2. 考研
  3. There are hidden factors which scientists call "feedback mechanisms". No one knows quite how they will interact with the changin

There are hidden factors which scientists call "feedback mechanisms". No one knows quite how they will interact with the changin

admin2005-06-26  101
问题     There are hidden factors which scientists call "feedback mechanisms". No one knows quite how they will interact with the changing climate. Here’s one example: plants and animals adapt to climate change over centuries. At the current estimate of half a degree centigrade of warming per decade, vegetation(植物)may not keep up. Climatologist James Hansen predicts climate zones will shift toward the poles by 50 to 75 kilometres a year— faster than trees can naturally migrate. Species that find themselves in an unfamiliar environment will die. The 1,000-kilometre-wide strip of forest running through Canada, the USSR and Scandinavia could be cut by half. Millions of dying trees would soon lead to massive forest fires, releasing tons of CO2 and further boosting global warming.
    There are dozens of other possible "feedback mechanisms". Higher temperatures will fuel condensation and increase cloudiness, which may actually damp down global warming. Others, like the "albedo" effect, will do the opposite. The "albedo" effect is the amount of solar energy reflected by the earth’s surface. As northern ice and snow melts and the darker sea and land pokes(戳)through, more heat will be absorbed, adding to the global temperature increase.
    Even if we were to magically stop all greenhouse-gas emissions tomorrow the impact on global climate would continue for decades. Delay will simply make the problem worse. The fact is that some of us are doing quite well the way things are. In the developed world prosperity has been built on 150 years of cheap fossil fuels.
    Material progress has been linked to energy consumption. Today 75 percent of all the world’s energy is consumed by a quarter of the world’s population. The average rich world resident adds about 3. 2 tons of CO2 yearly to the atmosphere, more than four times the level added by each Third World citizen. The US, with just 7 percent of the global population, is responsible for 22 percent of global warming.
"Feedback mechanisms" in Paragraph 1 most probably refers to______.
选项 A、how plants and animals adapt to hidden factors
B、how plants and animals interact with the changing climate
C、how climate changes
D、how climate zones shift
答案B
解析 在文章的第一段第一句话中，根据专家的解释，该词组的意思是“反馈机制”，接着讲到“没有人完全了解它们将如何与变化的气候相互作用”，此后都围绕这个话题展开，并举了植物和动物适应气候变化的例子。可见，列举植物和动物适应气候变化的例子是对“反馈机制”的解释。B项符合文章的意思。所以选B。
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