Since the appearance of life more than 3.8 billion years ago, Earth has experienced many episodes of accelerated species loss. But five crises exceed all others in their violence and scale. They are called mass extinctions. They eradicated up to 96% of marine species and forever altered ecosystems. After each disaster, certain species take advantage of the freed ecological niches, allowing them to diversify into new ecosystems.
The modern notion of mass extinction was popularized by American paleontologists Jack Sepkoski (1948-1999) and David M. Raup (1933-2015). Scientists consider an extinction to be "major" when it leads to the disappearance of at least 75% of species in a geologically brief period, generally less than 2 million years.
| Extinction Name | Date (million years) | Percentage of Extinct Species | Main Causes | Notable Consequences |
|---|---|---|---|---|
| Ordovician-Silurian | ~ 445 (Late Ordovician) | ~ 85% (no land life yet) | Massive glaciation, drop in sea level, ocean anoxia | Disappearance of conodonts and many trilobite families |
| Late Devonian | ~ 372 | ~ 75% (no land life yet) | Volcanic eruptions (traps), global anoxic events | Extinction of trilobites and collapse of stromatoporoid reefs |
| Permian-Triassic | ~ 252 | ~ 96% (marine) and ~70% (terrestrial) | Siberian Traps (giant volcanism), extreme global warming, ocean acidification | Collapse of marine life, known as the Great Dying, marked the most severe mass extinction in Earth's history |
| Triassic-Jurassic | ~ 201 | ~ 80% (marine and terrestrial) | Central Atlantic Magmatic Province volcanism, greenhouse gas emissions | Disappearance of large marine reptiles, early flying reptiles, and decline of primitive crocodilians |
| Cretaceous-Paleogene (formerly Cretaceous-Tertiary) | ~ 66 | ~ 76% (marine and terrestrial) | Chicxulub asteroid impact (Yucatán) + Deccan Traps | Extinction of non-avian dinosaurs and ammonites |
The drift of Gondwana toward the South Pole caused a sudden glaciation. Falling sea levels, ocean anoxia, and the collapse of trilobite and primitive coral reefs followed. 85% of species vanished, making it the 2nd deadliest extinction.
The first land forests destabilized soils. Excess nutrients suffocated the oceans (anoxia, acidification). Collapse of stromatoporoid and coral reefs. Disappearance of trilobites, goniatites, and armored fish. ~75% of marine species extinct, a slow crisis over 20 million years.
The Siberian Traps (giant volcanism) released CO₂ and methane. Extreme warming (+40°C in oceans), acidification, global anoxia, and toxic atmosphere. 96% of marine species and 70% of land vertebrates vanished, the worst crisis of life. 10 million years were needed to rebuild ecosystems.
Giant volcanism in the CAMP (Central Atlantic) caused massive global warming. Disappearance of conodonts (oceans), decline of primitive ichthyosaurs, extinction of early flying reptiles and primitive crocodilians (land). ~80% of species extinct; dinosaurs took advantage of the ecological void to dominate the Jurassic.
A 10 km asteroid hit Chicxulub (Mexico). Nuclear winter: dust blocked the sun for years. Collapse of food chains. Extinction of non-avian dinosaurs (land), ammonites, and mosasaurs (seas). ~76% of species extinct; mammals became the new masters of the planet.
If the five great mass extinctions teach us one thing, it is the paradoxical power of resilience. On one hand, life is strikingly fragile: glaciation, giant volcanic eruptions, or cosmic impacts can annihilate in a few thousand years what evolution patiently built over hundreds of millions of years. On the other, life is almost inexplicably tenacious: even after the Great Dying of the Permian-Triassic, life always ended up diversifying.
Fossil records are clear: after every major crisis, new groups appear. After the Ordovician-Silurian extinction, jawed fish flourished, replacing faunas dominated by trilobites and brachiopods. After the Late Devonian crisis, which saw the collapse of stromatoporoid reefs, amphibians emerged from the waters and colonized land, while the first winged insects appeared. After the Permian-Triassic Great Dying, the most devastating of all, dinosaurs—mere marginal reptiles at the start of the Triassic—became masters of the world for the next 135 million years. After the Cretaceous-Paleogene impact, mammals, small nocturnal creatures hiding in the shadows of dinosaurs, took off and diversified. Life does not just survive: it reinvents itself. However, this reinvention has a price, and that price is time. A time so dizzying (several million years) that it exceeds the limits of our perception.
The great extinctions reveal an essential truth: if life never truly goes out, it possesses the gift of forgetting. It is reborn constantly, with infinite patience, fitting into the immutable rhythm of the stars and galaxies, far beyond the human scale.
The Five Mass Extinctions: What do these planetary catastrophes reveal? 
Cryosphere: when the ice giants still protect us
The Nitrogen Cycle: From Air to Life 
The Jet Stream: When the Atmospheric River Overflows Its Banks 
The Carbon Cycle: The Harmonious Interaction of Oceans, Forests, and Subsoils 
Fatal Imbalance: The Unsuspected Power of the Infinitely Small 
The Water Paradox: Without it, no life 
Why 220V Alternating Current is in Our Outlets: A Matter of Physics 
The Last Glacial Shock: The Younger Dryas and Its Impact on Prehistoric Societies 
536: The Year Without a Summer and the Beginning of the Late Antique Little Ice Age 
The Minimal Cell: The Inevitable Emergence 
Evolution of Global Energy Consumption: From Steam Engines to Digital Servers 
The Demographic Transition: Growth or Decline? 
Lake Agassiz: A Deluge that Changed the Climate 
Drunken Forests: Understanding the Phenomenon of Permafrost Thaw 
There is Electricity in the Air! 
Why Doesn't CO2 Fall to the Ground? 
El Niño and La Niña: The Two Breaths of the Pacific That Shape Global Climate 
Endangered Species: Dynamics of Extinction 
The Toxic Legacy of Acid Rain 
Global Warming in Figures: What the Scientific Data Says 
What is Sustainable Development? 
The Aral Sea: A Lesson for Humanity 
Three Gorges Dam: Impacts on Ecosystems 
The Hottest Years Since Records Began 
Magnitude of future global warming 
Earth in Crisis: Collapse or Renaissance? 
Ice on the Brink: The Inevitable Decline of Arctic Sea Ice 
Earth's Water Reservoirs: From Oceans to Groundwater 
Sea Levels Are Rising, But How Fast? 
The Other Climate Threat: Earth Shrouded in Shadow and Humidity 
The Age of the Sahara: From Green Prairie to Stone Desert 
World Population from 1800 to 2100 
Oil: The Fall of a Giant in the Era of Renewable Energy 
Kamchatka King Crab: A Giant of the Oceans 
The
collapse of a society 
Slight Progress in the Global Ecological Footprint 
The South Atlantic Anomaly 
The phenomenon of soil sinking is called subsidence 
The disturbing cloud cover of the Earth 
The Planet's New Clouds
Desertec: A Solar Dream for Europe and Africa