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)
