Blowing Off Steam
Another Icelandic volcano is primed to erupt. What can these events teach us about climate change?

It’s not quite a sharknado, but the possible impending eruption of a mile-high volcano under Iceland’s largest glacier represents a fascinating example of a real-life natural disaster combo—quite literally fire and ice. Seismologists have detected some 3,000 tremors in the vicinity of Bárðarbunga since Saturday, a sign that the mountain might just be ready to blow. [UPDATE: An eruption might have begun on August 23.]

Four years ago, the eruption of Eyjafjallajokull, another ice-covered Icelandic volcano, disrupted air travel, caused billions of dollars in economic losses, damaged air quality across Europe, and may have cost soccer giants FC Barcelona the Champions League title. But aside from being a threat to airplanes and sporting dynasties, sub-glacial volcanoes can actually teach scientists some important things about the history of life on earth (and perhaps beyond)—and even climate change.

First, let’s start with what happens when a sub-glacial volcano goes up. The combination of lava and ice can be explosive, as this video demonstrates:

“If you pour lava onto a sheet of ice, it sometimes effervesces,” says Ben Edwards, a glacial volcanologist at Dickinson College. This is similar to what happens when you drop a Mentos candy into a Diet Coke. “It’s not quite as vigorous as a Mentos-type eruption, but it’s pretty impressive,” Edwards says. That Mentos effect is what made the Eyjafjallajokull eruption so spectacular. Hot magma vaporized ice immediately, and the steam explosion sent an ash cloud billowing high into the atmosphere.

So what can everyone expect if Bárðarbunga erupts?

In Iceland:

It would be disruptive to agriculture and some other economic sectors, but they’re kind of used to it. Sub-glacial eruptions happen all the time on the island. Historians have found references to volcano-induced darkness in Icelandic writings dating back to the 13th century. During seismically busy periods—which scientists say we could be entering now—Bárðarbunga and its associates erupt approximately once every six years.

Still, local flooding could be particularly severe in this case, if an eruption were to melt significant chunks of the Vatnajokull glacier, one of the biggest in Europe.

In the rest of Europe:

It’s harder to say. The size of the cloud generated by a sub-glacial eruption depends on the thickness of the ice and the composition of the gases, and volcanologists can’t predict those interactions in advance. Wind also plays a big role; other Icelandic volcanoes erupted in 1996 and 2011, but you probably didn’t hear about them because, unlike with Eyjafjallajokull, the wind blew the fallout away from the rest of Europe. Since we don’t know exactly if and when the eruption will come, no one knows for sure which way the winds will be blowing.

In the natural world:

From an environmental perspective, the eruption of Bárðarbunga would likely be a relatively minor event. Four years after the Eyjafjallajokull eruption, you can barely see any signs of the incident. Snow has covered the crater, and new ice has largely filled the cracks in the glacier. And not much wildlife lives nearby, anyway (the Arctic fox is Iceland’s only native land mammal). Massive volcanic eruptions like the one from the Phillipines’ Mount Pinatubo in 1991 can alter global climate, but Iceland’s eruptions haven’t been that big—at least in recent history.

In scientific circles:

Glaciovolcanologists (yep, it’s a thing) have developed interesting theories from studying specimens like Bárðarbunga. For example, recent genetics research suggests that terrestrial animal life has existed on Antarctica for millions of years—findings that puzzled many scientists, who had assumed that every once in a while, Antarctica’s historic glacial periods would have wiped out all animal life (mostly tiny invertebrates) on the continent. Sub-glacial volcanoes may be a key to this mystery.

“Where heat from a volcano’s magma chamber reaches the surface, it melts cavities in the ice,” says John Smellie, a professor of volcanology at the University of Leicester in the United Kingdom. “There you have warmth and moisture and possibly light. Sub-glacial volcanoes may have created safe havens where life could survive.”

Glacial volcano research also helps improve climate change modeling by preserving a record of ice sheets that melted long ago. Think of the ice as a sort of cast for a lava sculpture. “When a volcano erupts, it copies the ice in a sense,” says Smellie. “The ice tells the volcano how to erupt, when it can erupt, and what kind of lava forms.”

Smellie’s volcano research shows, for example, that the East Antarctic ice sheet is not the solid, unchanging block of ice we once thought it was. It is a fluid patchwork of subterranean rivers, rock, and shifting ice layers. How this moving mass of ice behaves is important information for climate change forecasts. The East Antarctic ice sheet is the largest in the world. If it collapses, it could raise global sea levels by more than 100 feet. Smellie’s research contributes to our understanding of how and when that might happen.

Now let’s talk Mars for a moment. In the 1980s, long before we landed a single rover on the Red Planet, volcanologists recognized the remnants of sub-glacial volcanic activity in satellite images. Not only did the evidence help prove the existence of water there (which provides at least a glimmer of hope for life), but the photos also suggested that ice covered the Martian equator during some periods (think thousands of years), and the poles at other times.

We now understand that the extreme tilting of Mars’s axis toward and away from the sun drastically affects the planet’s hydrological cycle. We know about these icy “seasons” 140 million miles away because of what’s rumbling beneath our own ice. Cool.

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