Stephen Hawking is issuing a dire warning to humanity: get off this planet in a thousands years, or else. The famed physicist says that a number of factors, including climate change, nuclear terrorism, the rise of artificial intelligence and other factors will threaten humanity int he near future, and it’s time for humans to look for another planet we can colonize.

It was part of a speech he made at Oxford University Union recently, saying that our reach into space is important because our time on Earth is limited. He said humans have done a lot of damage to its planet and it can’t endure our abuse much longer.

Asked what the greatest threat may be to our species, Hawking once again said it was full artificial intelligence, which he said bluntly could result in the “end of the human race” single-handedly. He said creating AI is like developing a virus, which will adapt and redesign itself for its own purposes, and not for humans, which wouldn’t be able to compete due to our slow evolutionary process.

“We need to avoid the temptation to anthropomorphize and assume that AI’s will have the sort of goals that evolved creatures to,” Hawking said in a recent Reddit AMA. “An AI that has been designed rather than evolved can in principle have any drives or goals. However, as emphasized by Steve Omohundro, an extremely intelligent future AI will probably develop a drive to survive and acquire more resources as a step toward accomplishing whatever goal it has, because surviving and having more resources will increase its chances of accomplishing that other goal. This can cause problems for humans whose resources get taken away.”