According to many Skeptics, volcanoes release more Carbon Dioxide than humans, therefore, any human release of the gas is trivial and does not contribute to Global Warming. However, according to the United States Geologic Service, we have released 100 times more CO2 than volcanoes. The United States Geological Survey (USGS) states:
Gas studies at volcanoes worldwide have helped volcanologists tally up a global volcanic CO2 budget in the same way that nations around the globe have cooperated to determine how much CO2 is released by human activity through the burning of fossil fuels. Our studies show that globally, volcanoes on land and under the sea release a total of about 200 million tonnes of CO2 annually.
…while 200 million tonnes of CO2 is large, the global fossil fuel CO2 emissions for 2003 tipped the scales at 26.8 billion tonnes. Thus, not only does volcanic CO2 not dwarf that of human activity, it actually comprises less than 1 percent of that value.
Figure 1: The proportion of volcanic emissions of CO2 (small illustration) compared to human emissions (large illustration).