The implications of persistent population growth
In 2011 the human population reached 7 billion. This statistic might have surprised the economist Thomas Malthus, who at the turn of the 19th century made some gloomy predictions about population growth.
He believed that overpopulation would soon lead to war and famine, as demand for food outstripped supply. In ecological terms, we would have exceeded our carrying capacity – the maximum population that our environment and all of its resources can support.
Malthus was writing from the perspective of a man living in a world of 1bn and didn’t foresee the advances in farming technology that would enable the planet to support many more people. However, by no means are all 7bn well fed. Around one in eight people suffer from chronic hunger, mostly in low- and middle-income countries, which are also predicted to see some of the biggest population increases over the coming decades. Population growth is slowing, but it is likely there will be more than 10bn of us by 2050.
The enduring growth of the human population is often referred to as the ‘population explosion’. But other species undergo shorter-lived booms, with dramatic effects. In the USA a sudden explosion in the grasshopper population can destroy millions of hectares of grazing land.
Scientists are trying to work out what causes grasshopper numbers to increase so suddenly, in order to predict when a plague might occur. The answer may lie in not one but a combination of factors, including the availability of the plants the insects use for food, and the ability of predators like birds and spiders to keep the insects’ eggs under control.Lead image:
Wellcome Library, London CC BY