During the past few years, the size of the world’s population has become a matter of public debate in a way not seen since the 1970s. The total number of people, 6.7 billion now, is forecast to surpass 9 billion by 2050. Many observers fear that an environment degraded by climate change will not be able to support so many. Half the British population, according to one opinion poll, think people should not have more than two children. Yet at the same time governments in Japan, Germany and Russia have been trying to reverse those countries’ falling populations. When is a growing population a blessing and when is it a curse? Is there a best size for the population of the world, or of any particular country? Should governments introduce population-control policies, whether voluntary or mandatory? And how important to demographic matters is climate change?
