理工类：模拟题The Effects of Global Warming
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 75 kilometres a year—faster than trees can naturally migrate. Species that find themselves in an unfamiliar environment will die. The 1000-kilometer-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 mechanism”. 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 (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 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 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 responsible for 22 per cent of global warming.
41 “Feedback mechanisms” in paragraph 1 most probably refer to ____________.
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
42 We can learn from the passage that ____________.
A some feedback mechanisms may slow down global warming
B the basic facts of global warming are unknown
C developing countries benefit from cheap fossil fuels
D developed countries have decided to reduce their energy consumption
43 James Hansen predicts that the shift of climate zones will be accompanied by ____________.
A the cutting of many trees
B desirable environmental changes
C successful migration of species
D unsuccessful migration of trees
44 It can be inferred from the passage that ____________.
A the developing world has decided to increase its energy consumption
B a third-world citizen adds less than a ton of CO2 yearly to the atmosphere
C the world climate would soon gain its balance if we stopped greenhouse gas emissions
D future prosperity of the world is dependent on cheap fossil fuels
45 Which of the following is the main topic of the passage? ____________
A Impact of global warming on climate.
B Prosperity and cheap fossil fuels.
C Material progress and energy consumption.