MSGID: 1:317/3 6279ead3   
   PID: hpt/lnx 1.9.0-cur 2019-01-08   
   TID: hpt/lnx 1.9.0-cur 2019-01-08   
    Newly discovered lake may hold secret to Antarctic ice sheet's rise and   
   fall    
      
     Date:   
         May 9, 2022   
     Source:   
         University of Texas at Austin   
     Summary:   
         Scientists investigating the underside of the world's largest   
         ice sheet in East Antarctica have discovered a city-size lake   
         whose sediments might answer questions about what Antarctica was   
         like before it froze, how climate change has affected it over its   
         history, and how the ice sheet might behave as the world warms.   
      
      
      
   FULL STORY   
   ==========================================================================   
   Scientists investigating the underside of the world's largest ice sheet   
   in East Antarctica have discovered a city-size lake whose sediments might   
   contain a history of the ice sheet since its earliest beginnings. That   
   would answer questions about what Antarctica was like before it froze,   
   how climate change has affected it over its history, and how the ice   
   sheet might behave as the world warms.   
      
      
   ==========================================================================   
   Revealed by heavily instrumented polar research aircraft, Lake Snow   
   Eagle is covered by 2 miles of ice and lies in a mile-deep canyon in the   
   highlands of Antarctica's Princess Elizabeth Land, a few hundred miles   
   from the coast.   
      
   "This lake is likely to have a record of the entire history of the East   
   Antarctic Ice Sheet, its initiation over 34 million years ago, as well   
   as its growth and evolution across glacial cycles since then," said   
   polar expert Don Blankenship, one of the paper's authors and a senior   
   research scientist at The University of Texas at Austin's Institute for   
   Geophysics. "Our observations also suggest that the ice sheet changed   
   significantly about 10,000 years ago, although we have no idea why."   
   Because it lies relatively close to the coast, researchers think that   
   Lake Snow Eagle might contain information about how the East Antarctic   
   Ice Sheet first began and the part played by the Antarctic Circumpolar   
   Current, a ring of cold water circling the continent that scientists   
   think is responsible for keeping it cool.   
      
   The study appeared May 9 in the journal Geology.   
      
   The first hint that the lake and its host canyon existed emerged when   
   scientists spotted a smooth depression on satellite images of the ice   
   sheet. To confirm it was there, researchers spent three years flying   
   systematic surveys over the site with ice penetrating radar and sensors   
   that measure minute changes in Earth's gravity and magnetic field.   
      
   "I literally jumped when I first saw that bright radar reflection,"   
   said the paper's lead author, Shuai Yan, a graduate student at UT   
   Austin's Jackson School of Geosciences who was flight planner for the   
   field research that investigated the lake.   
      
   What Yan saw was the lake's water that, unlike ice, reflects radar like   
   a mirror. Along with the gravity and magnetic surveys, which lit up the   
   underlying geology of the region and the depth of water and sediments,   
   Yan constructed a detailed picture of a jagged, highland topography with   
   Lake Snow Eagle nestled at the base of a canyon.   
      
   The newly discovered lake is about 30 miles long, 9 miles wide and 650   
   feet deep. The sediments at the bottom of the lake are 1,000 feet deep   
   and might include river sediments older than the ice sheet itself.   
      
   Moving forward, the researchers said getting a sample of the lake's   
   sediments by drilling into it would fill big gaps in scientists'   
   understanding of Antarctica's glaciation and provide vital information   
   about the ice sheet's possible demise from climate change.   
      
   "This lake's been accumulating sediment over a very long time, potentially   
   taking us through the period when Antarctica had no ice at all, to when   
   it went into deep freeze," said co-author Martin Siegert, a glaciologist   
   at Imperial College London. "We don't have a single record of all those   
   events in one place, but the sediments at the bottom of this lake could   
   be ideal."  Lake Snow Eagle was named after one of the aircraft used   
   in its discovery. It is one of many features uncovered by ICECAP-2,   
   an international collaboration to map the last unknown regions of   
   East Antarctica by polar research teams from the U.S., U.K., China,   
   Australia, Brazil and India. The team for this paper included scientists   
   from UTIG, Scripps Institute for Oceanography, Imperial College London,   
   the Australian Antarctic Division, and the Polar Research Institute of   
   China. The research was supported by the G. Unger Vetlesen Foundation   
   and funded by governments and institutions of the countries involved.   
      
      
   ==========================================================================   
   Story Source: Materials provided by University_of_Texas_at_Austin. Note:   
   Content may be edited for style and length.   
      
      
   ==========================================================================   
   Journal Reference:   
      1. Shuai Yan, Donald D. Blankenship, Jamin S. Greenbaum, Duncan   
      A. Young,   
         Lin Li, Anja Rutishauser, Jingxue Guo, Jason L. Roberts, Tas D. van   
         Ommen, Martin J. Siegert, Bo Sun. A newly discovered subglacial   
         lake in East Antarctica likely hosts a valuable sedimentary record   
         of ice and climate change. Geology, 2022; DOI: 10.1130/G50009.1   
   ==========================================================================   
      
   Link to news story:   
   https://www.sciencedaily.com/releases/2022/05/220509162802.htm   
      
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