If global warming doesn’t scare you enough already, consider the doom Stephen Hawking is convinced of—if humanity is careless, Earth could end up going the way of Venus.
Venus, you know, that planet with toxic clouds of sulfuric acid and an average temperature of 864 degrees Fahrenheit. Whatever oceans it may have had billions of years ago have long since been vaporized by a phenomenon otherwise known as a runaway greenhouse effect. When both Hawking and NASA are telling you this, you might want to pay attention.
So what exactly is a runaway greenhouse effect? It’s what our planet could be heading toward if we keep releasing harmful emissions, especially those that can survive long enough to reach our already endangered ozone layer, into the atmosphere. When a planet absorbs more solar energy than it can radiate back into space, the surface temperature skyrockets to the point where it can actually boil away all the oceans. That water vapor accumulates in the atmosphere and traps even more heat and sets off a vicious cycle. However ancient it seems, what happened on Venus 3 to 4 billion years ago is not impossible on Earth.
“We don’t have to go too far to understand how precarious our existence is,” Hawking explains in the second episode of his Emmy-winning series Favorite Places on Curiosity Stream. “Venus is like Earth in so many ways … but she’s a great example of the dangers that we face back home.”
In Favorite Places, Hawking takes off on the (CGI) SS Hawking on a mission to Venus, the sun, and past our solar system into a vast, unexplored (also CGI) universe where he ponders both the possible discoveries and catastrophic events that will transpire in the distant future. There is a subtle reference to his fear of AI in there when he soars over an alien planet in ruins, but closer to home, what scares the uber-scientist even more is the possibility of global warming getting out of control. No wonder he feels we have 600 years to get off this planet before it becomes hostile.
Earth possibly morphing into a neo-Venus sounds like a post-apocalyptic movie but is actually more science than fiction. Surface temperatures on the ocean only have to reach 80 degrees Fahrenheit for a critical amount of water vapor, which is one of the most effective greenhouse gases despite being nontoxic, to amass in the atmosphere and start trapping heat. There is already a place on Earth where this happens. Because ocean temps never go above 87, we’re not in dire peril—yet.
"Next time you meet a climate change denier, tell them to take a trip to Venus," Hawking says. "I will pay the fare."