The Cloudy Future of Arctic Sea Ice   
       
   Oct 15, 2014:  Climate change is a global phenomenon, yet Earth scientists are   
   keeping a wary eye on one place in particular--the Arctic.   
       
   "Polar regions are important for us to study right now," explains Tom Wagner   
   of NASA's Earth Science Division in Washington DC.  "They are changing   
   rapidly."   
       
   https://www.youtube.com/watch?v=cubJXXma-Z4&feature=youtu.be   
       
   A new ScienceCast video examines the shrinking coverage of Arctic sea ice and   
   how the reduction could affect worldwide weather.  Play it   
       
   One of the most visible of signs of warming is the retreat of Arctic sea ice.   
   Every year, sea ice waxes and wanes in a normal response to the changing of   
   seasons; the annual sea ice minimum occurs near the end of northern summer.   
   Since the 1970s, researchers carefully watched to see if the rhythm of Arctic   
   sea ice would respond to global warming.   
       
   At first there was little systematic change. Then came the 2000s.   
       
   "We started to see dramatic changes around 2005," recalls Walt Meier of NASA   
   Goddard. "In 2007 the bottom seemed to fall out." By the end of that year's   
   melt season, the Arctic Ocean had lost a chunk of ice cover equivalent to the   
   combined size of Alaska and Texas. "There was a lot of shock in the sea ice   
   community. I don't remember anyone thinking it could get that low that   
   quickly," Meier says.   
       
   What had been missing from most analyses, which focused on the shrinking area   
   of sea ice, was the fact that the ice had also thinned over the past decades,   
   making it much more vulnerable to weather and warming.   
       
   Since 2007, sea ice has continued to decline, on average, with annual ups and   
   downs.  The current minimum in Sept. 2014 is slightly lower than 2013's,   
   making it the sixth lowest in the satellite record. At one point a small area   
   of the Laptev Sea ice edge was only five degrees of the North Pole.   
       
   "Every day we are learning more about the implication these changes have for   
   the rest of the planet," continues Wagner.  "Change in Arctic sea ice is   
   probably influencing our weather."   
       
   http://tinyurl.com/qgkbxf2   
       
   Click to visit the ARISE home pageTo investigate that possibility, NASA is   
   flying an airborne mission over the Arctic Ocean.  Its name is ARISE, short   
   for "Arctic Radiation-IceBridge Sea and Ice Experiment."   
       
   Bill Smith, the project's Principal Investigator from the Langley Research   
   Center, explains the mission's goals: "We have reason to believe that loss of   
   sea ice creates more clouds.  Basically, we want to find out if that's true   
   and to determine the impacts."   
       
   Ice reflects sunlight back to space.  If the ice melts, that sunlight is no   
   longer reflected; it is absorbed. Moisture released from the warming sea   
   surface rises up to form clouds. Clouds themselves reflect sunlight, but they   
   also act like a blanket, keeping the earth beneath them warm.   
       
   The interplay between clouds and ice, cooling and warming, is complex. ARISE   
   aims to unravel the knot by taking a lot of data:   
       
   "Our C-130 is instrumented with a unique complement of sensors," says Smith.   
   "We have radiometers pointed up and down to measure incoming and outgoing   
   sunlight; an infrared thermometer to measure the  temperature of the sea   
   surface, a laser altimeter to measure the height (and thus the thickness) of   
   the ice; and more."   
       
   Earth-orbiting satellites regularly make measurements of the Arctic, but the   
   region is big and complex, so the data can be difficult to interpret.  By   
   comparing C-130 measurements with satellite data taken at the same time, Smith   
   and colleagues hope to add some "ground truth" to the problem.   
       
   "We need more information to understand how to interpret satellite   
   measurements, and an aircraft can help with that," he says.   
       
   If climate change continues apace, future summers could bring an ice-free   
   Arctic Ocean.  ARISE could tell us some of the implications . before that   
   happens.   
       
   Credits:   
   Author: Dr. Tony Phillips | Production editor: Dr. Tony Phillips | Credit:   
   Science@NASA   
       
   More information:   
       
   ARISE -- home page   
       
   2014 Arctic Sea Ice Minimum 6th Lowest on Record -- Science@NASA   
       
       
   Regards,   
       
   Roger   
      
   --- D'Bridge 3.99   
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