How Much Climate Change Can be Avoided by Mitigation? (June 8, 2009)

A paper published on April 21 with authors from the National Center for Atmospheric Research, Boulder, Colorado; the Institute for Atmospheric and Climate Science, ETH, Zurich, and Climate Central, Palo Alto, California,  in Geophys. Res. Lett., 36, L08703, doi:10.1029/2008GL037074 notes: "Avoiding the most serious climate change impacts will require informed policy decisions. This in turn will require information regarding the reduction of greenhouse gas emissions required to stabilize climate in a state not too much warmer than today."

According to Science's H. Jesse Smith the authors: "use a global coupled climate model to evaluate the consequences of a low-emission scenario developed by the United States Climate Change Science Program (CCSP), and thereby illustrate how aggressive mitigation can limit the rise of the global average tropospheric temperature to 1°C above current value by the year 2100. This temperature target is used because it is thought to represent the maximum at which the consequences of climate warming will remain manageable, before becoming dangerous. The authors also discuss ancillary climate consequences of this mitigation route, in an attempt to provide information relevant for the assessment of a wide range of policy options."

Or as the authors put it : "Compared to a non-intervention reference scenario, emission reductions of about 70% by 2100 are required to prevent roughly half the change in temperature and precipitation that would otherwise occur. By 2100, the resulting stabilized global climate would ensure preservation of considerable Arctic sea ice and permafrost areas. Future heat waves would be 55% less intense, and sea level rise from thermal expansion would be about 57% lower than if a non-mitigation scenario was followed."