A new study has said that global warming due to doubling of carbon dioxide emissions may be less severe than predicted by the Intergovernmental Panel on Climate Change in 2007.
According to the study, which was funded by the National Science Foundation and published in the journal Science, doubling of carbon dioxide would not lead to draconian rise in temperature.
"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," an Oregon State University researcher and lead author Andreas Schmittner said.
"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.
The 2007 IPCC report said the air near the surface of the Earth would warm on average by two to 4.5 degrees (Celsius) due to doubling of carbon dioxide emissions.
Some earlier studies had indicated that the temperature could rise by as much as 10 degrees or higher with a doubling of carbon dioxide.
The researchers compiled land and ocean surface temperature reconstructions from the Last Glacial Maximum and created a global map of those temperatures.
Atmospheric carbon dioxide was about a third less than before the Industrial Revolution, and levels of methane and nitrous oxide were much lower, sea levels were lower, the climate was drier (less precipitation), and there was more dust in the air, when the study was conducted.
All these factors, which led to cooling the Earth's surface, were included in their climate model simulations.
Thus researchers' mapping of temperatures has greater spatial coverage and showed less cooling during the Ice Age than most previous studies.