About 250 million years have passed since reptile-like animals evolved into mammals. Now a team of scientists predicts that mammals may only have 250 million years left.
Alexander Farnsworth, a paleoclimate scientist at the University of Bristol in England, who led the teamsaid the planet could become too warm for any mammal—including us—to survive on land. Researchers found that the climate will turn deadly thanks to a brighter Sun, a change in the geography of continents and an increase in carbon dioxide.
“It’s a triple whammy that’s unsurvivable,” Farnsworth said.
Throughout Earth’s history, its continental masses have collided to form supercontinents, which have then broken up. The last supercontinent, Pangea, existed between 330 and 170 million years ago. The study predicted that a new supercontinent — Pangea Ultima — will form along the equator within 250 million years.
The team found that, under a variety of possible geological and atmospheric conditionsPangea Ultima will be much hotter than the current continents. One reason is the Sun. Every 110 million years, the energy released by the Sun increases by one percent.
But the supercontinent will make things worse. The land is warming faster than the ocean. With the continents pushed into one giant landmass, there will be a vast interior where temperatures can soar.
On Earth today, rainwater and carbon dioxide react with minerals on the sides of mountains and hills, which are then washed out to sea to fall to the bottom—constantly drawing carbon dioxide from the atmosphere. But when Earth becomes the home of Pangea Ultima, that conveyor belt will slow down.
If Pangea Ultima behaves like previous supercontinents, it will be riddled with volcanoes that can release huge surges of carbon dioxide for thousands of years — causing temperatures to soar.
The researchers found that almost all of Pangea Ultima could easily become too hot for any mammal to survive. They could disappear in a mass extinction.
Farnsworth admitted that a few mammals could hardly survive. “You could survive in some areas of the northern and southern peripheries,” he said.
Still, he was confident that mammals would lose the dominance they have enjoyed for 65 million years. They could be replaced by cold-blooded reptiles that could tolerate heat.
Wolfgang Kiessling, a climate scientist at the University of Erlangen-Nuremberg in Germany who was not involved in the study, said the model did not take into account a factor that could mean a lot for the survival of mammals: the gradual decline in heat that escapes from the interior of the Earth. That could lead to fewer volcanic eruptions and less carbon dioxide into the atmosphere.
“Mammals could survive a little longer than the models show,” he said — perhaps 200 million years.
By: CARL ZIMMER
The New York Times
BBC-NEWS-SRC: http://www.nytsyn.com/subscribed/stories/6929351, IMPORTING DATE: 2023-10-09 18:50:07
