圖片由美國航太總署（NASA）哥達德科學顯影動畫（Goddard Scientific Visualization Studio）提供。
9月19日，綠色和平組織的執行長奈多（Kumi Naidoo）和國際環保組織「350.org」創辦人麥奇本（Bill McKibben）與NASA氣候學家韓森（James Hansen），在美國紐約斯堪地那維亞餐廳舉辦的綠色和平論壇討論極地的緊急狀況，希望號召並協調國際對於極地危機的回應。
Arctic sea ice cover is now at the lowest summer minimum extent since satellite records began in 1979, say scientists at the National Snow and Ice Data Center, NSIDC. The new data prompted forecasts of severe winter weather across the Northern Hemisphere and a call from conservationists for a coordinated international response to the polar crisis.
“We are now in uncharted territory,” said NSIDC Director Mark Serreze. “While we’ve long known that as the planet warms up, changes would be seen first and be most pronounced in the Arctic, few of us were prepared for how rapidly the changes would actually occur.”
On September 16, Arctic sea ice cover fell to the lowest summer minimum extent in the satellite record – 1.32 million square miles (3.41 million square kilometers), as shown in this animation from the NASA Goddard Space Flight Center.
This number is preliminary, and changing weather conditions could push the ice extent still lower, NSIDC scientists say. The Arctic sea ice is melting much more quickly than climate models had predicted.
Serreze said, “While lots of people talk about opening of the Northwest Passage through the Canadian Arctic islands and the Northern Sea Route along the Russian coast, 20 years from now from now in August you might be able to take a ship right across the Arctic Ocean.”
Arctic sea ice cover grows each winter as the Sun sets for several months, and shrinks each summer as the Sun rises higher in the northern sky. Each year, the Arctic sea ice reaches its minimum extent in September.
This year’s minimum follows a record-breaking summer of low sea ice extents in the Arctic. This year’s minimum will be nearly 50 percent lower than the 1979 to 2000 average.
“The strong late season decline is indicative of how thin the ice cover is,” said NSIDC scientist Walt Meier. “Ice has to be quite thin to continue melting away as the Sun goes down and fall approaches.”
NSIDC scientists say the Arctic used to be dominated by multiyear ice, or ice that survived through several years. Lately, the Arctic is increasingly characterized by seasonal ice cover and large areas are now prone to completely melt away in summer.
Today Greenpeace International Executive Director Kumi Naidoo, joined 350.org founder Bill McKibben and NASA climate scientist Dr. James Hansen at a Greenpeace panel discussion on the polar emergency at Scandinavia House in New York, to call for a coordinated international response to the polar crisis.
“Today’s announcement represents a defining moment in human history,” said Naidoo. “In just over 30 years we have altered the way our planet looks from space, and soon the North Pole may be completely ice free in summer.”
“Rather than dealing with the root causes of climate change the current response from our leaders is to watch the ice melt and then divide up the spoils,” said Naidoo.
McKibben said, “There’s no place on Earth where we see the essential irony of our moment playing out more perfectly than in the Arctic. Our response has not been alarm, or panic, or a sense of emergency. It has been: ‘Let’s go up there and drill for oil.’ There is no more perfect indictment of our failure to get to grips with the greatest problem we’ve ever faced.”
Greenpeace is urging the creation of a sanctuary in the uninhabited area around the North Pole and a ban on unsustainable industrial activity in the rest of the Arctic.
Since June 2012 more than 1.8 million people have joined Greenpeace’s Save the Arctic campaign (savethearctic.org), and the group intends to place an “Arctic Scroll” carrying these names on the seabed beneath the North Pole early next year as an act of opposition to corporate interest in the region.
Dr. Julienne Stroeve, a scientist with the NSIDC, is currently aboard a Greenpeace ship in the Arctic region of Svalbard, Norway, after researching the region’s record breaking ice melt.
“This new record suggests the Arctic may have entered a new climate era, where a combination of thinner ice together with warmer air and ocean temperatures result in more ice loss each summer,” said Stroeve. “The loss of summer sea ice has led to unusual warming of the Arctic atmosphere, that in turn impacts weather patterns in the Northern Hemisphere, that can result in persistent extreme weather such as droughts, heat waves and flooding.”
A Cornell University study published in the journal “Oceanography” in June explains more about how the melt-off of Arctic sea ice due to climate change can trigger a domino effect leading to increased odds of severe winter weather outbreaks in the Northern Hemisphere’s middle latitudes – think the “Snowmageddon” storm that paralyzed Washington, DC in February 2010.
Cornell’s Charles Greene, professor of earth and atmospheric sciences, said, “Everyone thinks of Arctic climate change as this remote phenomenon that has little effect on our everyday lives. But what goes on in the Arctic remotely forces our weather patterns here.”
The recent observations present a new twist to the Arctic Oscillation, or AO, a natural pattern of climate variability in the Northern Hemisphere. Before humans began warming the planet, the Arctic’s climate system naturally oscillated between conditions favorable and those unfavorable for invasions of cold Arctic air.
“What’s happening now is that we are changing the climate system, especially in the Arctic, and that’s increasing the odds for the negative AO conditions that favor cold air invasions and severe winter weather outbreaks,” Greene said. “It’s something to think about given our recent history.”
This past winter, an extended cold snap descended on central and Eastern Europe in mid-January, with temperatures approaching minus 22 degrees Fahrenheit and snowdrifts reaching rooftops.
There were record snowstorms in eastern U.S. cities, such as Washington, New York and Philadelphia, as well as many other parts of the Eastern Seaboard during the previous two years.
Europe and Alaska experienced record-breaking winter storms, and the global average temperature during March 2012 was cooler than any other March since 1999.
“A lot of times people say, ‘Wait a second, which is it going to be – more snow or more warming?’ Well, it depends on a lot of factors, and I guess this was a really good winter demonstrating that,” Greene said. “What we can expect, however, is the Arctic wildcard stacking the deck in favor of more severe winter outbreaks in the future.”