海角大神

A new study has shown that an East Antarctica ice shelf, once thought to be completely solid, is actually home to 55 liquid lakes.

By drilling through the surface of the Roi Baudouin ice shelf, researchers found that several of these lakes were 鈥渆nglacial,鈥� or completely enclosed by ice. In a study published Monday in the journal Nature Climate Change, they suggested that uncharacteristic melt could compromise the structural integrity of glaciers in the region.

鈥淢any people refer to East Antarctica as being too cold for significant melt,鈥� Jan Lenaerts, a glaciologist with Utrecht University, told the Washington Post. 鈥淚 mean there鈥檚 marginal melt in summer, but there鈥檚 not a lot.鈥�

Researchers say these englacial lakes may have been caused by a 鈥渕icroclimate鈥� on the ice sheet itself. In East Antarctica, strong 鈥渒atabatic鈥� winds blow from high peaks down toward the sea. These winds bring warm air and clear snow from the glacial surface, revealing vast stretches of blue ice.

This blue ice has a lower reflectivity than the white snow, increasing the amount of sunlight absorbed at the surface. This, coupled with bursts of warm air, might drive unusual amounts of ice melt in the region. Surface lakes might freeze over in colder months, but not all the way through.

鈥淲e see similar things going on on neighboring ice shelves, and also for instance on the Amery ice shelf, which is also a notorious, very large ice shelf on East Antarctica,鈥� Lenaerts said. 鈥淲e see this link between strong winds and blue ice formation, enhanced absorption of solar radiation, and the melt that is enhanced by this process.鈥�

Researchers haven鈥檛 directly linked the effect to anthropogenic climate change, but note that further warming will likely increase melting in the region. This melting could exacerbate the structural weaknesses of the Antarctic ice shelf, which was once considered rock solid, and cause large collapses. This so-called 鈥渉ydrofracturing鈥� can dump huge deposits of glacial ice into the ocean, driving up sea levels in the process.

Last month, NASA climate scientists found record-low sea ice levels in both the Arctic and the Antarctic. The northern record didn鈥檛 come as a surprise, given the long decline of Arctic sea ice. But until recently, Antarctic sea ice was actually expanding.

海角大神 reported:

Climate change skeptics have often argued that ice gain in the Southern Hemisphere, which hit record highs between 2012 and 2014, was evidence against human-induced warming. But recent studies appear to show that the trend is reversing.