VOA标准英语2008年-NASA Scientists See Hastened Arctic Warming

By Paul Sisco
Washington
09 January 2008
 

Recent satellite data from the U.S. Space agency NASA indicate that sea ice in the Arctic¹ and Greenland is melting at a faster rate than previously² projected.  VOA's Paul Sisco has the story.

Climate scientists at NASA's Goddard Space Flight Center in Greenbelt, Maryland, outside Washington, say the Arctic Ocean could be entirely³ 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."

"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 equivalent⁴ to about 100,000 square kilometers per year, which is quite a bit. What's happened in 2007 has just sent an exclamation⁵ point to this."

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. 

1 Arctic   

adj.北极的；n.北极

参考例句：

• They flew over the unlimited reaches of the Arctic.他们飞过了茫茫无边的北极上空。
• The sort of animal lived in the Arctic Circle.这种动物生活在北极圈里。

2 previously   

adv.以前，先前（地）

参考例句：

• The bicycle tyre blew out at a previously damaged point.自行车胎在以前损坏过的地方又爆开了。
• Let me digress for a moment and explain what had happened previously.让我岔开一会儿，解释原先发生了什么。

3 entirely   

ad.全部地，完整地；完全地，彻底地

参考例句：

• The fire was entirely caused by their neglect of duty. 那场火灾完全是由于他们失职而引起的。
• His life was entirely given up to the educational work. 他的一生统统献给了教育工作。

4 equivalent   

adj.（to）相等的，等价的；n.相等物，等值物

参考例句：

• Nodding your head is equivalent to saying "yes".点头就等于说“赞同”。
• You will receive the full equivalent of your money.你将收到与你的款项价值完全同等的物品。

5 exclamation   

n.感叹号，惊呼，惊叹词

参考例句：

• He could not restrain an exclamation of approval.他禁不住喝一声采。
• The author used three exclamation marks at the end of the last sentence to wake up the readers.作者在文章的最后一句连用了三个惊叹号，以引起读者的注意。