3/31/2011 2:46:43 PM
Winter Arctic Sea Ice Ties for Lowest Record
Every year could be a tough year for polar bears if humans don't take action to reduce CO2.
The National Snow and Ice Data Center reports that this winter's arctic sea ice extent tied for the lowest record since satellite tracking began in 1979: nearly eight percent less than the average of 6.12 million square miles recorded from 1979 to 2000.
Dr. Steven C. Amstrup, PBI's senior scientist, says that a combination of warmer than usual temperatures and ice-reducing circulation patterns led to late and weak ice development in much of the Arctic this winter—and this combination may lead to an early ice melt this year and large retreats of sea ice from polar basin coastlines.
"Because polar bears depend on the surface of the sea ice to catch seals, this could be a tough year for polar bears, with increased starvation especially among the young and very old," he says. "But events could transpire to prevent record or near record retreats as well."
But Amstrup warns that it's not "this" year that worries scientists, rather it's the more distant future if greenhouse gas (GHG) concentrations continue to rise.
He explains: "The laws of physics require that the world will continue to warm as greenhouse gas [GHG] concentrations rise. There will continue to be fluctuations in temperatures and other climate variables just as there are always have been. Temperatures, however, will fluctuate over a rising baseline. Because a warmer world will support less sea ice, fluctuations in sea ice cover will continue to occur BUT over a falling baseline.
"The natural chaos in the climate system may overshadow the global warming signal next year or the year after that. If we're lucky we'll have a series of cold years with circulation patterns that conserve sea ice. Ultimately, however, the GHG signal will clearly emerge from the variation in the system.
"After that, all of the years will be bad for polar bears. Without mitigation of GHG rise, the situation for polar bears and many other species can only worsen, and polar bears ultimately will disappear."