Massive Supereruptions Might Not Trigger the Apocalypse, Just Decades of Chaos

Finally, there’s some good news on the climate apocalypse front.

Climate experts have long believed that a volcanic supereruption—a mind-bendingly powerful explosion capable of altering Earth’s atmosphere—could wipe out a significant portion of life. But a new survey of geological records suggests the aftermath wouldn’t be quite as apocalyptic. It would still be bad—just not end-of-the-world-as-we-know-it bad.

This refreshing burst of optimism comes courtesy of a group of University of St. Andrews environmental scientists who were examining ice cores pulled from Greenland and Antarctica, as well as sediment cores from near the equator in the Pacific.

The cores contained tiny specks of ash, embedded in layers connected to the time period of the Los Chocoyos supereruption, which occurred in what is now known as Guatemala’s Atitlán caldera. While the Smithsonian’s Global Volcanism Project dates the eruption to 84,000 years ago, St. Andrews geologists claim to have more accurately dated the ash to 79,500 years ago.

Just for a frame of reference, the most powerful eruption in recent memory occurred on June 12, 1991, when the Philippines’ Mount Pinatubo finally blew, after months of earthquakes and magma slowly seeping to the top. The resulting ash cloud was 22 miles (35 kilometers) high, and 20 million tons of sulfur was emitted into the atmosphere, leading to a 1 degree F (0.5 C) drop in global temperatures from 1991 to 1993, according to the U.S. Geological Survey. So much rock and magma was ejected that the mountain’s shape was irrevocably altered, leaving behind a depression called a caldera that was 1.6 miles (2.5 kilometers) across. Because the signs of eruption were caught early, thousands of people were able to leave the area beforehand and commercial air travel steered clear. Even so, the force was so huge, $100 million of damage was caused to jets flying hundreds of kilometers away.

That eruption measured only a 6 on the Volcanic Explosivity Index. Los Chocoyos comes in at an 8, the lowest score required to register as a supereruption, which would still make it 100 times more powerful than Pinatubo.

https://gizmodo.com/ancient-residue-reveals-69-volcanic-eruptions-bigger-th-1848673029https://gizmodo.com/ancient-residue-reveals-69-volcanic-eruptions-bigger-th-1848673029

As for what effects Los Chocoyos had, the environmental scientists reported in Communications Earth and Environment that the cores do indicate a cooling effect that lasted between 10 and 20 years, a far cry from a worst case scenario of plummeting temperatures that lasted for 1,000 years or more. That likely led to an increase in the amount of sea ice, but things likely returned to normal after 30 years or so.

While the eruption predates human writing, or even speech, modern humans were roaming around at that time. Given that we’re still here, it appears Homo sapiens, and many other species, are capable of surviving these types of cataclysmic events. Fortunately, we likely won’t have to find out for ourselves, as supereruptions are rare. The last known one occurred 25,500 years ago in New Zealand, an event known as the Oruanui eruption.

“Our findings improve our understanding of how resilient the climate can be to supereruption-scale injections of stratospheric sulphate,” said Helen Innes, a research fellow at the University of St. Andrews who led the study, in a statement. “Continuing to identify the largest volcanic eruptions in ice cores and assign high-precision ages is essential to our understanding of the risk that major stratospheric sulphate injections pose to global climate.”

Ultimately, what this means is that even Mother Nature at her most violent might not wipe us out. We may yet destroy ourselves by doing damage to the environment that won’t be reversed for millennia, but that means our fate is in our hands. Whether that’s a positive notion or not depends entirely on how optimistic you feel about humankind’s collective sense of self preservation.