Elon Musk has issued a startling warning to the world.
The tech billionaire is concerned about the global population falling because of declining birth rates and says we need way more people on our planet.
Even though we're on the cusp of having eight billion people alive on Earth right now, Musk says civilisation will 'crumble' if we don't ensure that number continues to climb.
A study in The Lancet claimed the world's population is expected to peak in 2064 at 9.7 billion and then will drop to 8.8 billion by 2100.
That will be the first time in centuries that the total number of people on earth has fallen.
While some people have welcomed the idea of there being less people taking up the world's natural resources, Musk says it will be dire for everyone if that happens.
"There are not enough people. I can't emphasise this enough, there are not enough people," he told the Wall Street Journal.
"I think one of the biggest risks to civilisation is the low grow rate and the rapidly-declining grow rate.
"And yet so many people - including smart people - think there are too many people in the world and think the population is growing out of control. It's completely the opposite.
"Please look at the numbers, if people don't have more children, civilization is going to crumble. Mark my words."
The Lancet study, which was published last year, revealed how 'improvements in access to modern contraception and the education of girls and women' is driving fertility rates down.
The population of up to 23 countries, including Japan, Thailand, Italy, Spain, Portugal, South Korea, could shrink by more than 50 per cent.
"The global total fertility rate is predicted to steadily decline, from 2.37 in 2017 to 1.66 in 2100, well below the minimum rate (2.1 live births per woman) considered necessary to maintain population numbers," study author Stein Emil Vollset explained to IFLScience.
When speaking about the fact that he has six children, Musk explained to the Wall Street Journal that he was trying to lead by example regarding his outlook on fertility rates.
"I'm trying to set a good example. I'm trying to practice what I preach," he said.
The Tesla founder has a set of twins and a set of triplets with his ex-wife Justine Musk, as well as a toddler, named X Æ A-Xii with ex-girlfriend Grimes.