The Day After...Today?!?

[Nbadan]

Talk about life immitating art...



Evidence of Slowing Ocean Currents Alarms Scientists
By Usha Lee McFarling, Times Staff Writer

The powerful ocean currents that transport heat around the globe and keep northern Europe's weather relatively mild appear to be weakening, according to a new scientific report.

A group of British oceanographers surveyed a section of the Atlantic Ocean stretching from Africa to the Bahamas that has been studied periodically since 1957 and found the overall movement of water had slowed 30% in the past five decades.

The report, published in the current issue of the journal Nature, is the first evidence of such a slowdown.

Computer models have long predicted that the warming of the oceans and the "freshening" of the seas with water from melting glaciers and increased precipitation — all linked to the warming of the Earth by greenhouse gases — could slow the currents, but scientists did not expect to see such changes so soon.

"The result is alarming," Detlef Quadfasel, a climate expert at the University of Munich, wrote in a commentary accompanying the research, and provides "worrying support for computer models."...

LA Times

The North Atlantic current is a heat conveyor -- it carries warm water from the equatorial areas northward, which serves to create a milder climate in England than it warrants given its northern location.

Ocean water surrounding this current is much colder, and much more salty, and this differential of temperature and salinity helps to drive the pump effect.

Having dumped its heat off on the journey, the NA current then dives down to the ocean floor and circles back down to the southern hemisphere and the cycle continues endlessly.

Until....

As the overall ocean temperatures grow warmer, and as melting glaciers dump more fresh water into the ocean, the temperature and salinity differential is reduced, and the pump action slows... and may even stop.

When the NA current stops bringing that extra warmth up from the tropics, then northern Atlantic land masses return to the temperature more typical for high la udes -- cold. Like, Siberian Russia cold. Even a globally warmed Siberia is a of lot colder than England is right now.

[Nbadan]

More:

Measurements of ocean currents in the North Atlantic reveal that they have weakened by about 30 per cent since 1992. The findings, published in the journal Nature, fit computer predictions of what would happen when Greenland glaciers begin to melt because of global warming. The models suggest that extra freshwater released into the North Atlantic could weaken ocean currents and even shut down the Gulf Stream.

...

Scientists estimate that the detected 30 per cent weakening of the Atlantic currents could lead to a fall of about 1C in Britain's average temperatures over the next 20 years.

They also warn that the weakening could be the first signs of an accelerating trend that could eventually lead to a more drastic change, including a complete shutdown of the currents. If this were to happen, average temperatures in Britain could fall by between 4C and 6C, leading to winter temperatures similar to Newfoundland in Canada, which is on the same la ude as the UK but does not benefit from the Gulf Stream.

Independent