Famed physicist Stephen Hawking has sharp words for United States President Donald Trump this week, warning that his withdrawal from the Paris agreement could spell the end of life on Planet Earth.

“We are close to the tipping point where global warming becomes irreversible. Trump’s action could push the Earth over the brink, to become like Venus, with a temperature of two hundred and fifty degrees, and raining sulphuric acid,” he told BBC News.

“Climate change is one of the great dangers we face, and it’s one we can prevent if we act now,” he continued. “By denying the evidence for climate change, and pulling out of the Paris climate agreement, Donald Trump will cause avoidable environmental damage to our beautiful planet, endangering the natural world, for us and our children.”

Stephen Hawking is a man of few words, as the device that allows him to communicate limits him to about one per minute. When he does speak, the topic increasingly veers towards doomsday scenarios for humanity. Last year he said the substantial destruction of our species was a near certainty within 10,000 years, a prediction he has since revised to 1,000 and then to 500 years.

Hawking has offered several possible scenarios for the downfall of humans, but in his recent interview he refers specifically to the Venus syndrome, which supposes that if enough greenhouse gases enter Earth’s atmosphere there will be runaway global warming that will not stop until the planet is dead and dry.

In a sense, the Venus syndrome is Earth’s inevitable fate, barring some extraordinary event that pushes this planet out into a farther orbit. On a timescale of billions of years, the sun will grow brighter and hotter until the Earth can no longer let out as much energy as it takes in.

But few scientists believe that fossil fuel burning alone will be enough to send this planet over the edge. A 2013 paper found that we’d have to burn all the coal, oil, and gas on Earth 10 times over to spark a runaway greenhose effect.

Still, even if the oceans don’t boil away in humanity’s future, Hawking is absolutely right that climate change is a grave threat to the planet and its inhabitants. Whole countries will almost surely be swallowed by the seas; new wars will erupt over depleted food and water resources; refugees will flee conflict, floods, fires, and droughts. These are not distant doomsday predictions but facts of a warming world, already evident today.

Photos via Getty Images / Jemal Countess