【导读】最新一期美国《科学》杂志就全球人口问题刊登多篇文章。其中一篇文章预测说，世界人口今年10月底将达70亿，而2050年，全球人口将达93亿。
最新一期美国《科学》杂志就全球人口问题刊登多篇文章。其中一篇文章预测说，世界人口今年10月底将达70亿，而2050年，全球人口将达93亿。
这期《科学》杂志涉及人口的文章专题包括“90亿人口？”、“更多的人口一定是个麻烦么？”、“70亿人口和统计”等，涵盖了人口增长的历史、未来、机会等方方面面内容。
哈佛大学经济学家戴维布卢姆分析联合国数据后指出，全球人口1800年达到10亿，1925年达到20亿。过去半个世纪，全球人口由30亿激增至近70亿。预计第70亿个人可能于今年10月底出生。而2050年，全球人口将达到93亿，其中97%的增长将出现在发展中国家。
布卢姆说，医疗进步、疫苗效能提高、抗生素使用和公共卫生状况的改善提高了发展中国家人口的预期寿命。因此，未来人口增长大部分将出现在发展中国家。
他认为，只要政策干预适当，人口大幅增长不会带来经济灾难，而人口年龄结构的合理变化还可能促进经济发展。
联合国数据显示，到2050年，印度将是全球人口最多的国家，而美国届时将成为10个人口最多国家中唯一的发达国家。
In 2011, global population is expected to hit 7 billion.
生物探索推荐英文原文报道
World Population to Surpass 7 Billion in 2011; Explosive Population Growth Means Challenges for Developing Nations
Global population is expected to hit 7 billion later this year, up from 6 billion in 1999. Between now and 2050, an estimated 2.3 billion more people will be added -- nearly as many as inhabited the planet as recently as 1950. New estimates from the Population Division of the Department of Economic and Social Affairs of the United Nations also project that the population will reach 10.1 billion in 2100.
These sizable increases represent an unprecedented global demographic upheaval, according to David Bloom, Clarence James Gamble Professor of Economics and Demography at the Harvard School of Public Health, in a review article published July 29, 2011 in Science.
Over the next forty years, nearly all (97%) of the 2.3 billion projected increase will be in the less developed regions, with nearly half (49%) in Africa. By contrast, the populations of more developed countries will remain flat, but will age, with fewer working-age adults to support retirees living on social pensions.
"Although the issues immediately confronting developing countries are different from those facing the rich countries, in a globalized world demographic challenges anywhere are demographic challenges everywhere," said Bloom.
The world's population has grown slowly for most of human history. It took until 1800 for the population to hit 1 billion. However, in the past half-century, population jumped from 3 to 7 million. In 2011, approximately 135 million people will be born and 57 million will die, a net increase of 78 million people.
Considerable uncertainty about these projections remains, Bloom writes. Depending on whether the number of births per woman continues to decline, the ranges for 2050 vary from 8.1 to 10.6 billion, and the 2100 projections vary from 6.2 to 15.8 billion.
Population trends indicate a shift in the "demographic center of gravity" from more to less developed regions, Bloom writes. Already strained, many developing countries will likely face tremendous difficulties in supplying food, water, housing, and energy to their growing populations, with repercussions for health, security, and economic growth.
"The demographic picture is indeed complex, and poses some formidable challenges," Bloom said. "Those challenges are not insurmountable, but we cannot deal with them by sticking our heads in the sand. We have to tackle some tough issues ranging from the unmet need for contraception among hundreds of millions of women and the huge knowledge-action gaps we see in the area of child survival, to the reform of retirement policy and the development of global immigration policy. It's just plain irresponsible to sit by idly while humankind experiences full force the perils of demographic change."
