Unit阅读理解CET补充题.ppt

阅读理解 Unit 4 补充题1 （Para 1) There are hidden factors which scientists call “feedback mechanisms”. No one knows quite how they will interact with the changing climate. Heres 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 75kilometres a year- faster than trees can naturally migrate. Species that find themselves in an unfamiliar environment will die. The 1000 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 ions of CO2 and further boosting global warming. (Para 2) 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 earths surface. As northern ice and snow melts and the darker sea and land pokes through, more heat will be absorbed, adding to the global temperature increase. (Para 3) 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. (Para 4) Material progress has been linked to energy consumption. Today 75 per cent of all the worlds energy is consumed by a quarter of the worlds 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 seven per cent of the global population, is respon