Sources: ‘Global Mapping of Future Glaciovolcanism’ Global and Planetary Change, December 2020; ‘A new volcanic province: an inventory of subglacial volcanoes in West Antarctica’, Geological Society, London, May 2017
The effects wouldn’t end there. Eruptions rich in carbon dioxide, a greenhouse gas, could exacerbate global warming, outlasting the sulphur aerosols in the atmosphere that can cause initial periods of cooling. And the volcanoes now known to sit under the West Antarctic Ice Sheet could help speed ice melt into the ocean, raising sea levels.
Evidence suggests that what happened in Iceland after the last Ice Age was duplicated to a lesser extent around the world. Eruptions were between 2 and 6 times higher globally between 12,000 and 7,000 years ago owing to more frequent eruptions in areas that were losing their ice cover, according to a 2009 study in the journal Earth and Planetary Science Letters.
A violent history
Iceland is uniquely primed for frequent volcanic eruptions because of its location at the juncture of two tectonic plates that are pulling apart over an upwelling of anomalously hot material in the Earth’s mantle. Many smaller eruptions have little impact beyond their immediate vicinity, though they are still able to put on spectacular shows. Others can have lethal effects far beyond Iceland.
When Laki, southwest of Askja, erupted in 1783-84, the fluorine it expelled contaminated the island’s plants and water sources, killing more than half of Iceland’s livestock. This agricultural collapse led to a famine that killed around a fifth of the island’s human population, while the resulting haze of sulphurous fog that later reached Europe may have contributed to the deaths of thousands more people. And as far away as Africa and Asia, the eruption’s effects weakened monsoons, initiating more famines.
Near the southern coast under a small ice cap lies Katla, considered one of the world’s most dangerous volcanoes under ice. Katla has racked up more than 20 eruptions since the Middle Ages, averaging one every 60 years, and it is past due for another, having last erupted in 1918. During that eruption, heat pouring from Katla’s caldera rapidly melted the ice atop the volcano, releasing a torrent of water greater than the combined discharges of the Amazon, Mississippi, and Yangtze rivers at its peak. And, like Laki, Katla has explosive potential.
“The time for Katla to erupt is coming close … It is high time for European governments and airline authorities all over Europe and the world to start planning for the eventual Katla eruption,” then-Icelandic President Olafur Ragnar Grimsson told BBC News in 2010, following the eruption of Eyjafjallajökull. The ash cloud from that eruption caused €1.3 billion (US$1.4 billion) in losses from cancelled flights during a six-day European airspace ban, making it the world’s costliest eruption in the last century.
The Icelandic government has emergency plans in place for a Katla-style eruption and works with local police districts to create near-term risk assessments for other volcanoes.
But the government has also tapped its fiery foundation to its benefit, using it to heat homes and businesses and draw big-spending tourists to rejuvenating geothermal baths. After the Eyjafjallajökull eruption, the Icelandic government made volcanoes a pillar of a now multibillion-dollar tourism industry. Souvenir shops in the capital, Reykjavik, sell lava rocks from a recent eruption on the Reykjanes Peninsula for 2,000 Icelandic krona (US$14) apiece.
“Watching your friends disappear”
Like many Icelanders, 29-year-old Iris Ragnarsdottir Pedersen and her father, 62-year-old Ragnar Frank Kristjansson, have an intimate knowledge of the extremes of their land of ice and fire. Along the south coast in Svinafell, Ragnarsdottir Pedersen, a mountain guide, lives with her husband and their Icelandic sheepdog, Blika. Her father, a retired national park manager, has a small turf-roofed summer house next door. Towering over them is a large cliff, beyond which lies Vatnajokull ice cap and, under it, the volcano Oraefajokull.
After Oraefajokull erupted in 1362, sailors reported seaborne pumice floating “in such masses that ships could hardly make their way through it.”
Father and daughter both recall joining fellow Icelanders over the years to marvel at the glowing fountains and rivers of lava produced by eruptions. They also are familiar with the impact of climate change.