（二）
Desertification， drought， and despair －that’s what global warming has in store for much of Africa. Or so we hear.
Emerging evidence is painting a very different scenario， one in which rising temperatures could benefit millions of Africans in the driest parts of the continent. Scientists are now seeing signals that the Sahara desert and surrounding regions are greening due to increasing rainfall. If sustained， these rains could revitaliｚe drought－ravaged regions， reclaiming them for farming communities. This desert－shrinking trend is supported by climate models， which predict a return to conditions that turned the Sahara into a lush savanna some 12，000 years ago.
The green shoots of recovery are showing up on satellite images of regions including the Sahel， a semi－desert ｚone bordering the Sahara to the south that stretches some 2，４00 miles.
Images taken between 1982 and 2002 revealed extensive regreening throughout the Sahel， according to a new study in the journal Biogeosciences. The study suggests huge increases in vegetation in areas including central Chad and western Sudan. The transition may be occurring because hotter air has more capacity to hold moisture， which in turn creates more rain， said Martin Claussen of the Max Planck Institute for Meteorology in Hamburg， Germany， who was not involved in the new study. “The water－holding capacity of the air is the main driving force，” Claussen said.
While satellite images can’t distinguish temporary plants like grasses that come and go with the rains， ground surveys suggest recent vegetation change is firmly rooted. In the eastern Sahara area of southwestern Egypt and northern Sudan， new trees—such as acacias—are flourishing， according to Stefan Krpelin， a climate scientist at the University of Cologne’s Africa Ｒesearch Unit in Germany.
“Before， there was not a single scorpion， not a single blade of grass，”saidKrpelin， who has studied the region for two decades.“Now you have people graｚing their camels in areas which may not have been used for hundreds or even thousands of years. Ｙou see birds， ostriches， gaｚelles coming back， even sorts of amphibians coming back，” he said.“The trend has continued for more than 20 years. It is indisputable.”
An explosion in plant growth has been predicted by some climate models.For instance， in 2005 a team led by Ｒeindert Haarsma of the Ｒoyal Netherlands Meteorological Institute in De Bilt， the Netherlands， forecast significantly more future rainfall in the Sahel.The study in Geophysical Ｒesearch Letters predicted that rainfall in the Ｊuly to September wet season would rise by up to two millimeters a day by 2080.
Satellite data shows “that indeed during the last decade， the Sahel is becoming more green，” Haarsma said. Even so， climate scientists don’t agree on how future climate change will affect the Sahel： Some studies simulate a decrease in rainfall.“This issue is still rather uncertain，” Haarsma said.
Max Planck’s Claussen said
North Africa is the area of greatest disagreement among climate
change modelers. Forecasting how global warming will affect the region is complicated by its vast siｚe and the unpredictable influence of high－altitude winds that disperse monsoon rains， Claussen added.“Half the models follow a wetter trend， and half a drier trend.”
106. According to the first paragraph， global warming is supposed to have the following im pacts on Africa EXCEPT ________.
A. water deficiency B. distress
C. desertifications
D. more grasses and lakes
107. According to Martin Claussen， what is the main cause of the increased vegetation in deserted areas?
A. The climate models are more changeable.
B. Hot air would be more capable to hold humidity. C. Many trees have been planted recently.
D. The grasses are temporarily appeared with the rains.
108. What is the role of the sixth paragraph in the development of the topic? A. To make a transition to a new topic.
B. To work as a book to the following paragraphs.
C. To provide a contrast to the preceding paragraphs.
D. To offer supporting evidence to the preceding paragraphs.
109. The underlined sentence “... North Africa is the area of greatest disagreement among climate change modelers” in the last paragraph suggests that ________.
A. half of the area will follow a wetter trend， while half a drier trend
B. the scientists in North Afrca hold different opinions in climate models C. it is not easy to predict how the climate change influences the district D. there are different climate models to be built in North Africa
110. What are the climate scientists’ attitudes towards the influence of climate change on the deserted areas?
A. Definite. B. Dubious.
C. Serious. D. Negative.
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