The Great Dying: A Quarter-Billion Years Ago, Earth Faced Catastrophic Extinction Events
Life was put to the ultimate test a quarter-billion years ago as extinction events ravaged Earth’s biosphere, leaving a mere handful of species to claw their way back to survival.
A new study suggests that prolonged, intense climate fluctuations, similar to modern El Niños, exacerbated the ‘Great Dying’, driving many species to the brink of extinction.
Using proxies to measure seawater temperatures and updated climate modeling, an international team led by China University of Geosciences geologist Yadong Sun simulated the oceanic and atmospheric currents 250 million years ago.
Prior to the catastrophic extinctions, life had diversified, with forests of conifers and ancestors of modern mammals, birds, and reptiles thriving in a world with a single global ocean surrounding the continents.
However, a series of catastrophic events led to the extinction of many species, with as few as 10 percent of tetrapods surviving to found future generations. Ocean species faced a similar fate, with only one in five species surviving.
Researchers are puzzled by the severity of this period of mass extinction and have identified volcanic activity in Siberia around the Permian-Triassic boundary 252 million years ago as a significant contributing factor.
The team suspects that constant volcanic eruptions led to ozone depletion, increased carbon dioxide levels, and microbial blooms that disrupted the balance of oxygen in the oceans.
Large, short-term fluctuations in temperature and precipitation may have also played a role in exacerbating the extinction events, as seen in modern-day climate variations causing ecological losses.
By analyzing oxygen isotopes in ancient marine life fossils, researchers estimated temperature changes and suggested weakened atmospheric air currents could have contributed to the crisis.
Similar to modern El Niño events, ‘mega’ El Niño periods at the end of the Permian could have intensified climate shifts, making it difficult for species to adapt and leading to widespread extinctions.
While more evidence is needed to confirm these findings, the research sheds light on the potential impact of climate fluctuations on global ecosystems, especially in the face of a growing climate crisis.
Life eventually rebounded after the Great Dying, but the event serves as a stark reminder of the fragility of all species in the face of environmental challenges.
This research was published in Science.
