'We don't really consider it low probability anymore': Collapse of key Atlantic current could have catastrophic impacts, says oceanographer Stefan Rahmstorf

The Atlantic Meridional Overturning Circulation (AMOC) acts as a planetary conveyor belt bringing nutrients, oxygen and heat north from tropical waters.

But research into Earth 's climate history shows that the current has switched off in the past.

44 oceanographers from 15 countries published an open letter calling for urgent action in the face of weakening circulation.

The AMOC has a tipping point described in a famous study by the American oceanographer Henry Stommel in 1961 .

It's been known for a long time, but until recently it was considered as low probability but high impact.

Climate change would counteract that effect in most places, except around the North Atlantic .

Ocean takes up 25% of our CO2 emissions just by gas exchange at sea surface.

A collapse of the AMOC could enhance the risk of ice sheet instability in Antarctica , or passing the tipping point of the Greenland ice sheet would lead to more freshwater release from Greenland into the North Atlantic .

An AMOC collapse would cut the amount of land available worldwide for growing wheat and maize by more than half .