About 66 million years ago, the reign of the reptiles came to a dramatic end as a huge asteroid slammed into Earth. Scientists have now predicted that mammals will meet their maker in a similar cataclysm in about 250 million years’ time, as the continents collide to form a new supercontinent.
The current arrangement of continents we’re familiar with today is far from static – it’s just a freeze frame in a slow-motion process that takes hundreds of millions of years to complete. About 335 million years ago Earth was dominated by one big landmass known as Pangaea, which began breaking up in the early Jurassic period. Ever since, the fragments, which we call continents, have been drifting apart.
But on a round world, they can only drift so far apart before they start drifting back together again. Scientists have predicted that around 250 million years from now, all the continents will combine once more into a new supercontinent dubbed Pangaea Ultima. In a new study, scientists have created and analyzed supercomputer models of what the climate might be on this future supercontinent – and the picture it paints isn’t too rosy for us mammals.
According to the models, only between 8 and 16% of the planet’s landmass at that time would be habitable for mammals. That small sliver of paradise would exist along the coasts, while the inner areas would be covered with an enormous expanse of desert, where temperatures routinely soar to between 40 and 70 °C (104 and 158 °F).
It’s not just the distance from water that will make most of Pangaea Ultima unpleasant to live in – several other factors would contribute to the heat. Its likely position would be around the equator, levels of CO2 would perhaps double thanks to more volcanic activity, and even the Sun will be 2.5% hotter and brighter by then.
“The newly-emerged supercontinent would effectively create a triple whammy, comprising the continentality effect, hotter Sun and more CO2 in the atmosphere, of increasing heat for much of the planet,” said Dr Alexander Farnsworth, lead author of the study. “The result is a mostly hostile environment devoid of food and water sources for mammals. Humans – along with many other species – would expire due to their inability to shed this heat through sweat, cooling their bodies.”
Of course, there’s a lot of wiggle room in these models. For example, the supercontinent could end up located in the tropics, which would skew the climate towards the worst-case scenario, but the team says there’s also a chance it will reside near the North Pole, which could counter some of the heat.
Given we have a quarter of a billion years before this doomsday scenario, life has plenty of time to evolve and adapt to the heat. However, the researchers say that mammals have had a pretty constant upper temperature tolerance, while greatly adapting their ability to survive colder weather. As such, the team says that this might spell the end of mammalian rule on Earth (assuming they don’t go extinct before then). Other forms of life, like plants, could have trouble too.
It’s probably unlikely that modern humans would still be around to complain about the heat. We’ll either have evolved into something else, left Earth for greener pastures, or most likely, wiped ourselves out.
On the bright side, the researchers say that life itself could still pull through. After all, the planet has undergone global cataclysms many times in its 4.5-billion-year existence, and at least some forms of life have survived them all. Whatever emerges victorious on the other side could reign supreme until the Sun engulfs the Earth.
The research was published in the journal Nature Geoscience.
Source: University of Bristol
