Are humans responsible for climate change?

I'll pull the latest scientific evidence to answer whether humans are driving climate change.

Yes — according to the overwhelming scientific evidence and consensus, human activities are the principal cause of the climate change observed since the mid-20th century.

What the science says

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

•As NASA says, there is “unequivocal evidence that Earth is warming at an unprecedented rate” and that human activity “is the principal cause.”

•The 2023 National Climate Assessment similarly states: “Human activities—primarily emissions of greenhouse gases from fossil fuel use—have unequivocally caused the global warming observed over the industrial era.”

•Comprehensive syntheses state that: “Human activities, principally through emissions of greenhouse gases, have unequivocally caused global warming”

IPCC — the UN body for evaluating climate science

The Intergovernmental Panel on Climate Change (IPCC), with agreement of all 195 member countries, has made its strongest statement to date:

> it's "unequivocal" that human activity is driving climate change

> "It is unequivocal that human influence has warmed the atmosphere, ocean and land,"

> "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,"

Other IPCC assessments have similarly concluded that warming of the climate system is unequivocal; human influence on the climate system has been the dominant cause

How strong is the consensus?

•Today, 97 percent to 99.9 percent of climate scientists agree that climate change is happening and that human activity is the primary cause

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

Multiple independent analyses of peer-reviewed literature and surveys of experts put agreement at roughly 97% or higher, with recent reviews reporting >99%

Why scientists are confident it is human-caused, not natural

1.Physics of greenhouse gases: The warming is consistent with the basic physics of the greenhouse effect understood since the mid-1800s and maps to what is expected from human activity

2.Direct observations: Greenhouse gases that warm the planet have risen relentlessly due primarily to human activities — including burning fossil fuels — and cannot be explained by natural factors alone. Evidence shows the current warming cannot be explained by the Sun

3.Rate and fingerprint: The warming is far more rapid than anything experienced in many millennia and cannot be explained by natural variations in the climate

4.Chemical signature: Scientists know fossil fuels are the main source of the added carbon dioxide because of the chemical signature of the molecules in the atmosphere.

This does not mean natural climate variability does not exist — Earth's climate has changed naturally over millions of years due to orbital changes, volcanic activity and solar variations. However, those natural factors cannot account for the rapid warming, sea-level rise, ocean warming, ice loss and increase in extreme weather observed in recent decades. The human contribution — mainly CO2, methane, and nitrous oxide from burning coal, oil and gas, deforestation and agriculture — is the dominant driver.

Citations (3)

1nasa.govGovernment
Global warming consensus – Climate Change: Vital Signs of the Planet
Backs: “What the science says. NASA states: There is unequivocal evidence that Earth is warming at an unprecedented rate.”
2factcheck.orgNonprofits and think tanks
How do scientists know climate change is happening?
Backs: “NASA states: There is unequivocal evidence that Earth is warming at an unprecedented rate. Human activity is the principal cause. As NASA says, there is “unequivocal evidence that Earth is warming at an unprecedented rate” and that human activity “is the principal cause.””
3space.comNews and mediaquality 0.84
Human influence on global warming is ‘unequivocal,’ IPCC report says | Space
Backs: “it's "unequivocal" that human activity is driving climate change. "It is unequivocal that human influence has warmed the atmosphere, ocean and land,". "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…”