How melting glaciers can lead to more volcanic eruptions

Other continental regions, such as parts of North America, New Zealand, and Russia, could also observe an increase in volcanicity, Pablo Moreno-Yaeger, from the University of Wisconsin-Madison (US), said during the presentation.

Climate change & volcanic eruptions

Scientists first suggested that melting ice could affect volcanic activity in the 1970s. Usually, the weight of the ice exerts pressure on underground magma chambers of volcanoes. However, when glaciers or ice caps melt, this pressure is reduced, and underground gases and magma expand which can ultimately result in explosive eruptions.

Such a phenomenon has already occurred on the planet. For instance, in Iceland, during major deglaciation (the last of which occurred between 15,000 and 10,000 years before the present), volcanic eruption rates were 30 to 50 times higher than they are today.

Studies have also found that the decrease in pressure due to ice loss can result in the production of magma. That is because rocks held at lower pressure tend to melt at lower temperatures.

Another factor which seems to affect volcanic activity is precipitation. “Precipitation — also modified by climate change — can infiltrate deep underground and react with the magma system to trigger an eruption,” Thomas Aubry, a researcher at the University of Exeter (England), told Polytechnique Insights.

The latest study has reiterated these findings. It examined Chile’s Mocho Choshuenco volcano to estimate the age of volcanic rocks produced before, during, and after the last ice age. The research found that due to a thick ice sheet over the volcano, pressure had suppressed the volume of eruptions between 26,000 and 18,000 years ago. This led to the formation of a large reservoir of magma that had built up 10 to 15 km below the volcano’s surface. However, once this ice sheet melted, about 13,000 years ago, explosive eruptions took place.

The fallouts

Volcanic eruptions can cause temporary cooling as they release ash or dust into the atmosphere which blocks sunlight. These eruptions also emit sulfur dioxide into the atmosphere which is more effective than ash particles at cooling the climate. Sulfur dioxide goes into the stratosphere and reacts with water to form sulfuric acid aerosols. These aerosols reflect incoming solar radiation, leading to the cooling of the Earth’s surface.

“The aerosols can stay in the stratosphere for up to three years, moved around by winds and causing significant cooling worldwide. Eventually, the droplets grow large enough to fall to Earth,” according to the US Center for Science Education.

However, sustained volcanic eruptions can release large amounts of greenhouse gases, including carbon dioxide and methane, which could further heat the planet. This can become a vicious cycle — as global temperatures rise, there will be a higher rate of melting of ice, which could cause more eruptions and further global warming.