科技英语文章

科技英语文章

Arctic Melt

Earth's North and South Poles are famous for being cold and icy. Last year, however, the amount of ice in the Arctic Ocean fell to a record low1.

Normally, ice builds in Arctic waters around the North Pole each winter and shrinks during the summer. But for many years, the amount of ice left by the end of summer has been declining.

Since 1979, each decade has seen an 11.4 percent drop in end-of-summer ice cover2. Between 1981 and 2000, ice in the Arctic lost 22 percent of its thickness -- becoming 1.13 meters thinner.

Last summer, Arctic sea ice reached its skimpiest levels yet. By the end of summer 2007, the ice had shrunk to cover just 4.2 million square kilometers. That's 38 percent less area than the average cover at that time of year. Andit's a very large 23 percent below the previous record low, which was set just 2 years ago. This continuing trend has scientists concerned

There may be several reasons for the ice melt, says Jinlun Zhang, an oceanographer at the University of Washington3 in Seattle. Unusually strong winds blew through the Arctic last summer. The winds pushed much of the ice out of the central Arctic, leaving a large area of thin ice and open water4.

Scientists also suspect that fewer clouds cover the Arctic now than in the past. Clearer skies allow more sunlight to reach the ocean. The extra heat warms both the water and the atmosphere. In parts of the Arctic Ocean last year, surface temperatures were 3.5℃Celsius warmer than average and 1.5℃ warmer than the pr evious record high5.

With both air and water getting warmer, the ice is melting from both above and below. In some parts of the Beaufort Sea6, north of Alaska and western Canada, ice that measured 3.3m thick at the beginning of the summer measured just 50 centimeters by season's end.

The new measurements suggest that melting is far more severe than scientists have seen by just looking at ice cover from above, says Donald K. Perovich, a geophysicist at the U. S. Army Cold Regions Research and Engineering Laboratory in Hanover, N.H.7

Some scientists fear that the Arctic is stuck in a warming trend from which it may never recover.

练习：

1. Which of the following is closest in meaning to the word "build" in the first sentence of the second paragraph?

A) Construct. B) Extend. C) Create. D) Expand.

2. What is the ice cover in the Arctic by the end of 2007 summer?

A) 4.2 million square kilometers. B) 11.4 million square kilometers. C) 1.13 million square kilometers. D) 38 million square kilometers.

3. What are the reasons for the ice melt according to the scientists?

A) Strong winds and clear skies. B) Long summer and short winter.

C) Open water and thin ice. D) Light clouds and light winds.

4. Why is the ice melting from both above and below?

A) Because extra heat warms the air.

B) Because extra heat warms the water.

C) Because the temperature above the water is higher.

D) Both A and B.

5. What can be a possible title for the passage?

A) What are scientists looking for in the Arctic Ocean?

B) What are scientists doing in the Arctic Ocean?

C) Why are scientists worrying about the Arctic Ocean?

D) Why are scientists interested in the Arctic Ocean?

Experts Call for Local and Regional Control of Sites for Radioactive Waste

The withdrawal of Nevada's Yucca Mountain as a potential nuclear waste repository1 has reopened the debate over how and where to dispose of spent nuclear fuel and high-level nuclear waste. In an article in the July 10 issue of Science, University of Michigan2 geologist Rodney Ewing and Princeton University3 nuclear physicist Frank von Hippel argue that, although federal agencies should set standards and issue licenses for the approval of nuclear facilities, local communities and states should have the final approval on the siting of these facilities. The authors propose the development of multiple sites that would service the regions where nuclear reactors are located.