Around 201.6 million years ago, one of Earth’s most significant mass extinctions occurred, wiping out three-quarters of all living species.
This event marked the transition from the Triassic to the Jurassic period and set the stage for dinosaurs to thrive and dominate the planet.
The extinction coincided with massive volcanic eruptions that broke apart the supercontinent Pangaea, which included almost all of Earth’s landmasses at the time.
Scientists have long believed that these eruptions from the Central Atlantic Magmatic Province (CAMP) released large amounts of carbon dioxide (CO2), leading to increased global temperatures and ocean acidification.
However, a new study led by researchers from Columbia Climate School’s Lamont-Doherty Earth Observatory suggests the opposite: it wasn’t heat, but intense cold, that caused the mass extinction.
The study proposes that instead of spreading out over hundreds of thousands of years, the initial volcanic eruptions occurred in quick, powerful bursts that each lasted less than a century.
These rapid eruptions released massive amounts of sunlight-reflecting sulfate particles into the atmosphere, causing dramatic cooling, or “volcanic winters,” that many species couldn’t survive.
Lead author Dennis Kent explains, “Carbon dioxide takes a long time to build up and heat things, but the effect of sulfates is almost instant.”
This rapid cooling is similar to what humans can understand in a single lifetime. The researchers believe that the short-term, intense volcanic winters caused by sulfates were the primary drivers of the mass extinction, while the gradual rise in CO2 may have played a secondary role over time.
To reach these conclusions, the team studied ancient lava deposits from CAMP in Morocco, Nova Scotia’s Bay of Fundy, and New Jersey’s Newark Basin.
By analyzing the magnetic particles in these rocks, scientists could track shifts in Earth’s magnetic pole over time. They found that five major lava pulses occurred over about 40,000 years.
Each pulse, they estimated, erupted in less than 100 years—too fast for the magnetic pole to shift direction. This timing suggests that the pulses were highly concentrated events, releasing vast amounts of volcanic gases quickly.
The study compared these volcanic eruptions to Iceland’s Laki eruption in 1783, which caused crop failures and hardships across Europe. However, these CAMP eruptions were hundreds of times larger and more impactful, leading to massive environmental changes.
Below the volcanic layers, researchers found fossils of large Triassic animals like crocodile relatives, tree lizards, and giant amphibians, which vanished after the eruptions. In contrast, smaller feathered dinosaurs, turtles, lizards, and mammals survived, possibly due to their size and ability to shelter in burrows.
The findings highlight how concentrated volcanic events can cause significant environmental shifts. Co-author Paul Olsen noted, “Small events spread out over thousands of years are much less impactful than the same amount of volcanism happening in less than a century.”
This new understanding shifts the narrative, suggesting that sudden, intense volcanic cold spells were key to this ancient extinction, paving the way for dinosaurs to dominate the Jurassic period.
