Unraveling the Causes of the Permian Extinction: The Great Dying Explained
Discover why the Permian Extinction, Earth's most catastrophic mass die-off, reshaped life and what it reveals about planetary change.
The Permian-Triassic extinction, commonly known as the Great Dying, stands as Earth’s most severe extinction event—a cataclysm that erased an estimated 90% of marine species and around 70% of terrestrial vertebrate species nearly 252 million years ago. Today, scientists seek not just to determine what caused this biological catastrophe but to understand what it teaches us about the resilience and vulnerability of planetary life.
Understanding the Permian Extinction
The Permian extinction marked the dramatic end of the Paleozoic Era, giving way to the dawn of the Mesozoic, known as the Age of Reptiles. Its sheer scale dwarfed all other mass extinctions, including the event that wiped out the dinosaurs. Within just a couple of million years—or perhaps much less—the makeup of life on land and in oceans changed irrevocably. Paleontologists continue to uncover how interconnected earth’s systems are and how rapidly they can unravel.
What Happened During the Permian Extinction?
Approximately 252 million years ago, a chain of catastrophic events culminated in a mass extinction that saw:
- Massive loss of biodiversity: Roughly 90% of marine species and 70% of terrestrial vertebrates vanished.
- Collapse of marine ecosystems: Coral reefs, trilobites, and many dominant marine invertebrates disappeared entirely.
- Widespread extinction on land: Large amphibians and early reptiles perished alongside vast swathes of plant life.
- Profound transformation of Earth’s environments: Global temperatures soared, ocean chemistry altered, and land vegetation patterns were reshaped.
Unlike sudden extinction events caused by asteroid impacts, geological evidence suggests the Permian die-off unfolded over tens of thousands to several million years—a geological blink, but enough time to include phases of crisis and partial recovery before the final collapse.
The Main Suspect: Siberian Traps Volcanism
The leading scientific consensus attributes the Permian Extinction to massive volcanic eruptions in what is now Siberia. Known as the Siberian Traps, these eruptions covered an area that would span half the United States, releasing over four million cubic kilometers of lava and colossal amounts of gas into the atmosphere.
Key Features of the Siberian Traps Eruptions
- Occurred over less than a million years at the end of the Permian.
- Spewed immense quantities of carbon dioxide (CO2) and sulfur dioxide (SO2) into the atmosphere.
- Triggered both immediate and long-term environmental crises: acid rain, climate warming, ocean acidification, and deoxygenation.
Recent studies suggest two distinct waves of carbon emission—an initial pulse with relatively modest emissions, followed by a second, immensely larger release of volcanic CO2 closely linked with the timing and scale of the extinction itself.
Environmental Changes Triggered by the Eruptions
1. Greenhouse Warming
The release of greenhouse gases, primarily CO2, led to a pronounced warming of the planet. Scientists estimate a global average temperature spike of around 10°C—a scale of climate change rivaling, and far surpassing, what is forecast for today’s climate crisis.
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2. Ocean Acidification and Deoxygenation
- Acidified oceans: Excess CO2 absorbed by the oceans rapidly lowered pH, threatening organisms with calcium carbonate shells and disrupting food chains.
- Widespread anoxia: Heating reduced oxygen solubility while nutrient-rich volcanic ash promoted algal blooms that further consumed available oxygen, creating vast ‘dead zones.’ Marine life, especially those at higher trophic levels, could not survive these suffocating waters.
3. Acid Rain and Terrestrial Collapse
- SO2 and toxic compounds rained onto land, damaging forests, soils, and freshwater ecosystems.
- Wildfires and loss of plant cover destabilized environments, leading to massive erosion and further feedbacks into climate and habitat loss.
Evidence for the Volcanic Hypothesis
Geologists have assembled multiple lines of evidence linking the end-Permian extinction to Siberian Traps volcanism:
- Mercury anomalies: Spikes in mercury levels in marine sediments worldwide at the boundary indicate heightened volcanic activity, as volcanic eruptions are a primary natural source of mercury.
- Isotopic signatures: Changes in carbon and oxygen isotope ratios in rock layers show both a massive injection of carbon into the atmosphere and an abrupt shift in ocean and climate conditions.
- Layer dating: The synchrony of volcanic deposits and extinction horizons in geographically separate regions supports a global-scale, rapid catastrophe.
Other Proposed (and Supplementary) Causes
| Proposed Cause | Description | Status |
|---|---|---|
| Asteroid Impact | Evidence for an impact is weak compared to the later dinosaur extinction, but not entirely ruled out as a contributing factor. | Disputed/Minor |
| Methane Release | Warming could have destabilized methane clathrates on the seafloor, releasing even more greenhouse gases and exacerbating warming. | Possible Feedback, not main cause |
| Ozone Depletion | Volcanic gases might have triggered chemical reactions depleting the ozone layer, increasing UV radiation and damaging ecosystems. | Plausible Secondary Effect |
| Sea Level Changes | Shallow seas disappeared as sea levels fell, destroying habitats and stressing coastal species. | Additional Stressor |
Patterns of Extinction and Survival
The Great Dying was not uniform. Some groups suffered total collapse, while a few lineages proved unexpectedly resilient:
- Marine life: Trilobites, rugose corals, blastoids, and many brachiopods were among those that vanished forever.
- Terrestrial vertebrates: Most primitive amphibians and synapsids died out; however, a handful—including ancestors of mammals and archosaurs—persisted and later radiated.
- Plants: Evidence suggests plants were affected but not to the same catastrophic degree as animals; many lineages survived, allowing quicker vegetational recovery in some regions.
- Insects: This event was the greatest mass extinction for insects, with pronounced losses among major orders.
Recovery from the Permian Extinction
Earth’s recovery from this extinction was protracted and difficult. Full ecosystem complexity may not have returned for 5–10 million years. Key features of recovery include:
- Slow resurgence of biodiversity: New groups, such as early dinosaurs and mammals, eventually exploited ecological niches left vacant by the extinction.
- Evolutionary innovation: The crisis set the stage for adaptive radiation and evolutionary experimentation in both terrestrial and marine ecosystems.
- Persistent stress: Episodes of further environmental instability occurred for millions of years in the Triassic.
Why the Permian Extinction Matters Today
Scientists view the Permian Extinction as both a warning and an analogue for present and future planetary change:
- Rapid climate change proved devastating to biodiversity, ecosystems, and planetary systems when planetary limits were exceeded.
- Runaway greenhouse conditions can be initiated by sustained large-scale carbon emissions, whether from ancient volcanoes or modern fossil fuel combustion.
- Systemic impacts; the collapse was not isolated to one group or place but cascaded across interconnected earth systems—in a pattern relevant to understanding risk in a human-driven Anthropocene.
Frequently Asked Questions (FAQs)
Q: What was the main cause of the Permian-Triassic extinction?
A: The overwhelming scientific consensus points to massive volcanic eruptions in the Siberian Traps that triggered planetary-scale greenhouse warming, ocean acidification, and widespread environmental collapse.
Q: How rapid was the Permian mass extinction?
A: The main extinction pulse may have occurred in less than 60,000 years, a geologically short span, with environmental upheaval lasting several million years.
Q: Did anything survive the Great Dying?
A: Yes, while most species perished, some lineages—including the ancestors of mammals, dinosaurs, and certain plants—survived and later thrived.
Q: Could an extinction event like this happen again?
A: While geologic-scale volcanic episodes are rare, today’s rapid anthropogenic carbon emissions are causing similarly severe environmental changes, raising concerns about future large-scale extinctions.
Q: What lessons does the Permian Extinction hold for today?
A: It highlights the dangers of unchecked climate change and the critical importance of understanding complex feedbacks in Earth’s biosphere and climate systems.
References
- https://news.mit.edu/2018/permian-period-extinction-0919
- https://www.nature.com/articles/s41467-019-09620-0
- https://www.frontiersin.org/news/2025/03/11/252-million-year-old-climate-crisis-permian-extinction-co2-frontiers-earth-sciences
- https://www.montclair.edu/newscenter/2023/03/02/new-study-uncovers-cause-of-end-permian-mass-extinction/
- https://en.wikipedia.org/wiki/Permian%E2%80%93Triassic_extinction_event
- https://pmc.ncbi.nlm.nih.gov/articles/PMC2596898/
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