Climate change: Man vs volcanoes - mankind wins and it isn't even close

A few years ago, I had a debate with someone about climate change on Facebook. He told me that humans are grandiose to think that they are so powerful as to change the climate. Considering the size and scale of the earth compared to us, I took him at his word. I also recalled an article I read in Car and Driver that said that a few volcanoes in the last 250 years has coughed up more CO2 than all of human history combined. I took them at their word, too.

A few days ago, a conservative someone shared the following meme:

After this meme was posted on Google+, there were comments to follow. To refute the claims in the meme, someone else posted the following links:

https://www.skepticalscience.com/volcanoes-and-global-warming.htm

http://scied.ucar.edu/shortcontent/how-volcanoes-influence-climate

http://volcanoes.usgs.gov/hazards/gas/climate.php

A review of the results and the conclusions found therein show that relative to volcanoes, humans are the undisputed champions of CO2 production. The meme offers no citations, no source for reference. The comment with the links show references from teams of scientists sorting out the question: which source is greater for CO2, humans or volcanoes?

Side note: An interesting fact missing from the meme is that the sulfate aerosols created by volcanoes has a very high albedo and actually reflects sunlight back into space. For example, after the Mount Pinatubo eruption, global surface temperatures dropped by about .5 C.

The numbers are fairly consistent across the board. Where CO2 production from volcanoes is measured in millions of tons, human production of CO2 from burning fossil fuels and changes in land use are measured in the billions. One source estimates annual volcanic CO2 production to be between 65 and 319 million tons, indicating variations year to year. By comparison, human activity produces 30 billion tons of CO2, up to 10 times what the volcanoes cough up in a year.

Worldwide, humans are very consistent at one thing: increasing the production of CO2. Scientific American covered this topic in 2009 and found that humans were producing about 24 billion tons of CO2. 6 years later, we're talking 30 billion tons of CO2 a year. Every year. And the numbers keep going up. Well, for most countries anyway.

Happily, trends can change. The US is now leading the world in reducing emissions. Renewable energy sources are in a boom and most analysts have consistently underestimated the growth of renewable energy. The US is showing the world that we can grow the economy and cut CO2 emissions at the same time. That's something you won't hear from Senator James Inhofe.

So the next time conservatives trot out their volcanoes, you can remind them that volcanoes tend to cause cooling by ejecting sulfur dioxide which combines in the atmosphere to create aerosols that reflects sunlight. You can also point out that volcanoes can't hold a candle to human CO2 production.