研究称40年后10亿城市人口缺水 印度尤其堪忧
我们的信息化程度已经足够高，城市化应该逆向进行了，否则越来越多的大城市将成为生态噩梦美国一项研究显示，全球气候变暖加剧城市化弊病，预计２０５０年将有超过１０亿城市人口缺水，而印度城市状况尤其堪忧。
这项研究由美国大自然保护协会研究员罗布·麦克唐纳牵头，成果发布在美国《国家科学院学报》。
研究显示，按照当前城市化趋势，到２１世纪中叶，全球将有大约９.９３亿城市人口每天获取水量不足１００升；再加上气候变暖因素，缺水城市人口将额外增加１亿。
印度孟买、德里、加尔各答、本加卢鲁、金奈和海得拉巴等６座城市所面临缺水前景尤其堪忧。在非洲西部，尼日利亚拉各斯、贝宁科托努等城市同样面临用水短缺。
麦克唐纳认为，城市从其他地方抽取地下水或江河水，会破坏生态系统、威胁野生动物生存，“如果城市吸干河流，会给鱼、爬行动物和河流中一切生物带来真正恶劣的影响”。
研究人员建议人们改革农业，调整城市居民生活方式，以提高用水效率；提议设立国际基金，资助贫困国家保障城市居民获取足够饮用水。
当前，全球大约１.５亿人日均用水不足１００升；美国人日均用水为３７６升。
Billion-plus people to lack water in 2050: study
By Shaun Tandon (AFP) – 6 days ago
WASHINGTON — More than one billion urban residents will face serious water shortages by 2050 as climate change worsens effects of urbanization, with Indian cities among the worst hit, a study said Monday.
The shortage threatens sanitation in some of the world's fastest-growing cities but also poses risks for wildlife if cities pump in water from outside, said the article in the Proceedings of the National Academy of Sciences.
The study found that under current urbanization trends, by mid-century some 993 million city dwellers will live with less than 100 liters (26 gallons) each day of water each -- roughly the amount that fills a personal bathtub -- which authors considered the daily minimum.
Adding on the impact of climate change, an additional 100 million people will lack what they need for drinking, cooking, cleaning, bathing and toilet use.
"Don't take the numbers as destiny. They're a sign of a challenge," said lead author Rob McDonald of The Nature Conservancy, a private environmental group based near Washington.
"There are solutions to getting those billion people water. It's just a sign that a lot more investment is going to be needed, either in infrastructure or in water use efficiency," he said.
Currently, around 150 million people fall below the 100-liter threshold for daily water use. The average American has 376 liters delivered a day, although actual use varies widely depending on region, McDonald said.
But the world is undergoing an unprecedented urban shift as rural people in India, China and other growing nations flock to cities.
India's six biggest cities -- Mumbai, Delhi, Kolkata, Bangalore, Chennai and Hyderabad -- are among those most affected by water shortages. The study forecast that 119 million people would face water shortages in 2050 in the Ganges River delta and plain alone.
With an annual monsoon, India does not lack water. But it struggles to preserve the water from the wet season to the dry season, McDonald said.
West Africa, which sees some of the world's heaviest rainfall, will also face water shortages in cities such as Lagos, Nigeria, and Cotonou in Benin, the study found.
The study warned of threats to ecosystems if developing nations take water from elsewhere. India's Western Ghats region, a potential source for thirsty cities, is home to nearly 300 fish species, 29 percent of which are found nowhere else, it said.
"If cities are essentially drinking rivers dry, that has really bad effects on the fish and the reptiles and everything else in the river," McDonald said.
Instead, the study recommended reforms to agriculture -- usually the top consumer of water -- and improved efficiency, as nearly half of the water in some poor countries is wasted due to leaks.
"There is a lot of potential for increase in water-use efficiency in the agriculture sector, or indeed in the residential sector, to solve most of this challenge," McDonald said.
The study said there would be a need for international funding to help poorer nations "to ensure that urban residents can enjoy their fundamental right to adequate drinking water."
UN-led talks last year on climate change agreed on practicalities to set up a global fund to assist poor nations most hit by climate change, with a target of 100 billion dollars a year starting in 2020.
Other cities forecast by the study to face a water crunch include Manila, Beijing, Lahore and Tehran.
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