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  3. When Lewis Ziska wanted to see how a warmer wood with more carbon dioxide in the air would affect certain plants, he didn’t set

When Lewis Ziska wanted to see how a warmer wood with more carbon dioxide in the air would affect certain plants, he didn’t set

admin2011-03-10  37
问题    When Lewis Ziska wanted to see how a warmer wood with more carbon dioxide in the air would affect certain plants, he didn’t set up his experiment in a greenhouse or boot up a computer model. He headed for Baltimore. Cities are typically 7 degrees warmer than the countryside, as well as big sources of CO2. So Ziska, a plant physiologist at the U.S. Department of Agriculture, compa,ed ragweed growing in vacant lots in Baltimore with ragweed in rural fields—and discovered the dark side of sunny claims that global warming will produce a "greening of planet Earth". Urban ragweed grows three to five times bigger than rural ragweed, starts spewing allergenic pollen weeks earlier each spring and produces 10 times more pollen. In as few as 20 years the whole world will have CO2 levels at least as high as some cities do now. As climate changes due to the greenhouse effect, hayfever sufferers would do well to lay in copious supplies of Kleenex.
   From mosquitoes that carry tropical diseases such as malaria, to plants that produce allergenic pollen, scientists are finding that a warmer, CO2-rich world will be very, very. good for plants, insects and microbes that make us sick. Although the most obvious threat to human health is more frequent and more intense heat weaves, such as the one that killed thousands of people in Europe in 2003, that is only the beginning.
   In the case of plants, it’s not just that they grow faster and shed pollen earlier as the woad warms. The carbon-enriched air also alters their physiology. In a six-year study at a pine forest managed by Duke University, where pipes and fans adjust the CO2 concentration and the air, scientists found that elevated CO2 increases the growth rate of poison ivy. More surprising, by increasing the air’s ration of carbon to nitrogen, elevated CO2 also increases the toxicity of urushiol, the rash-causing oil. "Poison ivy will become not just more abundant in the future," says Ziska. "It will also be more toxic. "
   Plants interpret warmth and abundant CO2as: what a great climate for reproduction. Monitoring stations in Europe are recording higher pollen counts for allergenic grasses and trees, led by birch and hazel, notes a 2005 study by the Center for Health and the Global Environment at Harvard Medical School. Those counts are rising earlier each year: the warming already underway is shifting the pollen season by almost one day per year. By 2017, you’ll be reaching for tissues nine days sooner than you do now.  More good news: in a greenhouse world po]len will be not only more abundant but more allergenic, he and Ziska find.
   Since cities already have the high CO2 levels that the rest of the world can soon expect, "’there is no question these climate-related changes have already begun," says Arlington, Texas, Mayo," Dr. Robert Cluck. "Every summner we’re seeing West Nile virus earlier and earlier, and the higher levels of ozone that come with higher temperatures are increasing the rates of asthma and causing heart and lung damage comparable to living with a cigarette smoker. "
   In a greenhouse world, tropical diseases will expand their range and their prevalence. For instance, alternating floods and droughts—the pattern that comes with climate change—provide perfect conditions for mosquitoes that carry malaria, West Nile and dengue fever. Warming makes mosquitoes bit more. They’ll face fewer predators, too. The frequent droughts expected in a greenhouse world are murder on damselflies and dragonflies.
   As dengue fever, yellow fever and malaria extend their range to higher elevations and higher latitudes, those diseases could appear in the developed woad, too. The southern tier of western and eastern Europe, as well as the southern United States, are most at risk, says Harvard’s Epstein.  Dengue fever has already popped up on the Mexican side of the U.S. border, a worrisome expansion of its current range. Say this for the climate contrarians who insist that a warmer world will he a better, more productive world: if they’re referring to allergens and pathogens, they’re dead right.
Which of the following CANNOT be inferred from the passage?
选项 A、In a more productive world, hay fever sufferer will have an even more difficult time.
B、Cigarette smoker will stiffer more from heart and lung disease with the world becoming warner.
C、Tropical disease might spread to Europe and U.S.
D、CO2 level in the air has effect on the climate.
答案B
解析 推断题。第一段Ziska所做的实验结果表明生长在城市的豚草与生长在乡问的豚草相比，每年春天喷发致敏花粉的时间更早，喷发致敏花粉的数量高出十倍，这是由于城市的气温比乡村高，二氧化碳含量高所致。该段最后一句陈述影响：温室效应导致的气候变化会使干草热患者需要大量的纸巾。第四段第一句指出温暖和丰富的二氧化碳为植物繁殖提供大好气候，欧洲的监测站的记录显示，引起过敏的草和树木喷发花粉的数量不断增多，喷发花粉季节的时间也在往前推移，人们需要纸巾的时间，即产生过敏反应的时间，也随之向前推移。据此，我们已经可以推断，如果植物繁殖更加多产，干草热患者会更加痛苦，排除[A]；根据第七段第二、三句我们可以推断，热带疾病可能会传播到欧洲和美国，排除[C]；第五段第一句意为：城市已经达到了很高的二氧化碳水平，世界其他地方也会很快达到。因此Arlington说，毫无疑问，与气候相关的变化已经开始了。据此推断，空气中二氧化碳的水平会对气候产生影响，排除[D]；第五段最后一句意思是由气温升高引起的臭氧层水平的增高，对心脏和肺部造成的损害与和吸烟者一起生活造成的损害相当，仅仅凭这些，我们并不能推断出吸烟者会因为温室效应比不吸烟的人更容易患心脏和肺的疾病，故答案为[B]。  
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