Can the world support ten billion people? Since the industrial revolution, the number of humans has increased exponentially: in 1800, one billion people lived on our planet, then it took 127 years for the Earth’s population to double. Since then, however, doubling has taken place at ever shorter intervals and there are now almost 8 billion people. Experts estimate that there will be between 10 and 12 billion by the year 2100. Can population growth go on forever?
How do we feed 12 billion people (without resorting to Soylent Green)? Our rapidly growing world population presents us with a problem, because more people means greater resource consumption. We are already using up non-renewable raw materials at an alarming rate, and the burning of fossil fuels is driving us towards catastrophic climate change.
Not all people consume equally. If everybody in the world consumed as much as Europeans, we would need 2.8 planets worth of resources to sustain us. If we all lived like Americans, we would need almost 5 planets. How many people can the Earth support sustainably?
What do our readers think? We had a comment sent in from Boris arguing that our planet simply cannot support a global population of more than 7 billion people. Is that true?
We put Boris’ question to population research expert Dr Joel Cohen, Professor of Earth and Environmental Sciences at Columbia University. In his 1996 book “How Many People Can the Earth Support?” he investigated what factors influence the capacity of the Earth to support humans. So, how many people does he think the Earth can support?
Nobody knows. I wrote a 550-page book called ‘How Many People Can the Earth Support?’. I have reviewed estimates ranging from less than 1 billion to more than a trillion, or 1,000 billion people. The reason people give such different answers is because people make different assumptions about how people live.
Are they starving, or living in poverty or great wealth? By what means do they have to make a living? Will we have horse-drawn ploughs or will we have tractors? Will we have solar energy or energy from fossil fuels? Will we resolve our conflicts by killing each other or will we resolve our conflicts through diplomacy, mediation and peaceful means? All these questions and many more need to be answered and are usually assumed before a number is given. Therefore, I cannot answer your question. I am very sorry, but if someone tells you ‘I know the answer’, then that person is not thinking deeply.
For another perspective, we also put Boris’ comment to Robin Maynard, Director of Population Matters, which advocates for ethical and free will-based ways to slow and prevent population growth. What does he think?
That’s a good question, Boris. It’s also fantastic to hear that more and more young people are asking this question, because it is your future that this pressure will really affect. The truth is that, in terms of a fair and just world, we cannot currently feed humanity fairly with a population of 7.8 billion people. In Europe we live very well, but if everyone wanted to live like we do, we would need three Earths. And we don’t have three Earths.
So, you are right to ask the question: ‘How many people can the Earth support?’. There’s a whole range of factors there, but of course we at Population Matters want the population to decline in a controlled, free and unconstrained way, which is quite possible. Because that will make life better for future generations of humans, for the other species we share the planet with, and of course for our one living Earth.
Next up, we had a comment from Tamzin pointing out that it’s not just a question of feeding ten billion people, but also the “tons of rubbish” that a growing population produces. On the other hand, could a circular economy support a larger population? How would Robin Maynard of Population Matters respond?
Well, Tamzin, we don’t just talk about human populations at Population Matters. We talk about populations of things. So, for example: consumer waste. I think people have woken up to waste. It’s not just ‘out of sight, out of mind’, and we really need to get to a circular economy. There is a lot of good work being done. When I was your age, Tamzin, people didn’t recycle at all; we just threw everything away. It’s encouraging to see that across generations recycling is now something that everyone does. But we still have a long way to go.
Of course, it’s not just about the visible waste. It is the pollutants in the form of gases, especially climate gases, and pesticide residues in our soils that are still there after 50 years. So we have some real problems to deal with and I can only hope that the technological part of the equation will enable us to deal with that, but we still need to use less stuff. I think that’s the hardest part. For us in the West, with a high standard of living, we have to consume less and waste less and allow others in the developing world to consume a bit more but still waste less to balance things out.
What does population researcher Dr Joel Cohen think? What are his thoughts on the possibilities of a circular economy to support a growing population and reduce the amount of waste produced?
There is nothing on this Earth that can be thrown away. We cannot throw anything away except our time and our lives. Every physical object only changes its form and Tamzin is right that we must consider everything we use as something we will reuse. In every breath you and I breathe are molecules that the Roman emperors breathed. You can work out that in my breath now there is a certain number of molecules that Julius Caesar breathed, because in every breath there are a lot of molecules. So, yes, a circular economy is the future. But we need to see this future in a wider context.
In 1900, people were very worried that there would be no population growth in New York City because the horses would produce so much manure that the city would be knee-deep in horse manure if the population of New York continued to grow, and more people brought more horses. That didn’t happen because something changed. Transportation switched to cars, which don’t produce horse manure. Instead, they produce invisible manure – carbon dioxide – from burning fossil fuels, and now we are up to our necks in carbon in our atmosphere from cars and other sources. We need to learn that there is no way to throw this manure away.
We need renewable energy and recyclable materials of all kinds. A circular economy is the way of the future. But it will take a lot of ingenuity, hard work and a lot of vision to get there, because we have not been trained to think in terms of a circular economy.
How many people can the Earth support? Are our resources too scarce to feed a growing world population? Can a circular economy lead to better resource use? Do we need to slow down population growth? What do you think? Write to us!