Jul 6, 2017 by

Famed physicist warns that by exiting the Paris climate deal, the president could render Earth uninhabitable.

CREDIT: Dennis Van Tine/STAR MAX/IPx via AP

On his 75th birthday, renowned physicist Stephen Hawking told the BBC that President Donald Trump’s climate policies could permanently destroy the Earth’s livable climate.

“We are close to the tipping point where global warming becomes irreversible,” explained the world’s most famous scientist. “Trump’s action could push the Earth over the brink, to become like Venus, with a temperature of 250º” C (482°F).

While “climate change is one of the great dangers we face,” the good news, Hawking noted, is that “it’s one we can prevent if we act now.” The tragedy, though, is that “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.”

You may be wondering whether Hawking is right that humans could, in a worst-case scenario, create a truly runaway greenhouse effect (as Venus has). A 2013 Nature Geoscience study concluded, “A runaway greenhouse could in theory be triggered by increased greenhouse forcing, but anthropogenic emissions are probably insufficient.” So, no, it’s not very likely.

That said, human civilization would collapse long, long before we had Venus-level warming. A mere 4°C (7°F) warming would lead to “devastating” impacts such as “declining global food stocks,” the World Bank has warned.

And as one scientist explained, 21°F warming “would put half of the world’s population in an uninhabitable environment.” But if we return to the kind of business-as-usual emissions of carbon pollution team Trump wants, then we do risk warming of that magnitude and more.

The good news is that the rest of the world is committed to meeting its Paris CO2 reduction pledges. But we are fast approaching irreversible tipping points, as Hawking warns, so Trump’s pro-pollution policies might well be enough to ensure that we do cross them.

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