The doubling of the human population over the last 60 years is not the main cause of climate change. Instead, climate change is caused by overconsumption by the wealthiest in society and our inability to switch from fossil fuels to renewable energy.

From 1960 to 2020, the global population grew from 3 billion to 7.8 billion. The good news is that our population is increasing at a slower and slower rate every year. The United Nations predict that our population could be between 9.4 and 10.1 billion people by 2050 and will stabilise below that number by 2100. But that is still another 1.5 or 2 billion people.

The reason for this massive increase in population is the demographic transition. In pre-transitional societies high mortality rates are offset by high fertility rates, and population levels remain relatively constant. Basically, couples have as many children as they can to ensure that at least two survive to adulthood. With the stabilisation of food availability, increased sanitation and availability of treatment for common diseases, mortality rates drop rapidly but in many cases fertility rates stay high. Hence, a lot of babies are born and nearly all of them make it to adulthood and hence the population expands rapidly.

The rapid spread of vaccinations and the green revolution in the 1960s meant that at its peak, global population was growing at over two per cent per year. Global fertility in 1950 was an average of 5.0 live births per woman – it is now below 2.6. The rate at which this fertility rate falls, directly affects the final population size. In European countries, final population size at the end of the transition was roughly four times greater than pre-transition levels. In many other countries the final population size could be many times higher. Many people assume that access to family planning and contraception are key to reducing fertility. However, the first demographic transition started in Europe in the 19th century when these services were not available. It is women’s education up to and beyond secondary school level that is the critical control on fertility.

The emotive debate around population growth has given rise to some myths. The first is that we cannot produce enough food for everyone. The evidence presented is that there are 821 million people today on the brink of starvation. In fact, according to the World Food Programme, we produce enough food to feed ten billion people – easily enough to cover the predicted increase in population this century – so why are there starving people? It comes down to a lack of access to food, which is all about money. If you have money then you can always buy food. But when the very poor lose their livelihoods through civil unrest, war or crop failures they have no resources to fall back on and have no money to buy food. In a world of plenty they cannot afford that which they need to survive.

The second myth is that stabilising population is a key solution to climate change – this is misleading and unhelpful. It makes a simplistic assumption that everyone is equally guilty of causing climate change. This is not true. If we take a look at the historic legacy of carbon pollution in the atmosphere, then 25 per cent of that extra carbon has come from the USA and another 22 per cent from the EU. In comparison, Africa has contributed less than five per cent. If we look at lifestyle greenhouse emissions then the richest 10 per cent of the world’s population emit 50 per cent of its pollution, while the richest 50 per cent of the world’s population emit 90 per cent of its pollution. Massive overconsumption by the wealthy in each country is causing climate change, not how many poor people there are in the world.

Stabilisation of the world’s population using socially and economically just approaches is important for many reasons including increased food, water, resources and environmental security as well as improved healthcare and economic development.

While women’s education and universal access to family planning around the world would undoubtedly bring major benefits, they are not a global panacea to the problems of climate change. The role of urbanisation, ageing and consumption patterns are much more important than total numbers of people when trying to understand and control greenhouse gas emissions. We cannot use population as a way to blame the poor people of the world for climate change.

We can, however, imagine a world with ten billion people, all with access to clean, safe, cheap energy, food and water. Instead of focusing on a mythical smaller global population we should focus on achieving a stable global population supported by a fair and sustainable economy that reduces our burden on the planet.