As fertility declines across the globe, the U.S.' keeps growing due to immigration gains

A report from the United Nations reveals that global fertility rates are dropping faster than expected, potentially leading to a population decline before the end of the century. The United States, however is one of 50 places projected to be able to keep growing and there's one main reason behind that: immigration.

According to an analysis by NBC News, were it not for immigration, the United States would also be facing population declines. Instead, it is projected to grow from 345 million people in 2024 to 421 million by the end of the century.

The country's growth, the authors' say, will likely exacerbate climate-related issues around consumption, greenhouse gas emissions and other drivers of global warming, meaning a larger population will be exposed to climate risks, such as droughts, heat waves and other extreme weather events.

As Dean Spears, an associate professor of economics at the University of Texas at Austin, explained to NBC News:

"Just because a challenge might be emerging six decades into the future doesn't mean it doesn't make sense to be talking about now. Decades from now, people will be talking about these new population changes, with the same level of scholarly and social interest that we now talk about climate change."

Elsewhere, the study revealed than 60 countries and territories, including Italy, Japan, Russia, and China, have already reached their population peak, meaning that one in four people live in a country with a declining population.

The global fertility rate is currently 2.25 births per woman, a significant drop from 3.25 in 1990, resulting in significant social and economic implications worldwide which affect consumption, energy use, industrial production, resource availability, and the pace of climate change.

Despite this decline, the world's population is projected to increase from 8.2 billion in 2024 to a peak of nearly 10.3 billion over the next 50 to 60 years. However, it is expected to decrease to 10.2 billion by 2100, which is 6% lower than previous U.N. projections.

Besides the U.S., other countries expected to continue growing through 2054 include India, Indonesia, Pakistan, and Nigeria. In some African regions, such as Angola, the Central African Republic, the Democratic Republic of Congo, Niger, and Somalia, populations are expected to double between 2024 and 2054.

The report also highlights a rebound in global life expectancy, which rose to 73.2 years in 2023 from a pandemic low of 70.9 years in 2021. By 2100, global life expectancy is projected to reach 81.7 years. As life expectancies increase and fertility rates decline, the global population will age, with those 65 and older projected to outnumber children younger than 18 by 2080.