Global warming could be double than previous estimates

May 20th, 2009 - 11:57 am ICT by ANI  

Washington, May 20 (ANI): In a new study, scientists have determined that climate change odds are much worse than thought, with analysis showing that global warming could be double than the previous estimates.

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 interactively includes detailed treatment of possible changes in human activities, such as the degree of economic growth, with its associated energy use, in different countries.

The new projections indicate a median probability of surface warming of 5.2 degrees Celsius by 2100, with a 90 percent 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.

According to study co-author Ronald Prinn, the co-director of the Joint Program and director of MIT’s Center for Global Change Science, these and a variety of other changes based on new measurements and new analyses changed the odds on what could be expected in this century in the “no policy” scenarios - that is, where there are no policies in place that specifically induce reductions in greenhouse gas emissions.

Overall, the changes “unfortunately largely summed up all in the same direction,” he said. “Overall, they stacked up so they caused more projected global warming,” he added. (ANI)

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