Talk to people who care about the environment and you’ll hear plenty about pollution, deforestation, sustainability and climate change. What you won’t hear is the word “population,” unless it refers to populations of endangered species.
But if you think about it, the Earth’s booming human population is at the root of just about every environmental crisis that threatens the natural world. Last October 31, Earth’s population reached 7 billion people (unofficially, because there’s no way to pinpoint the actual day, but it was in the ballpark). Every last one of them taps into the planet’s resources as they eat, work and create waste in a myriad of different forms. By 2027 we’ll be up to 8 billion, and the U.N. predicts we’ll hit 9 billion in 2047.
Even now, however, the pressure on Earth’s resources is already extreme, and more people will only make it worse. Deforestation and other forms of habitat destruction, for example, are mostly the result of all those billions of people clearing land for places to live and grow food. Destroy natural habitats and you throw ecosystems out of whack, to say nothing of wiping species off the planet at such an alarming rate that scientists believe we may be seeing Earth’s sixth mass extinction (the previous five were caused by things like asteroid impacts or gigantic volcanic eruptions). All those billions of people burning wood and coal and oil, for heating, transportation, electricity and manufacturing, moreover, generate air pollution, including heat-trapping greenhouse gases.
Most of us never stop to think about the flip side of that equation, however: if the world had significantly fewer people, all of these strains on the planet would be much less. Two thousand years ago, the world’s population stood at about 300 million people, according to the U.N., and by 500 years ago, that number had climbed to half a billion, or one fourteenth of today’s population.
What if it had just stayed there? Would our current environmental problems be slashed by a factor of 14? Well, OK, probably not. Back in 1500, even the richest people had a standard of living far below what people in the U.S. have now: they had no electricity, no motorized transportation, a monotonous and not very nutritious diet. As a result, their impact on the planet was far less than what a half-billion people living at modern U.S. standards would be — and even so, the impact of pre-industrial civilization was hardly zero.