MIT study shows climate change is worse than thought
Ronald Prinn (second from right), director of MIT's Center for Global Change Science, and his group have revised theirmodel that shows how much hotter the Earth's climate will
get in this century without substantial policy change.
(Photo / Donna Coveney). Image sourced from MIT.
A new analysis from the Massachusetts Institute of Technology (MIT) shows that without rapid and massive action, global warming will be about twice as severe as previously estimated six years ago.
The study uses the MIT Integrated Global Systems Model, a detailed computer simulation of global economic activity and climate processes that has been developed and refined by the Joint Program on the Science and Policy of Global Change since the early 1990s.
The new research involved 400 runs of the model with each run using slight variations in input parameters, selected so that each run has about an equal probability of being correct based on present observations and knowledge. The MIT model includes detailed treatment of possible changes in human activities as well.
The new projections, published this month in the American Meteorological Society's Journal of Climate, indicate a median probability of surface warming of 5.2 degrees Celsius by 2100, with a 90% probability range of 3.5 to 7.4 degrees. This can be compared to a median projected increase in the 2003 study of just 2.4 degrees.
The difference is caused by several factors rather than any single big change. Among these are improved economic modeling and newer economic data showing less chance of low emissions than had been projected in the earlier scenarios. Other changes include accounting for the past masking of underlying warming by the cooling induced by 20th century volcanoes, and for emissions of soot, which can add to the warming effect. In addition, measurements of deep ocean temperature rises, which enable estimates of how fast heat and carbon dioxide are removed from the atmosphere and transferred to the ocean depths, imply lower transfer rates than previously estimated.
While the outcomes in the "no policy" projections now look much worse than before, there is less change from previous work in the projected outcomes if strong policies are put in place now to drastically curb greenhouse gas emissions.
This work was supported in part by grants from the Office of Science of the US Dept. of Energy, and by the industrial and foundation sponsors of the MIT Joint Program on the Science and Policy of Global Change.
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Katrice R. Jalbuena
Sources:
1 http://web.mit.edu/newsoffice/2009/roulette-0519.html
2 http://web.mit.edu/newsoffice/