An Explosive Backlash

So, having unintentionally focused on earthquakes, I would like to turn my attention to volcanoes. The way in which volcanism forces climate is well studied and documented to the extent that geoengineers have formulated a way to harness the cooling effect of an eruption in order to counteract the onset of global warming. For a better insight into the mechanisms that drive volcanism as a climate forcing factor and these proposed geoengineering schemes I would like to recommend a recent post written by my friend and fellow climate blogger Tom Hallam.

Nonetheless, there is little evidence circulating that climate change could reciprocally alter a volcano’s eruption schedule. The cardinal premise on which this is based comes from the logic that a thaw of global ice caps will remove a vast weight allowing magma from immense depths to be unleashed. Freysteinn Sigmundsson – a volcanologist at the University of Iceland – has stated:

“Global warming melts ice and this can influence magmatic systems… the end of the Ice Age 10,000 years ago coincided with a surge in volcanic activity in Iceland, because huge ice caps thinned and the land rose.” (World Climate Report, 2011)

One particular recent eruption made headlines worldwide… but not for its link to climate change. The eruption of Eyjafjallojokull in 2010 was famed for producing the mammoth ash cloud that grounded flights across Europe and spread animosity to millions (including myself, whose ticket to Miley Cyrus’ film premiere was rendered useless when the singer’s plane was unable to fly!) Scientists have struggled to link this huge eruption to climate change, saying that the glacier on which in sits was too small and light to influence local geology. Whilst theoretically, the reduction in Icelandic ice thus far has not been significant enough to trigger either a large eruption or a greater frequency of any magnitude events, Sigmundsson believes this will change in the coming decades (Sigmundsson et al., 2008).


His 2008 report showed that since 1890, 10% of Iceland’s biggest ice cap Vatnajokull has melted (Pagli & Sigmundsson, 2008). This has caused land to rise approximately 25 millimetres, consequently adjusting geological stresses. Rocks under an ice cap are at such high pressures that they are unable to expand enough to turn into liquid magma even if the temperature is high. The pressure decrease when ice melts therefore allows magma to form. Such results lead to the conclusion that an estimated 1.4 cubic km of magma had formed in response to the thaw. Ultimately, the study concludes that melting ice is the principal way in which climate change can have an impact on geology.