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A key part of the world's largest pack ice melts 10 times faster than expected, according to a study published Monday in the Nature Geoscience.
The solar heating of the oceans, which the study authors described as an "often overlooked process," was one of the main factors behind the unusually high rate of melt under the Ross ice floe in Antarctica. which stretches for hundreds of miles above the Southern Ocean like France.
During the summer, the sun warms the surface waters of the area, which then lower below the plateau and expose them to higher temperatures.
"Ice shelf stability is generally thought to be related to deep deep-sea heat exposure, but we found that sun-heated surface water also plays a critical role in melting ice trays." , said senior author Craig Stewart, a physicist at the National Institute for Water and Atmospheric Research (NIWA) in New Zealand, in a statement.
The Ross Ice Shelf slows the drainage of inland glaciers into the oceans. Its long-term stability is therefore important. If the plateau collapses, the rapid acceleration of the melting of Antarctic ice could lead to a rise in sea level of several meters.
Fortunately, scientists do not think Ross's ice platform is in immediate danger of collapse or severe erosion. Nevertheless, their study revealed that melting rates of the Ross Sea polynya, an area north-west of the plateau, were well above the plateau average.
To get an idea of the conditions inside this frozen structure, Stewart's team accumulated four years of observations at various locations on the plateau. The researchers used a radar to probe the density of the plateau and traveled hundreds of kilometers on the ice to retrieve data from disparate locations. They also collected measurements of temperature, salinity, and melting rate from a sensor deployed in the ocean under the plateau.
This connection between solar heating and melting ice has implications for the future stability of Ross ice floe, as it shows that the structure is more vulnerable to surface water temperatures than previously thought.
"Climate change is likely to result in a decrease in sea ice and an increase in surface temperatures in the Ross Sea, suggesting that melting rates in this region will increase in the future," Stewart said.
Although the stability of the Ross ice floe is not immediately threatened, the new study shows that critical parts of Ross could become more vulnerable in the coming decades, highlighting the need to keep an eye on this. gigantic frozen ground.
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