2023-04-20 04:13:28
Scientists worry that warming will disrupt ocean circulation in the North Atlantic, which is the setting for the movie After Tomorrow. But the bigger crisis lies in Antarctica, new research finds. Scientists simulated the impact of Antarctic ice melting on deep ocean currents. A study published in the journal Nature warned that melting ice in Antarctica would not only raise sea levels, but also slow down the circulation of deep sea water. The Antarctic circulation is expected to collapse in this century. Global climate and marine life have a huge impact.
The ocean gyre system, often called the global conveyor belt, follows a regular path through Earth’s oceans and churns the waters from top to bottom. The conveyor belt is driven by cold, salty water descending to the seafloor in two places, one in the far North Atlantic near Greenland, and the other in the Southern Ocean around Antarctica.
In both regions, the mechanism is the same. In cold polar conditions, a large amount of water freezes, the salt in the water is not incorporated into the ice, but remains in the residual liquid water, which becomes more and more salty, the water becomes saltier and denser, so the residual liquid water Heavier than the surrounding water, it eventually sinks to the bottom of the ocean.
every year about 250 Trillions of tons of salty water sink in this way around Antarctica and then spread north along the seafloor into the Indian, Atlantic and Pacific oceans. Similar numbers spread southward from Greenland. This process is also known as ocean overturning, and has remained largely unchanged for thousands of years.
As the world warms, less ice forms in the oceans at the ends of the planet each year, and more ice on the nearby ice sheets of Antarctica and Greenland is melting and releasing fresh water into the oceans. As a result, the surface waters in the Southern Ocean and around Greenland have become less salty, less dense and less able to sink.
Trends like this definitely affect ocean circulation, most previous studies have focused on the Atlantic Meridional Overturning Circulation (AMOC) In theory, this is an ocean current system that brings warm water from the tropics into the North Atlantic Ocean. The impact includes freezing the western part of the European continent into a deep freeze, but scientists believe that is unlikely to happen this century.
Antarctic Ocean circulation slowing impact is more dramatic
In the past, there were few studies on the Southern Ocean. After three years of computer modeling, scientists found that if the world continues to burn fossil fuels and produce high levels of pollution, it will 2050 Year, Antarctic overturning circulation may slow 42%is the predicted North Atlantic equivalent event 19% More than twice that, the slowing of the circulation will accelerate the melting of the ice, and humans will be in the 2050 year to 2100 Sometime between the years, start to see its impact on surface productivity. Once it collapses, it’s likely to remain collapsed until Antarctic melting stops, scientists say.
Antarctica is the largest ice bank in the world, and humans should expect the impact of this melting to be profound. The first is nutrients. Ocean currents stir up the decomposing debris of nutrient-rich marine life on the ocean floor, feeding the bottom of the food chain. Marine life in global waters depends on nutrients brought back to the surface, while the Antarctic Gyre moves nutrient-rich water northward from Antarctica. Moving, passing through New Zealand and into the North Pacific, North Atlantic and Indian Oceans, scientists estimate that nutrients exported from the Southern Ocean support approximately three-quarters of global phytoplankton production, the basis of food chains, reduced Antarctic circulation, and a source of nutrients for marine life will be the first to collapse.
In addition, a slowdown in Antarctic ocean overturning has other knock-on effects on Earth, for example, potentially shifting rain bands in the tropics by as much as 1,000 km, when the circulation completely disappears, the northern hemisphere will become wetter and the southern hemisphere will become drier.
The lead author, an MIT oceanographer, concludes that the slowing of ocean circulation will profoundly alter the ocean’s shifts in heat, freshwater, oxygen, carbon, and nutrients, and the impact will spread across the entire global ocean in the coming centuries. Oceanographers at the Potsdam Institute for Climate Impact Research in Germany believe that this is a very important paper, and that the methods and models are convincing.
The collapse of the North Atlantic circulation is still more than a century away and the Antarctic ocean circulation is only 30 years away, the researchers warn, and the impact will be so dramatic that those born today will witness it firsthand.
(First image source: Flickr/David Stanley CC BY 2.0)
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