The Yin-Yang of Polar Sea Ice   
       
   Dec. 4, 2014: The world is getting warmer.   
       
   It comes as no surprise, therefore, when researchers announce as they did this   
   past September that Arctic sea ice extent is still below normal, continuing a   
   years-long downward trend, covering less and less of the north polar seas with   
   a frozen crust. On the heels of that announcement, came another, a little more   
   puzzling.  While Arctic sea ice was melting, Antarctic sea ice was at an   
   all-time high.  In 2014, sea ice surrounding Antarctica covered more of the   
   southern oceans than it has since satellite record began in the late 1970s.   
       
   Is this also a sign of global warming?   
       
   "There is no doubt that climate change is real," says Walt Meier of NASA's   
   Goddard Space Flight Center.  "The two poles are just responding in their own   
   unique way to the same global phenomenon."   
       
   https://www.youtube.com/watch?v=hauoepPqns4&feature=youtu.be     
   A new ScienceCast video explores the curious differences between north- and   
   south-polar sea ice. Play it   
       
   He points out that Earth, taken as a whole, is losing sea ice. According to   
   satellite measurements from NASA and the National Snow and Ice Data Center,   
   the Arctic has lost an average of 20,800 square miles of sea ice a year since   
   the late 70s.  Meanwhile, the Antarctic has gained an average of 7,300 square   
   miles per year-not enough to balance loses at the other end of the planet.   
   But why do the Arctic and Antarctic behave in different ways?   
       
   "The increase we've seen in Antarctic sea ice is a little bit of a mystery,"   
   allows Meier.  "We're still trying to figure out how a warmer global climate   
   leads to these regional increases in ice cover."   
       
   The culprit could be weather.  Climate change is altering weather patterns   
   around the planet, and one of those changes is an increase in windiness around   
   the continent of Antarctica.  Cold air blows from the ice-covered continent   
   out over the sea, freezing the waters and pushing sea ice outward to cover   
   record-setting areas.   
       
   "That's one theory," says Meier.  "I think that winds are definitely playing a   
   substantial role.  But other factors could be at work, too." For instance, he   
   points out that glaciers melting around the edges of the continent could,   
   ironically, produce more ice in the surrounding ocean.  "Fresh meltwater from   
   glaciers is easier to freeze than briny seawater," he explains.   
       
   Snowfall could be important, too.  Snow landing on thin sea ice can weigh the   
   ice down and push it just below the water. Cold ocean water seeps up through   
   the ice and floods the snow - leading to a slushy mixture that freezes and   
   thickens the sea ice.   
       
   Some scientists feel that these processes could simply be due the natural   
   variations in the Antarctic region's climate. While it is clear that global   
   warming is playing a significant role in the loss of Arctic sea ice, the trend   
   in the Antarctic is small enough that it could be explained simply due to   
   natural variations in the region's climate. "Ultimately," says Meier, "we   
   expect that continued warming will take its toll, and even Antarctic sea ice   
   will begin to decline."   
       
   What we are seeing, he suggests, is the quirky regional way Earth responds to   
   a global stimulus.  Earth's climate system is complex, and climate change will   
   continue to have fascinatingly unpredictable consequences in the years ahead.   
       
   Credits:   
   Author: Dr. Tony Phillips | Production editor: Dr. Tony Phillips | Credit:   
   Science@NASA   
       
   More information:   
   Antarctic Sea Ice Reaches New Record Maximum -- Science@NASA   
   The Cloudy Future of Arctic Sea Ice -- Science@NASA   
   2014 Arctic Sea Ice Minimum 6th Lowest on Record -- Science@NASA   
       
       
   Regards,   
       
   Roger   
      
   --- D'Bridge 3.99   
    * Origin: NCS BBS - Houma, LoUiSiAna (1:3828/7)