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Ice Cores Reveal Green Arctic
Analyses of sediment cores show that Arctic summers 3.6 million years ago were a good 8 degrees C warmer than they are today, and supported Douglas Fir and hemlock. Sophie Bushwick reports.
The Arctic wasn't always covered in ice. Samples of sediment layers beneath a frozen lake show this region used to be a lot warmer””and may thaw out again in the future. The work is in the journal Science. [Julie Brigham-Grette et al, Pliocene Warmth, Polar Amplification, and Stepped Pleistocene Cooling Recorded in NE Arctic Russia]
El'gygytgyn, a Russian lake 100 kilometers north of the Arctic Circle, contains layers of sediment that date back to the lake's formation 3.6 million years ago. Analyses of sediment cores have revealed that back then summers reached about 15 to 16 degrees Celsius, a good 8 degrees warmer than modern Arctic summers. These warm temperatures, which supported plants like Douglas fir and hemlock, lasted until about 2.2 million years ago.
http://www.scientificamerican.com/podcast/episode.cfm?id=ice-cores-reveal-green-arctic-13-05-10