Climate change: causing volcanoes to go pop
With the British Science Association’s National Science and Engineering Week well under way, Bill McGuire explores ‘our world in motion’ and looks forward to the world we will bequeath to our children.
By Bill McGuire
When I first mention to someone that a changing climate is capable of causing volcanoes to go pop or the ground to shake, they think that I am either mad or having them on. Usually, this is just because they have not given the idea much thought, so that when I am given the opportunity to explain how this works they often become quite keen on the notion. Of course, the dyed-in-the-wool climate denier ideologues are already attacking the whole thesis; not on the basis of arguments rooted in science, but because it does not fit with their blinkered world view.
Plenty of people, however, are fascinated by a link between what happens in the fragile atmospheric envelope that sustains life on the surface of our world and what goes on in the solid Earth, or geosphere, as we geologists call it – hopefully enough to push the book well up the Amazon rankings. For some, in fact, the idea that we are ‘prodding with a stick’ a metaphorical slumbering giant beneath our feet brings a small frisson of apprehension and even greater concern about what the future might hold for their children and grand-children.
The coincidence of dramatic climate change and potentially hazardous shenanigans in our planet’s crust should come as a no surprise, as there is a mass of evidence for a geologically lively rejoinder in post-glacial times as our world was transformed from a blisteringly cold icehouse into the (broadly) mild mannered world we know and love. Over a period of about 15,000 years, a staggering 52 million cubic kilometres of water was shifted from the melting continental ice sheets into the ocean basins, raising sea levels by the height of 30-storey building. In response to the massive changes in stress and strain this engendered in the planet’s interior, giant quakes shook Scandinavia, tsunamis battered North Atlantic coastlines and the power of volcanoes was unleashed on an almost unprecedented scale.
On track as we are for hikes in global temperature and sea level comparable to those characteristic of post-glacial times, it is understandable that we should wonder whether the slumbering giant might start tossing and turning in earnest once again and ponder upon possible consequences. Alaska seems to be showing the way, in this regard, as the impact of crumbling glaciers and ice fields and thawing mountain permafrost is already making itself felt here in the form of increased earthquake activity and a greater frequency of giant landslides. Combining some of the most rapidly rising temperatures on the planet with an unrivalled level of tectonic activity, it looks as if Alaska is acting as the ‘canary in the cage’; providing a salutary warning of how the crust may respond in other parts of the world when global warming really begins to get a grip.
Just how big a response this will be depends almost entirely upon us – the human race. Concerted action to slash global greenhouse emissions and keep global average temperatures below the so-called ‘dangerous climate change’ guardrail of 2°C, may see the giant beneath our feet stirring briefly before falling once again into a deep sleep; the resulting geological response being muted. Unfortunately, such an optimistic viewpoint now seems completely untenable. With emissions up close to six percent in 2010; a year when the world’s economy was still bumping along the bottom, it is almost impossible to imaging a scenario in which emissions start falling soon by anything like the amount needed, especially when and if the global economy starts to take off once again. Furthermore, with the international community deciding effectively – at last December’s climate conference in Durban – to do little or nothing to tackle emissions until at least 2020, the picture looks unremittingly bleak.
Rather than a 2°C global average temperature rise, 4°C now seems more on the cards. This may not seem like much, but it translates to a 15°C increase at high latitudes, where most of our world’s ice is stored. Goodbye Greenland Ice Sheet; hello a probable sea-level rise – ultimately – of 6m or more. Given such circumstances, a vigorous, violent and widespread reaction from the solid Earth seems perfectly plausible, if not likely. From the perspective of early 2012, it looks as if we will be bequeathing to our children and their children, not only a hotter world, but a more geologically fractious one too.
Bill McGuire is an academic, science writer and broadcaster. He is currently Professor of Geophysical and Climate Hazards at UCL. Bill was a member of the UK Government Natural Hazard Working Group established in January 2005, in the wake of the Indian Ocean tsunami, and in 2010 a member of the Science Advisory Group in Emergencies (SAGE) addressing the Icelandic volcanic ash problem. He was also a contributing author on the recent Intergovernmental Panel on Climate Change (IPPC) report on extreme events. His books include Waking the Giant: How a changing climate triggers earthquakes, tsunamis, and volcanoes Surviving Armageddon: Solutions for a Threatened Planet and Seven Years to Save the Planet.