Yellowstone’s supervolcano gets all the attention these days, but it’s not the only vessel of apocalyptic eruptions. Today, there are several spots around the world that could bring about a game-changing eruption, and volcanologists are always on the hunt for ancient ones that until now have slipped beneath the radar.
Now it seems that they’ve confirmed another, and it’s been hiding in the Pacific Northwest. Writing in the journal Geology, the team – led by Washington State University (WSU) – explained that although the eruption has been known about for some time, geochemical analysis of its remnants reveals just how spectacular it was.
It began erupting 16.5 million years ago, and didn’t stop for tens of thousands of years; in doing so, it deposited up to 276 billion tonnes (305 billion US tons) of sulfur dioxide into the atmosphere, which turned into an unfathomably widespread acid rainstorm.
Sulfuric acid also happens to be a compound that’s a potent deflector of sunlight. When Mount Tambora erupted in 1815, for example, it released so much of the stuff that the Northern Hemisphere lacked a distinctive summer the following year.
That’s nothing compared to the Columbia River Flood Basalts (CRFB), whose sulfur output was 4,000 times that of Tambora. This is the equivalent of one Tambora paroxysm “every day for 11 to 16 years,” according to the researchers.
At the time, the planet was going through a warming spike known as the Miocene Climatic Optimum. However, this eruption coincided with a significant dip in global temperatures during its heyday, suggesting that its sulfuric belch was enough to quickly chill the planet.
Study co-author John Wolff, a professor of environmental science at WSU, said in a statement that a similar eruption today “would devastate modern society globally.”
“Supereruptions” are normally associated with heat, and understandably so. Whether they are quick, explosive, and feature pyroclastic flows, or they’re slow, effusive, and characterized by rivers of lava, many of them inject a considerable amount of carbon dioxide into the atmosphere, triggering global warming events.
There are those that also unleash a lot of sunlight-reflecting sulfur aerosols into the air, which initiates rapid global freezing. Take the eruption in Greenland, 717 million years ago, for example, that turned the planet into a gigantic snowball.
The CRFB was more like the latter than the former. It helps to explain a near-unprecedented cooling event that has been left without a viable antagonist ever since it was discovered.
You may have noticed that it’s termed a “flood basalt”. Emerging from fissures as fire fountains and lava flows, these eruptions build into a fiery sheet that seems to perpetually emerge from the hellish bowels of the planet.
This particular event was the third most significant flood basalt on the planet, topped only by the Deccan Traps – the one that accompanied the asteroid strike that finished off the age of the dinosaurs – and the Siberian Traps – the one that triggered the Great Dying, the most severe mass extinction ever known. Unlike the CRFB, these two events both chilled then boiled the planet by releasing a combination of sulfur aerosols and greenhouse gases.
In any case, whether it’s serious warming or serious cooling, it’s clear that flood basalts have the power to change the world and bring about an era of death – far more so than any explosive, Yellowstone-like supereruption.
Had the planet not enjoyed a 50 million year warming period at the time of the CRFB, there’s a chance it could have led to yet another mass extinction, one that might have altered the course of evolution in ways we can only imagine.
