Earth’s continents are not fixed in place. They drift, collide, and break apart over hundreds of millions of years, and new research suggests the next great reunion could create conditions so extreme that mammals, including humans, may not survive it. A study published in Nature Geoscience models the formation of a future supercontinent called Pangaea Ultima roughly 250 million years from now, projecting that the combination of a brighter sun and surging carbon dioxide levels could turn most of the planet’s land surface into an uninhabitable furnace.
What Pangaea Ultima Would Look Like
The basic premise is straightforward but unsettling. Over the next quarter-billion years, tectonic forces will push the world’s landmasses back together into a single enormous continent. The study published in Nature Geoscience names this hypothetical formation Pangaea Ultima and projects its assembly approximately 250 million years from now. A supercontinent of that scale would concentrate most habitable land in tropical and subtropical latitudes, surrounded by a vast global ocean. Interior regions would sit thousands of miles from any moderating coastal influence, creating conditions ripe for extreme heat and prolonged drought.
This is not the first time Earth has experienced a supercontinent. Pangaea, the most famous example, existed roughly 335 to 200 million years ago before splitting into the landmasses we recognize today. But the next iteration would arrive under very different circumstances. The sun is gradually growing more luminous over geological time, and by the time Pangaea Ultima forms, solar output will have increased by about 2.5% compared to present levels. That may sound modest, but when layered on top of other warming factors, the consequences for surface temperatures become severe, especially across a single, sprawling landmass with little access to cooling oceanic air.
A Hotter Sun Meets Rising CO2
The real danger lies in how multiple warming forces would stack on top of each other. The Nature Geoscience study models atmospheric CO2 concentrations ranging from 410 to 816 parts per million during the supercontinent era, driven largely by increased volcanic activity along newly forming tectonic boundaries. When continents collide, the geological upheaval tends to release enormous quantities of carbon dioxide from the Earth’s interior. Combined with a sun that is 2.5% brighter, this creates a feedback loop: higher CO2 traps more heat, which in turn accelerates evaporation and reduces the planet’s ability to cool itself through cloud formation and rainfall over continental interiors.
The result, according to the researchers’ climate simulations, is that large portions of Pangaea Ultima would experience temperatures well beyond what mammals can tolerate. Humans and other warm-blooded species rely on sweating and panting to regulate body heat, but those cooling mechanisms fail when both temperature and humidity cross certain thresholds. The study suggests that vast stretches of the supercontinent’s interior would become arid wastelands where sustained heat exposure would prove lethal to most complex land life. Coastal margins might offer some refuge, but the sheer scale of the continent would leave the majority of its surface area hostile to mammalian survival, with only scattered pockets retaining conditions suitable for large animals.
Echoes of the Permian-Triassic Extinction
The scenario carries uncomfortable parallels to the worst mass extinction in Earth’s history. The Permian-Triassic extinction event, sometimes called the Great Dying, occurred roughly 252 million years ago and wiped out the vast majority of species on the planet. That catastrophe was driven by a combination of factors that overlap with the Pangaea Ultima projections: extreme heat, elevated CO2, and widespread aridity. Massive volcanic eruptions in what is now Siberia pumped greenhouse gases into the atmosphere, and the resulting warming devastated both marine and terrestrial ecosystems. Researchers have drawn direct comparisons between that ancient disaster and the conditions their models predict for the distant future, as reporting in the UK press emphasizes with comments from the study’s authors.
The key difference is that the Permian-Triassic event unfolded over a geologically brief period, perhaps tens of thousands of years, while the formation of Pangaea Ultima would play out across tens of millions of years. That slower timeline might, in theory, give species more time to adapt. But the study’s climate models suggest the combined effect of increased solar luminosity and volcanic CO2 could push temperatures past any plausible evolutionary adaptation for mammals. In other words, the threat is not sudden catastrophe but a slow, grinding shift toward conditions that simply cannot support warm-blooded life on most of the planet’s land surface, even if some smaller or more heat-tolerant organisms persist in isolated refuges.
What the Models Cannot Tell Us
Projections spanning 250 million years inevitably carry enormous uncertainty. The study’s CO2 range of 410 to 816 ppm reflects that uncertainty, with the lower end roughly matching today’s atmospheric concentration and the upper end representing a scenario driven by intense volcanic outgassing. The actual trajectory will depend on variables that are impossible to pin down with precision, including the exact geometry of the future supercontinent, the rate and location of volcanic activity along its margins, and whether biological or chemical processes might sequester carbon more effectively than the models assume. Even small differences in continental layout could alter ocean circulation patterns and cloud cover in ways that meaningfully change local climates.
There is also the question of what happens between now and then. Human-caused climate change operates on a timescale of decades and centuries, not hundreds of millions of years, and the CO2 we are adding to the atmosphere today will have been cycled through geological processes long before Pangaea Ultima begins to take shape. The study is not a commentary on current emissions policy so much as an exploration of how tectonic and solar forces could independently create extinction-level conditions. Still, it offers a useful reminder that Earth’s climate has never been static, and that the conditions allowing complex life to thrive exist within a narrower window than we might assume, with long-term planetary habitability depending on a delicate balance between solar output, greenhouse gases, and continental configuration.
Survival on a Shifting Planet
The broader takeaway from this research is not that humanity faces imminent doom from tectonic forces. Two hundred and fifty million years is an almost incomprehensible span of time. Modern humans have existed for roughly 300,000 years, and our entire recorded history covers barely 5,000. The odds that Homo sapiens in anything like its present form will still be around when Pangaea Ultima coalesces are vanishingly small, whether because we have evolved into new species, migrated off-world, or disappeared entirely. The study instead underscores that even a seemingly stable, life-rich planet like Earth has an expiration date for complex organisms such as mammals, dictated by slow but inexorable changes in its star and its interior.
In that sense, the Pangaea Ultima projections function as a kind of cosmic perspective check. They highlight that present-day climate decisions matter enormously on human timescales while also existing against a backdrop of much larger planetary forces. Our current warming trajectory is rapid, dangerous, and entirely within our power to alter, unlike the distant tectonic and solar shifts described in the Nature Geoscience work. Recognizing that Earth will one day become hostile to mammals no matter what we do does not diminish the urgency of addressing near-term climate risks; instead, it emphasizes that the window for a flourishing, technologically capable civilization is finite, and what we choose to do with that window—scientifically, ethically, and environmentally—will shape how long complex life thrives before the planet’s deep-time evolution closes that chapter for good.
More from Morning Overview
*This article was researched with the help of AI, with human editors creating the final content.
