Greenland's meltwater will slow Atlantic circulation, climate model suggests

Editors' notes

This article has been reviewed according to Science X's editorial process and policies. Editors have highlighted the following attributes while ensuring the content's credibility:

fact-checked

peer-reviewed publication

trusted source

proofread

A team of climate scientists in Germany and China has found evidence, using a climate model, that in the coming years, freshwater inputs to the Irminger Sea Basin will have the biggest impact on the Atlantic Meridional Overturning Circulation (AMOC). Their paper is published in the journal Science Advances.

The AMOC is the primary ocean current in the Atlantic Ocean. It is made up of northward flows of warm, saltier water in the upper layers of the Atlantic Ocean and southward return flows of cold, denser, deeper water, and it includes the Gulf Stream. Prior research has shown that it plays a major role in the global climate system, especially for weather in Europe.

Research has also shown that climate change is affecting the AMOC, which could lead to unpredictable changes in weather patterns. These effects are thought to be due to changes in freshwater inputs to the AMOC, either due to changes in rainfall or snowmelts. Freshwater reduces the density of surface water, preventing it from sinking into a lower water layer, reducing the southern return flow.

In this new study, the research team wondered which source of freshwater inputs is having the most impact on the AMOC. To find out, they added features of the region to the Alfred Wegener Institute Climate Model, looking at each of the major sources of freshwater flow into the AMOC.

They found that freshwater inputs into the Irminger Sea Basin due to Greenland snowmelts are having the biggest impact of all known freshwater inputs. This, they note, is because of the unique position of the Irminger Sea Basin—it is located at the point in the AMOC where it makes its U-turn—changing course from north to south. Because of that, cold freshwater pouring directly into the current remains near the surface, slowing the current.

Such a slowdown is not overcome when the AMOC turns around again in the tropics, resulting in slowed warmer water moving north. The result is a slowdown of the entire AMOC, which reduces its strength, the impact of which is still uncertain.

More information: Qiyun Ma et al, Revisiting climate impacts of an AMOC slowdown: dependence on freshwater locations in the North Atlantic, Science Advances (2024). DOI: 10.1126/sciadv.adr3243

Journal information: Science Advances

© 2024 Science X Network