Changing climate could increase hazards in Alpine regions

Climate change could cause increasing but unpredictable hazard risks in mountainous regions, according to a new study. The study analyses the effects of two extreme weather events - the 2003 heatwave and the 2005 flood - on the Eastern European Alps to demonstrate how similar events, predicted to become more frequent under a changing climate, could have an impact on Alpine regions.

One problem with current global climate models is that they fail to account for variations on a very local level. Therefore, the impact of climate change at this scale is uncertain. In some regions, this may be of greater concern because local environmental features, such as glaciers, pose a hazard. In addition, the impact of climate change is expected to be magnified in snow or ice covered regions because melting snow drives further melting.

Temperatures in the European Alps have increased twice as much as the global average temperature since the late nineteenth century and are predicted to rise by an average of 0.3-0.5°C per decade in the next century. The impact of this rise will depend heavily on local effects, including height and which direction a slope is facing. For instance, permafrost can be found at lower levels on north-facing slopes - anywhere above 2600m, compared to 3000m on south-facing slopes.

Considering these local variations, Austrian and UK researchers studied the impact of recent climate events in the eastern European Alps to try to understand how future changes might affect the region, and what implications these changes might have for local communities.

The mean summer temperatures during the 2003 heatwave in a large area of the European Alps exceeded the 1961-1990 mean by 3-5°C. This triggered a record Alpine glacier loss that was three times above the 1980-2000 average. Furthermore, melting permafrost caused increased rock-fall activity.

The severe floods that occurred as a result of heavy rainfall in August 2005 were the most damaging for 100 years and led to high volumes of water and sediment being deposited downstream, causing an estimated €555 million worth of damage in Austria to buildings, railways, roads and industrial areas. In Switzerland, the event is estimated to have caused one quarter of all damage by floods, debris flows, landslides and rock falls recorded since 1972.

While human activity and land management are important, the researchers expect that global warming will cause ongoing and accelerating ice loss in the European Alps over the next decades and centuries, with significant impacts on hazard type, location and frequency.

The response of glaciers to extreme weather events is rapid and complex and the response of permafrost is even more difficult to quantify, particularly given the wide spacing of monitoring stations. Hazards are concentrated in high altitude areas where there is mountaineering and skiing infrastructure. Worryingly, there is little public awareness of these hazards. To improve hazard and risk management in mountainous regions, research needs to be conducted which addresses the problem of downscaling global climate models to accommodate local impacts of climate change.

Source: Keiler, M., Knight, J., Harrison, S. (2010). Climate change and geomorphological hazards in the eastern European Alps. Philosophical Transactions of the Royal Society A. 368: 2461-2479.

Keywords: climate change, energy, natural hazards

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