The Atlantic Reversal Meridional Circulation, or AMOC, continues to show signs of slowing due to climate change. A new study summarized in Science Daily provides more evidence that melting freshwater ice from the Greenland glaciers and ice cap dilutes the salinity of North Atlantic waters. The more salty waters are heavier and sink into the seabed, drawn in this formidable current towards the hot tropical latitudes. There, the water heats up and again flows north and northeast, carrying enormous amounts of heat to the northern latitudes of the Atlantic. Within AMOC is the Gulf Stream.
If this slowdown were to continue, the further weakening of the AMOC and the Gulf Stream would significantly reduce the northward heat transport and allow more extreme winter conditions at more northerly latitudes in eastern North America. and Europe. There is already growing but still inconclusive evidence that this process is underway, linked to dilute salinity born from warming high latitudes increasing the rate of freshwater ice melting.
As the University of Arizona study director Jianjun Yin put it, describing the weakening of heat transport to the north, “Think of it as two highways connecting two big cities,” said Yin. “If one is closed, the other receives more traffic. In the atmosphere, the traffic is the daily weather. So if the ocean heat transport slows down or stops, the weather becomes more extreme.”
As I have written in previous articles, this regional cooling in the midst of global warming may seem counterintuitive, but there is a large and growing body of data strongly suggesting that it is real.