Meltwater-induced weakening of the Antarctic overturning circulation could also shift tropical rainfall bands around a thousand kilometres to the north. And more greenhouse gases means more warming, making matters worse. This would accelerate global sea-level rise.Īn overturning slowdown would also reduce the ocean’s ability to take up carbon dioxide, leaving more greenhouse gas emissions in the atmosphere. These nutrients will be lost to marine ecosystems at or near the surface, damaging fisheries.Ĭhanges in the overturning circulation could also mean more heat gets to the ice, particularly around West Antarctica, the area with the greatest rate of ice mass loss over the past few decades. If the Antarctic overturning slows down, nutrient-rich seawater will build up on the seafloor, five kilometres below the surface. The resulting overturning circulation carries oxygen to the deep ocean and eventually returns nutrients to the sea surface, where they are available to support marine life. The sinking near Antarctica is balanced by upwelling at other latitudes. Show text description Hide text description Why does this matter?Īs part of this overturning, about 250 trillion tonnes of icy cold Antarctic surface water sinks to the ocean abyss each year.
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