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- Infection time: Disease is more severe when it hits in the morning, at least in mice
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Web edition: September 15, 2010
The verdict is in on this year’s Arctic sea-ice melt: third worst since satellites began keeping track of the northern polar cap in 1979.
Satellites and scientists continually monitor the Arctic Ocean’s skin of ice, which melts back in the summer and expands again in the winter. Researchers have been watching the ice’s decline with increasing alarm, especially after the summer of 2007 brought a record-breaking minimum. Ice extent recovered a bit in the summers of 2008 and 2009, but the long-term trend is unmistakable: The ice is shrinking in extent as well as thinning. Thinner ice is more prone to being broken up and melted away than thick ice that has already persisted for multiple years.
On September 15, the National Snow and Ice Data Center in Boulder, Colo., announced that this year’s ice seemed to have reached its minimum five days earlier, when it covered 4.76 million square kilometers. (Last year’s minimum was 5.10 million square kilometers.) At its minimum, ice has covered less than 5 million square kilometers in three of the last four years — an arbitrary cutoff to be sure, but an indicator of how the entire ice ecosystem appears to be changing. For other views of current ice cover, see here and here.
How much sea ice remains each year depends on a complex mix of factors including atmospheric patterns, ocean and air temperature and winds. This August, for instance, high pressure over the Beaufort Sea meant that ice began breaking up rapidly there compared with the previous month.
By at least one measure, this year’s minimum wasn’t that surprising. The Study of Environmental Arctic Change program runs an informal “sea ice outlook” in which people predict how much ice they think will be left at the end of the season, and why. This year the predictions made in August — 16 from scientists, two from the general public — ranged from 2.5 million to 5.6 million square kilometers. Include that extremely lowball estimate of 2.5 million kilometers, made by a member of the public, and you get a mean of … 4.8 million square kilometers, almost exactly what was seen.
Suggested Reading
A. Witze. Melting at the microscale. Science News. Vol. 177, June 19, 2010, p. 22.
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The southern hemisphere sea ice has been above average for much of the last several years, but is currently 35,000 sq Km below.
How about the report that data from the GRACE satellite showing increased ice in Antarctica? I know that's an inconvenient thing to report, but that's one of the problems of science. If we knew how things were going to move, we wouldn't need to study them.
A 2007 NASA study published in the October 4, 2007 issue of Geophysical Research Letters discusses the loss if Arctic ice cover. Nghiem said the rapid decline in winter perennial ice the past two years was caused by unusual winds. "Unusual atmospheric conditions set up wind patterns that compressed the sea ice, loaded it into the Transpolar Drift Stream and then sped its flow out of the Arctic," he said. When that sea ice reached lower latitudes, it rapidly melted in the warmer waters. "The winds causing this trend in ice reduction were set up by an unusual pattern of atmospheric pressure that began at the beginning of this century," Nghiem said. Despite the media’s hyping of global warming, Ignatius Rigor, a co-author of the NASA study, explained, “While the total [Arctic] area of ice cover in recent winters has remained about the same, during the past two years an increased amount of older, thicker perennial sea ice was swept by winds out of the Arctic Ocean into the Greenland Sea."
A NASA Study in the April 22, 2008 issue of Geophysical Research Letters blames natural high pressure leading to more sunny days for Arctic Ice Reduction. Excerpt: The shrinking expanse of Arctic sea ice is increasingly vulnerable to summer sunshine, new research concludes. The study, by scientists at the National Center for Atmospheric Research (NCAR) and Colorado State University (CSU), finds that unusually sunny weather contributed to last summer's record loss of Arctic ice. There was a high-pressure system that sat over the Arctic for much of the summer. It shooed away clouds, leaving the sun alone to beat down. That created higher ocean temperatures, which in turn accelerated the melt."
They also state “The authors note that, in addition to solar radiation, other factors such as changes in wind patterns and possibly shifts in ocean circulation patterns also influence sea ice loss. In particular, strong winds along regions of sea ice retreat were important to last year's loss of ice. The relative importance of these factors, and the precise extent to which global climate change is driving them, are not yet known.”
Here we have three NASA studies that explain the loss of Arctic ice in three totally unrelated ways. The Global Warming theory of NASA's Hansen that the increase of CO2 alone drives temperatures ever higher is shown to be false by NASA.
And, the scientists doing the work admit that they do not yet have the necessary understanding to explain why the climate is changing.
And the reason you published this article is???
Regarding the three NASA studies cited by NHChemist, your conclusion that, "The Global Warming theory of NASA's Hansen that the increase of CO2 alone drives temperatures ever higher is shown to be false by NASA." is a bit of a leap. I will admit that I haven't read the articles, but you don't say anything about what those articles state about what the cause of those phenomona were. I believe that changes in wind patterns (i.e., changes in climate) and associated shifts in ocean circulation patterns is within the realm of what could be caused by global warming.
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