingerprint” (e.g., depleted ¹³C and ¹⁴C) matches fossil fuel burning and land-use changes, not natural sources like volcanoes or the ocean. Humans have disturbed the carbon cycle by extracting and burning long-buried fossil fuels.[4]

2.Basic physics and the greenhouse effect: CO₂, methane, and other GHGs trap heat. This is well-established science dating back to the 19th century. Human emissions enhance the natural greenhouse effect.

3.Attribution and fingerprinting:

•Climate models reproduce the observed warming only when human GHG emissions (and other anthropogenic factors like aerosols) are included. Natural forcings alone cannot explain it.

•Patterns match human influence: warming of the troposphere/lower atmosphere and surface, cooling of the stratosphere/upper atmosphere (opposite of what increased solar output would do); ocean heat content rise; cryosphere loss; etc.[5]

•The rate of recent warming is unusually rapid compared to natural changes over millennia.

4.Ruling out natural causes: Solar output has been stable or slightly decreasing in recent decades. Orbital (Milankovitch) cycles operate over tens of thousands of years and are not driving the current multi-decadal trend. Volcanic activity and internal variability (e.g., El Niño) cause shorter-term fluctuations but not the long-term rise.[4]

Context and Nuance

Earth’s climate has always varied naturally (ice ages, etc.), but the current change is happening far faster and is driven primarily by human GHG emissions since the Industrial Revolution—mainly fossil fuel combustion, plus deforestation, agriculture, and industry. Human influence is now detectable in many extremes (heatwaves, heavy precipitation, etc.) and impacts across the globe.[6]

While details of future projections, regional impacts, and exact climate sensitivity involve ongoing research and some uncertainty ranges, the core conclusion—that humans are responsible for the bulk of recent warming—is settled science at a very high confidence level (comparable to or stronger than many other established scientific findings).

For primary sources, see IPCC AR6 reports, NASA Climate, NOAA Climate.gov, and the Royal Society’s evidence summaries.

Citations (6)

1nasa.govGovernment
https://science.nasa.gov/climate-change/scientific-consensus/
Backs: “This is the overwhelming scientific consensus, based on multiple independent lines of evidence from observations, physics, paleoclimate records, and climate models.”
evidence, article, points to yes. Claim: Overwhelming scientific consensus holds humans are the primary cause of current climate change; leading scientific organizations endorse this position.
2ipcc.chGovernment
https://www.ipcc.ch/report/ar6/wg1/chapter/summary-for-policymakers/
Backs: “Natural drivers (solar and volcanic) contributed roughly –0.1 to +0.1°C, and internal variability ±0.2°C.”
statistic, official document, points to yes. Claim: IPCC AR6: human influence unequivocally warmed climate; human-caused warming 0.8–1.3°C, best estimate 1.07°C, versus negligible natural drivers.
3cornell.eduAcademic
https://news.cornell.edu/stories/2021/10/more-999-studies-agree-humans-caused-climate-change
Backs: “Multiple studies find 97%+ of climate scientists and peer-reviewed papers agree that humans are the main cause; more recent analyses put it above 99% (e.g., >99.9% in a 2021 review of ~88,000 papers).”
statistic, article, points to yes. Claim: Over 99.9% of ~88,000 papers in a 2021 review agree humans caused climate change.
4nasa.govGovernment
https://science.nasa.gov/climate-change/causes/
Backs: “Humans have disturbed the carbon cycle by extracting and burning long-buried fossil fuels.”
evidence, article, points to yes. Claim: CO₂ rise, isotopic fingerprints matching fossil fuels, and ruling out solar, orbital and volcanic causes.
5royalsociety.orgAcademic
https://royalsociety.org/news-resources/projects/climate-change-evidence-causes/
Backs: “Patterns match human influence: warming of the troposphere/lower atmosphere and surface, cooling of the stratosphere/upper atmosphere (opposite of what increased solar output would do); ocean heat content rise; cryosphere loss; etc.”
evidence, article, points to yes. Claim: Warming patterns (troposphere warming, stratosphere cooling, ocean heat, cryosphere loss) match human influence and models require human emissions.
6ipcc.chGovernment
https://www.ipcc.ch/report/ar6/wg1/chapter/chapter-3/
Backs: “Human influence is now detectable in many extremes (heatwaves, heavy precipitation, etc.) and impacts across the globe.”
evidence, official document, points to yes. Claim: Human influence is detectable in many extremes such as heatwaves and heavy precipitation.