美國國家航空暨太空總署最新衛星數據指出，北極冰海和格林蘭島融化的速率，比先前預計更快。

北極冰海融化

華盛頓外圍馬里蘭州 Greenbelt 的美國航太署 Goddard 空間飛行中心氣候科學家表示，北冰洋的浮冰可能在 2013 年晚夏即消失殆盡。

美國航太署 Goddard 空間飛行中心浮冰衛星計劃科學家 Jay Zwally 說到道： ” 海洋浮冰急劇減少，速度比所有的預測都還要快速。我們不僅有大氣暖化的問題，同時海水暖化也加速這個問題。浮冰面積的減少，讓大家感到驚訝。這個顯著的偏差，讓我們知道也許我們已經到達極限點。

Jay Zwally

如果你某個程度推移玻璃杯然後放開來，玻璃杯還在；不過假如你推得太遠，越過極限點，那麼它就消失了。現在北冰洋發生的狀況，就是海冰正在變薄，面積正減少中。這會使冰洋吸收更多太陽熱力。即使氣候不再暖化，保持現狀，多數海洋浮冰在夏末將減少而且消失不見。所以目前北極冰洋很可能已到極限點。 ”

 

美國科羅拉多冰雪數據中心資深研究者 Mark Serreze 表示： “ 到了 2006 年九月，我們失去的浮冰，每十年超過百分之九。這相當於每年十萬平方公里，這是可觀的數量。 2007 年發生的事件，即是警訊。 ”

美國太空總署的衛星圖顯示出北極冰海在過去 30 年的平均面積。

美國太空總署的衛星圖顯示出北極冰海在過去 30 年的平均面積。綠色部份表示截至去年夏末所融化的面積。

Zwally 表示，顯然剩餘的冰也變薄了。 ” 重點是目前剩餘的面積變更薄了。以前這裏一向有很多浮冰，三到四、五、六公尺厚，而現在多數已經消失。 ”

所 有氣候模式都有其易變性和可能性，而融化的趨勢比預期來的嚴重。

另一個可能性是會比預計的更加惡化。這是北極冰洋發生的真實現況，我們藉由衛星圖確實看到比預計的更嚴重。他補充說明那些模式是經由地面觀察與測量得到證實。

Arctic melting

Climate scientists at NASA's Goddard Space Flight Center in Greenbelt, Maryland, outside Washington, say the Arctic Ocean could be mostly ice free in late summer 2013. 

"The sea ice is decreasing faster than all the models predicted," says Jay Zwally, the ice satellite project scientist at NASA Goddard, "We not only have the warming of the atmosphere, we have a warming of the ocean that is affecting this.  It has been surprising to everybody, this decrease in area. This is a marked departure, and this is suggesting to us that maybe we are getting at this tipping point."

Jay Zwally

"If you push something like a glass to a certain point, and leave go, it will come back; but if you push it too far, past a tipping point, then it is gone," he explains.  "Now what is happening in the Arctic Ocean is the sea ice is getting thinner; it is decreasing in area.  This opens up the ocean to more heating from the sun, so it is very likely that the Arctic Sea ice is now at this tipping point, where even if the climate doesn't warm any more, stays as it is, most of the sea ice will decrease and disappear at the end of the summer."

"Up through 2006, in September we've been losing ice at the rate of a little more than nine percent per decade,” says Mark Serreze, a senior researcher at the U.S. National Snow and Ice Data Center in Colorado. “That's equivalent to about 100,000 square kilometers per year, which is quite a bit. What's happened in 2007 has just sent an exclamation point to this."

NASA satellite image shows Arctic over the last 30 years

This satellite image from NASA shows the average sea ice in the Arctic over the last 30 years. The green area indicates the melt at the end of last summer.

Zwally says there is clear indication that the remaining is thinning. "The key thing is that this area that is remaining is now thinner," he said. "There used to be a lot of ice here that was three- four, five, six meters thick, and most of that is gone."

All climate models have variability and the possibility that melting trends may lead to results less severe than predicted.

"The other possibility is that it could be worse than the models predict and this is an example, a specific example of the sea ice in the Arctic where what is happening, what we see with the satellite is actually worse than the models predicted," he adds, and he says those models are supported by ground based observations and measurements.




source:www.voanews.com