The large system of ocean currents in the Atlantic Ocean that regulates climate could reach a tipping point sooner than previously thought.
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The Atlantic meridional overturning circulation (AMOC), one of the most important tipping points in Earth’s climate system, could collapse around mid-century under the current emissions scenario, a new study has found.
Published in Nature Communications on Tuesday, the analysis challenges the findings of the Intergovernmental Panel on Climate Change (IPCC), which in the recently published Sixth Assessment Report (AR6) suggested a collapse of AMOC in the 21st century to be very unlikely.
AMOC is a large system of ocean currents driven by differences in the density of water, which determines their temperature. It acts as a conveyor belt, redistributing heat throughout the Earth’s climate system by bringing it from the tropics in the Southern Hemisphere all the way to Greenland and carrying cold water back south.
The freshwater input from glaciers’ melting, however, significantly weakens these currents. While the flow has already been reduced by about 15% in the last five decades, a weakening of 24% to 39% is expected even before the tipping point is reached, something that could happen, as the new study suggests, as early as in 2050. A study published in 2021 found that AMOC is already at its weakest in over 1,600 years.
“A slowdown of the AMOC could have consequences around the world,” the IPCC explains. “Rainfall in the Sahel region could reduce, hampering crop production; the summer monsoon in Asia could weaken; regional SLR [sea level rise] could increase around the Atlantic, and there might be more winter storms in Europe.”
Indeed, scientists suggest that a partial collapse of this system could plunge Europe into the Ice Age. This happened once before, around 12,000 years ago. As Greenland melted waters flew into the North Atlantic Ocean, AMOC was brought to a virtual halt. This caused Europe and North America to become much colder and resulted in a global cooling of more than 10°C (18°F) that lasted for 1,200 years.
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