温暖的水域阻止了美国北极海冰的形成

Warm Waters Prevent Sea Ice Formation in US Arctic¹

Climate change has brought a difficult new reality for the U.S. Arctic. Open water -- rather than sea ice – has become normal for the Chukchi Sea in the month of November.

Researchers are studying how this "new normal" may affect coastal² communities in northern Alaska.

The researchers are from the University of Washington. The group is taking its 80-meter-long ship several places and will record observations. One of those places is Utqiaġvik, the northernmost community in America.

Jim Thomson is an ocean scientist with the team. He told The Associated Press that the researchers are trying to understand changes to the fall season in the Arctic.

Each day since mid-October, sea ice in the Chukchi Sea has been the lowest on record, said Rick Thoman. He is a climate expert at the University of Alaska Fairbanks' International Arctic Research Center.

For example, on November 7, the National Snow and Ice Data Center recorded sea ice at about one-sixth of the usual amount for that date from 1981 to 2010, Thoman said.

Less ice is a problem for people living on the coast. Communities north and south of the Bering Strait depend on coastal ice to act as a natural sea wall. The ice protects land from erosion³ caused by winter storms.

Sea ice also provides a place from which to catch seafood⁴ in Nome, a transportation center between villages in Kotzebue Sound. It also serves as a work area on which to kill walrus⁵ near the town of Gambell.

Sea ice is one of the most important physical elements of the Chukchi and Bering seas. The cold, salty water underneath⁶ ice creates columns that separate Arctic animals from valuable fish catches such as Pacific cod⁷ and walleye pollock. When sea ice melts, it creates conditions important for the growth of small organisms at the bottom of the food chain.

Sea ice also provides the main living space for polar bears. Female bears use ice as a place to give birth. And walrus mothers use sea ice as a resting place. They follow the ice edge south as it moves into the Bering Sea.

The formation of sea ice requires the ocean temperature to be about -1.8 Celsius⁸, the freezing point of saltwater. Historically, ice has formed in the northernmost waters. It gets moved by currents and wind into the southern Chukchi and Bering seas, where it cools the water. This helps even more ice to form, explained Andy Mahoney. He is a sea ice physicist⁹ at the University of Alaska Fairbanks' Geophysical Institute.

Mahoney said, "Even at the end of summer you couldn't get enough heat into the ocean to raise the water temperature" much above freezing. "So it didn't take much cooling to cool the ocean down to the freezing point."

But high summer temperatures have warmed the water column in the Bering and Chukchi seas. Water temperatures from the surface to the ocean bottom remain above normal. This leads to a delay in ice formation.

"We've got a cold atmosphere. We've got a strong wind. You'd think we'd be forming ice, but there's just too much heat left in the ocean," Mahoney said.

The water may be warm enough to melt ice moving south from northern areas.

"I haven't seen any direct observations where ice has been transported into the Chukchi Sea and then melted," Mahoney said. But he says water temperature maps that he has seen are still much above zero degrees Celsius. And even if you bring ice from somewhere else, it will soon begin melting because of the water temperature, he adds.

Thomson and other scientists will look at how the changes could affect coastlines, which are already eroding¹⁰. Less ice and more open water mean a big threat. Ice keeps down the size of waves. Open water increases the distance over which wave-causing winds can blow.

"We know from other projects and other work that the waves are definitely on the increase in the Arctic," Thomson said.

That means even more erosion and greater chances of winter flooding in villages. It also means increased danger to hunters in small boats, who will have to travel longer distances to find seals and walruses¹¹.

Words in This Story

Arctic - n. of or relating to the North Pole or the region around it

erosion - n. the gradual destruction of something by natural forces

walrus - n. a large animal that lives on land and in the sea in northern regions and that has flippers and long tusks¹²

column - n. something resembling a column in form, position, or function

polar bear - n. a large white bear that lives near the North Pole

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 coastal   

adj.海岸的，沿海的，沿岸的

参考例句：

• The ocean waves are slowly eating away the coastal rocks.大海的波浪慢慢地侵蚀着岸边的岩石。
• This country will fortify the coastal areas.该国将加强沿海地区的防御。

3 erosion   

n.腐蚀，侵蚀，磨损，削弱，减少

参考例句：

• The erosion of beach here is serious.这里海岸的腐蚀很严重。
• Drought and soil erosion had long been a major problem.干旱和水土流失一直是个老大难问题。

4 seafood   

n.海产食品，海味，海鲜

参考例句：

• There's an excellent seafood restaurant near here.离这儿不远有家非常不错的海鲜馆。
• Shrimps are a popular type of seafood.小虾是比较普遍的一种海味。

5 walrus   

n.海象

参考例句：

• He is the queer old duck with the knee-length gaiters and walrus mustache.他穿着高及膝盖的皮护腿，留着海象般的八字胡，真是个古怪的老家伙。
• He seemed hardly to notice the big walrus.他几乎没有注意到那只大海象。

6 underneath   

adj.在...下面，在...底下；adv.在下面

参考例句：

• Working underneath the car is always a messy job.在汽车底下工作是件脏活。
• She wore a coat with a dress underneath.她穿着一件大衣，里面套着一条连衣裙。

7 cod   

n.鳕鱼；v.愚弄；哄骗

参考例句：

• They salt down cod for winter use.他们腌鳕鱼留着冬天吃。
• Cod are found in the North Atlantic and the North Sea.北大西洋和北海有鳕鱼。

8 Celsius   

adj.摄氏温度计的，摄氏的

参考例句：

• The temperature tonight will fall to seven degrees Celsius.今晚气温将下降到七摄氏度。
• The maximum temperature in July may be 36 degrees Celsius.七月份最高温度可能达到36摄氏度。

9 physicist   

n.物理学家，研究物理学的人

参考例句：

• He is a physicist of the first rank.他是一流的物理学家。
• The successful physicist never puts on airs.这位卓有成就的物理学家从不摆架子。

10 eroding   

侵蚀，腐蚀( erode的现在分词 )； 逐渐毁坏，削弱，损害

参考例句：

• The coast is slowly eroding. 海岸正慢慢地被侵蚀。
• Another new development is eroding the age-old stereotype of the male warrior. 另一个新现象是，久已形成的男人皆武士的形象正逐渐消失。

11 walruses   

n.海象( walrus的名词复数 )

参考例句：

• Walruses have enormous appetites and hunt for food almost constantly. 海象食欲极大，几乎一直在猎取食物。 来自互联网
• Two Atlantic walruses snuggle on an ice floe near Igloolik, Nunavut, Canada. 加拿大努勒维特伊格卢利克附近，两头大西洋海象在浮冰上相互偎依。 来自互联网

12 tusks   

n.（象等动物的）长牙( tusk的名词复数 )；獠牙；尖形物；尖头

参考例句：

• The elephants are poached for their tusks. 为获取象牙而偷猎大象。
• Elephant tusks, monkey tails and salt were used in some parts of Africa. 非洲的一些地区则使用象牙、猴尾和盐。 来自英语晨读30分（高一）