The Long Thaw: How Humans are Changing the Next 100,000 Years of Earth's Climate
Friday, October 22, 2010
Kirk Road and Pine Street
When fossil fuel CO2 is released to the atmosphere, it enters the cacophony of the global carbon cycle. Over the centuries the extra CO2 will spread out between the atmosphere, the ocean, and the land surface. After this equilibration is complete, there will still be a fraction of the new CO2 that remains in the atmosphere. This excess CO2 awaits slow chemical reactions with dissolving rocks on land, called weathering reactions, to carry the carbon back into the solid earth in the form of CaCO3. The "lifetime" of fossil fuel CO2 in the atmosphere is a complicated question because there are multiple processes operating, but in general the CO2 concentration will be higher than natural for hundreds of thousands of years. Some components of the climate system, such as the ice sheets in Antarctica and Greenland, will respond most strongly to the "long tail" of the fossil fuel CO2, ultimately raising sea level by 10's of meters, something like 100 times more than the IPCC forecast for the year 2100.
David Archer is a professor in the Department of the Geophysical Sciences at the University of Chicago and a Fellow of the American Geophysical Union, publishing on Earth’s carbon cycle and its interaction with global climate. Dr. Archer has written a series of outreach books on climate change, including Global Warming: Understanding the Forecast, a text for non-science major undergraduates; The Long Thaw: How Humans are Changing the Next 100,000 Years of Earth’s Climate; and The Global Carbon Cycle, a primer in climate science. He teaches classes on global warming, environmental chemistry, and global biogeochemical cycles, and is regular contributor to the climate science blog site realclimate.org.