Professor Stephen Hawking has slammed President Donald Trump's decision to withdraw the United States from the Paris climate accord and said it could lead to a "tipping point" that "turns Earth into Venus".

Speaking to the BBC to mark his 75th birthday the author of a A Brief History of Time said: "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 added: "Climate change is one of the great dangers we face and it's one we can prevent if we act now.