The greatest mass extinction that ever visited this world took place roughly 250 million years ago, wiping out as much as 96 percent of all species. We know that it was volcanically-induced climate change that brought biology to the brink, but a new Scientific Reports study reveals just how widespread that volcanism was.
This mass extinction is sometimes called a Murder on the Orient Express scenario in that – major spoiler alert ahead – multiple antagonists caused the killing. At the start, you had catastrophic volcanism emerging from the Siberian Traps. A continent-sized lava flow that lasted for a million years, it released tens of trillions of tonnes of greenhouse gases and sunlight-blocking aerosols.
Initially, the aerosols took hold, and global temperatures plunged; without much solar radiation, photosynthesis in the oceans and on the land stalled, and food chains began to collapse. Then, carbon dioxide took hold as the planet experienced a sudden global warming event – two deadly extremes that life simply couldn’t adapt to fast enough.
A team of researchers led by New York University were curious about the true extent of this volcanic trigger. Looking at geological deposits in places all over the world, from the Arctic Circle to India and beyond, they found that there was a planet-wide spike in nickel at the time of the eruption.
This shows, according to a statement by NYU geologist and senior author Michael Rampino, that “the Siberian volcanic eruptions and related massive intrusions of nickel-rich magmas… apparently emitted nickel-rich volatiles into the atmosphere.”
The eruption was so extensive that these nickel deposits are now found all over the world. They are dramatic chemical markers that confirm the scale of the vicious volcanism.
Frighteningly, at this point, the apocalypse had just gotten started.
The warmer and more acidic oceans were destabilizing for the massive reserves of frozen methane on the seafloor. When this shorter lived but far more potent greenhouse gas was released, it's likely plenty of it made it into the atmosphere, leading to the Panthalassic and Tethys oceans becoming warmer and more acidic over time. Life was broiled and even a little dissolved all over the planet.
This massive uptick in carbon dioxide and methane unbalanced the chemistry of the planet; the rising temperatures and die-off of plant and algal life triggered the removal of a major gas – oxygen. Levels of this vital element plunged so much that life essentially began to suffocate.
All in all, from what started as a single lava flow effusing from what is now Siberia, a climate change-driven end of days was wrought. If it was slightly worse, it could have completely sterilized the planet, and we wouldn’t be here to learn about how a lucky 4 percent pulled through and gave rise to everything alive today.