D
Many disease researchers have warned that rising global temperatures could lead to more diseases. for example by allowing tropical diseases to expand their ranges into what are now mild regions. This is a particular fear for the diseases carried by insects such as malariac(疟疾） and
sleeping sickness.
But the reality is more complex, argues Kevin Lafferty. a disease ecologist. He argues that a warming climate could favour some diseases in certain regions while controlling them in others.
Lafferty does not deny that climate change might allow malarial mosquitoes to spread to new areas. However he believes that hotter and drier conditions may also get rid of mosquitoes from areas where they currently exist. If this were the case, he says. there would be little. if any, net
increase (净增长） in the risk of disease.
In addition, many mild regions such as southern Europe or the southern U.S. have good sanitation（卫生设备） and insect control programmes which, Lafferty says, would prevent diseases from becoming common even if climatic conditions were suitable.
Finally, he argues, climate change could wipe many species off the plant. Infectious pathogens（病原体） depend on their hosts for survival so they too may become endangered-especially if they,like malaria, rely on more than one host.
But Mercedes Pascual of the University of Michigan points out that there are large human populations in the east African highlands, just outside of the existing range of malarial mosquitoes.She said as temperatures rise, the mosquitoes will reach these areas. So the disadvantages will
outweigh the advantages of decreased risk elsewhere.
Most of the ecologists do, however, seem to agree on one point: predicting where a disease is going to go next involves far more than just considering climate. No matter what the results of the debate are, they all agree that health concerns should continue to play a critical role in climate policy and the debate shouldn't be regarded as weakening the case for action against global warming.
53. According to Kevin Lafferty, climate change__________
A. will not increase the spread of insect-bome diseases
B. may not significantly increase the risk of disease in the whole world
C. will not affect the dry regions where sanitation is good
D. may not affect viruses that depend on more than one host
54. What does Mercedes Pascual think of Lafferty 's conclusion?
A. She disagrees with it. B. She supports it.
C. She is not sure ofit. D. She thinks it needs proving.
55. We may infer from the passage that ___________
A. climate is the only factor in the predictior of the spread of diseases
B. when making a climate policy one should take health into account
C. the debate mentioned in the passage furthers the debate on global warming
D. a policy should be made immediately to try to stop climate change
56. We can learn from the passage that ___________
A. all the disease researchers agree that climate change will spread disease
B. nothing can be done to stop the present global warming
C. scientists have found ways to stop the wild spread of disease
D. ecologists have different views on whether the global warming will spread diseases further