Volcanoes don't cause climate change — but it could be the other way around

A recent report from the Icelandic Meteorological Office suggests that magma is building up underground near a volcano known as Askja, a mountain about the size of Mount St. Helens in Vatnajokull National Park in Iceland’s central highlands. Although volcanic eruptions are difficult to predict accurately, this indicates a high likelihood that Askja may erupt in the near future

Such events are nothing new in Iceland, an island nation of just 400,000 people that has numerous active volcanoes. But researchers funded by the Icelandic government believe that the rapid retreat of glaciers due to climate change is raising the threat to their nation, and may foreshadow increased volcanic activity all over the world. As glacial ice melts, the downward pressure on Earth’s thin outer crust eases, causing the ground to rebound. That can cause the dynamic subterranean forces below volcanoes to produce increased quantities of magma, leading to more frequent eruptions.

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“Iceland is essentially one of the best places in the world to study this … because we have both volcanism and glaciers,” volcanologist Michelle Parks of the Icelandic Meteorological Office told Reuters. “At the end of the day, what we’re aiming for with this project is a much bigger picture. It’s the future of volcanic eruptions. How large can they be? … And what’s in store for us in the future, not only in Iceland but for the rest of Europe and potentially farther afield.”

Volcanologists see early signs of this type of activity at Askja. If it continues, that could lead to a repeat of the conditions during the last major ice age, roughly 10,000 to 15,000 years ago. At that time, rates of volcanic eruption were much higher than they are today, indeed 30 to 50 times higher. That same set of circumstances, with the glaciers that weigh down Iceland's 34 active volcanic systems melting and losing volume due to rising temperatures, appears to exist now.

Ironically enough, climate-change deniers sometimes attribute the current rise in temperatures to volcanic activity, a hypothesis that has been thoroughly debunked. It’s true that volcanic eruptions can warm the Earth’s temperature, but scientific evidence clearly shows that’s not the chief culprit behind current climate change.

"The burning of fossil fuels and the manufacture of cement releases 37 billion metric tons of CO₂ into the atmosphere per year," Yves Moussallam, a professor of earth and environmental sciences and geochemistry at Columbia Climate School, told Salon last year. Volcanic activity, he estimated, "contribute about 100 times less CO₂” than those human activities.