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: Icelandic government officials recently met to discuss a dramatic scenario: what if the current that circulates Atlantic waters weakened significantly, or collapsed altogether? The ocean currents are changing, with major implications for climate around the world.
Yet our new article published in Nature Sustainability suggests most governments are not preparing for this possibility. Of 91 national adaptation plans submitted to the U.N. climate convention, only two even mention that key Atlantic current, and neither sets out concrete action in response to its possible collapse. The Atlantic meridional overturning circulation, or AMOC, is part of the giant conveyor belt of ocean currents that moves warm surface water northward in the Atlantic and sends colder deep water back south.
It plays a critical role in regulating the global climate by redistributing heat around the planet, influencing weather patterns and temperatures far beyond the Atlantic basin. As the climate warms, the AMOC is weakening and could continue to do so throughout this century. While a full collapse, in which major ocean currents completely reorient, is unlikely before 2100, a recent study projected a 50% weakening of the AMOC by the end of the century under an intermediate emissions scenario.
A collapse would not be unique in geological history. Studies show that the AMOC has undergone dramatic changes before, including a near-complete shutdown around 17,500 years ago, after the coldest period in the last ice age. A slowdown or collapse would have major implications for temperature and rainfall around the world.
In northern Europe, the loss of the heat AMOC transfers northward from the tropics could lead to winter cold extremes of -20°C (-4 degrees Fahrenheit) in London. Climate model experiments in which the AMOC is shut down show an average 29% weakening of the West African monsoons and 19% weakening of the Indian summer monsoon, increasing risks of food and water insecurity in regions that rely on monsoon rains. Other studies suggest an increased risk of severe drought in parts of Central America, West Africa and the Amazon region.
Fisheries and sea level would also be affected. So how can countries prepare for changes in ocean circulation whose timing is highly uncertain? Our article identifies practical steps to incorporate AMOC-related risks into adaptation decision-making.
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