Fact brief – Is there empirical evidence for human-caused global warming?
Posted on 28 October 2025 by Sue Bin Park
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Is there empirical evidence for human-caused global warming?
There are multiple lines of evidence that our greenhouse gas emissions are warming the planet.
The greenhouse effect is the process whereby “greenhouse” gases such as carbon dioxide create a kind of atmospheric blanket, absorbing outgoing heat energy and re-radiating a portion of it back down to Earth.
CO2 levels surged after humans began burning fossil fuels such as coal and oil. Today, we’re over 420 parts per million — up 50% from pre-industrial times and higher than for millions of years.
We know this increase is from burning fossil fuels, which produce a form of CO2 with extremely low levels of the carbon-14 isotope. The drop of carbon-14 in the atmosphere following the Industrial Revolution is a fossil fuel “fingerprint” of the CO2 spike.
Satellite measurements confirm a decrease in heat energy radiated out into space and an increase in heat energy re-radiated back down to Earth’s surface.
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 Institute of Physics The Carbon Dioxide Greenhouse Effect
Columbia University Climate School How Exactly Does Carbon Dioxide Cause Global Warming?
NOAA The Basics: Isotopic Fingerprints
UC San Diego The Keeling Curve
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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.
