Are humans responsible for climate change?

Yes, humans are the primary cause of recent climate change (the observed global warming since the Industrial Revolution, particularly since the mid-20th century). This is the position of the overwhelming scientific consensus, based on multiple independent lines of evidence from physics, observations, paleoclimate data, and climate models.[1]

The Intergovernmental Panel on Climate Change (IPCC), in its Sixth Assessment Report (AR6, 2021), states: “It is unequivocal that human influence has warmed the atmosphere, ocean and land.” Widespread and rapid changes have occurred across the climate system. Observed increases in well-mixed greenhouse gas (GHG) concentrations since around 1750 are unequivocally caused by human activities. The likely range of total human-caused global surface temperature increase from 1850–1900 to 2010–2019 is 0.8°C to 1.3°C, with a best estimate of 1.07°C. Well-mixed GHGs contributed a warming of 1.0°C to 2.0°C, while other human drivers (mainly aerosols) contributed some cooling, natural drivers contributed roughly –0.1°C to +0.1°C, and internal variability –0.2°C to +0.2°C.[1]

Scientific Consensus

Key Evidence

Multiple converging lines of evidence establish human responsibility:

Earth’s climate has always varied naturally, but the recent changes (roughly 1.1–1.3°C of warming so far, accelerating) stand out in rate, magnitude relative to the Holocene, and cause. Human activities are responsible for essentially all the long-term warming observed over the past ~150–170 years, especially since the mid-20th century.[9]

This conclusion rests on decades of research across disciplines and is reinforced by ongoing observations and improved methods. While details of regional impacts, exact climate sensitivity, and future projections involve ranges of uncertainty, the fundamental attribution to human GHG emissions is robust and “incontrovertible” according to recent reviews.