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A key region of the Antarctic ice floe Ross, the largest floating ice floe in the world of a size comparable to that of France, melts 10 times faster than the ice floe in general. The international team of scientists spent four years collecting data from Ross's ice floes to reach the conclusions published in Nature Geoscience.
In addition to warming the deep water of the oceans, solar heating of surface waters also plays a surprisingly important role – this is not exactly what you want when the sea ice is about the size of a sea. country of about 500 000 square kilometers.
"Previous studies have shown that when ice plateaus collapse, glacier feeding can be multiplied by two or three," said co-author Dr. Poul Christoffersen of the Scott Polar Research Institute in Cambridge. a statement. "The difference here is the sheer size of the Ross ice floe, which is more than 100 times larger than the ice floe we've seen disappear."
The discovery is based on custom-made radar measurements as well as temperature, salinity, fusion rate, and ocean current data collected from a borehole at a depth of 260 meters (850 meters). feet). In addition, the authors of the studies, Craig Stewart and Christoffersen, traveled more than 1,000 kilometers on snowmobiles to measure the thickness of the ice and map the melting rates at the base at various locations.
Rapid melting occurs under a thin but important part of the pack ice. The team found that the stabilization region was near the surface water heated by the sun that was flowing into a cavity, melting it three times faster than the usual summer speed. Strong winds and tidal forcing can lead to hot water in the cavity. In total, this vulnerable point melts 10 times faster than the expected average for the whole pack ice.
"Although some frontal regions are not important for the stability of ice platforms, others contain essential attachment points that maintain the location of the front. According to the authors, Ross Island appears to be one of these anchor points, and recent modeling shows that the rapid meltdown identified here has an influence on a structurally critical region in which changes occur. thickness of the ice can affect the speed of flow of the entire pack ice. "
The Ross ice floe, which accounts for 32% of total Antarctic ice, is relatively stable at this time, largely due to ice from glacier feeding and snow accumulation. However, this equilibrium could change in the future depending on the merging of the anchor point. Summer Sea ice concentrations in the Ross Sea are expected to decrease by 56% by 2050 as the duration of the ice-free period increases.
"Climate change is likely to result in a decrease in sea ice and an increase in Ross Sea surface temperatures, suggesting a future increase in melting rates in this region," said Dr. Stewart of the USSR. National Institute for Water and Atmospheric Research (NIWA). ).
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