Stephen Hawking was best known for explaining the universe, but he also gave serious warnings about Earth.
Before his death in 2018, Hawking said humanity could make the planet unlivable if population growth and energy use keep rising. Speaking at the Tencent WE Summit in November 2017, he warned that Earth could become uninhabitable within about 600 years if nothing changes. He pointed to the year 2600 and described a world so crowded people would be “standing shoulder to shoulder.” He also said massive electricity use could push the planet toward extreme heat — like a “giant ball of fire.”
Hawking didn’t limit his concerns to population and energy. He also warned about other major risks, including nuclear war, pandemics, and artificial intelligence if it is not managed responsibly.
Some online reports claimed NASA backed Hawking’s prediction, but the agency later denied making that statement. However, NASA has said it studies long-term threats to humanity, including climate and environmental damage.
In a 2016 interview with the BBC, Hawking added a broader point: a disaster might seem unlikely in any single year, but the risk grows over time. Across centuries, he said, a major catastrophe becomes much more likely.
His message was clear. The future is not guaranteed. But he believed the world needs smarter planning and faster action to avoid the worst outcomes.