Older

Fifty years ago, in 1976, the median age of the global population was just under 21 years. That means of the 4.1 billion people on Earth at the time, about half were younger than 21 and half were older. Today the median age is 31, and by 2050 the United Nations projects it will reach 36. The typical human being is steadily getting older.

What is the replacement rate?

The engine of that change is fertility. Demographers measure it using the total fertility rate, the average number of children a woman would have over her lifetime at current birth rates. The figure that matters most is the replacement rate, generally put at about 2.1 births per woman. That is the level at which a generation exactly replaces itself, keeping the population stable over the long run without immigration. The slight margin above two accounts for children who do not survive to adulthood.

The global fertility rate today is about 2.2, barely above replacement and down from approximately five in the 1960s. The United Nations expects it to reach the replacement level around the middle of this century and to keep falling after that. More than half of all countries are already below replacement, including China, the United States, India, Japan and most of Europe.

In practical terms, a fertility rate below replacement means that, over time, each generation is smaller than the one before it. Fewer babies today means fewer working-age adults tomorrow, and a growing share of retirees supported by a shrinking workforce. That is the pressure now facing pension systems, health services and labour markets from Italy to South Korea. It is why population ageing, more than raw numbers, is becoming the defining demographic story of the century.

President Trump on Thursday announced that grocery stories and air conditioning companies will be allowed to keep using high-polluting refrigerants for longer than they would have under a law he signed during his first administration.

“This was a tremendous burden, a tremendous cost,” said Trump, surrounded in the Oval Office by executives from supermarket chains including Kroger, Fairway, Neimann Foods and Piggly Wiggly. “It was making the equipment unaffordable, and the actual benefit was nothing.”

The move loosens rules meant to restrict hydroflourocarbons, a class of climate-damaging chemicals used in cooling equipment. HFCs are known as “super pollutants” because their impact on climate change can be tens of thousands of times greater than carbon dioxide during their shorter lifespans.

In the move Thursday, the Environmental Protection Agency extends the deadline for companies to comply with a 2023 rule transitioning refrigerators and air conditioners off HFCs and onto new cooling technologies. Reducing these chemicals and moving to cleaner refrigerants has long been a bipartisan issue.

Trump is also proposing exemptions from a rule requiring leak repairs on large-scale refrigeration systems.

The administration framed the changes as part of its effort to bring down high grocery costs. EPA administrator Lee Zeldin said the actions will save $2.4 billion for Americans and safeguard 350,000 jobs.

“Americans who wanted to be able to fix their equipment were instead being required to buy far more costly new equipment and that just doesn’t make any sense,” said Zeldin.

David Doniger, senior attorney at the Natural Resources Defense Council, said the move will not only harm the climate, but U.S. competitiveness in global refrigerant markets as well.

“The EPA is catering to a small group of straggling companies by derailing the shift away from these climate super-pollutants,” he said. “The industry at large supports the HFC phasedown and has already invested in making new refrigerants and equipment, currently installed in thousands of stores.”

Danielle Wright, executive director of the North American Sustainable Refrigeration Council, an environmental nonprofit, said any perceived near-term savings from the rollbacks will be outweighed by the future costs.

“Business owners are far more worried about the escalating cost of keeping aging, high‑global-warming-potential equipment running than they are about the cost of installing new, compliant systems,” she said.

Trump dismissed the climate concerns, saying his changes “are not going to have any impact on the environment.”

He said he wants to get rid of the technology transition rule entirely in the future.