Retreating ice cover exposes more of the ocean surface, allowing more moisture to evaporate into the atmosphere and leading to more precipitation.īecause saltwater is denser and heavier than freshwater, this "freshening" of the North Atlantic would make the surface layers more buoyant. Some freshwater would come from the ice-melt itself, but the main contributor would be increased rain and snow in the region. Some scientists worry that melting Arctic sea ice will dump enough freshwater into the North Atlantic to interfere with sea currents. Image courtesy Argonne National Laboratory. Studies looking at more recent data peg the rate at 14% per decade, suggesting that the decline of Arctic sea ice is accelerating.Ībove: A global ocean circulation between deep, colder water and warmer, surface water strongly influences regional climates around the world. According to a 2002 paper by Josefino Comiso, a climate scientist at NASA's Goddard Space Flight Center, this year-round ice has been retreating since the beginning of the satellite record in 1978 at an average rate of 9% per decade. The view from orbit clearly shows a long-term decline in the "perennial" Arctic sea ice (the part that remains frozen during the warm summer months). Other ice-watching satellites, operated by NASA, NOAA and the Dept.
Using microwaves, rather than visible light, AMSR-E can penetrate clouds and offer uninterrupted surveillance of the ice, even at night, explains Roy Spencer, the instrument's principal investigator at the Global Hydrology and Climate Center in Huntsville, Alabama. NASA's Aqua satellite, for instance, carries a Japanese-built sensor called the Advanced Microwave Scanning Radiometer-EOS ("AMSR-E" for short). There are several satellites keeping an all-weather watch on ice cover in the Arctic. Sign up for EXPRESS SCIENCE NEWS delivery But the facts do suggest that the changes we're seeing in the Arctic could potentially affect currents that warm Western Europe, and that's gotten a lot of people concerned."
"It's difficult to predict what will happen," cautions Donald Cavalieri, a senior scientist at NASA's Goddard Space Flight Center, "because the Arctic and North Atlantic are very complex systems with many interactions between the land, the sea, and the atmosphere.
Andrew Marshall, a veteran Defense Department planner, recently released an unclassified report detailing how a shift in ocean currents in the near future could compromise national security. Some scientists believe this shift in ocean currents could come surprisingly soon-within as little as 20 years, according to Robert Gagosian, president and director of the Woods Hole Oceanographic Institution. Right: Retreating Arctic ice, 1979-2003, based on data collected by the Defense Meteorological Satellite Program (DMSP) Special Sensor Microwave Imager (SSMI).