Billionaire tech entrepreneur Elon Musk, who has fathered 10 children, said on Monday the world needs to "make more babies" -- and keep digging for oil.
The richest man on the planet, who has repeatedly warned that low birth rates pose a "danger" to civilization, said ahead of an energy conference in Norway that the world is facing a "baby crisis".
Asked about the greatest challenges facing the world, Musk cited the transition to renewable energies but also said the birth rate was "one of my favourite... things to be concerned about."
"We don't want the population to drop so low that we'll just eventually die," Musk, founder of American electric car manufacturer Tesla and SpaceX, told reporters in Stavanger, southwest Norway.
"At least make enough babies to sustain the population," he added.
Many Western societies and populated countries such as China are facing declining birth rates and ageing societies.
"They say civilization might die with a bang or with a whimper," added Musk. "If we don't have enough kids, then we will die with a whimper in adult diapers. And that will be depressing."
He also said the planet still needed new fossil fuel sources.
"I think realistically we do need to use oil and gas in the short term, because otherwise civilization would crumble," he said, adding that "some additional exploration is warranted at this time".
He went on to advocate the maintenance of nuclear power plants, describing himself as "pro-nuclear".
Several European countries had decided to phase out nuclear power, but following Moscow's invasion of Ukraine in February and Europe's subsequent push to wean itself off of Russian oil and gas, the nuclear debate has reignited.
"I know this may be an unpopular view in some quarters, but I think if you have a well-designed nuclear power plant, you should not shut it down," Musk said.
The businessman, who has been divorced three times, has fathered 10 children, one of whom died at 10 weeks old.
Earlier this year one of his children, who recently turned 18, filed a petition in a California court to change her name and gender identity to female.
Court documents said that she did not want "to be related to my biological father in any way, shape or form" as one of the reasons for the name change.
Musk also has two children with the musician Grimes, a girl they named Exa Dark Sideræl Musk -- although the parents said they will mostly call her Y -- and a boy born in May 2020 called "X Æ A-12", or more simply, X.
Musk announced last autumn that he was "semi-separated" from the singer.
The American press recently revealed that he also had twins in November with an executive at Neuralink, Musk's brain-implant maker, a few weeks before the birth of Exa Dark Sideræl Musk.