Are humans responsible for climate change?

Is climate change driven by human activity? I'll gather the latest scientific consensus and evidence to answer.

Yes, according to the overwhelming scientific evidence and consensus - humans are responsible for modern climate change as the principal cause.

Scientific Consensus

•There is unequivocal evidence that Earth is warming at an unprecedented rate. Human activity is the principal cause.

•Using the scientific method, scientists have shown that humans are extremely likely the dominant cause of today's climate change.

•Multiple studies published in peer-reviewed scientific journals show that human activities are the primary cause of the observed climate-warming trend over the past century.

•Nearly all actively publishing climate scientists say humans are causing climate change.

•Today, 97 percent to 99.9 percent of climate scientists agree that climate change is happening and that human activity is the primary cause. This figure is repeated as 97% to 99.9% of climate scientists agree.

IPCC Assessment

The United Nations Intergovernmental Panel on Climate Change (IPCC) provides the most comprehensive assessment:

•According to the Summary for Policymakers of the Sixth Assessment Report (AR6) "Climate Change 2021: The Physical Science Basis" on 9 August 2021, it is unequivocal that human influence has warmed the atmosphere, ocean and land.

•In its recent summary report, the IPCC stated that, "It is unequivocal that human influence has warmed the atmosphere, ocean and land… climate change is already affecting many weather and climate extremes in every region across the globe". The same conclusion is stated as "it is unequivocal that human influence has warmed the atmosphere, ocean and land".

•The report says it is unequivocal that climate change is occurring and confirms there is at least 95% certainty that human activities are the principal cause.

•An earlier assessment stated there is 95 percent certainty that humans have caused most of the warming of the planet's surface that has occurred since the 1950s.

•The IPCC is now 95 percent certain that humans are the main cause of current global warming.

•The fact that the IPCC has agreed — with the agreement of all 195 member countries — that it is unequivocal that human activity is causing climate change, is the strongest statement that the IPCC has ever made.

Evidence That It Is Human-Caused, Not Natural

Natural climate variability does occur, but it cannot explain current warming:

•These shorter-term variations are mostly due to natural causes, and do not contradict our fundamental understanding that the long-term warming trend is primarily due to human-induced changes in the atmospheric levels of CO2 and other greenhouse gases.

•Models combined with other evidence demonstrate that the global warming of the past 150 years cannot be explained by natural causes or by variations in the Sun's output.

•Natural-only model runs do not match modern observed temperatures. Models including both natural processes and human-released greenhouse gases match much more closely.

•While the Sun has played a role in past climate changes, the evidence shows the current warming cannot be explained by the Sun.

How Humans Cause It

The mechanism is well-understood:

•The burning of fossil fuels like coal and oil has increased the concentration of atmospheric carbon dioxide (CO2), which is a greenhouse gas that traps heat in the atmosphere and causes global warming.

While natural drivers such as orbital variations and volcanic activity have caused climate to change throughout Earth's history, the current warming trend is occurring at an unprecedented rate and the preponderance of evidence indicates that human activities—particularly emissions of heat-trapping greenhouse gases—are mostly responsible.

Citations (3)

1nasa.govGovernment
Climate Change - NASA Science
Backs: “Yes, according to the overwhelming scientific evidence and consensus - humans are responsible for modern climate change as the principal cause. Scientific Consensus. There is unequivocal evidence that Earth is warming at an unprecedented rate.”
2nasa.govGovernment
The scientific method and climate change: How scientists know
Backs: “There is unequivocal evidence that Earth is warming at an unprecedented rate. Human activity is the principal cause. Using the scientific method, scientists have shown that humans are extremely likely the dominant cause of today's climate change.”
3hko.gov.hkGovernment
Global Climate Change
Backs: “The United Nations Intergovernmental Panel on Climate Change (IPCC) provides the most comprehensive assessment: According to the Summary for Policymakers of the Sixth Assessment Report (AR6) "Climate Change 2021: The Physical Science Basis" on 9 August 2021, it is unequivocal that human influence has warmed the…”