5. What are the possible causes of the climate getting warmer? What can be done to stop it?
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Polar bears
are getting thinner. It is not a diet and it is not because there is less
food to catch. It is because the world is getting warmer. Giant white bears that live in the north of Canada are at the moment impatiently (1) ice to form. They need the ice to form a "bridge" to their food - seals. Seals usually (2) land among the icebergs. However, as the climate becomes warmer, winter is getting shorter and sea ice is decreasing in the area. This is making polar bears' lives increasingly difficult. Bears need to eat as much food as possible in the winter to make themselves fat enough to (3) five months without food in the summer and autumn. During the five-month ice-free season, the bears (4) fast (绝食). "For every week a bear has not been hunting food on ice, it is 10 kilograms lighter," said a scientist. The average temperature of the region has risen from 0.3 to 0.4 degrees centigrade since 1950. With the change of the climate, the sea ice is melting earlier in the spring. Thus the hunting season for bears is getting shorter. And the bears, (5) , weigh between 80 and 85 kilograms less than they did in 1985. |