The creation of Earth’s next supercontinent Pangea Ultima could lead to a mass extinction of mammalian life in 250 million years, and render the vast majority of our planet’s landmasses unfit for human habitation, according to the results of a new study.
Life on our planet is doomed. It’s not a question of if, but when. In a best case scenario, Earth will remain habitable for several billion years to come, right up to the point when the radiation blasting out from our ageing Sun exacerbates the warming caused by a runaway greenhouse effect, making Earth too toasty to handle.
However, the authors of a new study published in the journal Nature Geoscience believe Earth’s shifting land masses could render the vast majority of our planet uninhabitable to life long before that.
2/n We show that the assembly of Pangea Ultima in 250 million years will likely lead to extreme heat that could lead to the mass extinction of mammals and other life. Below is a monthly animation of surface temperatures (°C) through an average month of the year. pic.twitter.com/YV3H6KqACs
— Alex Farnsworth? (@Climate_AlexF) September 25, 2023
The international team of researchers - including lead author Dr. Alexander Farnsworth of the University of Bristol - set out to model the climate of Earth’s future supercontinent Pangea Ultima. This colossal landmass is expected to form around the equator roughly 250 million years from now, when modern day Africa, Europe, and the Americas collide together.
At this time, it is thought that the increased radiation from the Sun could heat up an atmosphere saturated with the carbon dioxide created as a side effect of Pangea Ultima’s creation, which could trigger widespread Volcanism.
The researchers used a supercomputer to simulate the climate of Pangea Ultima, while taking into account elements such as temperature, rain, wind, and humidity that could affect the supercontinent 250 million years down the line.
The modelling revealed that huge swathes of this supercontinent could experience temperatures exceeding 40 °C, which would trigger a mass extinction among mammals. In modelling carried out for the worst case scenario, which would see atmospheric carbon dioxide rise to 1,120 parts per million, a mere 8% of the planet’s surface could remain habitable.
“The oldest known mammal fossil is thought to be about 225 million years old,” explained Dr. Farnsworth, while speaking to IGN. “So mammals have existed for a long long time and lived through some very hot greenhouse periods in the past and survived. So why not in the future?”
According to Farnsworth, one of the reasons humans were able to survive extreme temperature events throughout Earth’s history was by migrating away to more hospitable regions. However, this will not be possible with Pangea Ultima.
“...this supercontinent is centred right over the equator and tropics, making migrating away more difficult,” explained Farnsworth. “Some land does exist that they could live in, but that would be a highly competitive place with other species.”
In this grim future, life would have to cling to the shoreline, while avoiding the gargantuan desert in the centre of Pangea Ultima, which would be lethal to all but the most specialised of mammals. It is also unlikely that humans would be capable of evolving to adapt to the extreme high temperatures expected in the far future.
“Mammals' great success has been the ability to adapt to lots of climate regimes, particularly cooler climates (e.g. generating our own body heat, fur, hair, hibernation, estivation, etc..),” continued Farnsworth. “However, the upper-temperature limits are more difficult to exceed due to physiological limitations.
“In general, it is thought mammals can only increase this upper temperature limit by around 0.6C per million years which will be too slow to adapt to the type of heat we simulated in the future.”
Mammals wouldn’t be the only form of life affected by the slow but cataclysmic shift in Earth's climate. Ocean and plant life would likely also be heavily affected, disrupting food chains and giving rise to the potential for a new species to rise to dominance.
In a Nature news release detailing the research Farnsworth noted that any humans who survived the extremes would need to be highly specialised. “Do humans become more specialist in desert environments, become more nocturnal, or keep in caves?” remarked the scientist. “I would suspect [that] if we can get off this planet and find somewhere more habitable, that would be more preferable.”
While speaking to IGN, Farnsworth noted that the new research could help scientists observing distant worlds better understand what goes into making a planet habitable. “With the James Webb Space telescope potentially we are now able to sense water vapour and oxygen on other planets' atmospheres which are in the so-called Habitable zone (i.e. the distance from a star at which liquid water could exist),” he explained. “This work shows that the arrangement of any continents that may exist can play a large impact on such a planet's habitability for human habitation.
“So if you were Nasa and only had the budget to send one space mission to a world in a distant solar systems habitable belt with known water and oxygen, and say we had a space telescope powerful enough to see if continents exist on those planets, I would send it to the planet that had dispersed continents like we have today, rather than a giant supercontinent that might be in the tropics.”
Whilst most supercontinent theories assume that the landmass will coalesce around the equator, another, known as Amasia, envisions the continental collision occurring over the North Pole. In this scenario, temperatures would be more hospitable to life, but other elements such as cold stress and weathering feedback would once again stretch humanity’s physiology and survival capabilities to the limits.
Anthony is a freelance contributor covering science and video gaming news for IGN. He has over eight years experience of covering breaking developments in multiple scientific fields and absolutely no time for your shenanigans. Follow him on Twitter @BeardConGamer
Image Credit: Alex Farnsworth and Chirs Scotese
