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  3. Alaska is disappearing slowly but surely. Since the 1950s, it is estimated t

Alaska is disappearing slowly but surely. Since the 1950s, it is estimated t

游客2024-08-20  10
问题     Alaska is disappearing slowly but surely. Since the 1950s, it is estimated that as much as 15 percent of Alaska’s area has disappeared. But how can a whole state be disappearing?
    One reason for Alaska’s gradual disappearance is the melting of its glaciers. According to one geologist at the US Geological Survey, about 98% of Alaska’s glaciers are either unmoving or diminishing. This diminishing seems mainly due to the increase in global temperatures. Since the 1960s, the average year—round temperature has increased by 5°F. Additionally, the average winter temperature has increased by 8°F. Presently, an estimated 24 cubic miles of ice is disappearing from Alaskan glaciers every year. It may be even more in the near future, as some scientists predict that the average world temperature could go up 2. 5 to 10 °F by the year 2100.
    Another problem contributing to Alaska’s gradual disappearance is its melting permafrost. Much of the land in Alaska was permanently frozen, or frozen for most of the year. This maintained its stability. Now, the melting permafrost is causing a number of problems on land. Roads and utility poles are collapsing. Also, the hard permafrost, which originally prevented beaches from eroding during violent storms is now melting. Affected villages are forced to move somewhere else. For villages on small low islands, one terrible storm could wipe out the entire community.
    Some scientists believe that human activity is linked to the global increase in weather temperature. Whether the rising temperatures are caused by human activity or natural changes, the fact remains that Alaska is warming. Sadly, this could be a preview of what will happen to the rest of the world in the next century.
Summary:
There is a big problem in Alaska. The【49】______are melting. Scientists【50】______that 15 percent of Alaska has already melted. They say this change is the result of【51】______in the Earth’s【52】______. The higher temperatures are【53】______several problems in Alaska. The ground that was【54】______before is now beginning to defrost. This could be a(n)【55】______of what will happen to the rest of the world in the next century. [br]
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答案 causing
解析 第三段提到永久性冻土的融化引起了一系列的问题，而气温升高是冻土融化的原因，所以导致这些问题的根本原因还是气温升高。
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