About 66 million years ago, the reptilian reign came to a dramatic end when a giant asteroid crashed into Earth. Scientists now predict that mammals will be wiped out in a similar cataclysm in about 250 million years, as the continents collide to form a new supercontinent.
The layout of the continents we are familiar with today is far from static - it is just a freeze-frame in a slow-motion process that took hundreds of millions of years to complete. About 335 million years ago, Earth was dominated by a single landmass called Pangea, which began to break up during the early Jurassic period. Since then, these fragments of what we call continents have drifted apart.
But, on a round world, they can only drift so far before they start drifting together again. Scientists predict that in about 250 million years, all continents will combine again to form a new supercontinent, called "Pangaea Ultimate Continent." In a new study, scientists created and analyzed supercomputer models of future climate on this supercontinent—and the picture it paints isn't promising for us mammals.
According to these models, only 8 to 16 percent of Earth's land mass will be habitable by mammals. This small slice of paradise will exist along the coast, while the interior will be covered by endless desert, where temperatures often soar to 40 to 70°C (104 to 158°F).
Much of Pangea Ultima is uninhabitable not just because it's far from water, but there are other factors that contribute to the heat. Its location could be near the equator, where carbon dioxide levels could double due to increased volcanic activity, and even then the Sun's temperature and brightness could increase by 2.5%.
Dr. Alexander Farnsworth, the lead author of the study, said: "The emerging supercontinent will effectively create a triple whammy, including the continental effect, a hotter sun and more carbon dioxide in the atmosphere, increasing the heat over much of the Earth." Dr. Alexander Farnsworth, the lead author of the study, said: "The result is that much of the Earth will be harsh and mammals will lack food and water. Humans and many other species will die because they cannot dissipate heat and cool their bodies through sweating."
Of course, these models still have a lot of wiggle room. For example, the supercontinent could end up in the tropics, which would tip the climate toward the worst-case scenario, but the team says it could also be near the Arctic, which could offset some of the heat.
Given that we have 2.5 billion years to prepare for this doomsday scenario, life has plenty of time to evolve and adapt to high temperatures. However, the researchers say the upper limits of mammals' tolerance for temperature are fairly stable, while their ability to survive cold weather is also highly tuned. Therefore, the team says, this could mean the end of mammal dominance on Earth (assuming they don't go extinct before then). Other life forms, such as plants, are also in trouble.
It's probably unlikely that modern humans still complain about the heat on Earth. We have either evolved into other organisms, left the Earth in search of greener pastures, or are most likely extinct.
On the bright side, researchers say life itself can still survive. After all, the Earth has experienced many global catastrophes in its 4.5 billion-year history, and at least some life forms have survived these catastrophes. Whichever form of life prevails during the cataclysm, it's possible that they could dominate before the sun engulfs the Earth.
The research was published in the journal Nature Geoscience.