Planet Earth has been around for 4.5 billion years, more or less, and has changed a lot in that time. What began as a ball of molten, churning magma eventually cooled and developed several small tectonic plates; a few billion years or so later, the planet was covered in various supercontinent formations and teeming with life.
But the Earth is still young, cosmologically speaking. We’re barely more than a third of the way through its likely lifespan, and there’s still a lot of change ahead of us.
Unfortunately, it seems unlikely we will survive them. According to a study published last year, which used supercomputers to model the climate for the next 250 million years, the world of the future will once again be dominated by a single supercontinent – and will be virtually uninhabitable by any mammal.
“The outlook for the far future appears very bleak,” Alexander Farnsworth, a senior research fellow at the University of Bristol’s Cabot Institute for the Environment and lead author of the study, confirmed in a statement.
“Carbon dioxide levels could be twice as high as they are now,” he explained. “Since the Sun is also predicted to emit about 2.5 percent more radiation and the supercontinent is primarily located in the hot, humid tropics, much of the planet could face temperatures between 40 and 70 °C [104 to 158 °F].”
The new supercontinent — known as Pangea Ultima, after the ancient supercontinent Pangea — would create a “triple whammy,” Farnsworth said: not only would the world have to deal with about 50 percent more CO2 in the atmosphere from current levels; not only would the Sun be hotter than it currently is—this happens to all stars as they age, due to the evolutionary push and pull between gravity and fusion going on inside the core—but the sheer size of the supercontinent would make it almost completely uninhabitable. This is due to the continentality effect – the fact that coastal areas are cooler and wetter than inland areas, and the reason why summer and winter temperatures are much more extreme in, say, Lawrence, KS, than in Baltimore.
“The result is a largely hostile environment with no food and water sources for mammals,” Farnsworth said. “Widespread temperatures between 40 and 50 degrees Celsius and even greater daily extremes, accompanied by high levels of humidity, would ultimately seal our fate. Humans – along with many other species – would die because of their inability to expel this heat through sweat, cooling their bodies.”
And that’s the point: it’s kind of the best case scenario. “We think that CO2 could rise from about 400 parts per million (ppm) today to more than 600 ppm many millions of years into the future,” explained Benjamin Mills, professor of Earth system evolution at the University of Leeds, who led the calculations for the study. “Of course, this assumes that people will stop burning fossil fuels, otherwise we’ll see those numbers much, much sooner.”
So while the study paints an ominous picture of Earth many millions of years from now, the authors caution us not to forget the problems that are just around the corner. “It is vital not to lose sight of our current climate crisis, which is the result of human emissions of greenhouse gases,” warned Eunice Lo, a climate change and health researcher at the University of Bristol and co-author of the paper.
“We are already experiencing extreme heat that is harmful to human health,” she pointed out. “This is why it is crucial to achieve net zero emissions as soon as possible.”
The study was published in the journal Nature Geoscience.