What is the cause of overpopulation

Fewer people on earth - how does that affect the climate?

A little over a year ago, a white racist shot dead 22 people in El Paso, Texas. Most of the murdered people were of Hispanic American origin. Shortly before the act, he wrote in his online manifest: "If we get rid of enough people, our lives could become more sustainable." The man was inspired by the terrorist in Christchurch, New Zealand, who five months earlier had killed 51 Muslim believers in attacks on two mosques and who described himself as an "eco-fascist" in his manifesto.

However, the fears and actions of the two men contradict scientific evidence on overpopulation and climate change.

According to demographers, overpopulation is not the problem at all when it comes to climate change. The question is rather where the next generations of young people should come from. Fertility is falling, people are getting older, and by the end of the century the number of people will fall in almost every country in the world, according to a study published in July by The Lancet.

The Institute for Health Metrics and Evaluation (IHME), which published the study, assumes that the number of people on earth will peak at 9.7 billion in just four decades. It will decrease to 8.8 billion by the end of the century.

By 2050, 151 countries will have an aging population

China's population is likely to decline by 48 percent in 80 years

In 80 years the population in countries like Spain and Japan would halve. It would be similar in China. This would make India and Nigeria the largest countries in the world. Only in twelve countries, including Somalia and South Sudan, would there be enough births to keep the population stable.

And if the world meets the United Nations' goals for universal education and contraception, there would be 1.5 billion fewer people in just 80 years than there are today.

This demographic change would change society significantly. Who will pay for the pension? Will countries fight for young immigrants in the future? When, if at all, will people be able to retire?

This raises a question that the environmental movement has pursued for decades - and right-wing extremists use it as a justification:

Are fewer people good for our planet?

Unequal emissions

That overpopulation is the cause of environmental degradation seems like a convenient explanation. It is not the consumption that harms the planet, but the sheer mass of people - a change in behavior would make no sense.

According to the IHME study, a smaller world population also means fewer emissions. Fewer people would defuse the world food problem. And there would be less danger of "crossing the planet's boundaries."

But the problem, according to the scientists, is that people don't produce greenhouse gases straight away.

"This is an extremely superficial analysis," says Arvind Ravikumar, assistant professor of power engineering at Harrisburg University of Science and Technology.

Countries with the highest birth rates are the least responsible for climate change

Climate change is responsible for extreme weather events

It is correct: According to the IPCC, the UN expert body on climate science, population growth has increased global greenhouse gas emissions. But rising incomes have a much stronger impact on the rise in per capita emissions.

The richest countries have 50 times more emissions than the poorest countries. However, it is precisely in these countries with low incomes and low emissions that the number of people is growing fastest.

"Sometimes people use the population argument to relieve rich countries," says Zeke Hausfather, climate scientist at the Breakthrough Institute in California. "In reality, our consumption and our economy are the reasons for the increased emissions."

In a world with many people who use renewable energies, the CO2 emissions can be lower than in a world with few people and a large consumption of fossil fuels, so the argument of the institute.

Large and rapidly growing countries such as China and India can lower their emissions by building cheap solar and wind power plants - despite rising incomes and high populations.

But construction companies across Africa and some parts of Asia are struggling to get loans for climate-friendly infrastructure. So far, rich countries have not kept their promise, which is also anchored in the Paris Climate Agreement: to support poorer countries in combating climate change with 85 billion euros per year.

"We cannot tell these countries that there are already a lot of greenhouse gases and that they should stop using energy," says Leiwen Jiang. He is a senior fellow at the NGO Population Council in New York and was a former lead author of the IPCC. "But we can help them improve their technology."

Lower birth rates are less of a contribution to reducing emissions in poorer countries. Nevertheless, there are other ways in which they can help to better deal with climate change. If women have only as many children as they want, they could get paid jobs, says Jiang. This economic boom could help financially weak communities better respond to the increasing heat waves, floods and storms that climate change brings with it.

The education of girls is a key factor in falling birth rates

A dark past

The concept of overpopulation has a dark past.

Even if you accept that more people also produce more CO2, "what is the solution?" Asks Ravikumar.

"Is the solution to reduce the world population by force? And if so, whose population should be reduced?"

Like the terrorists in El Paso and Christchurch, many governments throughout history have trampled on the rights of marginalized groups. Countries like the United States and Canada forcibly sterilized indigenous women in the 20th century. Australia has done the same for people with disabilities. India sterilized a total of 6.2 million men in 1976, mostly from poorer backgrounds. The country was encouraged by foreign donors to keep the population under control. More than 2,000 men are believed to have died in botched operations.

From the late 1970s onwards, China limited population growth through fines, sterilization and forced abortions as part of a decades-long one-child policy. Such practices among Uighur women continue to this day, according to an investigation published by the Associated Press last month.

Falling birth rates can mean economic growth and help countries cope better with climate change.

Different population models

Globally, women have fewer children because more girls go to school and more people have access to contraception. Both are human rights goals.

But there are uncertainties in calculating global birth rates. Demographers disagree about how far and how quickly the global birth rate will fall.

The IHME predicts that the world population will shrink from 2064 onwards. The United Nations, on the other hand, says the population will continue to grow over the course of the century. The difference between the two models will be around 2 billion people by 2100. Both research groups accept the possibility of opposing developments because the forecasts are very uncertain.

One reason for the discrepancy: In contrast to the IHME, the UN assumes that birth rates will increase when countries get richer.

However, surveys show that women across Europe and North America have fewer children than they would like. The reason: There are too many hurdles, such as childcare that is too expensive, pressure at work and the fact that men do too little housework. But since Germany reduced some of these obstacles, the birth rate has risen again.

"The UN forecasts convey the optimism that human progress will always go on," says Sara Hertog. She is a demographer at the UN and adds that changing birth rates in themselves is neither good nor bad news. "I hope fertility levels reflect the number of children people want to have."

Adaptation: Sarah Mewes

An earlier version of this article stated that the obstacles for women in Germany have been removed, rather than downsized. This has now been corrected. The editors apologize for the mistake.

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