The Age of Supereruptions: Effects on Life

All of us, young and old, belong to an anxious generation.  The ever-present threat of nuclear war heightens our perception of risks.

A good example is how, back around the turn of the century, after media reports surfaced that Yellowstone is a supervolcano, most laypeople, including me, pictured the environmental consequences of any Yellowstone eruption as a global nuclear winter.

We can relax a little about that.  No scientific law requires supervolcanoes to always have supereruptions.

According to volcanologists, chances for another supereruption at Yellowstone are 1 in 730,000, or 0.000014%.

Nevertheless, our planet is still more likely to experience a supereruption somewhere on its surface than a large meteorite impact. (Self)

We must prepare for life during and after a supereruption.  But since one hasn’t happened in recorded history yet (Oppenheimer), how can we know what to expect?

Supereruption scenarios

While we laypeople and the media try to get psyched for the volcanic apocalypse with doomsday documentaries and fiction, researchers are using supercomputers to model supereruptions as realistically as possible.  (See, for instance, Jones and others; Mastin and others; Oppenheimer, Chapter 14; Sparks, Self, and others; Self)

Scientists have three types of data to work with:

  • Evidence of past supereruptions from the geologic record, which may include ice cores as well rock formations and deep sea drilling.
  • Well-documented “normal” eruptions, like Mount Pinatubo’s magnitude 6.1 (Oppenheimer) eruption in 1991, in which hypothetical extreme values can be substituted.
  • Fossil evidence from living beings near a supereruption.  It was signs of lung disease in plant eaters that first clued investigators in on the long-distance lethal effects from one of Yellowstone’s supereruptions.  (BBC)

Some model results, based on data from Earth’s last known ignimbrite eruption, which happened at Indonesia’s Toba volcano 74,000 years ago, show that this magnitude 8.8 (Mason and others) cataclysm could have triggered a global chill. (Rampino and Self)

The “volcanic winter” scenario is indeed one possibility . . . but there are others that are much more benign.

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