Stephen Hawking has a simple message for humanity: Haul your butt to Mars (and beyond). In a speech delivered this week at the Oxford Union, the legendary scientist says humanity can only survive another thousand years or so on Earth thanks to growing threats that include climate change, nuclear war, and artificial intelligence, CNN reports.

“I think the human race has no future if it doesn't go to space," the Daily Express quotes Hawking as saying. According to the Christian Science Monitor, Hawking says it's a "near certainty" that disaster will strike the human race within a thousand years if it stays on Earth, which he calls "fragile." There are some challenges on Earth, such as the depletion of its natural resources, humanity won't be able to overcome, he argues. Fortunately, the rate of space exploration is speeding up again, with private companies like Boeing and SpaceX picking up the slack from NASA and other government agencies. NASA is continuing its search for "goldilocks" planets, and Elon Musk recently outlined his plan for colonizing Mars. Hawking himself sounded optimistic, the Independent reports. “Remember to look up at the stars and not down at your feet," he said Monday.

More from Newser:

"However difficult life may seem, there is always something you can do and succeed at. It matters that you don’t just give up.” (This planet has three sunrises and three sunsets every day.)

This article originally appeared on Newser: Stephen Hawking: Humans Have 1K Years Left on Earth