Fact brief – Are changes in solar activity causing climate change?
Posted on 21 November 2025 by Sue Bin Park
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Are changes in solar activity causing climate change?
The rise in global temperatures over the past century cannot be explained by the small changes in the sun’s energy output.
The sun varies slightly in brightness through several natural cycles, including an 11-year sunspot cycle, but these shifts are small and largely cancel out over decades. Satellite measurements show total solar irradiance actually drifted slightly downward since the late 1970s, which would have caused mild cooling, not rapid warming.
Over longer timescales, research has found that solar changes account for 1% of the 1.4°C (2.5°F) of warming since pre-industrial times. In contrast, greenhouse gas emissions from burning fossil fuels cause far more warming and align closely with the measured temperature rise.
Change in the sun’s activity has been small and cannot explain the recent rise in global temperatures. The dominant driver of today’s climate change is not the sun, but greenhouse gas emissions from our use of fossil fuels.
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
NOAA Couldn’t the Sun be the cause of global warming?
NOAA Climate Change: Incoming Sunlight
NASA Global Temperature – Earth Indicator
IPCC Climate Change 2021: The Physical Science Basis report
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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.
