May 21, 2009

Global warming might be worse than thought

A Massachusetts Institute of Technology analysis suggests the impact of global warming could be much worse than thought, at least double previous estimates.

In what is called the most comprehensive modeling yet concerning how much hotter the Earth's climate will get this century, MIT researchers discovered that without rapid and massive action, the problem will be about twice as severe as estimated six years ago -- and could be even worse.

The study involved 400 runs of the MIT Integrated Global Systems Model, a detailed computer simulation of global economic activity and climate processes. Each run involved slight variations in input parameters.

Study co-author Ronald Prinn, director of MIT's Center for Global Change Science, said the new projections involved improved economic modeling. Other changes included accounting for cooling induced by 20th century volcanoes and for emissions of soot, which can add to the warming effect.

Prinn said the new analyses changed the odds on what could be expected during this century in a scenario in which no policies are in place that specifically induce reductions in greenhouse gas emissions.

There is significantly more risk than we previously estimated, Prinn said. This increases the urgency for significant policy action.

The study appears in the American Meteorological Society's Journal of Climate.