In the second episode of his new series Stephen Hawking’s Favourite Places, the renowned theoretical physicist used the example of Venus to illustrate the impact increased greenhouse gases can have on a habitable planet.

“Venus is like Earth in so many ways, a sort of kissing cousin. She’s almost the same size as Earth, a touch closer to the sun. She has an atmosphere”, he explained.

NASA says that Venus looked very much like Earth four billion years ago and was habitable for approximately two billion years. The reason why the planet turned uninhabitable is due to increased greenhouse gases in its atmosphere.

As the planet warmed, and more heat was trapped in the atmosphere, water resources kept suffering excessive evaporation. The feedback loop continued until the oceans evaporated, affecting the planet’s capacity to accommodate life.

“This is what happens when greenhouse gases are out of control”, he said.

Stephen Hawking says that Venus is a warning of a planet that can become uninhabitable when it warms up due to greenhouse gases. – Filepic

“Next time you meet a climate-change denier, tell them to take a trip to Venus; I will pay the fare”, he added.

Last June, Stephen Hawking said that the next 100 years will be very decisive for the future of the planet, with the main threats being a nuclear war, genetically engineered viruses and global warming.

In addition, he has openly criticised US President Donald Trump on his views on climate change and lack of action. Last July, when President Trump withdrew the US from the Paris Agreement he told BBC: “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. By denying the evidence of climate change and pulling out of the Paris Agreement, Donald Trump will cause avoidable environmental damage to our beautiful planet endangering us and our children”.

Stephen Hawking’s Favourite Places is an Emmy award-winning documentary series released exclusively on CuriosityStream. – Climate Action