Atlantic ocean current circulation is on course for an abrupt shift that spells disaster

Atlantic ocean circulation is approaching a “devastating” turning point: Atlantic ocean current circulation is on course for an abrupt shift that spells disaster for the environment, The Guardian writes, citing a new study published in Science Advances. The expected shift in Atlantic meridional overturning circulation (Amoc) — which sends warm water from south to north and regulates global weather patterns — forecasts more impending extreme weather events worldwide.

What is Amoc? Amoc — which houses a section of the Gulf Stream and other strong currents — functions as a marine conveyor belt transporting heat, carbon, and nutrients from tropical regions towards the Arctic Circle. Upon reaching the Arctic, it cools and descends into the depths of the ocean. This circulation process aids in distributing energy across the globe and regulates the effects of man-made global warming.

Climate change is the culprit: Amoc is being eroded by the rapid melting of glaciers in the Arctic, which pour fresh water into the ocean and obstruct the warmer, saltier tropical water from sinking. The researchers measured salinity levels at the southern extent of the Atlantic Ocean between Cape Town and Buenos Aires, and then simulated transformations spanning 2k years using computer models of the global climate. They discovered that a gradual decrease can result in a rapid collapse within fewer than 100 years, leading to catastrophic outcomes.

Devastating consequences: The collapse of Amoc is expected to cause sea levels to rise by 1 meter in some regions in the Atlantic, flooding coastal cities. It is also expected to cause erratic fluctuations in global temperatures, causing warming in the Southern Hemisphere and cooling in the north. Europe will see its rainfall levels fall and the continent will cool dramatically, while the Amazon’s wet and dry seasons will flip, potentially driving it to its own tipping point. The speed at which climatic shifts are expected to occur will be “devastating,” rendering adaptation impossible, the study’s authors said.

When is this supposed to happen? Amoc has already declined 15% since 1950, bringing it to its weakest state in over a millennium, and one study forecasts the tipping point will occur between 2025 and 2095. A 2019 study by the IPCC projected that Amoc would weaken over this century, but that a full collapse before 2100 was unlikely.