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Something strange has been swirling in the waters around Antarctica. From the 1970s until a decade ago, the floating sea ice that came from the continent was growing, even though climate change was already there. Then, in 2016, suddenly and spectacularly – and he did not recover – as global warming appears to be reaching the Southern Ocean. Rather than being a local issue, the loss of sea ice has a major impact on the Antarctic ice sheet, which sea level up to 190 feet if it disappeared.
Now scientists say they have discovered the cause of the sudden rise and fall, thanks to the help of underwater robots. It all comes from salt, wind, and churn. “One of the most important aspects of this study is that the ocean plays a major role in controlling how the ice changes from year to year, decade to decade,” said Earle Wilson, a Stanford University oceanographer and author of the new book. paper to describe the research.
Doing the grunt work here was a data collection machine known as Argo floats. Shaped like a torpedo and about the size of a man, they sink thousands of feet, testing things like temperature and salinity, before returning to the surface and sending the data back to a satellite. Because they float silently, the instruments can for years gather information about how things are changing.
Now, forget about robots and think about swimming in the ocean. When you jump into the water, you are hit by a sudden shock of cold water. This is because the sun warms the surface, while the depth is cold. This also happens in the world’s oceans, although apparently cold water goes much deeper.
These differences occur in the waters surrounding Antarctica. Because it was cold during the day, the air cools on the surface of the sea, while the warm water flows down. (Argo’s robots can detect this in detail as it ascends and descends.) With warmer water far from the surface, more ice can form.
As the ice sheet increased in the decades leading up to 2016, more rain made the surface water fresher, as opposed to the saline water below, which led to poor water circulation. (The more liquid the salt, the more viscous it is.) This blocked the deep heat, causing the water to condense.
Then the sky played another trick, as the wind picked up and shifted. This pushed the groundwater out of Antarctica and caused deep warming. “What we saw was a violent storm that burned the ground and caused the water to recede,” Wilson said.
This eruption may have been caused by climate change: As the Earth warms, the atmosphere releases hot air, which strengthens the wind and changes its direction. Scientists, however, are still investigating how much of this change could be due to “climate change,” or what would happen if humans hadn’t emitted so much carbon since the Industrial Revolution.
In any case, the system moved around 2016. Beyond bringing warm water, all that wind would have broken the ice, both by pushing the blocks together and creating waves. “Recent research has shown that atmospheric and ocean temperatures may be contributing to the sudden change in Antarctic sea ice since 2016, and this paper helps advance the argument that ocean temperatures are important,” said Zachary Labe, a climate scientist at the Climate Central research group who studies Antarctic ice but was not involved in the paper.
As the glaciers shrink, they put more ice in some areas. Antarctic land ice is fueled by ice that floats along the coast. These important resources are already in serious trouble such as ocean warming and a powerful underwater storm to destroy their stomachs, to weaken them. When they lose the sea ice that floats around, they lose a lot of protection, because the floating particles absorb the energy of the waves. In addition, good sea ice is very transparent, which means that it reflects the heat of the sun into the atmosphere, reducing the temperature of the surrounding area. Because these glaciers hold back the ice, losing it would mean the loss of most of the world’s glaciers.
Although Argo’s probes provided valuable information, scientists are still searching for more measurements. “Overall, we need international support to continue developing observational networks in the Antarctic polar region, for ocean and air monitoring,” said Labe. “This is very important because of the rapid changes we are starting to see in this part of the world in terms of climate change, which will lead to a rise in water levels around the world.”
The big question now is whether we’re seeing much lower sea ice, or whether the atmosphere and oceans can recede enough to encourage multi-year growth. The promise of the new research is that it will help researchers refine their models to determine how much the water around Antarctica could change, and how quickly. Perhaps the sea ice will see years of great decline, followed by years of growth. “But long term, many decades will be bad,” Wilson said. “It could be my guess, but we don’t know for sure.”
