北极环境变化威胁北极熊生存空间

Changing Arctic Conditions Threaten Polar Bears 北极环境变化威胁北极熊生存空间

American researchers spent two summers studying polar bears on the Arctic sea ice. They found that sea ice, where polar bears spend much of their lives, is melting faster than experts predicted it would. The researchers say this change in the animals’ home territory is threatening their survival.

The scientists published a report on their study in the journal Science. The report says polar bears face a difficult future unless countries reduce air pollution.

Polar bears live on the ice. It is where they hunt, mate and raise their young. But a team of researchers has found that the animals’ ice habitat is warming up, and shrinking.

The team was from the University of Wyoming. Its members worked in the Arctic between 2008 and 2010. Merav Ben David was among the researchers. She says they learned that polar bears often have trouble finding food. She says the lack of food can affect their mental health.

“So if shortening of the spring hunting season, lengthening¹ of the summer season where they are food-deprived and still experiencing difficulties in getting food in the winter, polar bears are stressed physiologically²."

Ms. Ben David says if the animals do not eat enough food in the spring, they are in poor health when winter arrives.

The researchers traveled on helicopters and ships. They captured more than 20 polar bears, and tested their blood. Before releasing the animals, the researchers equipped them with devices to measure temperature. They then followed the movement of the polar bears on ice and on land.

Other studies had suggested that the bears could deal with a lack of food in the summer by reducing their activity -- like the animals do when they hibernate³ in the winter. But Ms. Ben David says the researchers discovered that did not happen.

“We found that polar bears -- like their nearest relatives the brown bears -- are incapable⁴ of reducing their metabolic⁵ rate to the level that we see during winter hibernation⁶. So there are limits on how long they can go without feeding in the summer.”

Ms. Ben David says 20,000 to 25,000 polar bears live in the Arctic. She says the world should take action to protect them.

“If we want to be responsible citizens of this planet, we have to do everything in our power to stop, reverse the trend of sea ice loss.”

She says countries must work to limit the greenhouse gases that studies have linked to rising temperatures. She says if that does not happen, polar bears could one day disappear from our planet.

I’m Christopher Jones-Cruise.

Words in This Story

habitat – n. the environment where a plant or animal normally lives

deprived – adj. to not have something

stressed – adj. related to strong feelings or concerns

physiologically – adv. of or relating to the body

hibernate – v. to spend the winter sleeping or resting

incapable – adj. not able to do something

metabolic rate – n. the rate at which a living thing (animal, people) turns food into energy

reverse – v. to cause something to stop or return to an earlier state

trend – n. a general direction of change; a way of behaving

greenhouse gases – n. gases blamed for the greenhouse effect, which is defined as the warming of the atmosphere by air pollution

Are animals in your country being affected⁷ by changes in their habitat? We want to hear from you. Write your thoughts in the comments section.

1 lengthening   

（时间或空间）延长，伸长( lengthen的现在分词 )； 加长

参考例句：

• The evening shadows were lengthening. 残阳下的影子越拉越长。
• The shadows are lengthening for me. 我的影子越来越长了。 来自演讲部分

2 physiologically   

ad.生理上，在生理学上

参考例句：

• Therefore, the liver and gallbladder cannot be completely separated physiologically and pathologically. 因此，肝胆在生理和病理上不能完全分离。
• Therefore, the liver and gallbladder are closely related physiologically and pathologically. 因此，肝胆在生理和病理上紧密联系。

3 hibernate   

v.冬眠，蛰伏

参考例句：

• Bears often hibernate in caves.熊常在山洞里冬眠。
• Some warm-blooded animals do not need to hibernate.一些温血动物不需要冬眠。

4 incapable   

adj.无能力的，不能做某事的

参考例句：

• He would be incapable of committing such a cruel deed.他不会做出这么残忍的事。
• Computers are incapable of creative thought.计算机不会创造性地思维。

5 metabolic   

adj.新陈代谢的

参考例句：

• Impressive metabolic alternations have been undergone during embryogenesis.在胚胎发生期间经历了深刻的代谢变化。
• A number of intoxicants are associated with metabolic acidosis.许多毒性物质可引起代谢性酸中毒。

6 hibernation   

n.冬眠

参考例句：

• Bears wake up in the spring after a winter of hibernation.熊经过一个冬天的冬眠后在春季苏醒。
• The tortoise spends the winter months in hibernation.乌龟在冬眠中度过寒冬季节。

7 affected   

adj.不自然的，假装的

参考例句：

• She showed an affected interest in our subject.她假装对我们的课题感到兴趣。
• His manners are affected.他的态度不自然。