Circulation Of Atlantic Ocean: Bad News For Climate System And Humanity

A new study stressed that the Atlantic Ocean's circulation is approaching a tipping point, which will have a bad impact on the climate system and humanity.

One of the most famous climate tipping points is the Atlantic meridional overturning circulation (AMOC), which has the potential to collapse due to freshwater intake in the North Atlantic.

Abrupt Shift

Using computer models and historical data, the researchers created an early warning signal for the breakdown of the AMOC, a large network of ocean currents that plays an important role in global climate regulation.

They discovered that AMOC is already on pace for an abrupt shift, which has not occurred in more than 10,000 years and would have catastrophic consequences for broad sections of the Earth.

AMOC, which includes a portion of the Gulf Stream and other significant currents, is a marine conveyor belt that transports heat, carbon, and nutrients from the tropics to the Arctic Circle, where they cool and sink into the deep ocean. This churning helps to spread energy around the planet and mitigates the effects of human-caused global warming.

The new study, published in Science Advances, breaks new ground by looking for warning indicators in salinity levels at the southern end of the Atlantic Ocean between Cape Town and Buenos Aires. Simulating changes over 2,000 years on computer models of the global climate revealed that a gradual decrease can lead to a dramatic collapse in less than 100 years, with disastrous implications.

The paper stated that the results provided a "clear answer" about whether such an abrupt shift was possible.

"This is bad news for the climate system and humanity because up until now, one could think that AMOC tipping was only a theoretical concept and tipping would disappear as soon as the full climate system, with all its additional feedbacks, was considered," the paper read.

According to an earlier study, AMOC has decreased by 15% since 1950 and is at its weakest point in more than a millennium, raising concerns about an impending collapse.

Until now, no one has agreed on how serious this will be. One study last year, based on changes in sea surface temperatures, projected that the tipping point might occur between 2025 and 2095. However, the UK Met Office said large, rapid changes in AMOC were "very unlikely" in the 21st century.

Consequences Of AMOC Collapse

The AMOC collapse had some serious consequences.

Sea levels in the Atlantic would increase by a meter in certain areas, flooding several coastal communities. The wet and dry seasons in the Amazon would reverse, perhaps driving the already vulnerable jungle over its own tipping point.

Temperatures around the world would be significantly more unpredictable. The southern hemisphere would get warmer. Europe would cool drastically and receive less rainfall. While this may sound desirable in comparison to the present heating trend, the changes would occur ten times faster than now, making adaptation practically impossible.

René van Westen of Utrecht University, the lead author, said that there was insufficient data to predict whether this would occur in the following year or century, but that when it does, the alterations will be permanent on human timeframes. Meanwhile, the direction of travel is undeniably worrying.

"We are moving towards it. That is kind of scary. We need to take climate change much more seriously," van Westen said.