An imperfect analogue

The melting of the Greenland ice sheet during the last interglacial period — 130,000 to 114,000 years ago — was a result of both higher Arctic summer temperatures and the distribution of incoming solar radiation, reports a paper published online in Nature Geoscience. Consequently, the authors suggest that the last interglacial period is not an adequate analogue for future climate change. Willem Jan van de Berg and colleagues used a series of numerical models and calculations to assess the factors that controlled the surface mass balance of the Greenland ice sheet during the last interglacial period. During this period, summer temperatures over Greenland were about two to four degrees Celsius higher than today, and the ice sheet was significantly smaller. The team estimates that only about 55% of that decline can be attributed to the higher summer temperatures. The rest they attribute to changes in the Earth’s orbit, which led to an increase in the amount of solar radiation reaching the high northern latitudes during the summer months. In an accompanying News and Views, Andrey Ganopolski writes: “The last interglacial period cannot be considered as a straightforward analogue for future Greenland melt.”

doi: 10.1038/ngeo1245

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