Scientists warn hundreds of dormant volcanoes could soon erupt

A volcano in the throes of eruption truly is a force of nature.

Molten rock, ash and gases from deep within the Earth’s mantle find their way up to the surface and either flow slowly out of a fissure or explode suddenly into the air.

In recent years there have been a number of high-profile eruptions, including ones in Italy and Indonesia.

Now, experts are warning that hundreds of dormant volcanoes around the world will likely become more active and erupt thanks to climate change.

Researchers from the University of Wisconsin-Madison in the USA said melting glaciers could be silently setting the stage for more explosive and more frequent eruptions in the future.

And areas such as North America, New Zealand and Russia could be at risk, they said.

‘Glaciers tend to suppress the volume of eruptions from the volcanoes beneath them,’ Pablo Moreno-Yaeger, one of the study’s authors, explained.

‘But as glaciers retreat due to climate change, our findings suggest these volcanoes go on to erupt more frequently and more explosively.’

His team used argon dating and crystal analysis across six volcanoes in southern Chile, including the now dormant Mocho-Choshuenco volcano, to investigate how the Patagonian Ice Sheet’s advance and retreat influenced past volcanic behaviour.

By precisely dating previous eruptions and analysing crystals in erupted rocks, the team tracked how the weight and pressure of glacial ice altered the characteristics of magma underground.

They discovered that during the peak of the last ice age – around 26,000-18,000 years ago – thick ice cover suppressed the volume of eruptions and allowed a large reservoir of magma to accumulate up to 15km below the surface.

But as the ice sheet melted rapidly at the end of the last ice age, the sudden loss of weight caused the Earth’s crust to ‘relax’ and gasses in the magma to expand.

This buildup of pressure triggered explosive volcanic eruptions from the deep reservoir.

‘The key requirement for increased explosivity is initially having a very thick glacial coverage over a magma chamber, and the trigger point is when these glaciers start to retreat, releasing pressure – which is currently happening in places like Antarctica,’ Mr Moreno-Yaeger said.

‘Our study suggests this phenomenon isn’t limited to Iceland, where increased volcanicity has been observed.

‘Other continental regions, like parts of North America, New Zealand and Russia, also now warrant closer scientific attention.’

The researchers explained that increased volcanic activity could have global climate impacts.

In the short term, eruptions release aerosol that can temporarily cool the planet, as seen after the 1991 eruption of Mount Pinatubo in the Philippines, which reduced global temperatures by around 0.5°C.

However, with multiple eruptions, the effects reverse.

‘Over time the cumulative effect of multiple eruptions can contribute to long-term global warming because of a buildup of greenhouse gases,’ Mr Moreno-Yaeger said.

‘This creates a positive feedback loop, where melting glaciers trigger eruptions, and the eruptions in turn could contribute to further warming and melting.’

The research was presented at the Goldschmidt Conference in Prague.