Humankind generates upto 100 times as much CO2 as venting from volcanoes each year: Report

After a decade-long study, an international team of researchers has found that human activity on Earth produced enough carbon dioxide emissions to produce 100 times the effect that all the volcanoes combined. The total emissions from all the volcanoes that go off in a year is an average of 0.3 to 0.4 gigatons/year, and the corresponding figure for human-made emissions is 37 gigatons.

This suggests that volcanoes aren't nearly carbon-polluting enough to tip the climate change scales, as some prevailing theories have claimed in recent years.

With some rare exceptions over millions of years, the quantity of carbon released from the Earth's mantle has been in relative balance with the quantity returned through the downward subduction of tectonic plates and other processes, according to the study's researchers. The study, published in the journal Elements, also points out that only one-fifth of 1 percent of Earth's total carbon (some 43,500 gigatonnes) exists at or above the surface — in oceans, land, and the atmosphere.

Emissions from Mt St Helens mid-eruption in May 1980. Image: Richard Bowen

 

The total yearly out-gassing of CO₂ (release of a gas that was dissolved, trapped, frozen, or absorbed in some material) from volcanoes and other geological processes like heating of limestone in mountain belts, was estimated by DCO experts at roughly 300 to 400 million metric tonnes (0.3 to 0.4 Gt). Celina Suarez, one of the study's lead authors from the University of Arkansas, said that modern humanmade emissions were the "same magnitude" as past carbon shocks that accompanied mass extinctions.

"We are on the same level of carbon catastrophe, which is a bit sobering," she told AFP.

"In the past, we see that these big carbon inputs to the atmosphere cause warming, cause huge changes in both the composition of the ocean and the availability of oxygen," Marie Edmonds, co-author from Earth Sciences at Queens' College, Cambridge added. "The amount of CO2 pumped into the atmosphere by anthropogenic (manmade) activity in the last 10-12 years (is roughly the same) to catastrophic changes during these events we've seen in Earth's past."

Annual rates of CO2 emitted from various sources compared. Image: Elements

In the past, events like the Chixculub impact in Yucatan Province, Central America some 65 million years ago and others like asteroid or meteor impacts, similar carbon catastrophes.

An event to which extinction of the dinosaurs and most other plants and animals of the time has been attributed.

These events create an imbalance in the carbon cycle and result in rapid global warming accompanied by secondary effects like changes to the weathering rate of silicates, the water cycle, as well as ecosystems and habitats around the world. While Earth could rebalance itself over time, it might need a mass extinction to do so, the researchers think.

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