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| Arctic ice grows again in August after record 2012 melt |
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.jpg) The area of Arctic sea ice was nearly 30% greater in August than a year ago, according to recent satellite data, though projections based on longer-term trends suggest the sea ice will continue its decline over time.
Arctic sea ice covered 2.35 million square miles in August, up from 1.82 million square miles a year earlier, according to the National Snow and Ice Data Center, or NSIDC, in Boulder, Colo. The level recorded last year was a record low.
Arctic sea ice partially melts each summer and re-forms in the winter. "It's been much colder in the Arctic this summer, so not much ice has melted," said Julienne Stroeve, climatologist at NSIDC. The measurements were based on data obtained from U.S. weather satellites. The nearly 30% year-to-year increase partly reflects the extreme low level of sea ice in August 2012.
"If you get a record one year, you don't expect another record the next year," said Chris Rapley, professor of climate science at University College London. He also noted that data on the area of sea ice doesn't capture the whole picture, because it doesn't include the thickness — and therefore volume — of sea ice. Scientists say they need to obtain better data to gauge changes to Arctic ice volumes.
Arctic sea ice will be a key issue addressed in an October report by the United Nations Intergovernmental Panel on Climate Change that is expected to reiterate a long-term declining trend in Arctic summer sea ice.
NSIDC data show that monthly August ice extent in the Arctic declined 10.6% a decade from 1979 to 2013. Estimates for further declines vary, but some models suggest that the Arctic will lose its August ice cover entirely by 2060, according to Dr. Stroeve.
The primary significance of this year's increase is that the "narrative of the 'spiral of death' for the sea ice has been broken," according to Judith Curry, climatologist at the Georgia Institute of Technology. "It remains unclear as to what extent the decline in sea ice over the past decades is caused by natural variability versus greenhouse warming. Whether the increase in 2013 is a one year blip in a longer declining trend, or whether it portends a break in this trend remains to be seen."
Scientists are continuing to debate the cause of the decline in the rate of warming over the past 15 years. A significant contributing factor seems to be associated with a shift in Pacific Ocean circulation patterns.
(Source: The Wall Street Journal)
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