人口超载已经成为北京的重大现实难题。环境人口承载力是指在一定生活水平和环境质量要求下,在不超出生态系统弹性限度条件下,环境系统所可能支撑的人口数量。一个区域环境人口承载力取决于这个区域环境系统的瓶颈因素。北京位于全国严重缺水地区,按照联合国标准,属于极度缺水 Population overload has become a major real problem in Beijing. Environmental population carrying capacity refers to the amount of population that an environmental system may support under certain living standards and environmental quality without exceeding the limits of ecosystem resilience. The carrying capacity of a regional environment depends on the bottleneck of the environmental system in the region. Beijing is located in a serious water-scarce area in the country. According to the United Nations standards, Beijing is extremely short of water