Mammals’ stay on Earth has reached half, scientists predict | ET REALITY


has been about 250 million years since reptile-like animals evolved into mammals. Now a team of scientists predicts that mammals may only have another 250 million years left.

The researchers built a virtual simulation of our future world, similar to models that have projected human-caused global warming over the next century. Using data on the movement of continents across the planet, as well as fluctuations in the chemical composition of the atmosphere, the new study projected much further into the future.

Alexander Farnsworth, a paleoclimate scientist at the University of Bristol who led the team, said the planet could become too warm for any mammals, including ourselves, to survive on land. Researchers found that the climate will become deadly thanks to three factors: a brighter sun, a change in the geography of the continents and an increase in carbon dioxide.

“It’s a triple whammy that’s impossible to survive,” Dr. Farnsworth said. He and his colleagues published their study Monday in the journal Nature Geoscience.

Scientists have been trying to predict the fate of life on Earth for decades. Astronomers expect our sun to become increasingly brighter and, in about 7.6 billion years, could engulf the Earth.

But life probably won’t last that long. As the sun dumps more energy on the planet, Earth’s atmosphere will warm, causing more water to evaporate from the oceans and continents. Water vapor is a powerful greenhouse gas and will therefore trap even more heat. It is possible that within two billion years it will warm enough to boil the oceans.

In 2020, Dr. Farnsworth turned his attention to the future of the Earth as a way to distract himself from the pandemic. He met a study predict how the continents will move around the planet in the distant future.

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, called Pangea Ultima, will form along the equator within 250 million years.

In his primary research, Dr. Farnsworth builds models of the ancient Earth to reconstruct past climates. But he thought it would be interesting to use his models to see what life will be like on Pangea Ultima. The climate he ended up in took him by surprise.

“This world was very hot,” he said.

Dr. Farnsworth recruited Christopher Scotese, a retired University of Texas geophysicist who had put together the Pangea Ultima model, and other experts to run more detailed simulations of that distant future, tracking the atmosphere moving over the oceans. , the supercontinent and its mountains.

“They did a lot of things, which impressed me quite a bit,” said Hannah Davis, an earth systems scientist at the GFZ German Research Center for Geosciences, who was not involved in the research.

The researchers found that, under a variety of possible geological and atmospheric conditions, Pangea Ultima will be much hotter than the current continents. One of the reasons for the drastic change is the sun. Every 110 million years, the energy released by the sun increases by 1 percent.

But the supercontinent will make things worse. For one thing, the land warms faster than the ocean. With the continents pushed into one giant landmass, there will be a vast interior where temperatures can soar.

Pangea Ultima will also influence the climate thanks to its topography, which will include vast expanses of flat land far from the ocean. On Earth today, rainwater and carbon dioxide react with minerals on the slopes of mountains and hills, which are then washed out to sea and fall to the sea floor. The result is that carbon dioxide is constantly removed 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 belching carbon dioxide, according to the model. Thanks to the turbulent movements of molten rock deep within the Earth, volcanoes can release huge surges of carbon dioxide over thousands of years: explosions of greenhouse gases that will cause temperatures to soar.

Currently, humans are warming the planet by releasing more than 40 billion tons of carbon of fossil fuels every year. If global warming continues unabated, biologists fear it will lead to the extinction of several species, while people will not be able to survive the heat and humidity in large areas of the planet.

In Pangea Ultima, Dr. Farnsworth and his colleagues concluded, things will probably get much worse for mammals like us. 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.

Dr. Farnsworth admitted that a few mammals could barely survive in refuges on the margins of Pangea Ultima. “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 the past 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 decline could lead to fewer volcanic eruptions and less carbon dioxide into the atmosphere.

“Mammals may survive a little longer than expected,” he said: maybe 200 million years, give or take.

Eric Wolf, a planetary climate scientist at the University of Colorado who was not involved in the new study, said the research could one day help us detect life on other planets. As scientists begin using powerful space telescopes to observe planets in other solar systems, they will be able to measure their continental arrangements to infer what types of life might survive there.

“We are trying to prepare for the many worlds we will see,” Dr. Wolf said.

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