Over the past 2 billion years, Earth’s continents have collided together to form a supercontinent every 200 to 600 million years, known as the supercontinent cycle. This means that the current continents are due to come together again in a couple of hundred of million years’ time.
The resulting new supercontinent has already been named Pangea Proxima—a landmass very similar to Pangea as it existed 200 million years ago. Like Pangea in the past, Pangea Proxima will be covered in vast deserts devoid of animal and plant life, but according to a new study, it will be an even more extreme place to survive.
The international team of scientists led by researchers at University of Bristol, presents the first-ever supercomputer climate models for Pangea Ultima and demonstrates how climate extremes will dramatically intensify when the world’s continents eventually merge to form one hot, dry and largely uninhabitable landmass.
The findings project how these high temperatures are set to further increase, as the sun becomes brighter, emitting more energy and warming the Earth. Tectonic processes, occurring in the Earth’s crust and resulting in supercontinent formation would also lead to more frequent volcanic eruptions which produce huge releases of carbon dioxide into the atmosphere, further warming the planet.
“The outlook in the distant future appears very bleak. Carbon dioxide levels could be double current levels. With the sun also anticipated to emit about 2.5 percent more radiation and the supercontinent being located primarily in the hot, humid tropics, much of the planet could be facing temperatures of between 40 to 70 degrees Celsius,” explains lead author Dr. Alexander Farnsworth.
“The newly-emerged supercontinent would effectively create a triple whammy, comprising the continentality effect, hotter sun and more carbon dioxide in the atmosphere, of increasing heat for much of the planet. The result is a mostly hostile environment devoid of food and water sources for mammals.”
Mammals, including humans, have survived historically thanks to their ability to adjust to weather extremes, especially through adaptations such as fur and hibernating in the cold, as well as short spells of warm weather hibernation.
While mammals have evolved to lower their cold temperature survivable limit, their upper temperature tolerance has generally remained constant. This makes exposure to prolonged excessive heat much harder to overcome and the climate simulations, if realized, would ultimately prove unsurvivable.
“Widespread temperatures of between 40 to 50 degrees Celsius, and even greater daily extremes, compounded by high levels of humidity would ultimately seal our fate. Humans—along with many other species—would expire due to their inability to shed this heat through sweat, cooling their bodies,” concludes Farnsworth.
Based on the heat tolerance of modern species, the findings indicate only somewhere between 8 and 16 percents of land—like coastal zones or high latitude zones—would be still habitable for mammals. The study didn’t consider other animal or plant groups, but it is likely that they also will face a hard time.
The end-Permian extinction some 252 million years ago, coinciding with the formation of Pangea, killed some 90 percent of the planet’s species. But life finds a way. At the time the ancestors of mammals and dinosaurs were among the survivors, repopulating all the continents after Pangea started to break up.