Climate change

Out-of-reach goal to limit warming

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Even if the world makes long-term cuts to carbon emissions of 90% relative to 2009 levels, it will miss the target of limiting global warming to 2 °C by the end of the millennium. Only if larger cuts are made — both long term and globally, starting in the next couple of decades — at an annual rate of at least 3% could that target be met.

Pierre Friedlingstein at the University of Exeter, UK, and his colleagues used a coupled climate–carbon-cycle model to simulate global warming until the year 3000 in various scenarios. If a 3% yearly reduction rate began 30 years from now for a total emissions cut of 90%, the average global temperature would be nearly 3 °C higher in 3000.

When the authors accounted for the climate's sensitivity to the effects of increased atmospheric carbon, they found that only when the sensitivity is low could a more conservative mitigation rate of 1% per year implemented within the next 10 years meet the 2 °C target.

Nature Clim. Change 10.1038/nclimate1302 (2011)

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