I see versions of this nonsense claim all the time. This one went hugely viral. So let's dig into the actual numbers, cars versus volcanoes. (1/x) 
Human activities released 33 billion tons of CO2 in 2019. About 16% of that, or 5 billion tons, is associated with road transportation. iea.org/articles/globa…
Calculating "every car in history" isn't easy, since car use has grown enormously over the past 120 years. Being extremely conservative, the total is 20 times this year's amount, or 100 billion tons. 3/x
Now for volcanoes. Mount St Helens blew out 10 million tons of CO2. Mt. Merapi emitted much less, probably between 100,000 and 1 million tons. We'll take the high end for the sake of argument. 4/x
Being very conservative, then, cars have emitted 100,000 times as much CO2 as Mt Merapi. The real number might be closer to a million. Just to be clear: CARS HAVE EMITTED AT LEAST 100,000 TIMES AS MUCH CO2 AS THIS VOLCANO. 5/x
But there are many volcanoes! Add them all up and they emit an estimated 400 million tons of CO2 per year. That's from all volcanoes on Earth, both on land and undersea. 6/x volcanoes.usgs.gov/vhp/gas_climat…
Now we can do a straight comparison. CO2 emissions from cars last year: approximately 5 billion tons. CO2 emissions from volcanoes last year: approximately 400 million tons. Cars accounted for >10 times as much CO2 as every volcano in the world combined. 7/x
Doubters complain all the time about exaggeration by climate scientists. But here is a viral claim that the doubters trot out all the time--and it is exaggerated by a factor of 100,000 or more. This is not a good-faith argument; it is disinformation. 8/8 fin
PS: The idea that economy-wrecking taxes are the only way to fight climate change is a straw-man argument, designed to scare people into inaction. In reality, inaction is the biggest danger. e360.yale.edu/features/deep-…
