“The human species will have to populate a new planet within 100 years if it is to survive,” famed physicist Stephen Hawking, PhD says in “Expedition New Earth” — a documentary that debuts this summer as part of the BBC’s forthcoming Tomorrow’s World TV series.

He cites “climate change, overdue asteroid strikes, epidemics and population growth” as reasons to leave.

That 100 figure is dramatically lower that Hawking’s previous warning of 1,000 years in a speech November 15, 2016 at Oxford Union, according to the London-based Express newspaper. “We must continue to go into space for the future of humanity,” he said.

In an afterword to a 2016 book titled How to Make a Spaceship: A Band of Renegades, an Epic Race, and the Birth of Private Spaceflight by journalist Julian Guthrie, Hawking said he believes that “life on Earth is at an ever-increasing risk of being wiped out by a disaster, such as a sudden nuclear war, a genetically engineered virus, or other dangers. I think the human race has no future if it doesn’t go to space.”

Hawking has also warned about the risks of artificial intelligence and an alien encounter.