~444 000 000 years ago species lost: ~85% of marine life
almost all life lived in the oceans, sudden, massive ice age caused sea levels to drop drastically, destroying shallow coastal habitats. When the glaciers later melted rapidly, ocean oxygen levels plummeted, suffocating the surviving marine species.
~375–360 000 000 years ago species lost: ~75% of all species
rapid evolution of early land plants caused them to develop deep roots, which broke down rocks and released massive amounts of nutrients into the oceans, this triggered colossal algal blooms that sucked all the oxygen out of the water (eutrophication), starving marine life.
~252 000 000 years ago species lost: ~96% of marine life and 70% of land life
massive volcanic eruptions in the Siberian Traps pumped huge amounts of CO₂ into the air, triggering catastrophic global warming, ocean acidification, and a near-total loss of marine oxygen, and extinciton of trilobites.
~201 000 000 years ago species lost: ~80% of all species
massive volcanic activity occurred as the supercontinent Pangea began to split apart. The erupting volcanoes released huge volumes of greenhouse gases, causing rapid climate change and ocean acidification. This event cleared out large competitors and predators, directly allowing early dinosaurs to grow massive and dominate the planet.
~66 000 000 years ago species lost: ~75% of all species
massive 6-mile-wide asteroid slammed into Earth near the modern-day Yucatan Peninsula in Mexico, creating the Chicxulub crater. The impact launched trillions of tons of dust and soot into the atmosphere, blocking out the sun and triggering a global "impact winter" that collapsed food chains and ended the reign of the non-avian dinosaurs.
The Vulnerability: Large mammals, amphibians, and island-dwelling species are being hit the hardest. According to global biodiversity assessments, roughly 1 million plant and animal species currently face extinction within the coming decades.
process of ecological self-healing is slow, typically taking 2 to 10 million years to fully restore pre-extinction biodiversity levels:
- after the crash, a tiny handful of extremely hardy, opportunistic species take over. With competitors and predators gone, these "weed-like" species multiply exponentially, creating incredibly uniform, low-diversity landscapes across the globe.
- microbial and Planktonic Recovery: The foundation of the food web heals first. Microscopic ocean plankton and land plants stabilize their numbers, resetting the planetary carbon and oxygen cycles.
- ecological Release and Speciation: As the environment stabilizes, the surviving generalists begin to adapt to the empty habitats. A single surviving lineage will rapidly branch out into dozens of new species to fill vacant roles (e.g., small mammals rapidly evolving to fill the massive roles left behind by extinct dinosaurs).
- Complex Web Rebuilding: Finally, top predators and highly specialized species reappear, locking the ecosystem back into a resilient, stable state.