According to the latest study by a team of scientists from the National Center for Atmospheric Research (NCAR), the University of Washington, and McGill University, the Arctic ice pack is recovering less and less from summer melting. By 2040 the Arctic, including the North Pole, could be completely ice free during the summer months.
The new data, presented at the American Geophysical Union’s Fall Meeting, currently taking place in san Francisco, indicates that the ice is no longer being replenished during the winter months to the extent necessary to maintain the historic balance.
In addition the trend is “likely to accelerate so rapidly that the Arctic Ocean could become nearly devoid of ice during summertime as early as 2040,” said the NCAR bulletin. “We have already witnessed major losses in sea ice, but our research suggests that the decrease over the next few decades could be far more dramatic than anything that has happened so far,” stated NCAR scientist Marika Holland, the study’s lead author. “These changes are surprisingly rapid.”
The research was funded by the National Science Foundation, NCAR’s principal sponsor, as well as by NASA.
What effect would this have on the world’s oceans? An earlier NCAR study (See IJ web site March 24 – See also Sept. 25, 2005) concluded that there is significant evidence that the “Arctic summers by 2100 may be as warm as they were nearly 130,000 years ago, when sea levels eventually rose up to 20 feet (6 meters) higher than today.” For low lying areas – including cities like London, New York, Tokyo, Los Angeles and others – the effect would be wholesale disaster.
After analyzing the current rate of Arctic melting the NCAR team simulated future ice loss, using the most up to date computer simulations. “The model results indicate that, if greenhouse gases continue to build up in the atmosphere at the current rate, the Arctic’s future ice cover will go through periods of relative stability followed by abrupt retreat,” said the bulletin.
“For example, in one model simulation, the September ice shrinks from about 2.3 million to 770,000 square miles in a 10-year period. By 2040, only a small amount of perennial sea ice remains along the north coasts of Greenland and Canada, while most of the Arctic basin is ice-free in September. The winter ice also thins from about 12 feet thick to less than 3 feet.”
The research team singled out “several reasons for the abrupt loss of ice in a gradually warming world. Open water absorbs more sunlight than does ice, meaning that the growing regions of ice-free water will accelerate the warming trend. In addition, global climate change is expected to influence ocean circulations and drive warmer ocean currents into the Arctic.
“As the ice retreats, the ocean transports more heat to the Arctic and the open water absorbs more sunlight, further accelerating the rate of warming and leading to the loss of more ice,” Holland explained. “This is a positive feedback loop with dramatic implications for the entire Arctic region.”
The NCAR scientists stressed that the amount of greenhouse gases -principally man-made hydrocarbon emissions consisting mostly of CO2 – “can affect the probability of abrupt ice loss. By examining 15 additional leading climate models, they found that if emissions of carbon dioxide and other greenhouse gases were to slow, the likelihood of rapid ice loss would decrease. Instead, summer sea ice would probably undergo a much slower retreat.”
“Our research indicates that society can still minimize the impacts on Arctic ice,” Holland concluded.
The study and additional information can be consulted at: http://www.ncar.ucar.edu.
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