Two new studies are adding to concerns about one of the most troubling scenarios for future climate change: the possibility that global warming could slow or shut down the Atlantic's great ocean circulation systems, with dramatic implications for North America and Europe.

The research, by separate teams of scientists, bolsters predictions of disruptions to global ocean currents - such as the Gulf Stream - that transfer tropical warmth from the equator to northern latitudes, as well as a larger conveyor system that cycles colder water into the ocean's depths. Both systems help ensure relatively mild conditions in parts of Northern Europe that would otherwise be much colder.

The papers offer insight into how rapidly melting Arctic ice could slow or even temporarily halt the ocean's normal circulation. Credit:Mariusz Kluzniak

The papers offer insight into how rapidly melting Arctic ice could slow or even temporarily halt the ocean's normal circulation, with possible effects ranging from plunging temperatures in northern latitudes to centuries-long droughts in south-east Asia. A fictional version of this scenario was depicted in the 2004 disaster film Day after Tomorrow, although most scientists believe the movie's vision of ice sheets over New York and Europe are highly unlikely.

One study, by three scientists from Germany's Alfred Wegener Institute, uses computers to model how Greenland's rapid thawing could affect the Atlantic meridional overturning circulation, the system that pushes cold, dense saltwater into the deep ocean and helps transport warm water northward, helping to warm Europe's climate.