The rapid growth of cities worldwide over the next two decades will cause significant risks to people and the global environment, according to analysis.
Researches from Yale and Stanford predict that by 2030 urban areas will expand by 590,000 square miles—nearly the size of Mongolia—to meet the needs of 1.47 billion more people living in urban areas.
“It is likely that these cities are going to be developed in places that are the most biologically diverse,” said Karen Seto, a famous scientist at Yale University. “They are going to be growing and expanding into forests, biological hotspots, savannas(热带稀缺大草原), coastlines—sensitive and vulnerable places.”
Urban areas, they found, have been expanding more rapidly along coasts. “Of all the places for cities to grow, coasts are the most sensitive. People and buildings along the coast are at risk of flooding and other environmental disasters,” said Seto.
The study provides the first estimate of how fast urban areas globally are growing and how fast they may grow in the future. “We know a lot about global patterns of urban population growth, but we know significantly less about how urban areas are changing,” she said. “Changes in land cover associated with urbanization lead to many environmental changes, from habitats loss and agricultural land conversion(转化) to changes in local and regional climate.”
The researchers examined studies that used satellite data to map urban growth and found that from 1970 to 2000 the world’s urban footprint had grown by at least 22,400 square miles—half the size of Ohio.
“This number is numerous, but, in actuality, urban land expansion has been far greater than what our analysis shows because we only looked at the published studies that used satellite data,” said Seto. “We found that 48 of the most populated urban areas have been studied using satellite data, with findings in journals. This means that we’re not tracking the physical expansion of more than half of the world’s largest cities.”
Half of urban land expansion in China is driven by a rising middle class, whereas the size of cities in India and Africa is driven primarily by population growth. “Rising ines translate into rising demand for bigger homes and more land for urban development, which has a great effect on biodiversity conservations, loss of carbon sinks and energy use.”
【小题1】According to the passage, the most dangerous place for city expansion is the .A．forestB．desertC．savannasD．coastline【小题2】The underlined word “vulnerable” (in Para. 3) probably means “ ”.A．diverse in plantsB．beautiful in sceneryC．easily damagedD．very productive【小题3】From Para. 5, we can infer that .A．urbanization is a good way to improve people’s standards of livingB．cities develop very fast and more and more people e to live in citiesC．more and more agricultural farmlands are used to make room for local animalsD．in the past, researchers focused their attention on the expanding urban areas【小题4】Cities in Africa bee bigger and bigger mainly because of their .A．growing populationB．rising middle classC．unique living patternsD．economic developmentD
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(答案→)D
解析：本文主要讲述的是城市化的迅速发展导致了很多城市的规模扩大，城市人口变多，对环境产生很大的影响和破坏。
【小题1】D 细节题。根据文章第三段“Of all the places for cities to grow, coasts are the most sensitive. People and buildings along the coast are at risk of flooding and other environmental disasters,” said Seto.可知最危险的地方就是海岸线，故D正确。
【小题2】C 推理题。根据本句“They are going to be growing and expanding into forests, biological hotspots, savannas(热带稀缺大草原), coastlines—sensitive and vulnerable places.”可知这里的sensitive and vulnerable places就是 指coastlines而这个地方又是对环境破坏很敏感的地方，海岸线的生态环境又是特别容易受到影响的地方。故C正确。
【小题3】B 推理题。根据本段1,2行The researchers examined studies that used satellite data to map urban growth and found that from 1970 to 2000 the world’s urban footprint had grown by at least 22,400 square miles—half the size of Ohio.可知现在城市的发展速度很快，城市的居民的数量也越来越多。故B正确。
【小题4】A 细节题。根据文章最后一段1,2行Half of urban land expansion in China is driven by a rising middle class, whereas the size of cities in India and Africa is driven primarily by population growth.可知中国的城市人口变多是因为中国的中产阶级变多，而非洲则是因为人口的迅速增加。故A正确。