by Bard Amundsen and Else Lie
Oslo, Norway (SPX) Feb 01, 2013
After Earth's mean surface temperature climbed sharply through the 1990s, the increase has levelled off nearly completely at its 2000 level. Ocean warming also appears to have stabilised somewhat, despite the fact that CO2 emissions and other anthropogenic factors thought to contribute to global warming are still on the rise.
Climate sensitivity is a measure of how much the global mean temperature is expected to rise if we continue increasing our emissions of greenhouse gases into the atmosphere.
A number of factors affect the formation of climate development. The complexity of the climate system is further compounded by a phenomenon known as feedback mechanisms, i.e. how factors such as clouds, evaporation, snow and ice mutually affect one another.
"In our project we have worked on finding out the overall effect of all known feedback mechanisms," says project manager Terje Berntsen, who is a professor at the University of Oslo's Department of Geosciences and a senior research fellow at the Center for International Climate and Environmental Research - Oslo (CICERO). The project has received funding from the Research Council of Norway's Large-scale Programme on Climate Change and its Impacts in Norway (NORKLIMA).
When the researchers at CICERO and the Norwegian Computing Center applied their model and statistics to analyse temperature readings from the air and ocean for the period ending in 2000, they found that climate sensitivity to a doubling of atmospheric CO2 concentration will most likely be 3.7C, which is somewhat higher than the IPCC prognosis.
Terje Berntsen emphasises that his project's findings must not be construed as an excuse for complacency in addressing human-induced global warming. The results do indicate, however, that it may be more within our reach to achieve global climate targets than previously thought.
The project's researchers may have shed new light on another factor: the effects of sulphur-containing atmospheric particulates.
Geophysicists at the research institute CICERO collaborated with statisticians at the Norwegian Computing Center on a novel approach to global climate calculations in the project "Constraining total feedback in the climate system by observations and models". The project received funding from the Research Council of Norway's NORKLIMA programme.