Besides having a disastrous impact on sea levels and weather, a warming climate could also trigger catastrophic volcanic eruptions across the planet
Volcanic eruptions alter the climate by spewing smoke and ash into the atmosphere, but scientists now also think the opposite might be true – changes in climate could actually cause volcanic eruptions.
According to Gioachino Roberti, a PhD student at the University of Clermont Auvergne, glaciers can suppress volcanic eruptions by providing mountains with structural stability.
As the climate becomes warmer, ice melting from these mountains removes support from their slopes, potentially leading to landslides and collapse.
“Imagine the ice like some sort of protective layer – when the ice melts away, the mountain is free to collapse,” said Mr Roberti.
“If your mountain is a volcano you have another problem.
“Volcanoes are a pressurised system and if you remove pressure by ice melting and landslide, you have a problem.”
Presenting his work at the European Geosciences Union General Assembly, Mr Roberti explained a case study he and his collaborators had investigated in Canada.
Though not famous for its volcanic activity, Canada is home to hundreds of potentially active volcanoes. The scientists chose to focus on Mount Meager, a glaciated volcano north of Vancouver.
Mount Meager’s last eruption was over 2000 years ago, but Mr Roberti chose to focus on Mount Meager for a more recent natural disaster that took place there.
In summer 2010, the largest landslide in Canadian history occurred on the southern part of the volcano.
“The glacier base of the slope retreated and during the hottest part of the summer, the slope catastrophically failed – the whole mountain started to move at a very high velocity,” said Mr Roberti.
This was followed in 2016 by the formation of ice caves in the glacier as hot volcanic gases seeped out of the volcano.
“This is the first time this has happened there – so the equilibrium of the mountain is changing,” said Mr Roberti.
To understand these events, the scientists used numerical modelling of the volcano to examine the link between melting ice on the glacier and changes to the magma “plumbing system” inside it.
They found that landslides had the potential to destabilise the magma chamber and trigger an eruption – a phenomenon that can be linked directly to a warmer climate.
“We see a correlation between high temperature, ice melting and landslides,” said Mr Roberti.
“Today’s increasing temperature is likely to cause other large landslides.”
Other scientists welcomed the research by Mr Roberti and his colleagues, although they noted the complexity of the systems involved and the difficulty in making direct links between climate change and eruptions.
“This new research nicely demonstrates that if you change the load on a volcanic mountain – for example by removing some ice – the likelihood of a mechanical collapse and possible ensuing eruption will be slightly increased,” said Professor David Rothery, a geoscientist at The Open University who was not involved in the research.
“Eruptions are triggered by a complex array of factors. I suspect that many eruptions caused by glacial melting might happen eventually anyway, given enough time – but this research shows that warming could increase the chances of those eruptions happening sooner rather than later.”
Dr David McGarvie, another researcher at The Open University who was not involved with the research, said that evidence is still lacking for ice-capped volcanoes like Mount Meager erupting due to ice melting. However, he noted this was not the case for volcanoes buried under ice sheets in Iceland and Antarctica.
“There is more and better evidence across Iceland that when the ice sheet underwent major reduction at the end of the last glacial period, there was a large increase in both the frequency and volume of basalt erupted – with some estimates being 30 times higher than the present day,” he said.
However, he said the scale of ice melting currently being seen is not on the same scale as the end of the glacial period.
Presenting his research alongside Mr Roberti was Matthias Schlögl, a PhD student at the University of Natural Resources and Life Sciences in Vienna, whose studies also focused on climate change-driven landslides.
As landslides tend to be caused by heavy rainfall – which is expected to increase due to climate change – these events are likely to become more common in the future.
Mr Schlögl’s research has explored the impact such landslides will have on Europe’s transport network.
“Landslides are an important issue today, and we expect that climate change – particularly changes in rainfall patterns and changes in temperature – will increase, and will furthermore affect the slope stability and trigger additional landslide events in the future,” Mr Schlögl said.
Scientists are becoming increasingly confident in attributing the rise in frequency and severity of natural disasters to climate change.
The drought currently affecting Cape Town has been linked with climate change, as was Hurricane Harvey when it struck the south east US at the end of 2017.
The new results presented by these researchers suggests that geological phenomena as well as weather events are being fundamentally altered by the changing climate.