Climate change from CO2 may not be as bad as predicted
By Bryan Clark
December 20, 2011
According to a recent study funded by the National Science Foundation's Paleoclimate Program, climate change may be far less sensitive to carbon dioxide fluctuations than previously predicted.
The most notable predictions of CO2-based climate change came from the Intergovernmental Panel on Climate Change (IPCC) report in 2007. The report suggested that should the CO2 in the Earth's atmosphere double from pre-Industrial standards (pre-1850), it could result in a global 2 to 4.5 degree Celsius (3.6 - 8.1 degrees Fahrenheit) temperature increase worldwide. The mean level in this finding was 3 degrees Celsius (5 degrees Fahrenheit). This, of course, would be catastrophic, leading to the melting of polar ice, as well as significant sea temperature increases and global flooding due to rising ocean levels.
It appears that that these dire numbers might not be accurate according to a the lead author of the new report, Oregon State University researcher Andreas Schmittner.
"Many previous climate sensitivity studies have looked at the past only from 1850 through today, and not fully integrated paleoclimate date, especially on a global scale," said Schmittner. "When you reconstruct sea and land surface temperatures from the peak of the last Ice Age 21,000 years ago - which is referred to as the Last Glacial Maximum - and compare it with climate model simulations of that period, you get a much different picture.
"If these paleoclimatic constraints apply to the future, as predicted by our model, the results imply less probability of extreme climatic change than previously thought," Schmittner added.
"In fact, a climate sensitivity of more than 6 [degrees] would completely freeze over the planet," Schmittner pointed out. This didn't happen. The ice sheets and glaciation only reached so far toward the equator and then stopped.
Some independent studies have suggested that the CO2 sensitivity might be 10 degrees Celsius or higher, although these studies are deemed "of low probability" by those within the climate change community.
"The best-fitting models had a climate sensitivity of about 2.3 - 2.4 degrees. So that is slightly less than the IPCC best estimate of 3."
Schmittner is also quick to note, however, that his model is far from perfect. For instance, it was unable to take into account changes in clouds once they absorbed sunlight. He expects the study would be much more accurate if cloud changes could somehow be figured in.
The study was published online in the journal Science.
Source: Oregon State University