专家：2050年地球或将面目全非

A growing, more affluent population competing for ever scarcer resources could make for an "unrecognizable" world by 2050, researchers warned at a major US science conference Sunday。

The United Nations has predicted the global population will reach seven billion this year, and climb to nine billion by 2050, "with almost all of the growth occurring in poor countries, particularly Africa and South Asia," said John Bongaarts of the non-profit Population Council。

To feed all those mouths, "we will need to produce as much food in the next 40 years as we have in the last 8,000," said Jason Clay of the World Wildlife fund at the annual meeting of the American Association for the Advancement of Science (AAAS)。

"By 2050 we will not have a planet left that is recognizable" if current trends continue, Clay said。

The swelling population will exacerbate problems, such as resource depletion, said John Casterline, director of the Initiative in Population Research at Ohio State University。

But incomes are also expected to rise over the next 40 years -- tripling globally and quintupling in developing nations -- and add more strain to global food supplies。

People tend to move up the food chain as their incomes rise, consuming more meat than they might have when they made less money, the experts said。

It takes around seven pounds (3.4 kilograms) of grain to produce a pound of meat, and around three to four pounds of grain to produce a pound of cheese or eggs, experts told AFP。

"More people, more money, more consumption, but the same planet," Clay told AFP, urging scientists and governments to start making changes now to how food is produced。

Population experts, meanwhile, called for more funding for family planning programs to help control the growth in the number of humans, especially in developing nations。

"For 20 years, there's been very little investment in family planning, but there's a return of interest now, partly because of the environmental factors like global warming and food prices," said Bongaarts。

"We want to minimize population growth, and the only viable way to do that is through more effective family planning," said Casterline。上周日，研究人员在一个大型美国科学会议上警告说，随着地球人口越来越多，越来越富，人们对匮乏资源的争夺可能会导致地球到2050年变得“面目全非”。

联合国预测，全球人口今年将达到70亿，到2050年将达到90亿。非营利性组织人口理事会的约翰•邦戈兹说：“世界人口的增长基本都发生在贫穷国家，尤其是非洲和南亚地区的国家。”

在美国科学促进会的年度会议上，世界自然基金会的詹森•克莱说，要养活这些人，“未来40年内，我们需要生产出过去8000年产出粮食的总和”。

克莱说，如果人口还按目前的趋势增长，那么“到2050年我们的星球将会面目全非”。

俄亥俄州立大学的人口研究项目主任约翰•卡斯特林说，人口激增将会加剧资源损耗等问题。

不过，在未来40年人们的收入也会增长——全球人口平均收入会是现在的3倍，而发展中国家收入会达到现在的5倍——这会给全球食物供应增加压力。

专家们说，收入增长之后，人们会吃更多食物链上层的东西，会比他们赚钱少的时候消耗更多肉类。

专家们对法新社表示，生产1磅肉需要约7磅(合3.4公斤)谷物，生产1磅奶酪或者鸡蛋需要3到4磅谷物。

克莱对法新社说：“我们会有更多的人口，更多的钱，消耗的也更多，但是我们只有一个地球。”克莱认为科学家和政府应该尽快开始研究转变生产食物的方法。

同时，人口专家呼吁为生育控制项目提供更多资金，以控制人口数量的增长，特别是发展中国家的人口数量增长。

邦戈兹说：“20年来，尽管我们对生育控制的投资微乎其微，但是我们也收到了一些投资回报。这种回报从一定程度上是由于全球变暖和食物价格飞涨等环境因素迫使的。”

他接着说：“要想减少人口增长，唯一可行的方法就是借助更有效的生育控制项目。”