A tremendous synthesis of information took place in 2013, revealing our best value yet for the total amount of CO2 emitted from natural release events within Earth. They found:
- 33 measured degassing volcanoes emit a total of 60 million tons of CO2 per year.
- There are a total of ~150 known degassing volcanoes, implying (based on the measured ones) that a total of 271 million tons of CO2 are released annually.
- 30 historically active volcanoes are measured to emit a total of 6.4 million tons of CO2 per year.
- With ~550 historically active volcanoes total, they extrapolate this class of object contributes 117 million tons per year.
- The global total from volcanic lakes is 94 million tons of CO2 per year.
- Additional emissions from tectonic, hydrothermal and inactive volcanic areas contribute an estimated 66 million tons of CO2 per year, although the total number of emitting, tectonic areas are unknown.
- And finally, emissions from mid-ocean ridges are estimated to be 97 million tons of CO2 annually.
Add all of these up, and you get an estimate of around 645 million tons of CO2 per year.
Källor: How Much CO2 Does A Single Volcano Emit? – Forbes och Deep Carbon Emissions from Volcanoes – Michael R. Burton, Georgina M. Sawyer och Domenico Granieri – Reviews in Mineralogy and Geochemistry (2013)
645 miljoner ton är mycket, inte tu tal om det, men i jämförelse med människors utsläpp om 29 miljarder ton per år är det 2.22%.
In fact, even if we include the rare, very large volcanic eruptions, like 1980’s Mount St. Helens or 1991’s Mount Pinatubo eruption, they only emitted 10 and 50 million tons of CO2 each, respectively. It would take three Mount St. Helens and one Mount Pinatubo eruption every day to equal the amount that humanity is presently emitting.
Det krävs tre utbrott av Mount St. Helens och en Mount Pinatubo per dag för att matcha människors nuvarande utsläpp av koldioxid!