Living in an age of unprecedented human-caused climate change sure is fun! This new study published in Nature shows that the Gulf Stream is at its slowest in at least 1,600 years, probably because of climate change. What are the effects of this? It ain’t good. Since most people not connected to a university don’t have a pricey Nature subscription or even if they do, they aren’t used to climatological language, here’s a good run-down of what this means.
As global temperatures rise with the levels of heat-trapping gases in the atmosphere, the AMOC could be disrupted by an influx of freshwater from increasing precipitation in the North Atlantic and the melting of sea ice and glaciers on land. The added freshwater lowers the water density in the zone where deepwater forms, backing up and weakening the overall flow of the AMOC like a clogged sink. That slowdown means less heat is transported northward, leading to cooler ocean temperatures in a region below Greenland, and warmer temperatures off the U.S. east coast. That warming leads to higher sea levels along the coast and raises sea temperatures where economically valuable cold-loving species like cod and lobster live.
There are some indications the cold spot below Greenland can alter atmospheric patterns in a way that channels warm air over Europe, increasing the likelihood of sustained summer heat waves, says Levke Caesar, a PhD student at the Potsdam Institute for Climate Impact Research (PIK) and co-author of the other new study. The changing ocean temperatures from an AMOC slowdown could also potentially help lock in colder winter conditions over the eastern U.S., PIK’s Stefan Rahmstorf, a co-author of the same research, has posited, although the evidence there is not clear.
A big part of the study is that climate models are probably missing the worst impacts of this and, like a lot of research around climate change, is indicative that this is all going to be a lot worse than we think.