14 DAY TRIAL // The American space agency NASA started measuring the extent of Arctic ices in 1979, via its satellite program. Since then, it has conducted constant investigations of the North Pole, and has drawn maps of ice extents during every minimum and maximum extent of the ice sheets. Measurements for this year indicate that the levels of ice in the region are at their 3rd lowest recorded level in 30 years. The numbers were calculated at the National Snow and Ice Data Center, the University of Colorado in Boulder (UCB), LiveScience reports.
Since observations first began, experts realized that something was wrong with the ice sheets. Global warming acted on them yearly, and with increasingly visible effects. Each winter, less and less ice formed to replace the amounts that had melted during the previous summer. The ice that did form tended to be thinner than historical records show, therefore a lot more likely to melt faster in the following season. With it, ice spreads that had not melted the previous year were also more exposed to UV radiation, and melted away.
According to NSIDC research scientist Walt Meier, the levels of ice spread recorded for 2009 are higher than those of the record-setting last couple of years, but well below the 1979-2000 average, and wildly off the map when compared with the losses that would have been inflicted by natural variability alone. The 2009 minimum is still some 620,000 square miles below the 30-year average, which translates into an area as large as Alaska. “We are still seeing a downward trend that appears to be heading toward ice-free Arctic summers,” Meier adds.
The only reason why this year did not see a record-setting low level of ice, experts say, is because of fortunate atmospheric circulation patterns that helped Arctic ice sheets spread during the month of August. However, Meier says, the ice that now covers a large part of the North Pole is thin, single-year ice, and not the multi-year variety that used to be predominant in the region. This means that, next year, this ice will be the first to melt down and expose the real extent of the damage done to the Arctic by climate change.