The end of the great population boom is in sight. By the time the world added its 8 billionth person on Nov. 15, the UN was already able to predict (pdf) that the global population will peak around 2080, at 10.4 billion. From there, the number declines. The human race shrinks.
But where the next 2.4 billion people will be added still matters a lot, particularly in a world that is expected to grow warmer over these coming decades. Among developing countries, the nine countries with the biggest populations in 2100 will be: India, China, Nigeria, Pakistan, the Democratic Republic of Congo, Ethiopia, Tanzania, Indonesia, and Egypt.
Even as early as 2070, though, eight of these nine countries will have many “hot zones”—areas where mean annual temperatures are above 29° C (84.2° F). Daily life without cooling technology will become extremely difficult, access to water will be scarce, and disruptions to agriculture will be severe.
In these circumstances, migration will become inevitable, with millions of people leaving their overheated villages and cities in search of a kinder climate. (By 2050, according to one estimate from the Institute for Economics and Peace, there could be 1.2 billion climate refugees.) Just as inevitably much of this migration will run northwards—from South and Central America to northern North America, for instance, or from Africa and the Middle East towards Europe.
This can, in one sense, be a gift-wrapped solution for the wealthier countries of the north, where the populations will have grown older, and where governments will be rapidly running out of workers to tax. Migrants can fill out the thinning ranks of the labor force—as long as the political will to accept them exists.
Immigration policies will, as a result, creep closer and closer to the center of all political conversation in the developed world. In the near term, any moves to encourage immigation will be unpopular, said Manoj Pradhan, who founded Talking Head Macroeconomics, a research firm in London. The kind of nativism found in Donald Trump’s America, or in the Brexit referendum, or in other swings to the right in Europe, are ready examples of anti-immigrant sentiment.
“So we will definitely feel the ill-effects of this first,” Pradhan said. “But even if politics is a little unstable for the near future, I have no doubt that, in the long term, people will begin to see immigration as the great benefit it can be.”