Demystifying science | What is the link between population and climate?

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Have our GHG reduction objectives taken into account the exponential increase in population?
—Richard Champagne

Yes, but some demographers believe that the projections underestimate the future population of the planet.

The more people there are, the more greenhouse gas (GHG) emissions there are, says Marian Starkey, vice president of Population Connection, a Washington NGO whose mission is to prevent overpopulation of Earth. “So the thing to do, both in terms of the wealth of countries and the fight against climate change, is to ensure that the world population stops growing,” explains M^me Starkey.

Population Connection is convinced that demographic forecasts overestimate the fall in fertility in African countries in the decades to come. “The IPCC projections [Groupe d’experts intergouvernemental sur l’évolution du climat de l’ONU] are based on these demographic predictions, says M^me Starkey. But if they underestimate the future population, that’s a problem. »

M^me Starkey cites in particular a recent study by Jane O’Sullivan, an agronomist at the University of Queensland in Australia, whose work on developing countries has led to a crusade against overpopulation and speeches deploring the aging of the population. Published last fall in the journal worldthe study notes that in several war-affected countries, including Sudan, the Democratic Republic of Congo, Afghanistan and Mali, fertility is increasing rather than decreasing.

“We are betting on a reduction in fertility in Africa, but everything depends on the education of women and access to family planning programs,” says M.^me Starkey. And with global assaults on reproductive freedom, for example in the United States, the outlook is not encouraging. »

Among the main population projections, those of the UN are often the highest. They predict a peak in the world population of over 10 billion (compared to 8.1 billion currently) towards the end of the century. Last winter, demographers at the University of Washington funded by the Gates Foundation predicted a peak of 9.7 billion in 2064. “The authors speak of a collapse in fertility, but 1.6 billion people Plus, it’s not really a collapse,” says M^me Starkey.

Population Connection was founded 50 years ago, when the world’s population was experiencing an unprecedented increase.

Worrying, the fall in fertility?

Conversely, some economists argue that the fall in fertility, not only in rich countries, but also in emerging countries like China, will undermine the fight against climate change. “In all living species, the survival of the species is linked to the ability to reproduce,” explains Michael Platt, a neuroeconomist at the University of Pennsylvania who has just published, in Nature Mental Healthan essay sounding the alarm about falling fertility.

“I think the fertility crisis is linked to a sense of despair in the face of growing economic inequality, which will diminish humanity’s drive for survival,” says Mr. Platt. Without this desire to survive, how will we have the energy and imagination to find the answers to climate change? »

To this analysis, many respond that the salvation of the Earth requires economic decline. M^me Starkey qualifies this avenue: “Historically, countries have become richer by having fewer children,” she says. It is now said that countries whose populations are stagnating are in danger economically, but this remains to be demonstrated. We think it will instead lead to an increase in productivity. And there is always immigration to increase the population. »

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