Billionaire businessman Elon Musk has voiced his concerns about the global population decline, calling it one of the world's most pressing challenges.

Sharing a post on X, Musk highlighted a graph originally posted by the Tesla Owners Silicon Valley account.

The graph projected population changes between 2018 and 2100 for key nations, including India, Nigeria, the United States, Indonesia, and Pakistan, that underscored the looming demographic shifts.

The account posted: "Population collapse is humanity's greatest threat... Elon Musk."

Musk retweeted the statement and wrote: "Yes."

Experts have already recognised that the world is heading toward population decline, though there is an ongoing debate about the speed of this trend.

Some of the key factors contributing to population decline include declining fertility rates, emigration, and aging populations. In many nations, the average number of children per woman is below 2.1-the threshold required to sustain a stable population.

In 2023, the average number of children per woman in England and Wales dropped to 1.44, the lowest ever recorded, according to the Office for National Statistics. Globally, fertility rates have declined significantly, falling from an average of 5.3 children per woman in 1963 to less than half that figure today, the Daily Express reported.

Despite fertility rates below replacement levels, the United States is projected to remain the fourth-largest nation in 2100, with population stability supported by positive net migration. Similarly, Canada and Australia are expected to maintain semi-stable populations through migration.

By 2100, current growth nations such as Indonesia and Pakistan are predicted to experience slight population declines, while the Democratic Republic of the Congo and Ethiopia are expected to surpass them in population size around the turn of the century.

Elon Musk has earlier voiced concerns about global population decline, warning that "population collapse is coming."