New Iceland current could sway N. Atlantic climate

WASHINGTON,  (Reuters) – A newly discovered deep,  cold current flowing off Iceland’s coast may reveal that the  North Atlantic is less sensitive to climate change than  previously thought, researchers reported yesterday.
The new current, the North Icelandic Jet, feeds the  Atlantic Meridional Overturning Circulation, a giant pattern  known as the “great ocean conveyor belt,” or by the  disconcerting acronym AMOC.

Because this pattern is critically important for regulating  Earth’s climate, including European and North American  climates, any strong influences on it, and their response to a  warming Earth, are of keen scientific and practical interest.

The “conveyor belt” current, introduced to movie-goers in  the Al Gore environmental film “An Inconvenient Truth,” carries  warm surface water from the tropical Atlantic toward the  Arctic. In the process, the water warms the air in high  latitudes, then cools, sinks and returns toward the equator,  flowing as a deep stream at lower ocean depths.

Climate specialists reckoned that most of the cold water  that made up that deep south-flowing stream came from off the  Greenland coast and was made up of fresh glacier-melt water,  produced by new warmth in glacier-covered Greenland.

Because fresh water freezes at a higher temperature than  salt water, these specialists suggested that this fresh water  from glaciers and other warming-related phenomena would get  into the North Atlantic, where it could freeze and prevent the  water from sinking to make up the bottom of the conveyor belt.

 AMOC RUNNING AMOK?  

If that happened, and the AMOC was disrupted or slowed at  the place in the far north where the warm water at the surface  cools and sinks — called the overturning — it could  eventually lead to a colder Northern Hemisphere.

However, the newly confirmed North Icelandic Jet appears to  contribute more to the deeper part of the AMOC than the  Greenland current does, according to research published in the  journal Nature Geoscience. (For a graphic, see:  http://link.reuters.com/qev33s)

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