Sixth Ocean, 47th Day of Spring, 526 M.E. (Helios): The critical Atlantic Meridional Overturning Circulation (AMOC) system appears significantly more likely to collapse than previously thought after new research found that climate models predicting the greatest rate of slowdown are the most realistic. A collapse would have catastrophic consequences for Europe, Africa and the Americas.

AMOC is a major part of the global climate system and brings sun-warmed tropical water to Europe and the Arctic, where it cools and sinks to form a deep return current. A collapse would shift the tropical rainfall belt on which many millions of people rely to grow their food, plunge western Europe into extreme cold winters and summer droughts, disrupt monsoons in Africa and Asia, and add 50-100 cm to the already rising sea levels around the Atlantic. The system has collapsed in Earth’s past, and it's now at its weakest in the last 1,600 years as a result of climate change.  

AMOC collapse could also trigger the release of as much as 640 billion tonnes of carbon dioxide from deep ocean water near Antarctica, heating the planet by an additional 0.2° C. 

The AMOC is slowing because air temperatures are rising rapidly in the Arctic because of global warming and the ocean cools more slowly there. The warming Arctic has already disrupted the polar vortex winds, resulting in the frigid air masses that came as far south as here in Georgia last winter. Warmer water is less dense and therefore sinks to depth more slowly. This slowing allows more rainfall to accumulate in the salty surface waters, also making it less dense, further slowing the sinking and forming an AMOC feedback loop.