UNITED NATIONS - The world's population will likely reach 9.2 billion in 2050, with virtually（实质上,实际上） all new growth occurring in the developing world, a U.N. report said Tuesday.
According to the U.N. Population Division's 2006 estimate, the world's population will likely increase by 2.5 billion people over the next 43 years from the current 6.7 billion — a rise equivalent（相等的,相当的） to the number of people in the world in 1950.
Hania Zlotnik, the division's director, said an important change in the new population estimate is a decrease in expected deaths from AIDS because of the rising use of anti-retroviral drugs and a downward revision of the prevalence of the disease in some countries.
The new report estimates 32 million fewer deaths from AIDS during the 2005-2020 period in the 62 most affected countries, compared with the previous U.N. estimate in 2004.
This change contributed to the slightly higher world population estimate of 9.2 billion in 2050 than the 9.1 billion figure in the 2004 estimate, the report said.
The report also said most population growth will take place in less developed countries, whose numbers are projected to rise from 5.4 billion in 2007 to 7.9 billion in 2050. The populations of poor countries like Afghanistan, Burundi, Congo, Guinea-Bissau, Liberia, Niger, East Timor and Uganda are projected to at least triple（三倍的） by mid-century.
By contrast, the total population of richer countries is expected to remain largely unchanged at 1.2 billion. The report said the figure would be lower without expected migration of people from poorer countries, averaging 2.3 million annually（一年一次）.
According to the report, 46 countries are expected to lose population by mid-century, including Germany, Italy, Japan, South Korea and most of the former Soviet republics.
Zlotnik said most countries in Asia and Latin America have reached the "relatively beneficial stage" of having more working-age adults than children or elderly in their populations, "and they will remain in that stage for at least two more decades."
But their populations will then start to age, heading in the same direction as Europe and North America, she said.
"Europe is the only region at this moment where the number of people aged 60 and over has already surpassed the number of children," she said. "We expect that Asia and Latin America will have by 2050 an age distribution that is very similar to the one that Europe has today."
African countries will have an increase of working-age adults by 2050, but the continent's overall population will also nearly double in that time, Zlotnik said.
"So it is the continent that is going to have to absorb（吸收,吸引） a very high increase, and it will have to absorb it at levels of development that are the very lowest that we have in this world," she said.
中文：（并非全文翻译）
联合国预计，在未来43年内，世界60岁及以上的老年人口可能增加近两倍，到2050年达到20亿人，占全球总人口的约四分之一。
世界人口将增至92亿
联合国经济及社会事务部人口司在“世界人口展望”的2006年修订本中预测，未来43年世界人口将从现有的67亿增加至92亿，增加幅度超过三分之一。
该报告预测，世界人口会如所预料的在2050年超越90亿大关，不过，它指出，较发达地区的人口数量，不会出现太大的改变，但这些地区的人口却会急速老化。
该报告指出，世界人口的增长会来自较落后地区，年轻人也会集中于这些落后地区，特别是世界最贫穷的50个国家。目前，这些落后国家的人口还很年轻，在可预见的未来预料只会适度老化。其他发展中国家的人口，预料也会同发达国家一样，进入急速老化的阶段之中。
该报告指出，发达国家现有的生育率，不足以达到人口替代水平，这一趋势将持续下去，而落后国家的生育率也会下降，但仍比世界其他地区来得高。
整体而言，从2007年至2050年，发达国家人口将大致维持在12亿人的水平，但世界最落后的50个国家的人口却很可能增加超过一倍，从2007年的8000万增至2050年的17亿；其他发展中国家的人口增长速度将保持强劲但速度较慢，从46亿增加至62亿。
在个别国家方面，包括德国、意大利、日本、韩国、大部分的前苏联加盟共和国和好几个小岛国在内的46个国家，到2050年的人口预料将比现在少，但阿富汗、布隆迪、刚果、几内亚比绍、利比里亚、尼日尔、东帝汶和乌干达的人口未来40年内将增加两倍。
报告也发现，世界未来40年的25亿人口增幅当中，将近半数将来自印度、尼日利亚、巴基斯坦、刚果、埃塞俄比亚、美国、孟加拉和中国。
尽管移民壁垒重重，但预料穷国人民移居至富国情况将能缓解世界劳动力短缺问题。
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