The Permian period, spanning roughly 299 to 252 million years ago, experienced one of the most dramatic climate shifts in Earth’s history. It began locked in an ice age, with glaciers covering parts of the southern hemisphere, and ended in a scorching greenhouse world so hot it triggered the largest mass extinction ever recorded. Between those extremes, the planet dried out, seasonal weather intensified to levels far beyond anything today, and CO2 levels swung from near-modern concentrations to values many times higher.
From Ice Age to Greenhouse
The early Permian was the tail end of a long glacial period known as the Late Paleozoic Ice Age, which had gripped the planet since the Carboniferous. Ice sheets spread across Gondwana, the southern supercontinent that included what is now Antarctica, Australia, South America, Africa, and India. In Antarctica, regions like Victoria Land and the Darwin Glacier area show clear evidence of ice-marginal and glacial marine environments during the early Permian, though the ice sheet was likely smaller than some older models predicted.
CO2 levels during this glacial peak were remarkably low. Reconstructions show atmospheric CO2 bottomed out around 200 parts per million near 298 million years ago, comparable to concentrations seen during recent ice ages on Earth. For much of the Late Paleozoic Ice Age, CO2 hovered around 300 to 330 ppm. Then, starting around 294 million years ago, CO2 began climbing rapidly. This rise marked the beginning of the end for the ice age, kicking off a transition from icehouse to greenhouse conditions that played out over millions of years. Published estimates for the broader Carboniferous-Permian interval show CO2 ranging wildly, from below 100 ppm during glacial lows to as high as 2,000 ppm during the warmest phases.
This was the first time Earth transitioned from an icehouse to a greenhouse while extensive tropical forests already covered the land. The interplay between rising CO2, retreating ice, and changing vegetation made the Permian a uniquely complex chapter in climate history.
Pangea and Extreme Seasons
The Permian world looked nothing like today’s map. Nearly all of Earth’s landmass was fused into the supercontinent Pangea, stretching from pole to pole. This enormous land configuration had profound effects on weather patterns, most notably the creation of what geologists call a megamonsoon system.
The megamonsoon began in the late Carboniferous and intensified throughout the Permian, eventually peaking in the Triassic. Think of the modern East Asian Monsoon, with its dramatic wet and dry seasons, then scale it up to continental proportions. Pangea’s sheer size meant that interior regions sat thousands of kilometers from the nearest ocean, receiving almost no moisture. Seasonal temperature swings were extreme: blistering summers in the continental interior gave way to harsh, dry winters. The megamonsoon was a major driver behind the disappearance of the Permian’s coal-forming swamp forests, the spread of arid landscapes, and a steady increase in seasonality as the period progressed.
The intensity of the megamonsoon depended heavily on how Pangea’s landmasses were arranged. Recent modeling suggests that the eastern margin of Pangea, where smaller continental blocks had welded on, may have experienced an even stronger monsoon system than previously thought. The result was a world where rainfall was concentrated in violent seasonal bursts along coastlines, while vast interior regions stayed parched year-round.
Widespread Aridity and Evaporite Deposits
One of the clearest fingerprints of Permian climate is the global distribution of evaporite deposits: thick beds of salt, gypsum, and other minerals that form when shallow seas or lakes evaporate under intense heat. The Permian through Jurassic interval, roughly coinciding with Pangea’s existence, represents a peak in evaporite accumulation across Earth’s history. These deposits appear at latitudes consistent with modern arid belts, confirming that Permian aridity followed familiar climate patterns but at a much greater scale.
Red beds, another hallmark of dry conditions, are found across Permian-age rocks on nearly every continent. Deserts expanded through the middle and late Permian as the megamonsoon intensified and ice sheets retreated. By the late Permian, much of Pangea’s interior resembled an enormous desert belt, with sand dune deposits preserved in rock formations from what is now the American Southwest to northern Europe and beyond.
Ocean Temperatures and the Late Permian
Before the end-Permian extinction, tropical sea surface temperatures ranged from about 22 to 25°C, warm but not catastrophically so. These conditions supported diverse marine ecosystems, including extensive reef systems built by organisms quite different from modern corals.
The late Permian saw a steady warming trend that accelerated dramatically at the very end of the period. Massive volcanic eruptions in what is now Siberia, known as the Siberian Traps, released enormous quantities of CO2 and other greenhouse gases over a geologically short span. This pushed tropical ocean temperatures from 25°C up to around 30 to 32°C across the Permian-Triassic boundary. That 7°C jump in tropical waters was devastating. Warm water holds less dissolved oxygen, and many marine organisms simply could not survive in seas that hot.
The warming didn’t stop at the boundary. Temperatures continued climbing into the Early Triassic, eventually producing sea surface temperatures exceeding 40°C during the Late Smithian Thermal Maximum, several million years after the initial extinction pulse. At those temperatures, the tropical oceans were essentially lethal to most complex life. This prolonged heat is one reason recovery from the end-Permian extinction took so long, roughly 5 to 10 million years before ecosystems began to resemble anything diverse again.
Climate Zones Across Pangea
Despite the overall trend toward warmth and aridity, the Permian wasn’t uniformly hot and dry everywhere at once. The planet had distinct climate belts, shaped by latitude and distance from the ocean.
High southern latitudes started the period under ice and transitioned through cool-temperate conditions with seasonal frost. The tropics, straddling the equator where much of Pangea sat, shifted from humid coal-swamp environments in the early Permian to increasingly seasonal and then arid conditions by the middle and late Permian. Northern mid-latitudes, including parts of what would become Europe and North America, cycled through semi-arid to fully arid conditions, leaving behind the thick evaporite and red bed sequences that define Permian geology in those regions.
Coastal areas and regions near the Tethys Sea (the ocean embayment that cut into Pangea’s eastern side) retained more moisture than the deep interior. These coastal strips likely supported the last refuges of lush vegetation as the continental interior dried out. The contrast between wet coastlines and bone-dry interiors would have been sharper than anything on Earth today, simply because no modern continent is large enough to create that degree of continentality.
How the Permian Climate Ended
The final chapter of Permian climate is inseparable from the end-Permian mass extinction, the worst biodiversity crisis in the fossil record. The Siberian Traps eruptions injected CO2 at rates high enough to overwhelm Earth’s natural carbon-buffering systems. Tropical sea surface temperatures spiked by roughly 7°C in a geologically brief window. Ocean chemistry shifted toward acidic and oxygen-poor conditions. On land, soils destabilized, and fungal spores briefly dominate the fossil record in many locations, suggesting widespread forest die-off and decay.
About 90% of marine species and roughly 70% of land vertebrate species went extinct. The Permian ended not with a slow fade but with a climate catastrophe driven by volcanic carbon release on a scale the planet hadn’t experienced before. The world that emerged on the other side, the Early Triassic, was hotter, more barren, and biologically impoverished, a stark illustration of what runaway greenhouse warming can do to a living planet.