Title: Volcanic Versus Anthropogenic CO2
Speaker: Terry Gerlach
Publication: The Outcrop, March 2013, p. 41
The climate change debate has revived the belief, widespread among climate change skeptics, that volcanoes emit more CO2 than the 37 billion metric tons per year from human activities. In fact, CO2 emissions from human activities dwarf all published estimates of the annual global volcanic CO2 emission rate—i.e., annual CO2 output
from divergent plate, intraplate, and convergent plate subaerial and submarine volcanoes. In 2010, human-generated CO2 was about 140 times greater than global volcanic CO2.
On average, humanity’s ceaseless emissions release an amount of CO2 comparable to that of the 1980 Mount St. Helens paroxysm every 2.5 hours, the 1991 Mount Pinatubo paroxysm every 12 hours, and the estimated annual global volcanic CO2 every 2.5 days. The claim that volcanic CO2 exceeds anthropogenic CO2 requires either unbelievable volumes of magma production or unbelievable concentrations of magmatic CO2. Scaling up volcanism to the hypothetical intensity required to generate CO2 emissions at anthropogenic levels suggests that humanity’s CO2 emissions may already exceed the annual CO2 emissions of several continental flood basalt eruptions or the CO2 output of 1-10 explosive super eruptions every year.