The shrinking of the Arctic ice (by the way, the main indicator of climate change) to a record not predicted, no computer model, and some experts believed at all like impossible.
August 26 National Data Center Snow and Ice USA (NSIDC) announced that the ice area decreased to 4.1 million km ². This is 70 thousand km? less than the previous anti-record set in 2007. Meanwhile, melt season is not completed. As of September 9, the figure had fallen by 14% to 3.54 million km ².
Melting in a relatively normal weather conditions: registered just one big storm, which could accelerate the decay of the ice. Mark Serriz, director of NSIDC, explains this by saying that most of the Arctic cover is now thin first-year ice, formed just last winter. It is much easier to break up and disperse. "We have entered a new regime — the expert explains. — Sea ice in the spring is in such poor condition that the main part of it can not survive the summer melt season, even in the absence of extreme weather conditions. "
Computer models that simulate the response of ice on global warming, saying that the Arctic will be ice-free in summer months in 2040? 2100's, and various scholars define this "freedom" in their own way. However, the observed trend suggests that summer sea ice could disappear by 2030 — despite all of the models used by the Intergovernmental Panel on Climate Change in preparing the next report.
Mr. Serriz tries to explain the confusion over high natural variability and the fact that the model does not take into account the changes in ice thickness. Much uncertainty exists in the "feedback" that is, the reaction is held on ice melting (eg, ocean, free of ice and absorbs more heat, which increases the melting).
There is a lack of flow of information and the Arctic Ocean. Thus, a study in 2008 identified 20 previously observed vortex flows to the north of Canada, each 15 × 20 km in diameter. "What role do they play in the process of mixing of waters of the ocean, we still do not know", — says Yves Gratton, of the National Institute for Scientific Research (Canada).
Accelerated loss of ice and water to be heated. Unlike the rest of the World Ocean, the coldest water in the Arctic (from? 1 to £ 2? C) is on the surface, below (at 200 € 300 m) in the Arctic is more saline and warm (1? C) water Atlantic. This top layer (halocline) acts as an insulator, protecting the sea ice from the warm water.
But halocline vulnerable to warming again emphasizes Henning Bauch of the research center GEOMAR (Germany). Thinning of the halocline (which is still, thankfully, is not observed), not only jeopardize the sea ice will melt and carbon-rich permafrost beneath the coastal shallows, releasing the greenhouse gas into the atmosphere.
Meanwhile, Arctic biology is changing, for the retreat and thinning of the ice allows more sunlight to penetrate the active upper layers of the ocean, leaving some habitat, said Jorgen Berg of the University of Tromsø (Norway). The main types of Arctic plankton Calanus hyperboreus and C. glacialis replaced Atlantic C. finmarchicus. And replace Arctic cod Arctogadus glacialis comes its Atlantic cousin Gadus morhua.
But other species exhibit unexpected resistance. In January, north of Svalbard was discovered that scud Apherusa glacialis (small crustaceans, feeding on algae growing under the ice and is a major source of food for many arctic birds) are less dependent on the distribution of sea ice than assumed. At the right moment, this body is lowered into the deep and drifts with the currents closer to the pole.
It seems that the inhabitants of the Arctic adaptive features should not be underestimated. Mr. Berg recalls that over the last 2.5 million years of Arctic Ocean several times dismissed by summer ice (8? 6.5 thousand years ago, during the Holocene thermal maximum in the Arctic was much less ice than today) but the mass extinction happened.
The solid lines marked average ice limit as of August 18, 1979? 2000, dotted line — anti-record of 2007. (The picture is from the magazine Nature.)
The consequences of the melting go far beyond the Arctic itself. Antirecord this year heralds harsh and snowy winter in parts of Europe and North America. Recent research, though preliminary, have shown a link between the state of Arctic sea ice in late summer and the location of areas of high and low atmospheric pressure over the North Atlantic. The highs and lows may remain relatively stable for several weeks, forming cyclones and stable at low temperatures.
Ralph Yayzer from the Institute for Polar and Marine Research. Alfred Wegener Institute (Germany) found a strong correlation between the state of Arctic sea ice in late summer 1989? 2011 and anomalies in atmospheric pressure, which stand for the extreme weather conditions such as the long winter cold snap. According to his hypothesis, the Arctic Ocean, open to excess, in the fall gives off heat the atmosphere at high latitudes. Warming tends to reduce the gradient of the large-scale atmospheric pressure and weakens the dominant in the northern hemisphere westerlies. These winds are usually warm and moist air to the Atlantic Ocean, Western Europe, and their attenuation increases the likelihood of cold weather in the latter.
Prepared according to Nature News.