Atlantic Meridional Overturning Circulation slowing much faster than expected
It seems that the 2004 Hollywood blockbuster disaster movie The Day after Tommorrow, while highly exaggerated, had the seed of scientific fact based upon the possible disruption that could occur from the slowdown or catastrophic cessation of the Atlantic ocean Meridional Overturning Circulation (AMOC), also known as the thermohaline circulation or Great ocean conveyor belt.
A new study by Rahmstorf et al (2015) published in Nature Climate Change has found evidence for a slowdown of the overturning circulation. This is based upon multiple lines of observation suggesting that over recent decades the current system has been weaker than ever before in the last century, or even in the last millennium.
The Gulf Stream is part of this circulation system with warm waters, which are naturally lighter, flowing north, and responsible for the mild climate of north western Europe. In the sub-polar region these waters cool, become more dense, and sink to the bottom before they start flowing south along the ocean bottom towards the tropics, then the South Atlantic and the Southern Ocean. The conveyor belt of currents connects the Atlantic, Indian, Pacific and Southern Oceans providing heat transfer and mixing throughout the globe.
Related Links: What’s going on in the North Atlantic? at Realclimate Blog | New Research Shows Exceptional Slowdown In Major Atlantic Ocean Currents Greg Laden's Science Blog