Fact brief - Do volcanoes emit more CO2 than humans?

Skeptical Science is partnering with Gigafact to produce fact briefs — bite-sized fact checks of trending claims. This fact brief was written by Sue Bin Park from the Gigafact team in collaboration with members from our team. You can submit claims you think need checking via the tipline.

Do volcanoes emit more CO2 than humans?

Volcanoes release CO₂, but the amount is minimal compared to human-caused emissions.

According to the U.S. Geological Survey, volcanoes emit around 180-440 million tons of CO₂ annually. In contrast, human activities, primarily burning fossil fuels, emitted 41.5 billion tons of CO₂ in 2022—over 100 times more.

Volcanoes are part of the Earth’s slow carbon cycle, where carbon is gradually recycled between the Earth’s mantle and atmosphere over millions of years. Volcanic CO₂ is eventually reabsorbed by the weathering of rocks and ocean absorption, keeping the carbon cycle in balance over long timeframes.

Human activity, however, is releasing carbon at a rate far beyond what the natural carbon cycle can handle, overwhelming the Earth’s ability to balance CO₂ levels. While volcanic CO₂ emissions have been stable for millions of years, human-caused emissions have rapidly accelerated since the Industrial Revolution, making human activity the dominant driver of rising atmospheric CO₂.

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Sources

USGS Volcanic gases can be harmful to health, vegetation and infrastructure

Our World in Data CO? emissions

NASA The Carbon Cycle

USGS Volcano Watch — Which produces more CO2, volcanic or human activity?

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.