Volcanic eruptions: towards a catastrophe before the end of the century?

What if the risks of major volcanic eruptions were much higher than we think? In Europe, we live with the idea that these events hardly pose a life-long threat. The incident that occurred on January 15 in the Tonga archipelago is nevertheless a wake-up call, warn two British researchers in an article in the journal Nature.

An explosion of an underwater volcano in the Tonga archipelago that day destroyed 90% of the uninhabited island of Hunga Tonga Ha’apai and formed an ash plume half the size of the France. In the aftermath, an atmospheric shock wave circled the Earth several times, and according to the calculations of CNRS scientists, the explosion threw into the air a volume of matter of about 10 km3, making it the most powerful to occur in the 21st century, with a force equivalent to that, devastating, of Pinatubo (Philippines) in 1991.

After such a shock, logic would dictate that we enter a long period of calm. However, nothing is less certain. “Recent data from ice cores suggest that the probability of an eruption of magnitude 7 or greater (10 to 100 times larger than Tonga) this century is 1 in 6,” warn Lara Mani, a researcher at the Center for the Study of Existential Risks (CSER) at the University of Cambridge and her colleague Mike Cassidy, based at the University of Birmingham. Eruptions of this magnitude have in the past caused abrupt climate change and even the collapse of civilizations. “However, little investment has been made to limit what they could do to us,” lament the scientists, who ask that the subject be taken more seriously.

Limited offer. 2 months for 1€ without commitment

“Not planning anything is reckless”

According to them, a major eruption poses as much risk as the fall of a large asteroid on Earth. However, if there is a plan and research to deflect possible threatening celestial bodies, nothing equivalent has emerged to try to counter the effects of an out of control volcano. Certainly, controversial studies have already considered the use of particles in the atmosphere to mitigate human-induced warming by deflecting solar radiation. But the reverse scenario (using particles to avoid cooling) hasn’t really caught the eye so far. “It is theoretically possible to release a short-lived heating agent, or to use a high-altitude aircraft to release non-toxic substances that bind to sulfur-containing aerosols, thereby promoting their removal from the atmosphere.” , assure the two authors of the article.

Of course, the use of these geoengineering techniques is up for debate. But to be rigorous, it must be based on a maximum of knowledge. “Not planning anything to respond to large eruptions is akin to recklessness,” the scientists warn. Thanks to ancient traces of sulfur in the ground, we now know that around 1,300 volcanoes have erupted in the past 10,000 years. However, of the 97 large-magnitude eruptions detected in ice core records, only a handful can be attributed to specific volcanoes. The location of other disasters remains a mystery.

L’application L’Express

To track analysis and decryption wherever you are

Download the app

At a time when the earth’s orbit is cluttered with thousands of satellites of all kinds, one might think that our surveillance system scrutinizes the slightest plume and accumulates data permanently. It is not so. Only about 27% of eruptions since 1950 have been monitored with at least one instrument such as a seismometer. Current satellites do not have the resolution necessary to closely study thermal changes, gas leaks or deformations of the ground… For more than two decades, volcanologists have been asking for dedicated observation devices without success. Often, they have to rely on the goodwill of private companies to obtain accurate images. Unacceptable for Lara Mani and Mike Cassidy: a one in six chance of seeing a disaster occur is the equivalent of a dice roll.