Update on Artic Ice Cover–Arctic Ice Decreasing Faster Than Predicted
A study funded by NASA and the National Science Foundation has found that the Arctic ice cover is diminishing even more rapidly than the most advanced computer models had predicted. Research by scientists at the National Center for Atmospheric Research (NCAR) and the National Snow and Ice Data Center (NSIDC) at the University of Colorado, revealed that the estimates of 18 computer models used by the Intergovernmental Panel on Climate Change (IPCC) significantly underestimated the rate at which the ice is melting.
The scientists, comparing past climatic model simulations with measurements made by satellites and other instruments, found that computer models simulated a loss of September ice cover of 2.5 percent a decade from 1953 to 2006, with the fastest rate at 5.4 percent per decade. However, data obtained from early aircraft and ship reports, along with later satellite observations, which are considered the most reliable, reveal that Arctic ice was melting at about 7.8 percent per decade during the fifty three year period. This indicates the ice may disappear much sooner than IPCC predictions suggested. The study has found that the melting of the ice cover is about 30 years ahead of schedule. The inaccurate, simulated computer models projected an Arctic seasonally free of sea ice anytime from 2050 until well past 2100.
Scientists conducting the study have speculated that the models did not take into account the full effect of increased greenhouse gases in the atmosphere. The models indicated that about half the loss of ice from 1979 to 2006 was due to greenhouse gas increases and the rest to natural climate variations, when in fact, the rise in greenhouse gases may be a much larger factor.
Since September is the time of year when sea ice is at a minimum, the loss of ice in March is much less, but even these computer models missed the mark by a large margin , with the actual ice loss averaging about 1.8 percent per decade, three times greater than the computer models had foretold. The dynamics of the Arctic region make it particularly sensitive to climate change; loss of sea ice results in less solar energy being reflected off the surface and more dark open water, which causes more energy to be absorbed. This feedback loop has contributed to the increasing rate of melting to the point at which, according to satellite observations, it has increased to 9.1 percent per decade from 1979 to 2006
This entry was posted on Friday, August 17th, 2007 at 6:48 pm and is filed under Public Relations, Space Agency News, Technical Concerns. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.
