北极熊的生存环境因为全球气候变暖已经变得越来越恶劣了。但是近日有人证明北极熊可以在全球气候变暖的情况下生存,真的是这样吗,我们来看看下面的雅思阅读材料。
THIS month has seen qualified good news for polar bears. On December 16th researchers from the United States and Canada predicted that even though the extent of the summer ice in the Arctic Ocean is expected to decline precipitously over the next few decades, a refuge of sorts will remain for them. Meanwhile, in a paper in Nature, a group American climatologists argued that a sudden and irreversible decline of the sea ice may, after all, not be the most likely outcome of global warming.
The refuge will be along the northern shores of Canada and Greenland, Stephanie Pfirman, of Barnard College in New York, and her colleagues told the autumn meeting of the American Geophysical Union in San Francisco. Even in summer, ice will persist there because increased melting will be compensated for by the arrival of ice from the centre of the Arctic Ocean, and even from as far away as Europe and Asia. Then, as now, prevailing winds and resultant ocean currents carry ice to North America. That is why the ice on the Eurasian side is typically young and about one metre thick, whereas that near Canada can be eight metres thick and as many years old.
Dr Pfirman arrived at this conclusion after running a computer model called the Community Climate System Model version 3, or CCSM3, which was developed by the University Corporation for Atmospheric Research in Boulder, Colorado. According to this model, the Arctic Ocean will be more or less ice-free by 2050 if no special effort is made to reduce greenhouse-gas emissions the business as usual scenario. The reason is that when large stretches of ocean, for lack of reflective ice cover, absorb more heat from the sun than is usually the case they will be unlikely ever to freeze over again. Even after this destructive feedback cycle has taken its course, however, the models calculations of ice growth and transport show that the refuge at the American side of the Arctic, all 500,000 square kilometres of it, will be there for the last polar bears.
【雅思阅读材料:气候变暖下挣扎的北极熊】相关文章:
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