Periods of exceptional climate change in Earth history are associated with a dynamic response from the solid Earth, involving enhanced levels of potentially hazardous geological and geomorphological activity. This response is expressed through the adjustment, modulation or triggering of a wide range of surface and crustal phenomena, including volcanic and seismic activity, submarine and sub-aerial landslides, tsunamis and landslide ’splash’ waves glacial outburst and rock-dam failure floods, debris flows and gas-hydrate destabilisation. Looking ahead, modelling studies and projection of current trends point towards increased risk in relation to a spectrum of geological and geomorphological hazards in a world warmed by anthropogenic climate change, while observations suggest that the ongoing rise in global average temperatures may already be eliciting a hazardous response from the geosphere.
Lots of people have asked me whether there has been any connection between global warming and the recent earthquakes and other geological activity. Today, the UK’s Royal Society published an amazingly timely special series of scientific papers on the topic. Seven leading experts co-authored the editors’ introduction (quoted above).
Reuters reported on Friday, “A thaw of Iceland’s ice caps in coming decades caused by climate change may trigger more volcanic eruptions by removing a vast weight and freeing magma from deep below ground, scientists said.” Last week, FoxNews reported, “A huge glacier has broken off and plunged into a lake in Peru sparking a 23-meter high tsunami wave that destroyed a nearby town.” Local governor Cesar Alvarez said: “Because of global warming the glaciers are going to detach and fall on these overflowing lakes. This is what happened.”
We already knew that methane hydrates were at risk of destabilizing and becoming a positive or amplifying feedback to global warming (see “Science stunner: Vast East Siberian Arctic Shelf methane stores destabilizing and venting“). Two articles in this issue go further:
Maslin et al. review the current state of the science as it relates to gas hydrates as a potential hazard. The authors note that gas hydrates may present a serious threat as the world warms, primarily through the release of large quantities of methane into the atmosphere, thus forcing accelerated warming, but also as a consequence of their possible role in promoting submarine slope failure and consequent tsunami generation….
In a second paper, Dunkley Jones et al. look back to the PETM [Palaeocene-Eocene thermal maximum], the most prominent, transient, global warming event during the Cenozoic, in order to evaluate the effects of the rapid release of thousands of gigatonnes of greenhouse gases on the planet’s climate, ocean–atmosphere chemistry and biota, for which the PETM perhaps provides the best available analogue. Dunkley Jones et al. support the view that, while gas-hydrate release was probably not responsible for an initial, rapid, CO2-driven warming, the as yet unknown event responsible for this subsequently triggered the large-scale dissociation of gas hydrates, which contributed to further warming as a positive feedback mechanism.
That’s from the Preface by the Director of the Benfield UCL Hazard Research Centre, Dr. Bill McGuire, an expert on the geological consequences of climate change. The article by Maslin et al. concludes:
Models of the global inventory of hydrates and trapped methane bubbles suggest that a global 3°C warming could release between 35 and 940 GtC, which could add up to an additional 0.5°C to global warming. The destabilization of gas hydrate reserves in permafrost areas is more certain as climate models predict that high-latitude regions will be disproportionately affected by global warming with temperature increases of over 12°C predicted for much of North America and Northern Asia.
Yes, in the scenario where we blow past 3°C warming, the Arctic gets uber-warm and a staggering amount of methane seems all but certain to be released (see “M.I.T. doubles its 2095 warming projection to 10°F — with 866 ppm and Arctic warming of 20°F“):
The shrinking of both the Greenland and Antarctic ice sheets in response to regional warming may also lead to destabilization of gas hydrates. As ice sheets shrink, the weight removed allows the coastal region and adjacent continental slope to rise through isostacy. This removal of hydrostatic pressure could destabilize gas hydrates, leading to massive slope failure, and may increase the risk of tsunamis.
Dunkley Jones et al find, “Palaeotemperature proxy data from across the PETM indicate a coincident increase in global surface temperatures of approximately 5–6°C.” They find the methane hydrate were accompanied by lots of other carbon, which wouldn’t be a big surprise given how many other amplifying carbon-cycle feedbacks there are (see “Stunner: Nature review of 20 years of field studies finds soils emitting more CO2 as planet warms“).
The paper “Recent and future warm extreme events and high-mountain slope stability,” notes that “Warm extremes can trigger large landslides in temperature-sensitive high mountains by enhancing the production of water by melt of snow and ice, and by rapid thaw.” Not surprisingly, the paper finds:
The number of large slope failures in some high-mountain regions such as the European Alps has increased during the past two to three decades. There is concern that recent climate change is driving this increase in slope failures, thus possibly further exacerbating the hazard in the future….
We describe several large slope failures in rock and ice in recent years in Alaska, New Zealand and the European Alps, and analyse weather patterns in the days and weeks before the failures. Although we did not find one general temperature pattern, all the failures were preceded by unusually warm periods; some happened immediately after temperatures suddenly dropped to freezing.
We assessed the frequency of warm extremes in the future by analysing eight regional climate models from the recently completed European Union programme ENSEMBLES for the central Swiss Alps. The models show an increase in the higher frequency of high-temperature events for the period 2001–2050 compared with a 1951–2000 reference period. Warm events lasting 5, 10 and 30 days are projected to increase by about 1.5–4 times by 2050 and in some models by up to 10 times.
Here’s more on European impacts:
The slope failure hazard in mountainous terrain is also addressed by Keiler et al. in a paper that examines the influence of contemporary climate change on a broad spectrum of geomorphological hazards in the eastern European Alps, including landslides, rock falls, debris flows, avalanches and floods. In the context of the pan-continental 2003 heat wave and the 2005 central European floods, the authors demonstrate how physical processes and human activity are linked in climatically sensitive alpine regions that are prone to the effects of anthropogenic climate change…. The authors conclude that future climate changes are likely to drive rises in the incidence of mountain hazards and, consequently, increase their impact on Alpine communities.
The paper “How will melting of ice affect volcanic hazards in the twenty-first century?” concludes
Glaciers and ice sheets on many active volcanoes are rapidly receding. There is compelling evidence that melting of ice during the last deglaciation triggered a dramatic acceleration in volcanic activity…. A greater frequency of collapse events at glaciated stratovolcanoes can be expected in the near future, and there is strong potential for positive feedbacks between melting of ice and enhanced volcanism. Nonetheless, much further research is required to remove current uncertainties about the implications of climate change for volcanic hazards in the twenty-first century.
Finally, scientists find a modest negative feedback, albeit an unpleasant one!
And, coincidentally enough, there’s a paper “Climate effects on volcanism: influence on magmatic systems of loading and unloading from ice mass variations, with examples from Iceland”
Pressure influences both magma production and the failure of magma chambers. Changes in pressure interact with the local tectonic settings and can affect magmatic activity. Present-day reduction in ice load on subglacial volcanoes due to global warming is modifying pressure conditions in magmatic systems. The large pulse in volcanic production at the end of the last glaciation in Iceland suggests a link between unloading and volcanism, and models of that process can help to evaluate future scenarios. A viscoelastic model of glacio-isostatic adjustment that considers melt generation demonstrates how surface unloading may lead to a pulse in magmatic activity. Iceland’s ice caps have been thinning since 1890 and glacial rebound at rates exceeding 20 mm yr−1 is ongoing. Modelling predicts a significant amount of ‘additional’ magma generation under Iceland due to ice retreat.
Finally, we have “Response of faults to climate-driven changes in ice and water volumes on Earth’s surface,” which finds:
Numerical models including one or more faults in a rheologically stratified lithosphere show that climate-induced variations in ice and water volumes on Earth’s surface considerably affect the slip evolution of both thrust and normal faults. In general, the slip rate and hence the seismicity of a fault decreases during loading and increases during unloading. Here, we present several case studies to show that a postglacial slip rate increase occurred on faults worldwide in regions where ice caps and lakes decayed at the end of the last glaciation. Of note is that the postglacial amplification of seismicity was not restricted to the areas beneath the large Laurentide and Fennoscandian ice sheets but also occurred in regions affected by smaller ice caps or lakes, e.g. the Basin-and-Range Province. Our results do not only have important consequences for the interpretation of palaeoseismological records from faults in these regions but also for the evaluation of the future seismicity in regions currently affected by deglaciation like Greenland and Antarctica: shrinkage of the modern ice sheets owing to global warming may ultimately lead to an increase in earthquake frequency in these regions.
Just to be clear about what these papers are and aren’t saying, the Guardian reports:
Richard Betts, a climate modeller at the Met Office Hadley Centre in Exeter, said: “This is a new area of academic research with potentially interesting implications. It was previously assumed there was no link at all between climate change and these events, but it is possible to speculate that climate change might make some more likely. If we do get large amounts of climate change in the long term then we might see some impacts.”
He said there was no evidence that current levels of global warming were influencing events such as last week’s earthquake in China that killed hundreds of people and the volcanic eruption in Iceland that grounded flights across Europe.
Experts say global warming could affect geological hazards such as earthquakes because of the way it can move large amounts of mass around on the Earth’s surface. Melting glaciers and rising sea levels shift the distribution of huge amounts of water, which release and increase pressures through the ground.
These pressure changes could make ruptures and seismic shifts more likely. Research from Germany suggests that the Earth’s crust can sometimes be so close to failure that tiny changes in surface pressure brought on [by] heavy rain can trigger quakes.
One should be cautious in linking individual geological events directly to climate change. We’ll have to wait for more study and more detailed statistical analysis. Though obviously for certain events, such as a glacier collapse leading to a tsunami or large slope failures in ice, they are inevitably going to be seen as driven by warming. And the destabilization of gas hydrate reserves in permafrost areas remains a core prediction of climate science.
Anyway, more things to worry about from unrestricted greenhouse gas emissions, as if there weren’t enough already: