About 201.6 million years ago, Earth experienced one of the most catastrophic mass extinctions, wiping out almost 75% of all species. This turmoil, which marked the transition from the Triassic to the Jurassic period, coincided with powerful volcanic eruptions that ripped apart the supercontinent Pangea, paving the way for dinosaur dominance.
What caused the mass extinction?
However, despite decades of research, the mechanisms behind this extinction remain unclear. The most prominent theory suggested that volcanic carbon dioxide (CO2) increased global temperatures, leading to extreme ocean warming and acidification that proved unsustainable for most species.
A new study published in the Proceedings of the National Academy of Sciences challenges this long-held belief and provides evidence that the primary trigger is strong cooling from volcanic sulfates rather than warming.
The study suggests that volcanic winters caused by massive, short-lived lava eruptions plunged the planet into bitter cold, instantly disrupting ecosystems that had long adapted to a warmer climate.
Volcanic cooling as the main factor
The team, led by Dennis Kent of Columbia University’s Lamont-Dougherty Earth Observatory, analyzed data from the Mid-Atlantic Igneous Province (CAMP), a volcanic region that erupted when Pangea broke apart.
Unlike the gradual accumulation of CO2, which would cause warming over thousands of years, volcanic sulfate aerosols have an almost immediate cooling effect by reflecting sunlight from the Earth.
“Carbon dioxide and sulfates act not only in opposite ways, but also in opposite time periods. Carbon dioxide takes a long time to form and heat up, but the effect of sulfates is almost instantaneous,” Kent explained.
This new understanding places the initial events that led to the extinction within a “lifespan” time frame. This makes it relevant to humanity’s current understanding of rapid climate change, Kent notes.
The mysterious effect of explosions
The Triassic-Jurassic extinction has long been associated with CAMP eruptions, but the timing and intensity of these eruptions are unclear. In an earlier study in 2013, Kent and colleagues linked CAMP to this extinction through permanent magnetic polarity in rock layers and identified near-simultaneous extinction times in present-day North America, Europe, and northern Africa.
However, the actual size and impact of these explosions remain a matter of debate; most people assume that these occurred gradually over thousands of years.
Magnetic evidence of catastrophic explosions
The current study provides a clearer picture by examining magnetic particles in rocks from Morocco, the Bay of Fundy in Nova Scotia, and the Newark Basin in New Jersey. By magnetically aligning particles preserved in these lava deposits, Kent and his team found that each of the first five eruptions occurred in less than 100 years; This is too short a time for the Earth’s magnetic pole to change enough to change the direction of the particles.
These findings show that the explosions were actually monumental, intense blows. The impact of small events spread out over tens of thousands of years has a much smaller impact than the same total volume of volcanism concentrated over less than a century, according to study co-author Paul Olsen, a paleontologist at Lamont-Dougherty.
This concentration likely released large amounts of sulfate quickly enough to create the large-scale cooling that caused ecological collapse.
Destructive effects of volcanic cooling
The cooling effect of sulfate aerosols is short-lived, unlike CO2. Sulfates tend to fall from the atmosphere within a few years, leading to temporary but extreme volcanic winters.
However, the rapid and intense pulses of CAMP eruptions would be hundreds of times more powerful than the Laki eruption in Iceland in 1783, causing repeated severe cold snaps, leading to major crop failures and climate disturbances across Europe.
In CAMP regions, temperatures have dropped significantly and ecosystems have fundamentally changed. Sediments just below the first CAMP lava flow reveal fossils of Triassic animals such as large semi-aquatic relatives of crocodiles, arboreal lizards, and flat-headed amphibians.
They disappear above these layers of lava. Small feathered dinosaurs and early mammals, which were already extant but of limited diversity, appear to have survived, perhaps because of their smaller size, ability to burrow into the ground, or other adaptive features that helped them survive colder conditions.
Rapid climate change: Lessons from the past
This revised chronology and understanding of CAMP eruptions not only transforms our understanding of the Triassic-Jurassic extinction but also highlights how intense environmental shocks can cause rapid, large-scale destruction.
The authors suggest that the massive and sudden release of volcanic sulfates led to a radical adaptation in which only a few resistant species survived. These findings resonate today as we face accelerating climate change, highlighting the potentially devastating consequences of rapid environmental changes.
Kent and his team’s research suggests that Triassic-Jurassic extinctions may be a lesson in environmental instability, as extreme cold wiped out many species long before prolonged heat took their toll. According to Olsen, the extent of environmental consequences depends on the intensity of the events. This research’s look at past mass extinctions offers insight into today’s ecological challenges, reminding us of the power and unpredictability of planetary forces.
Source: Port Altele
