The myth that a single volcanic eruption puts more CO2 into the atmosphere than all of mankind to date, let alone 10,000 times more, is one of the most pervasive as well as one of the most demonstrably false climatological claims out there. It stems, ultimately, from a geologist named Ian Plimer, infamous for writing a
widely discredited book titled
Heaven and Earth, which attempted to argue that humans have had an insignificant effect on global climate.
In a 2009
editorial written for Australia’s ABC news, he echoed a sentiment he had argued with similar inelegance in his book by providing the following statement, widely spread nearly word-for-word in climate skeptic circles, without any supporting citation: “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.”
This brief statement — a mere 28 words — yields a remarkably dense buffet of spurious claims and outright falsehoods. It also is rife with ambiguity. What numbers is he actually comparing? What is a volcanic “cough”? From a fact-checking standpoint, there are no interpretations of Plimer’s second sentence that can produce a factual assertion. The only way to make the first sentence work is with a scientifically useless comparison. All other interpretations fall well short of reality.