We’ve all seen images of massive volcanoes erupting in a shower of sparks and red-hot lava, with clouds of smoke and ash billowing in the sky. Active volcanoes around the world, including those under the ocean, are a natural source of carbon dioxide — the primary greenhouse gas causing global warming.


Yet human emissions of carbon dioxide now dwarf the emissions coming from volcanoes.

Gerlach: “Carbon dioxide emissions from human activities are on the order of a hundred times greater than the emissions from all the volcanoes on the earth. Period.”

That’s Terrence Gerlach, retired U.S. Geological Survey volcanologist. Gerlach says that at the start of the Industrial Revolution, human activities and volcanoes were roughly equal sources of carbon dioxide.

But humans today burn enormous quantities of coal, oil, and natural gas, releasing billions of tons of carbon dioxide each year. As a result, our emissions of CO2 are now much larger than the emissions from volcanoes. And in turn, global levels of atmospheric CO2 are now higher than they have been in more than eight hundred thousand years.

Reporting credit: ChavoBart Digital Media.
Photo: Augustine (volcano), photographed in January 2006. Courtesy of U.S. Geological Survey. Photographer: Game McGimsey.

More Resources
Volcanic Versus Anthropogenic Carbon Dioxide
Humans Dwarf Volcanoes for CO2 Emissions
Volcanic vs. Anthropogenic CO2

A regular contributor to Yale Climate Connections since 2012, David Appell, Ph.D., is a freelance writer living in Salem, Oregon, specializing in the physical sciences, technology, and the environment. His...