- The Great Dying, formally known as the Permian–Triassic extinction event, was the most catastrophic mass extinction in Earth’s history, occurring about 252 million years ago at the boundary between the Permian and Triassic periods.
- It is estimated that around 90–96% of marine species and 70–75% of terrestrial vertebrate species perished, along with countless plants and insects. This event fundamentally reshaped life on Earth, wiping out dominant ecosystems of the late Paleozoic Era and paving the way for the rise of dinosaurs and, much later, mammals. The sheer scale of the Great Dying surpasses all other extinction events, including the one that ended the age of the dinosaurs 66 million years ago.
- The causes of the Great Dying remain the subject of intense scientific study, but most evidence points to a cascade of environmental catastrophes triggered by massive volcanic eruptions in Siberia, known as the Siberian Traps. These eruptions released enormous amounts of lava, ash, and greenhouse gases, especially carbon dioxide and methane, into the atmosphere. The resulting global warming is believed to have raised average temperatures by as much as 8–10°C. Oceans warmed significantly, reducing their oxygen content and triggering widespread anoxia (oxygen depletion). Methane release from destabilized seafloor deposits may have further amplified greenhouse conditions, creating a runaway climate crisis.
- The environmental consequences of these changes were devastating. In the oceans, rising acidity and declining oxygen levels led to the collapse of reef ecosystems, mass die-offs of trilobites, brachiopods, and many other groups, and the near-total disappearance of certain plankton populations that formed the base of marine food chains. On land, extreme heat and aridification destroyed forests and swamps, leading to widespread desertification. Many amphibians and early reptile lineages vanished, while only a few resilient groups survived, such as the ancestors of modern reptiles and mammals. The devastation was so profound that entire ecological structures collapsed, forcing life to rebuild from a drastically reduced foundation.
- Recovery from the Great Dying was slow and uneven, taking an estimated 5 to 10 million years for ecosystems to stabilize. Early Triassic environments were often dominated by disaster taxa—hardy organisms capable of surviving in stressed ecosystems with limited competition. These included certain types of bivalves in the seas and hardy reptilian lineages on land. Eventually, new evolutionary opportunities opened up: the extinction cleared ecological space for archosaurs (ancestors of crocodiles, dinosaurs, and birds) and early synapsids (ancestors of mammals), which would become central players in the next phase of Earth’s history.
- The Great Dying remains a sobering reminder of the fragility of life in the face of environmental upheaval. It demonstrates how interconnected climate, geology, and biology are, and how rapid planetary changes can disrupt even the most resilient ecosystems. By studying this extinction event, scientists not only gain insight into the ancient past but also find warnings relevant to modern times, as human-driven climate change, ocean acidification, and habitat destruction echo some of the very processes that contributed to Earth’s greatest biological crisis.
