Investment guru Jeremy Grantham has warned that falling birth rates in the developed world could accelerate in coming years due to increasing chemical toxicity, allowing only wealthy people to have children.

“If we do not ban whole classes of chemicals in the next 10 years, we will face a crash in the number of new births,” the 81-year-old co-founder of Grantham Mayo Van Otterloo (GMO) wrote in a letter.

“This interference is growing at such a rapid rate that if left alone it is likely to leave us sterile in a few decades with only the rich able to easily afford the healthy lifestyles and the exotic medical help required to have babies,” said Grantham, who predicted the tech bubble and financial crisis.

Gantham has used numerous recent media appearances to discuss how the climate race is rapidly altering the world’s economic and investing future.

He doubled down on his environmental warning in a recent discussion with Barron’s, but offered some general investment advice.

“Americans as a whole are too protective of the giant companies. The companies that are really working have all sprung out of venture capital in the last two decades. Venture capital is the one place where America has been exceptional,” he said. “It doesn’t mean you’re making money, by the way. There’s no quicker way to lose money than betting blindly on a rapidly growing industry,” he said.

However, environmental concerns are a main passion for Grantham, who has announced he was devoting almost his entire fortune, more than $1 billion, to the fight against climate change.

He recently warned Bloomberg that "humanity is in the “race of our lives,” a terrifying competition between the Earth’s rising temperatures and the many ways people are responding to the crisis. 

“People listen but don’t really take it in. If that continues, climate change is going to trample through your portfolio and kick its ass," he told Barron's. "And you have to care about it, because it’s not just an issue for your miserable portfolio. It’s an issue for your grandchildren,” he said.

“Capitalism has a way of taking perfectly reasonable human beings who play at the weekend with their grandchildren, who are occasionally altruistic, and turning them during the workweek into Milton Friedman zombies working to maximize short-term profit. If you said, ‘My only objective as a human being is to maximize my own advantages,’ that’s a workable definition of sociopath,” he said.

“And yet that is what the corporations do. And we treat them as damned human beings. It’s remarkable. So wake up,” he warned.

Material from Bloomberg, Reuters and the Associated Press has been used in this report.

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