We Have a Date for Mass Extinction of Mammals

We may be living at the halfway point of mammalian survival. That's according to a new study that poses a terrifying future for our planet that humans will likely find too hot to endure. Researchers expanded on a previous study that predicted landmasses would converge in about 250 million years to form a supercontinent dubbed Pangea Ultima, using advanced climate models to predict what life on the supercontinent might look like. The result isn't great, at least not for mammals, who've survived for 250 million years up to this point. A hotter sun, effects from geological changes, and a 50% increase in today's carbon dioxide levels will combine in "a triple whammy that becomes unsurvivable," University of Bristol climate scientist Alexander Farnsworth, lead author of the study published Monday in Nature Geoscience, tells the New York Times.

The sun's luminosity increases by about 1% every 100 million years, per the Jerusalem Post. That means in another 250 million years, the sun will be 2.5% brighter and emit 2.5% more radiation than today. This would further warm Earth's atmosphere and trigger more water to evaporate from oceans and land, according to the research. Water vapor traps more heat and land warms faster than oceans, so temperatures are likely to spike in the vast, flat interior of the supercontinent. At the same time, numerous volcanoes forced out of the Earth by the movement of the land would release large amounts of carbon dioxide for thousands of years, warming the planet even further, per the Times.

Researchers predict temperatures ranging from 40 to 70 degrees Celsius, compounded by high humidity. "The result is a primarily hostile environment devoid of food and water sources for mammals," Farnsworth tells the Post. "Humans—along with many other species—would expire due to their inability to shed this heat through sweat, cooling their bodies." While the Post describes the outcome as "the first mass extinction of a magnitude comparable to the era of the dinosaurs," Farnsworth concedes some mammals might be able to survive in the northern and southern peripheries of the supercontinent formed along the equator, accounting for 8% to 16% of the land. But in that case, they would lose their place of dominance, to be replaced by coldblooded reptiles more tolerant of heat, he tells the Times. (More mass extinction stories.)