Environmental Baggage: Impact of fewer people on the planet

He was inspired by a terrorist in Christchurch, New Zealand, who five months earlier had killed 51 Muslim worshippers in attacks on two mosques and identified as an “eco-fascist.” Neither the fears nor the actions of the two men are grounded in science.

Fertility is falling, people are aging, and by the end of the century humans will be shrinking in number on almost every country on Earth, according to a recent study published in the journal Lancet. Far from an overpopulation crisis, demographers are asking where the next generations of young people will come from. The study from the Institute for Health Metrics and Evaluation (IHME) projects the number of people on the planet will peak just four decades from now, at 9.7 billion, before falling to 8.8 billion by the end of the century.

In 80 years, countries like Spain and Japan would halve in size. China would shrink by almost as much, leaving India and Nigeria as the world’s biggest countries. Only in 12 countries, including Somalia and South Sudan, would there be enough babies to keep populations stable. The rest would be aging.

And if the world meets targets for universal education and contraception — the positive driving force behind falling fertility — there would be 1.5 billion people fewer in 2100 than there are today. That demographic shift would transform societies. Who would pay for elderly health care? Would countries fight over young migrants? When, if at all, would people get to retire? It also raises a question that has dogged the environmental movement for decades and is being increasingly weaponised by the far-right: Shouldn’t fewer people be good news for the planet?

Unequal emissions

Overpopulation is a convenient idea. To some, it means their consumption isn’t what’s damaging the planet, but rather the sheer mass of people — so there’s little point in changing their behavior.

The IHME study says fewer people on the planet would mean lower carbon emissions, less stress on global food systems and less chance of “transgressing planetary boundaries.” But the problem, scientists say, is that people do not emit equally. “It’s this superficial analysis,” said Arvind Ravikumar, assistant professor of energy engineering at Harrisburg University of Science and Technology.

Population growth has increased greenhouse gas emissions, according to the IPCC, the UN panel of climate science experts, but it is dwarfed by the rise in emissions per person, which is tied to income. People in the richest countries emit 50 times more than those in the poorest — and it is in these low-income, low-emitting countries where human numbers are growing fastest.

“Sometimes people try to use population as a way to let rich countries off the hook,” said Zeke Hausfather, a climate scientist at the Breakthrough Institute in California, “whereas in reality, it’s our consumption and our level of economic activity that drives emissions more than the number of people we have.” A world with lots of people running on clean energy could have lower emissions than one with few people powered by fossil fuels. Big, fast-growing countries like China and India are building cheap solar panels and wind turbines that could bring their total emissions down even as incomes and populations rise. But developers across Africa and other parts of Asia are struggling to secure loans for green infrastructure. Rich countries have so far failed to deliver on a $100 billion-a-year promise they made under the Paris Agreement to help poorer countries fight climate change.

“We cannot tell these countries that, okay, we already have a lot of greenhouse gases, you should stop using energy,” said Leiwen Jiang, a senior associate at the Population Council in New York and former IPCC lead author. “But we can help them improve their technology.” While lower-than-expected fertility rates may do little to cut emissions in poor countries, they could help them cope with climate change in a different way. If women had only as many children as they wanted, they would be able to take on more paid work, said Jiang. That economic boost could help cash-strapped communities respond to the increasingly severe heat waves, floods and storms that climate change has brought.