Humans, Not Volcanoes, the Biggest Source of CO2 Emissions

(CN) – Human burning of forests and fossil fuels creates 40 to 100 times more carbon emissions than all of Earth’s volcanoes combined, according to research that will be presented later this month at the National Academy of Sciences in Washington.

The 10-year-old Deep Carbon Observatory program, made of more than 1,200 scientists across 55 countries, released a series of papers in the journal Elements describing a summary of what researchers have discovered about carbon and its effects on all life on Earth.

One aspect of the program’s research is volcanic activity. Scientists estimate only two-tenths of 1% of Earth’s total carbon (43,500 metric gigatons) is found on land, in the sea and in the air. The rest, approximately 1.85 billion metric gigatons, is found within the Earth itself. This carbon is often released to the surface through emissions by volcanoes and other geological processes like the heating of limestone.

About 400 of the planet’s 1,500 active volcanoes are estimated to be currently venting carbon dioxide, while another 670 are likely producing diffuse emissions. The program has set up emission monitoring on many of the world’s most active volcanoes using miniature instruments, allowing scientists to have a greater understanding of just how much CO2 is being released into the air.

The researchers estimate that 280-360 million metric tons of CO2 are emitted each year from volcanoes and volcanic regions alone. Comparatively, humans are responsible for some 21 billion metric tons of carbon dioxide annually, according to the U.S. Geological Survey.

"Earth is unique among the planets in our solar system in that it has liquid water at its surface, fosters life, and has active plate tectonics,” said Sami Mikhail, senior lecturer at the University of St. Andrews in the United Kingdom. “Identifying all linkages between these phenomena serve as important steps in humanity's enduring quest to understand the origins of Earth-like habitability. One absolute certainly, however, is that carbon plays a governing role.

“For example, Earth's clement environment is related to atmospheric chemistry, which is warm enough to stabilize liquid water at its surface but cold enough to permit plate tectonics, and it is an incontrovertible fact that the carbon content of our atmosphere and oceans are directly linked with Earth's climate."

In high concentrations, carbon dioxide is fatal to humans as it can displace oxygen and effectively act as an asphyxiant. According to the program’s researchers, natural emissions from the Earth alone in cool night air can create dangerous levels of CO2 sufficient enough to kill livestock.

While the program is examining the role of carbon, it is also using its research to help identify when volcanoes are likely to erupt. Through constant monitoring of volcanoes, scientists discovered that the level of carbon dioxide relative to sulfur dioxide in volcanic gases changes before an eruption. Gas monitoring is now being used to help forecast volcanic eruptions.

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