So I'm watching a fully awesome TV show about Hawaii's big volcano, Kilauea, on the big island. Jeff Sutton at the U.S. Geological Survey has been studying it for years, if not decades, because Kilauea has been erupting constantly since January 3rd 1983.
One of many lava deltas from Kilauea:
Taking gas readings as a full time job shows that Kilauea spews between 3000 and 8000 metric tons of CO2 per day. A metric ton is 1000 kilograms, or 2200 pounds, heavier than the smallest Honda Civic. So Kilauea spews between 3000 and 8000 Honda Civics a day, but not as iron, glass and rubber, but as carbon dioxide.
The Chaiten volcano in Chile in 2008:
Mr. Sutton said that annually the toxic spew contains between 3.5 and 5.0 million metric tons of CO2. The TV show's narrator went on to say that the Earth averages 1500 active volcanoes a year. If they all spew forth like Kilauea, let's see who is worse, humans or volcanoes. And we'll use the worst case of 5 million metric tons a year.
1500 Kilauea-sized volcanoes = 1500 x 5 million metric tons CO2 = 7.5 billion
7.5 billion metric tons x 2200 pounds per metric ton = 16.5 trillion pounds
500 mile Chaiten ash cloud crosses Argentina and hits the Atlantic:
So how do humans compare? I don't want to go to any left wing blogs for data, let's try a different route.
Let's get the real deal. This Department of Energy web page has several Excel spreadsheets showing exactly how much carbon dioxide each country in the world emits from each type of fossil fuel.
The very first spreadsheet shows CO2 emissions from all fossil fuels. The US emits nearly 6 billion metric tons a year, Europe about 4.7 billion, Asia and Oceania about 11 billion. The world combined emits 29.2 billion metric tons. The US apparently accounts for 1/5th of the world's CO2 emissions, just as everybody has been saying.
Here's Mount Pinatubo erupting in 1991:
If we take the exact figure in the spreadsheet, 29.19542 billion metric tons, and multiply by 2200 pounds per metric ton, we have 64,229,924,000,000 pounds of CO2, or about 64.2 trillion pounds.
Human machines worldwide emit 3.89 times more CO2 than 1500 full-on Kilauea volcanoes.
By the way, back in 1980, before Kilauea began erupting, the world's CO2 emissions from fossil fuels were a bit over 18.5 billion metric tons, which is more than 2.5 times more than 1500 full-on Kilaueas. But it didn't erupt for another 2 years.
Now, you ask, how much CO2 do the Earth's volcanoes actually emit? Let me do some research and get back to you... Several months later and I'm still not sure. All I know is that five different programs, such as How the Earth Was Made, all agree that Kilauea is the most active volcano on Earth. One TV program highlighted all the most active volcanoes on Earth, and still said Kilauea was more active than all of them, such as Mount Etna in Sicily.
Here's one of Mt. Etna's recent eruptions:
The good news in all of this? These active volcanoes prove the Earth's core and mantle are still molten, and that's the only thing keeping us alive. They create a magnetic field that protects us from the solar wind, and keeps our atmosphere from being stripped away by it.