Posted on 30 September 2025 by Sue Bin Park

Skeptical Science is partnering with Gigafact to produce fact briefs — bite-sized fact checks of trending claims. You can submit claims you think need checking via the tipline.

Are humans responsible for climate change?

Our rapid burning of fossil fuels has caused a buildup of heat-trapping carbon dioxide gas in our atmosphere.

Until we started burning fossil fuels, the CO₂ moving between the Earth’s atmosphere, oceans and land remained relatively steady for thousands of years. Fossil fuel burning took trapped carbon from the solid Earth, where it had been safely stored for millions of years, and injected it — as CO₂ — into our atmosphere.

Humans have emitted more than one trillion metric tons of carbon dioxide since the Industrial Revolution — about one-third of atmospheric CO₂ today.

The carbon dioxide released by human activity is unique. Certain forms of carbon that are rare in natural CO₂ are found in larger amounts in fossil fuels. Because of that, human-generated CO₂ has a ‘fingerprint’ that can be detected in air samples.

This CO2 has raised temperatures at a rate not seen in millions of years.

Go to full rebuttal on Skeptical Science or to the fact brief on Gigafact

This fact brief is responsive to quotes such as this one.

Sources

American Geophysical Union Changes to Carbon Isotopes in Atmospheric CO2 Over the Industrial Era and Into the Future

Frontiers in Earth Science Carbon Isotope Chemostratigraphy Across the Permian-Triassic Boundary at Chaotian, China: Implications for the Global Methane Cycle in the Aftermath of the Extinction

Environmental Defense Fund 9 ways we know humans caused climate change

Please use this form to provide feedback about this fact brief. This will help us to better gauge its impact and usability. Thank you!

About fact briefs published on Gigafact

Fact briefs are short, credibly sourced summaries that offer "yes/no" answers in response to claims found online. They rely on publicly available, often primary source data and documents. Fact briefs are created by contributors to Gigafact — a nonprofit project looking to expand participation in fact-checking and protect the democratic process. See all of our published fact briefs here.