Some of us familiar with the doomsday warning from “Chicken Little” proclaiming that the sky is falling will be curious to know that the Arctic is falling; and has fallen to its lowest sea ice levels in recorded history with two weeks left in this year’s melt season according to the University of Colorado National Snow and Ice Data Center. The news is a confirmation of the drastic warming in the region and a likely harbinger of larger changes to come.
According to scientists from NASA and the NASA-supported National Snow and Ice Data Center (NSIDC) in Boulder, Colo., the amount is the smallest size ever observed in the three decades since consistent satellite observations of the polar cap began.
The extent of Arctic sea ice on Aug. 26, as measured by the Special Sensor Microwave/Imager on the U.S. Defense Meteorological Satellite Program spacecraft and analyzed by NASA and NSIDC scientists, was 1.58 million square miles (4.1 million square kilometers), or 27,000 square miles (70,000 square kilometers) below the Sept. 18, 2007, daily extent of 1.61 million square miles (4.17 million square kilometers).
The sea ice cap naturally grows during the cold Arctic winters and shrinks when temperatures climb in the spring and summer. But over the last three decades, satellites have observed a 13 percent decline per decade in the minimum summertime extent of the sea ice. The thickness of the sea ice cover also continues to decline.
“The persistent loss of perennial ice cover — ice that survives the melt season — led to this year’s record summertime retreat,” said Joey Comiso, senior research scientist at NASA’s Goddard Space Flight Center in Greenbelt, Md. “Unlike 2007, temperatures were not unusually warm in the Arctic this summer.”
The new record was reached before the end of the melt season in the Arctic, which usually takes place in mid- to late-September. Scientists expect to see an even larger loss of sea ice in the coming weeks.
“In 2007, it was actually much warmer,” Comiso said. “We are losing the thick component of the ice cover. And if you lose the thick component of the ice cover, the ice in the summer becomes very vulnerable.”
“By itself it’s just a number, and occasionally records are going to get set,” NSIDC research scientist Walt Meier said about the new record. “But in the context of what’s happened in the last several years and throughout the satellite record, it’s an indication that the Arctic sea ice cover is fundamentally changing.”
Climate change has come to the Arctic at a faster pace than seen anywhere else on Earth.
To put it in perspective, the data center reported that surface ice is being lost at a rate of 29,000 square miles per day, roughly an area the size of South Carolina. What is more, sea ice normally reaches its low point in September so it is thought likely that this year’s melt will continue to grow.
Professor Peter Wadhams, from Cambridge University, told BBC News: “A number of scientists who have actually been working with sea ice measurement had predicted some years ago that the retreat would accelerate and that the summer Arctic would become ice-free by 2015 or 2016.
“I was one of those scientists – and of course bore my share of ridicule for daring to make such an alarmist prediction.”
But Prof Wadhams said the prediction was now coming true, and the ice had become so thin that it would inevitably disappear.
“Measurements from submarines have shown that it has lost at least 40% of its thickness since the 1980s, and if you consider the shrinkage as well it means that the summer ice volume is now only 30% of what it was in the 1980s,” he added.
“This means an inevitable death for the ice cover, because the summer retreat is now accelerated by the fact that the huge areas of open water already generated allow storms to generate big waves which break up the remaining ice and accelerate its melt.
“Implications are serious: the increased open water lowers the average albedo [reflectivity] of the planet, accelerating global warming; and we are also finding the open water causing seabed permafrost to melt, releasing large amounts of methane, a powerful greenhouse gas, to the atmosphere.”
Opinions vary on the date of the demise of summer sea ice, but the latest announcement will give support to those who err on the pessimistic side.
A recent paper from Reading University used statistical techniques and computers to estimate that between 5-30% of the recent ice loss was due to Atlantic Multi-decadal Oscillation – a natural climate cycle repeating every 65-80 years. It’s been in warm phase since the mid 1970s.
But the rest of the warming, the paper estimates, is caused by human activity – pollution and clearing of forests.
If the ice continues to disappear in summer there will be opportunities as well as threats.
Some ships are already saving time by sailing a previously impassable route north of Russia.
Oil, gas and mining firms are jostling to exploit the Arctic – although they’re being strongly opposed by environmentalists. Greenpeace has been protesting at drilling by the Russian giant Gazprom.
Among the many threats, the warming is bad for Arctic wildlife. Thanks to the influence of sea ice on the jet stream the changes could affect weather in the UK.
The changes – if they happen – could unlock frozen deposits of methane which would further overheat the planet.
Warmer seas could lead to more melting of Greenland’s ice cap which would contribute to raising sea levels and changing the salinity of the sea, which in turn could alter ocean currents that help govern our climate.
In the grand global debate over climate change or global warming, the evidence appears to be irrefutable; that is, that something is rapidly happening to what was once a fairly predictable science. The world is locked on a precipitous changing weather course in which no one can effectively predict its outcome.
Yes the Arctic sea ice levels are falling, but when you think about it, there may not be much anyone, not even “Chicken Little,” can do about it.
Contributor D. Chandler