Sea current circulating at the bottom of Antarctica is slowing. It is an invisible phenomenon that can have devastating consequences. The flow rate of these waters, known as Antarctic bottom waters between 1992 and 2017 (AABW in English) already reduced by 30%. This is a condition that is already affecting the availability of oxygen on the seafloor and is slowly cutting this region off from the rest of the planet. This slowdown, therefore, profound implications for climate, sea level and marine life.
The brake on this Antarctic undercurrent, which is cited as one of the many dangers from climate change, is ahead of schedule. This is expressed in a study published by an international research group. Nature Climate Change, warned of the butterfly effect that such interruption of the current could have on the rest of the planet.
The Antarctic Current carries trillions of tons of cold, dense, oxygen-rich water from the continental shelf to the depths of the ocean. as if it were a large underwater waterfall.
This Antarctic ‘bottom water’ then spreads northward across the Pacific, Indian and Atlantic oceans, along the seafloor and through deep ocean currents, before slowly rising again thousands of kilometers away.
Like the lungs pumping oxygen into the blood, AABW redistributes heat, carbon, oxygen and nutrients across the planet. It is therefore vital that the climate and ecosystems work to maintain their proper functioning. It is also the main route by which oxygen reaches the depths of the ocean.
The consequences of this fact
This slowdown has several consequences. On the one hand, can disrupt the climate system on the other hand, it reduces the habitable space of species and may ultimately limit the ocean’s capacity to act as a carbon sink, with consequent repercussions on the current climate change process.
Scientists had already predicted that this could be one of the consequences of climate change, but they never imagined it would happen decades ahead of schedule.
“The slowdown could cut the connection between the Antarctic coast and the depths of the ocean,” the authors of this study write. Speech Where do they report their results?.
Already reduced by 30%
Specifically, the data analyzed show that the circulation of this current has decreased by almost a third (30%) over the past three decades. AND it already has consequences, as deep oxygen levels are already lowered, just as the models predicted.
Behind this situation lies the dissolution of the region as a result of climate change. And the water that forms when ice melts is at a lower temperature than what is normally found on the surface. “Colder waters are less dense and therefore less prone to sinking, which slows sea circulation,” the scientists explain. In other words, The deep, cold water layer rich in oxygen is being replaced by warmer water with less oxygen.
Without oxygen and with more CO2
The lack of oxygen has implications for all marine life. Well, even though the fauna of the ocean depths has adapted to living in conditions where oxygen is scarce, having little is not the same as having nothing.
not enough oxygen habitable areas will decrease – estimated to be up to 25%- and deep-sea species will be forced to adapt, move or die.
But the problems don’t just affect this particular part of the world. If the current stops, also will become an empowering element of climate change.
In addition to oxygen and heat, the Rolling Current carries carbon dioxide from the depths of the ocean. There it is stored and removed from the atmosphere. However, as ocean storage capacity decreases, more CO2 remains on the surfacewill feed back global warming.
Antarctic ice loss is expected to continue, or even accelerate, as the planet warms. “We are almost certain that we will cross the 1.5°C global warming threshold by 2027”Indicate the signatories of the study.
More ice loss means cooling and less mixing of surface water. Therefore, the slowdown of this current and its consequences will be exacerbated.
And as the researchers insist, “The consequences of slowing will not be limited to Antarctica”. The knocked-down circulation covers the entire global ocean, and such a collapse would make the climate crisis worse.
Connection: https://www.nature.com/articles/s41558-023-01667-8
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