Study Reveals Ancient Arctic Climate Swings

http://www.livescience.com/environment/060531_arctic_climate.html

Scientists have uncovered the Arctic region's history of climate change buried beneath layers of ocean ice from a newly collected sediment core.

The 1,312-foot-long cylindrical sediment core sample provides a 56-million-year record of the continent's temperature trends. It reveals that approximately 45 million years ago, the Arctic went from being a warm greenhouse to the frosty ice-covered continent that we know today.

The sediment sample also revealed abundant remains of a freshwater fern known as Azolla, dating back to about 49 million years ago, which indicate that there was freshwater flowing from the Arctic Ocean as far south as the North Sea. Without an inflow of salty waters, any excess precipitation compared with evaporation created a freshwater environment in the Arctic Ocean.