Danger on the deep ocean currents near Antarctica

According to scientists, the deep ocean currents circulation that develops around Antarctica may soon collapse. The stagnation of the ocean floor caused by this loss in ocean circulation will have long-term effects on the climate and marine ecosystems. The findings are described in a recent study conducted by Scientia Professor Matthew England, Deputy Director of the ARC Centre for Excellence in Antarctic Science (ACEAS) at UNSW Sydney. Lead author Dr. Qian Li, formerly of UNSW and now at MIT, as well as co-authors from the Australian National University (ANU) and CSIRO contributed to the work, which was published today in Nature. The overturning circulation, a network of currents that covers the world’s oceans, is driven by cold water that dips close to Antarctica and produces its deepest flow. The globe is turned over, dispersing heat, carbon, oxygen, and nutrients. This affects the climate, sea level, and marine ecological production. According to Prof. England’s modeling, the Antarctic overturning would decelerate by more than 40% in the following 30 years if global carbon emissions keep increasing at the current rate. This trajectory appears to be heading in the direction of collapse.

Simulation of the deep ocean

Each year, water that is frigid, salty, and oxygen-rich sinks near Antarctica. The oxygen from this water subsequently travels northward into the deep Indian, Pacific, and Atlantic Oceans. According to Prof. England, if the seas had lungs, this would be one of them. The volume of Antarctic deep water produced under the IPCC’s “high emissions scenario” up until 2050 was modeled by the multinational team of scientists. The model includes theories about how glacier meltwater may affect circulation, as well as features of ocean dynamics that earlier models were unable to account for. Even while the Antarctic overturning has largely remained steady for thousands of years, it is predicted that due to growing greenhouse gas emissions, it will dramatically slow down during the next few decades.

Effects of less frequent Antarctic overturning

The oceans below 4,000 meters would become stagnant if this deep ocean current ceased to exist. Prof. England claims that this would “trap nutrients in the deep ocean, limiting the nutrients available to support marine life near the ocean surface.” The Australian Antarctic Program Partnership’s Dr. Steve Rintoul, a co-author, claims that the model simulations demonstrate a slowdown of the overturning, which subsequently results in a rapid warming of the deep ocean. The deep ocean is actually already warming, according to Dr. Rintoul’s own measurements. According to the study, as Antarctica’s ice melts, the ocean waters nearby become less thick, slowing the overturning circulation there. As the earth warms, it is predicted that the melting of the Antarctic and Greenland ice sheets would quicken. Dr. Adele Morrison, an associate professor at ACEAS and the ANU Research School of Earth Sciences, adds that “our study reveals that the melting of the ice sheets has a profound impact on the overturning circulation that regulates Earth’s climate.” It’s feasible that an iconic water mass will go extinct in the long run, according to Prof. England. The oceans will be significantly harmed for millennia to come by such huge changes in the ocean’s overturning of heat, freshwater, oxygen, carbon, and nutrients.

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