Antarctic Ocean Circulation is slowing down dangerously sooner than expected

Climate-change-driven changes in the water cycle to the deepest parts of the ocean around Antarctica could reverberate across the planet and intensify global warming, according to new research, decades ahead of schedule.

Accelerating melting of Antarctic ice and rising temperatures due to emissions of planet-warming gases will have a significant impact on the global network of ocean currents that transport nutrients, oxygen and carbon, scientists say.

Not only does this threaten marine life, it also risks replacing the ocean’s vital role in absorbing carbon dioxide and heat.

A previous study using computer models suggested that the „overturning cycle” of water in the deepest parts of the oceans could decrease by 40 percent by 2050 if emissions were high.

But new research published Thursday — based on observational data — found that the process had already declined by 30 percent between the 1990s and 2010s.

„Our data show that the impacts of climate change are running ahead of schedule,” said lead author Kathryn Gunn of the Australian science agency CSIRO and Britain’s University of Southampton.

As Antarctica’s deep ocean acts as a major „pump” for the global network of ocean currents, the impacts could be significant.

„As the ocean circulation slows, more carbon dioxide and heat is released into the atmosphere, which accelerates global warming,” Gunn told AFP.

„In some ways, it’s not surprising that this is happening. But it’s time.”

Understanding changes in the remote area has been difficult because of a lack of data and challenges for scientific research, from obtaining funding to dealing with extreme conditions at sea.

The authors used observational data collected by hundreds of scientists over decades and then „filled in the gaps” with computer modeling.

Carbon storage

The oceans are an important regulator of climate, absorbing the vast majority of additional planet-warming carbon that humans have injected into the atmosphere since the mid-1800s, as well as accounting for more than 90 percent of the increased heat.

Sea surface temperatures have risen significantly — hitting new records earlier this year — as warming polar ice caps melt and dump large amounts of freshwater into the ocean.

This disrupts the vital life support function for marine life.

New research published in the journal Natural climate changeIt was found that oxygen reaching the deep ocean has decreased.

„Deep-sea animals are adapted to low-oxygen conditions, but still need to breathe,” Gunn said.

„These oxygen losses can cause them to seek refuge in other areas or change their behavior. This type of oxygenation affects biodiversity and food webs.”

Beyond the impact on animals, changes to these major ocean pumps are expected to reduce the amount of carbon the ocean can absorb, as well as draw down hundreds of thousands of subsurface carbon safely stored in the ocean depths. years.

Ariane Burich, of Monash University’s School of Earth, Atmospheric and Environment in Australia, said the study was significant because it „provides additional support, including observational evidence, that melting Antarctic ice and shelves affect the global ocean overturning cycle.”

Burich, who was not involved in the study, said this would have „major implications for the absorption of heat and carbon in the ocean.”