Abrupt changes in North American climate during early Holocene times

Article Abstract:

Studies of the Greenland ice cores have provided insights into the Holocene climatic dynamics. Analyses of varved sediments from Deep Lake in Minnesota, USA indicates a pronounced climate cooling from 8.9 to 8.3 kyr before present, possibly distinguished by increased outbreaks of polar air, falling precipitation temperatures and a higher proportion of the annual precipitation falling as snow. The abrupt onset could be due to a reorganization of atmospheric circulation and cooling of the Arctic airmass in summer. The timing and duration indicates its distinction from the cold snap occurring in Greenland and other regions 8,200 years ago.

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Is the ocean at the helm?

Article Abstract:

An analysis of patterns of wintertime sea surface temperature in the North Atlantic over a number of decades, along with records of the overlying atmospheric circulation, mapped through sea-level pressure distributions, indicates that the patterns develop in an extremely organized manner over decade timescales. The patterns were found to propagate in the direction of the main ocean currents. It has been shown that sea surface temperature anomalies and linked sea-level pressure anomalies are involved in a whole-ocean oscillation.

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Stirring times in the Southern Ocean

Article Abstract:

Researchers have undertaken a fertilization experiment in the Southern Ocean around Antarctica, and deduced scientific implications for interpreting past climate change.

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