Overview article - Is the Atlantic Overturning Circulation Approaching a Tipping Point?

The evidence for an ongoing weakening of the Atlantic overturning circulation (AMOC) is overwhelming, even without direct observations of the current strength over the last century, argues Rahmstorf, who has been working on this research topic for more than 30 years. This is shown not only by a characteristic "fingerprint" of this weakening in the observed temperature changes in the North Atlantic, but also by salinity data from the North and South Atlantic. In addition, various studies with palaeoclimatic data indicate that the current is already weaker than it has been for at least a thousand years.

It has been known for more than half a century that this current has a tipping point; this has been repeatedly confirmed over the last few decades in numerous studies using different models. In past climate changes in the Earth's history over the last 100,000 years, the AMOC has already repeatedly " tipped" and triggered dramatic global climate impacts.

"The risk of the AMOC tipping as global warming continues should be taken very seriously, considering the devastating consequences of such an event," says Rahmstorf. On the basis of a whole series of new studies in recent years, the risk already appears to be significantly greater in this century than scientists had long assumed. "In order to minimise this risk, the precautionary principle should apply: extensive emission reductions are essential in order to stop global warming as close to 1.5 degrees Celsius as possible in accordance with the Paris Climate Agreement."