AMOC Devolving
LiveScience: “Atlantic ocean currents are weakening — and it could make the climate in some regions unrecognizable.” A mysterious patch of water in the North Atlantic, located to the southeast of Greenland, has baffled scientists for decades. This mass of seawater was paradoxically colder from 1901 to 2021 than during the late 1800s, even as the seas around it became ever warmer. A broad network of thermohaline currents may be slowing down [including the Gulf Stream], which form a huge and seemingly permanent loop known as the Atlantic Meridional Overturning Circulation (AMOC). “Weaker currents could unleash freezing weather in parts of Europe, exacerbate sea level rise along the U.S. East Coast, and trigger droughts around the equator.” Part of the story begins with waters flowing north from the tip of South Africa riding on the surface of the ocean, absorbing heat from the atmosphere as they glide through the tropics and subtropics. “They release this heat into the North Atlantic near Greenland, leading to a warming effect that is particularly strong in Northwest Europe.” But growing rivers of meltwater from the Greenland Ice Sheet and the Arctic are diluting the salt concentrations of surface waters, preventing them from plunging to the seafloor. Maya Ben-Yami, an early-stage researcher who specializes in climate tipping points at the Technical University of Munich, states the AMOC makes air temperatures in countries like Norway 18 to 27ºF (10 to 15ºC) warmer, on average, than they would be otherwise. The sinking step near Greenland requires very salty, dense surface waters to plunge down the water column and merge with bottom currents, thence taking about a thousand years to reach the depths around Antarctica. Problem is that direct measurements of the AMOC’s strength only go back to 2004, so researchers rely on indirect “fingerprints” — climate parameters they think are linked to the AMOC — to identify long-term trends in Atlantic circulation. Lots more to this article, which I chose for its colorful graphic [though South Atlantic is cut off]. So dive into the link at the beginning, the water’s — sort of — fine.
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