Ocean May Cause Recurring Extreme Winters in Europe

As a blizzard barrels down on the northeast, scientists have announced that there may be a way to predict extreme winters across Europe. Scientists have found that by identifying the set of environmental conditions that are associated with pairs of severe winters across consecutive years, it may be possible to apply these findings to future extreme winters.

During the recent severe winters of 2009 and 2010, scientists from the National Oceanography Center (NOC) measured strong reductions in the strength of the Atlantic meridional overturning circulations (AMOC). This is essentially a conveyor belt of water that transports heat toward northwest Europe. It's this transfer of heat that contributes to the milder winters experienced in this part of Europe than at similar latitudes in western Canada.

The researchers also discovered that extreme winters coincided with high pressure over the Arctic and a band of low pressure immediately to the south, a set of atmospheric conditions known as a negative Arctic Oscillation. Yet what's interesting is that the scientists believe that the ocean with its conveyor belt of water plays a role in preserving these atmospheric conditions over the North Atlantic. This, in turn, allows extreme winters to reappear the following year.

"Ocean surface temperature anomalies can affect the atmospheric conditions," said Adam Blaker, one of the researchers, in a news release. "The ocean can store these anomalies by trapping them beneath the ocean surface during the summer and mixing them back to the surface the following winter, providing a seasonal 'memory.' Our research could help predict when these pairs of severe winters will occur in the future."

The findings are published in the journal Climate Dynamics.

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