Climate scientists, even those who warn of catastrophe due to manmade climate change, mocked Stephen Hawking’s absurd suggestion that by pulling the United States out of the Paris climate accord, President Donald Trump would turn the Earth into the planet Venus.

“We are close to the tipping point where global warming becomes irreversible. Trump’s action could push Earth over the brink, to become like Venus, with a temperature of two hundred and fifty degrees, and raining sulphuric acid,” Hawking, a renowned cosmologist and author of A Brief History of Time, told BBC News in an interview on Sunday.

“A good example that even brilliant scientists sometimes say silly things when it’s outside their field of expertise (see Nobel disease),” tweeted Zeke Hausfather, a climate scientist at U.C. Berkeley who has supported the alarmist position on global warming.

A good example that even brilliant scientists sometimes say silly things when it's outside their field of expertise (see Nobel disease) https://t.co/QPsmB1bsv0 — Zeke Hausfather (@hausfath) July 2, 2017

Other scientists proved much harsher. “Stephen Hawking’s wacky & bizarre opinions on climate change (e.g. Earth becoming Venus) pollute policy debate,” declared Ryan Maue, an atmospheric scientist at the Cato Institute’s Center for the Study of Science.

Stephen Hawking's wacky & bizarre opinions on climate change (e.g. Earth becoming Venus) pollute policy debate. https://t.co/kK5eCZmPZo — Ryan Maue (@RyanMaue) July 3, 2017

Bjorn Lomborg, director of the Copenhagen Consensus think thank and author of Cool It: The Skeptical Environmentalist’s Guide to Global Warming, explained exactly why Hawking’s suggestion was silly. “Stephen Hawking being silly: No risk of climate runaway to Venus US Paris cuts were just 0.2% of needed to 2°C,” Lomborg tweeted.

Stephen Hawking being silly:

No risk of climate runaway to Venus

US Paris cuts were just 0.2% of needed to 2°Chttps://t.co/fnbbCkQihg pic.twitter.com/FaDZFY4K8c — Bjorn Lomborg (@BjornLomborg) July 3, 2017

Lomborg is correct. The Paris climate accord only aimed to be a first step to keep Earth’s climate from rising “out of control,” as in by 2 degrees Celsius … by 2100. Venus does indeed have a temperature of two hundred and fifty degrees, and it does rain sulphuric acid. But Venus is closer to the Sun — much closer. In fact, Venus is 25.72 million miles closer to the Sun than the Earth is.

The idea that carbon emissions could turn Earth into Venus is not just laughable, it’s insane. Venus has a much different atmosphere, and is millions of miles closer to the Sun. Even if carbon emissions were proven to be linked to warming temperatures, and even if that rise was truly catastrophic, they would have no chance of turning the Earth into Venus.

But Hawking insisted that Trump posed a threat to the Earth. “Climate change is one of the great dangers we face, and it’s one we can prevent if we act now,” the cosmologist said. “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.”

This is not the first time Hawking has criticized Trump. During the campaign last year, Hawking called Trump “a demagogue who appeals to the lowest common denominator.” The cosmologist also had a rosy view of immigration, suggesting that it enables scientific progress.

But Hawking also proved pessimistic on the prospect that humans will solve immense problems. “I fear evolution has inbuilt greed and aggression to the human genome,” he said. “There is no sign of conflict lessening, and the development of militarised technology and weapons of mass destruction could make that disastrous. The best hope for the survival of the human race might be independent colonies in space.”

Human ingenuity, unleashed by the free market, has developed solutions to seemingly insurmountable problems before. Thomas Malthus argued that humans would starve, but the green revolution has enabled the feeding of billions. Already, sustainability and environmental concerns have driven a whole host of innovations, and liberal mayors have insisted they will try to meet the demands of the Paris climate accord, even though the federal government will not.

Carbon emissions will never turn Earth into Venus. Science is a wonderful thing, but Stephen Hawking stands as a reminder that an expert in one field is not an expert in all.