http://rsta.royalsocietypublishing.org/content/368/1919/2311.full...
The theme of slope destabilization and failure, this time in a subaerial setting, is continued in a paper by Huggel et al., which examines recent large slope failures in the context of short-term, extreme warming events. Huggel and colleagues demonstrate a link between large slope failures in Alaska, New Zealand and the European Alps, and preceding, anomalously warm episodes. The authors present evidence supporting the view that triggering of large slope failures in temperature-sensitive high mountains is primarily a function of reduced slope strength due to increased production of meltwater from snow and ice and from rapid thaw processes. Looking ahead, they expect more frequent episodes of extreme temperature to result in a rise in the number of large slope failures in elevated terrain and warn of potentially serious consequences for mountain communities.
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. Importantly, Keiler et al. note that, while the European Alps, alongside other glaciated mountain ranges, are being disproportionately impacted upon by climate change, this is further exacerbated by regional factors, including local climatology and long-term decay of glaciers and permafrost. 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.
There is strong evidence for a crustal response to the rapidly changing post-glacial climate being elicited by load changes, either as a consequence of unloading at high latitudes and high altitudes due to ice-mass wastage, or as a result of the loading of ocean basins and continental margins in response to a 100 m or more rise in global sea level. The following three papers address the influence of load changes in the context of the triggering of seismicity and volcanism. In the first, Guillas et al. present the results of a statistical study of a putative correlation between contemporary variations in the El Niño–Southern Oscillation (ENSO) and the occurrence of earthquakes on the East Pacific Rise (EPR). The authors observe a significant (95% confidence interval) positive influence of the Southern Oscillation Index (SOI) on seismicity, and propose that increased seismicity on the EPR arises due to the reduced sea levels in the eastern Pacific that precede El Niño events, and which can be explained in terms of the reduction in ocean-bottom pressure over the EPR by a few kilopascals. Guillas et al. note that this provides an example of how variations in the atmosphere and hydrosphere can drive very small changes in environmental conditions that are able, in turn, to trigger a response from the Earth’s crust. Most importantly, they speculate that, in a warmer world, comparable and larger changes associated with ocean loading due to global sea level rise, or unloading associated with the passage of more intense storms, may trigger more significant earthquake activity at submarine fault systems that are in a critical state.
Continuing the theme, Hampel et al. take a broader look at how faults have responded to variations in ice and water volumes as a consequence of past climate change. Using numerical models, the authors demonstrate that climate-driven changes in ice and water volume are able to affect the slip evolution of both thrust and normal faults, with—in general—both the slip rate and the seismicity of a fault increasing with unloading and decreasing with loading. Adopting a case-study approach, Hampel and colleagues provide evidence for a widespread, post-glacial, seismic response on faults located beneath decaying ice sheets or glacial lakes. Looking ahead, the authors point to the implications of their results for ice-mass loss at high latitudes, and speculate that shrinkage of the Greenland and Antarctic ice sheets as a consequence of anthropogenic warming could result in a rise in the frequency of earthquakes in these regions.
In a similar vein, Sigmundsson et al. evaluate the influence of climate-driven ice loading and unloading on volcanism, focusing on Iceland and, in particular, on the Vatnajökull ice cap. Noting that a significant pulse of volcanism in Iceland, at the end of the last glaciation, flags a link between unloading and volcanism, the authors model the effects of contemporary ice-mass loss at Vatnajökull on future magmatic activity. Using a viscoelastic model of glacio-isostatic adjustment that incorporates melt generation in the underlying mantle, Sigmundsson and co-authors predict that ice wastage will result in additional magma generation beneath Iceland. The authors expect more frequent or more voluminous volcanic activity to be a consequence of enhanced melt generation, but also observe that it could take longer than decades or centuries for the resulting magma to reach the surface. Sigmundsson et al. also show that ice unloading is likely to drive shallow magma reservoirs progressively towards failure, although this effect will be small and therefore contribute only to modulating ‘normal’ activity.
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My profound "No" simply meant, that's not what they said. You've put words in their mouths.
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