Famed British physicist and author Stephen Hawking isn't shy about stating his fears, most recently warning people that they must leave Earth in order to survive.
Speaking with BBC News, Hawking expressed his newest fear: that President Trump's decision to ditch the Paris climate accord could have an "irreversible" impact on climate change.
"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.
Hawking added: "Climate change is one of the great dangers we face, and it's one we can prevent if we act now. 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."
In recent years, Hawking had warned that humans have 1,000 years to leave Earth. Now, he predicts we only have 100 years left. "I am convinced that humans need to leave Earth. The Earth is becoming too small for us. Our physical resources are being drained at an alarming rate," Hawking said during a speech in Norway last month.
In the same interview with BBC News, Hawking offered a pessimistic view, saying he thought humanity's days on Earth were numbered.
The interview was timed to coincide with Hawking's 75th birthday.