Climate Change Caused by Humans
Fiction: Volcanoes Emit More CO2 Than Humans

Fiction: Volcanoes Emit More CO2 Than Humans

Ian Plimer, a well-known skeptic who has consistently been shown to be incorrect, often states: "Over the past 250 years, humans have added just one part of CO2 in 10,000 to the atmosphere. One volcanic cough can do this in a day."

Is he correct? No, he is not even close!

Humans have emitted about 100 ppm since the Industrial Revolution. So how much do volcanoes emit? Tamino (2009) has two blog posts where he shows that even supervolcanoes do not even come close to 100 ppm. This Web page summarizes his two posts so please visit Open Mind if you want more details.

  1. Do You Believe Ian Plimer?
  2. CO2 and the Volcanoes

As discussed in Misleading: Nature Emits Much More CO2 Than Humans, in the past few years humans are adding CO2 at a rate of nearly 2 ppm per year which is equivalent to almost 16 Gt (billion tons) CO2 per year. The entire output of the Mt. Pinatubo explosion was about 10 Gt (Tamino, 2009) so even if ALL of the output from Mt. Pinatubo was CO2 (and it wasn't) humans are emitting much more than that huge volcano. Instead Mt. Pinatubo had the opposite effect; climate change caused by the eruption (mainly due to sulfates ejected by the volcano) caused the soil and biosphere to sequester more CO2 than usual, decreasing the growth rate of atmospheric CO2! (Ibid)

Tamino also shows four of the greatest volcanic eruptions in history and how their output is dwarfed by the output from humans. Figure 1 - 4 below show the change in CO2 after these supervolcanic eruptions. None of these are close to the output by humans.

Figure 1: Lake Toba, Sumatra, Indonesia, some time between 67,500 and 75,500 years ago

Figure 2: Lake Taupo, North Island, New Zealand – Oruanui eruption ~26,500 years ago.

Figure 3: Whakamaru, North Island, New Zealand – Whakamaru gnimbrite/Mount Curl Tephra ~254,000 years ago

Figure 4: Yellowstone Caldera, Wyoming, United States – 640,000 years ago

According to the United States Geological Survey (2009):

Another good article on this topic is found in the June 14, 2011 issue of EOS which concludes:

Scott A. Mandia
Professor - Physical Sciences
T-202 Smithtown Sciences Bldg.
533 College Rd.
Selden, NY 11784
(631) 451-4104

Last updated: 06/28/11