A study of ice and fire

While the discovery of 91 volcanoes is a triumph for Antarctic exploration, it is unclear what it represents for the future of global climate change.

A new Edinburgh University study has found evidence of 91 additional volcanoes under the West Antarctic Ice Sheet, nearly tripling the number of known volcanoes in the area and putting it on a par with the East African Rift System as one of the world’s largest volcanic regions.  

“We were amazed,” Robert Bingham the paper’s co-author said. “We also suspect there are even more on the bed of the sea that lies under the Ross ice shelf, so that I think it is very likely this region will turn out to be the densest region of volcanoes in the world, greater even than east Africa, where mounts Nyiragongo, Kilimanjaro, Longonot and all the other active volcanoes are concentrated.”

While at least 138 likely volcanic cones were identified in the deep basins of West Antarctica, more remain to be discovered. Due to erosion, the volcanic cones found are likely to be relatively young, meaning that older volcanoes, tindar (spiked ridges of erupted material), and smaller volcanoes that aren’t identifiable due to uncertainties in the data would be missed. Likewise, the lack of data on what lies beneath the floating Ross Ice Shelf means the total volcanic region is likely to be “considerably larger.”

The researchers note that they “are not able to determine whether the different volcanoes are active or not,” though other regions in the world which share the same thin, stretched crust and rift patterns are very active.  In West Antarctica, they “may still be active,” though the ice cover, over 2 kilometers thick in some places, makes studying subglacial volcanic activity difficult.

While experts disagree on whether the West Antarctic Rift System is currently volcanically active, Bingham notes, “The big question is: how active are these volcanoes? That is something we need to determine as quickly as possible.”

An inactive volcano system could actually be beneficial in the fight against climate change.  Volcanic deposits form rough subglacial “protuberances”, slows down ice flow like Velcro.

But an active rift could pose a major threat to the stability of the West Antarctic ice shelf and global ocean levels. Only two volcanoes are known to be currently active in Antarctica: Mount Erebus, atop the Erebus hotspot, which has erupted continuously for decades; and Deception Island, where the unpredicted 1969 subglacial eruption produced meltwater, steam and a large surface mudflow which destroyed the UK and Chilean observatories.

According to geologists, both previous studies and recent seismic activity have suggested that Marie Byrd Land, east of the Ross Ice Shelf, where many of the newly-discovered cones are, may also be another volcanic hotspot.

“If one of these volcanoes were to erupt it could further destabilise west Antarctica’s ice sheets,” warns Bingham. “Anything that causes the melting of ice – which an eruption certainly would – is likely to speed up the flow of ice into the sea.”  

The melting of ice sheets, as a result of global warming, may trigger increased volcanic activity, which in turn may cause a feedback loop. Isostatic rebound, where land masses ‘bounce back’ from glacial compression, reduces pressure on magma, causing eruptions and increased subglacial heat. This melts ice at the bottom of glaciers, not only contributing directly to ice loss but also lubricating the glacier and increasing its speed as it flows into the ocean, contributing to isostatic rebound.

“The most volcanism that is going on in the world at present is in regions that have only recently lost their glacier covering – after the end of the last ice age,” Bingham explained. “Theory suggests that this is occurring because, without ice sheets on top of them, there is a release of pressure on the regions’ volcanoes and they become more active.”

If the huge West Antarctic Ice Sheet were to disintegrate, it could raise sea levels by 3.3 to 4.8 meters. Chris Rapley, head of the British Antarctic Survey notes that “Current computer models do not include the effect of liquid water on ice sheet sliding and flow,” which means our current estimates of sea level rise as a consequence of glacial loss may be dangerously low.

However, Dr. Matt King, of the University of Tasmania, urged caution when talking to Salon Magazine: “These newly-discovered volcanos have only been identified based on their shape – we really know very little about them other than they exist. We don’t know when they were last active or even if some could be active now. … This discovery really does show how poorly we know Antarctica, even after 60+ years of scientific endeavours.”

Alden Mathieu

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