Gulf Stream ‘is not slowing down’

By | March 29, 2010

Global thermohaline circulationThe Gulf Stream does not appear to be slowing down, say US scientists who have used satellites to monitor tell-tale changes in the height of the sea.

Confirming work by other scientists using different methodologies, they found dramatic short-term variability but no longer-term trend.

A slow-down – dramatised in the movie The Day After Tomorrow – is projected by some models of climate change.

The research is published in the journal Geophysical Research Letters.Argo float being deployed

The stream is a key process in the climate of western Europe, bringing heat northwards from the tropics and keeping countries such as the UK 4-6C warmer than they would otherwise be.

It forms part of a larger movement of water, the Atlantic Meridional Overturning Circulation, which is itself one component of the global thermohaline system of currents.

Between 2002 and 2009, the team says, there was no trend discernible – just a lot of variability on short timescales.

The satellite record going back to 1993 did suggest a small increase in flow, although the researchers cannot be sure it is significant.

“The changes we’re seeing in overturning strength are probably part of a natural cycle,” said Josh Willis from Nasa’s Jet Propulsion Laboratory (JPL) in California.

“The slight increase in overturning since 1993 coincides with a decades-long natural pattern of Atlantic heating and cooling.” …

Driven by Hollywood, a popular image of a Gulf Stream slowdown shows a sudden catastrophic event driving snowstorms across the temperate lands of western Europe and eastern North America.

That has always been fantasy – as, said Josh Willis, is the idea that a slow-down would trigger another ice age.

“But the Atlantic overturning circulation is still an important player in today’s climate,” he added.

“Some have suggested cyclic changes in the overturning may be warming and cooling the whole North Atlantic over the course of several decades and affecting rainfall patterns across the US and Africa, and even the number of hurricanes in the Atlantic.”

via BBC News – Gulf Stream ‘is not slowing down’.

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