Far below the surface of the water of the seas and oceans, streams of water move like thermal belts that channel temperature and the fluxes of carbon, oxygen and nutrients around the planet.
According to a new study by Irina Marinov and Raffaele Bernardello, from the University of Pennsylvania, along with other colleagues from McGill University, global warming could have an influence by slowing down the speed of these convection marine belts, which would have serious consequences for the climate in the future.
“Based on our observations, less deep currents are now forming near Antarctica. This is worrying because it will reduce the capture of heat and carbon dioxide from human activity , creating a feedback loop that will enhance climate change. “
Oceanographers have found that deep Antarctic waters, which form a huge stream of cold, salty, dense water that flows 2,000 meters below the surface from the coast of the frozen continent to the equator, has shrunk in recent decades.
The problem is that the Antarctic Ocean absorbs almost 60% of the anthropogenic heat produced on Earth and 40 to 50% of the carbon dioxide produced by human activity.
If the creation of that current is stopped, the “Antarctic vacuum cleaner” would stop working. The first reason, according to these scientists, has to do with the fact that climate change has increased rainfall throughout the Antarctic continent, raising fresh water levels on the surface.
Fresh water is more dynamic than salt water and does not sink into the layers of the ocean as the saltier does. The consequence is less open ocean convection in the Southern Ocean and a slowdown in activity in deep waters.
Examining data from 20,000 points, the researchers showed that the surface of the Southern Ocean has gained in fresh water for the past 60 years. At the same time they found that the vertical gradients of salinity and density have increased, which indicates that the mixture of cold and warm waters and salty and sweet has been reduced. “The convective process is shutting down as the water is getting sweeter, ” Marinov said, in light of 36 complex simulation models of changing weather patterns.
Seven of the models suggest that the increase in freshwater in the Southern Ocean could completely disrupt convection by 2030 , while almost all other analyzes show strong drops in convection and formation of deep Antarctic waters throughout the 21st century. .
