Glaciers pouring into the Antarctic sea not only break apart into icebergs, but also underwater waves that cause multiple impacts below the surface. These are real tsunamis that have only now been discovered. by researchers. In addition, its frequency is increasing due to global warming.
In February 2020, a group of scientists from the British Antarctic Survey (BAS) aboard a research vessel, purely by chance, witnessed the calving of the William Glacier in Börgen Bay in mid-Antarctica.
It is a glacier 4.5 kilometers wide and 42 meters above sea level. The detachment lay more than a kilometer in front of this ice floe, a “frequent and generalized” phenomenon that occurred between 2015 and 2021, and even six times a year, as reflected by satellite monitoring. small breaks.
effects on the ocean
At the moment of separation, the researchers noticed that their measurements “off scale” at that very moment.
For example, before the front of the glacier broke, the water temperature was observed to be colder at a depth of about 50 or 100 meters and warmer in the lower layers. Again, After calving, the situation “changed drastically” with much more homogeneous temperatures at different depths.
This is because, in addition to reporting breaking ice on the surface, “internal” submarine tsunamis recorded as high as a houseAccording to research published in the journal Science Advances.
“It was amazing to see that and we were lucky to be in the right place at the right time. Many glaciers end in the sea, and their ends often break into icebergs. This can cause big waves on the surface, but we now know that it also creates waves in the ocean.”says the study’s lead author, Professor Michael Meredith, head of the polar oceans team at BAS. “When these inland waves break, they cause the sea to stir, and this affects life in the sea as well as how warm the ocean is at different depths and how much ice it can melt.”
While some of the ice from glaciers melts in the ocean, most breaks up into icebergs ranging in size from tiny bits to the surface of a country.
Until now, summer winds and tides have been mainly blamed for the mixing of the oceans, without suspecting that an iceberg’s calf could cause internal tsunamis, Meredith says.
a rising phenomenon
Tsunamis are caused by geophysical events such as earthquakes or landslides that cause water to move suddenly. But the possibility that the breaking up of a glacier could cause them had never been considered before.
Therefore, researchers believe that Underwater tsunamis are a phenomenon that occurs “always” in Antarctica.Because of the thousands of glaciers breaking up there, as they believe it must be in Greenland and other parts of the Arctic.
about It is a phenomenon that is expected to increase due to global warming, which accelerates the collapse of glaciers. In the case of the William Glacier alone, its retreat due to landslides is the retreat of the glacier by about 55 meters per year since the middle of the last century.
“Existing computer models do not take this into account.allows us to predict what might happen in Antarctica. This discovery changes our understanding of how the ocean around Antarctica mixes and will advance knowledge of what this means for climate, ecosystems and sea level rise.
Reference work: https://www.science.org/doi/10.1126/sciadv.add0720
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