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The idea that extreme heat could one day cause a mass extinction and end the dominance of humans and other mammals might sound like something out of sci-fi movie.
Yet new findings indicate that the planet might face this crisis if continents fuse into one landmass. Some researchers say it could be the first extinction of its kind since the dinosaurs vanished.
In a recent study, investigators used powerful climate models to show how a future supercontinent, called Pangea Ultima, might alter global conditions. Projections suggest a much hotter and drier environment with limited options for survival.
The work appears in Nature Geoscience and was led by Dr. Alexander Farnsworth, a Senior Research Associate at the University of Bristol. His team examined tectonic plate movement, solar changes, and greenhouse gas levels.
Supercontinent Pangea Ultima
Geologists have long argued that Earth’s continents move gradually over time. Pangea Ultima is the name given to the hypothesized supercontinent that might emerge millions of years from now.
If this happens, much of the terrain would sit far from oceanic cooling influences, a situation known as the continentality effect.
“The newly-emerged supercontinent would effectively create a triple whammy, comprising the continentality effect, hotter sun and more CO2 in the atmosphere, of increasing heat for much of the planet,” Dr. Farnsworth explained.
Three drivers of human extinction
One factor is the expansive landmass itself, which traps regions in scorching interiors.
Another is that the sun will brighten over time, delivering stronger radiation. Volcanic activity adds more carbon dioxide to the mix, further warming the atmosphere.
“Widespread temperatures of between 40 to 50° Celsius (104 to 122° Fahrenheit), and even greater daily extremes, compounded by high levels of humidity, would ultimately seal our fate,” Dr. Farnsworth added.
“Humans – along with many other species – would expire due to their inability to shed this heat through sweat, cooling their bodies.”
With the sun also anticipated to emit about 2.5% 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°C (104 to 158°F).
Impact on other mammals
Researchers note that mammals have historically endured shifts in temperature, sometimes by growing thicker coats in cold climates or relying on hibernation.
Yet sustained heat is harder to escape, since sweating is essential for body cooling. As conditions climb, mammals cannot regulate heat for long without access to cooler refuges and reliable water sources.
Study findings hint that only 8% to 16% of land on the future supercontinent would stay within a tolerable range.
Dryness complicates matters by limiting water supplies and reducing vegetation. With so much territory turning arid, the quest for food and hydration would become daunting.
Humans and extinction warnings
“It is vitally important not to lose sight of our current Climate Crisis, which is a result of human emissions of greenhouse gases,” urged co-author Dr. Eunice Lo, Research Fellow in Climate Change and Health at the University of Bristol.
“While we are predicting an uninhabitable planet in 250 million years, today we are already experiencing extreme heat that is detrimental to human health. This is why it is crucial to reach net-zero emissions as soon as possible.”
Recent decades have seen rising temperatures that strain resources. Heat waves threaten crops, disrupt energy grids, and place communities at risk.
Many call for faster emission cuts to prevent even harsher conditions. Some experts believe effective policies and public awareness could still temper the worst near-term damage.
Future carbon dioxide levels
Projections in the study used tectonic and ocean chemistry models to gauge carbon dioxide levels.
Higher volcanic outgassing over the coming eons points to an increase from current readings to well above 600 parts per million. Such elevated concentrations would create conditions hostile to many organisms.
Greenhouse gases would accumulate and trap more heat in the atmosphere. This feedback loop amplifies warming, making survival increasingly difficult on a planet with minimal oceanic influence.
“We think CO2 could rise from around 400 parts per million (ppm) today to more than 600 ppm many millions of years in the future,” noted Professor Benjamin Mills at the University of Leeds.
“Of course, this assumes that humans will stop burning fossil fuels, otherwise we will see those numbers much, much sooner.”
Remembering past extinction events
Many eras of Earth’s history ended in severe biodiversity loss.
About 443 million years ago, marine habitats shrank during the Ordovician-Silurian Extinction, removing roughly 85% of sea life.
Near 360 million years ago, the Late Devonian wiped out up to 75% of species. Later came the Permian-Triassic Extinction about 252 million years ago, erasing over 90% of marine species and 70% on land.
Around 200 million years ago, massive eruptions drove the Triassic-Jurassic Extinction, cutting species by around half.
Some 66 million years ago, an asteroid impact ended the non-avian dinosaurs in the Cretaceous-Paleogene Extinction, eliminating about 75% of all species.
Human extinction and exoplanets
This analysis also broadens how scientists evaluate exoplanets. If continents merge, planetary heat can spike, even if a world is inside a so-called habitable zone.
Researchers think other planets might face analogous shifts, where tectonic movement and solar intensity escalate temperatures. Rotation rates and air chemistry may further affect habitability.
“This work also highlights that a world within the so-called ‘habitable zone’ of a solar system may not be the most hospitable for humans depending on whether the continents are dispersed, as we have today, or in one large supercontinent,” Dr. Farnsworth concluded.
“Understanding these configurations can guide experts who look for environments that support life beyond Earth.”
Today, we already see the impact of climate stress on our resources and health. Scientists warn us that higher temperatures and more extreme weather events could become the norm if we fail to manage our emissions.
While the prospect of a distant supercontinent meltdown might seem remote, it underscores the importance of taking meaningful steps now.
The full study was published in the journal Nature Geoscience.
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