The United Nations has released population data confirming the continuation of long-term global demographic trends and a larger global population than previously projected. Nations cannot afford to ignore trends including reduced fertility among most nations and limited family planning for others, and growing ranks of the elderly and accelerated urbanization pose new challenges.
The world population is larger. Global population achieved a milestone in 2011, hitting the 7 billion mark. Currently at 7.2 billion, the world is projected to increase by almost another billion people, climbing to 8.1 billion by 2025.
The population is older. Countries continue to age substantially, with those aged 60 or older the fastest growing segment. In developed countries, almost one in four is an older person, with more older people than children. Fertility is lower and family size smaller. The decline in population growth at the world level is the consequence of near universal reduction of fertility. Women are marrying later or not at all, postponing childbearing and having fewer or no children,and fertility has fallen to 2.5 children per woman. People are also living longer. Life expectancy is higher in most countries due to systematic progress against mortality. One can expect to live to age 77 in developed countries and to age67 in developing countries.
The world is more urbanized. More than half of the world‘s population consists of urban dwellers, and this is expected to climb to two-thirds by mid-century. International migration is increasing in both volume and impact.Although the increase in the number of migrants has faltered in the aftermath of the global economic recession, more people than ever reside in a country other than where they were born. There are 232 million international migrants, 3 percent of world population.
Most of the planet‘s people will live in cities. Virtually all expected population growth will be concentrated in the urban areas of poor countries increasing the threat of pollution and epidemic. By 2050, the number of people living in cities will almost be equal to today‘s world population. In 1950, only two cities in the world had at least 10 million inhabitants. Today, 23 megacities have more than 10 million inhabitants; by 2025, the number of megacities is projected to reach 37.
联合国公布的人口数据证实， 全球人口的长期趋势仍呈持续增长态势， 全球人口数量要大于此前的预测值。各国已承担不起无视发展趋势造成的后果。 这些趋势包括： 大多数国家生育率下降， 而另一些国家在推行计划生育政策方面的力度有限， 老龄人口的持续增加和城市化进程的加速构成新的挑战。
世界人口在增加。 全球人口 2011 年达到 70 亿的标志值， 具有里程碑意义。 全球人口目前已达 72 亿。 到 2025年， 世界人口预计还将增加 10 亿， 达到 81 亿。
人口在老龄化。 各国老龄化幅度仍很高， 60 岁及以上者是增长速度最快的群体。 在发达国家， 差不多每 4个人中就有 1 个老年人， 老年人数量已超过儿童数量。 生育率更低。 家庭规模在缩小。 从世界范围看， 导致人口增量下滑的原因是， 生育率几乎普遍在下降。 女性晚婚， 或者根本不结婚， 晚育， 少育， 或不生育。 生育率已降至每名女性生育 2.5 个孩子。 人们也更长寿。 大多数国家的预期寿命更高， 因为在应对死亡率方面取得了系统性的进展。 发达国家和发展中国家的预期寿命分别可达 77 岁和 67 岁。
当今世界的城市化程度更高了。 城市居民占世界人口一半以上。 预计到本世纪中叶， 城市居民所占世界人口比例将增加 2/3。 国际移民的数量和影响都在持续增加。 虽然全球经济衰退导致移民数量下降， 但在非出生地定居的人数超过了以往任何时候。 国际移民数量目前为 2.32 亿， 占世界人口的 3%。
地球上的大多数人都将生活在城市里。 几乎所有预测新增人口都将集中在穷国的城市地区， 这将增加环境污染和传染病流行的风险。 到 2050 年， 城市人口数量几乎等同于当今世界人口的数量。 1950 年， 世界只有两个城市的居民数量达到 1000 万。 而今已有 23 个特大城市的人口数量超过 1000 万； 到 2025 年， 特大城市数量预计会达到 37 个。