Guest essay by Eric Worrall
Volcanic eruptions are now the fault of that wicked little molecule.
Climate change could trigger volcanic eruptions across the world, warn scientists
Melting of ice on volcanoes can increase risk of landslides and destabilise magma ‘plumbing system’ inside, say researchers
Wednesday 11 April 2018 17:28 BST
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.”
Gioachino Roberti provides the example of Mount Meager in British Columbia;
… Mount Meager is an ice-clad volcanic complex in British Columbia, Canada, known for its large landslides and an eruption about 2430 years ago. In 2010 a major collapse associated with glacier retreat occurred on the south flank of Mount Meager, and in 2016 fumaroles formed ice caves in one of its glaciers. This glacier is bordered by a large unstable slope moving about 4 cm/month. If this slope failed, a long run-out debris avalanche would reach the floor of Lillooet River valley, with possible destructive effects on downvalley infrastructure. … We conclude that the change in effective stress following the landslide has the potential to destabilize the magmatic chamber and trigger an eruption. …
There is no doubt some glaciers help hold in volcanic eruptions. But plenty of volcanoes tunnel out of their glaciers without any extra help – Arctic volcanoes like Eyjafjallajökull have regularly blown their tops since the end of the last ice age. Hot magma has a tendency to melt ice.
Pinning the weakening of Mount Meager’s ice cap on CO2 is further complicated by the fact that British Columbia had a wildly variable climate well before the industrial age.
A 477-year dendrohydrological assessment of drought severity
Severe summer streamflow droughts are impacting many watersheds on Vancouver Island, British Columbia. Small coastal basins that are the primary water source for most communities and essential to Pacific salmon populations have been particularly affected. In the face of more extreme climate change-induced droughts, water managers often underestimate worst-case scenario low flows because the most extreme naturally occurring events are rarely captured within short instrumental records. To provide a long-term perspective on recent droughts on Vancouver Island, we developed a 477-year long dendrohydrological reconstruction of summer streamflow for Tsable River based on a network of annual tree-ring width data from climate-sensitive conifer trees. Explaining 63% of the instrumental streamflow variability, to our knowledge the record is the longest of its kind in British Columbia. We demonstrate that targeting the summer streamflow component derived from snowmelt is powerful for determining drought-season discharge in hybrid runoff regimes, and we suggest this approach may be applied to small watersheds in temperate environments that are not usually conducive to dendrohydrology. Our findings suggest that since 1520, 21 droughts occurred that were more extreme than recent “severe” events like those in 2003 and 2009. Recent droughts are therefore not anomalous relative to the ~400 year pre-instrumental record, and should be anticipated within water management strategies. In coming decades, worst-case scenario natural droughts compounded by land use change and climate change could result in droughts more severe than any since 1520. The influence of the Pacific Decadal Oscillation on instrumental and modeled Tsable River summer streamflow is likely linked to the enhanced role of snowmelt in determining summer discharge during cool phases.
Read more: Research Gate
Given the extreme natural climate variability of many Arctic regions like British Columbia, and the historical instability of many glacier capped volcanoes, I suggest it is premature to conclude humans are contributing significantly to the risk of volcanic eruptions.