There is a lot of cross-border information on storms in Northern, Western and Central Europe. This information is summarized on the page for Europe in the window 'Storms: European scale'. Additional information that specifically refers to individual countries is presented on the Storm pages of these countries.

Vulnerabilities - Trends in the past

Economic losses from windstorms significantly increased in Switzerland between 1950 and 2010 (10). On a centennial timescale, increasing damage to Swiss forests from winter storms between 1858 and 2007 was found (11). Windstorms have accounted for approximately 1/3 of the total losses relating to buildings from natural hazards in Switzerland since 1950 (10). Storms are also the main damage factor to Swiss forests (12). This increase is due to decadal variability (9): from an analysis of quantitative (e.g., volumes of windfall timber, losses relating to buildings) and descriptive (e.g., forestry or insurance reports) information on the impact of historical windstorms, a time series of high-impact windstorms in Switzerland since 1859 was reconstructed. It was concluded that storminess in Switzerland during the 20th century was high until around 1920, then low to medium until around 1970. The latest 40 years were characterized by a gradual increase from the calm 1970s to the extreme storms in the 1990s and a quieter situation since. The decadal variability is present in both the wind data (i.e., the hazard) as well as the loss and damage information (9).

The incidence of heavy storms affecting Swiss forests increased in the last decade of the 20th century. In 1990, Hurricane Vivian damaged a volume of 4.9 million m3 of wood. Forest damage due to Hurricane Lothar at the end of 1999 was the most severe ever recorded: 13.8 million m3 of timber was felled (compared with a normal annual harvest of 4.5 million m3), and an area of about 46,000 hectares was severely affected (1).

With ongoing population growth, economic development, and urban sprawl on the one hand and very few extreme events causing severe damage from the early to the late 20th century on the other hand, more and more buildings have been placed in exposed areas. Accordingly, the damage potential of floods, mudflows, landslides or winter storms has become much larger. Climate change adds a new risk to this situation as the frequency and magnitude of extreme events increases (1).

Vulnerabilities - Projections for the future

According to a study by Swiss Re and ETH Zürich (2,3), winter storms represent the largest loss potential for Europe and the second largest for Switzerland, where only loss potential from floods is higher. Several climate models were coupled with an insurance loss model and future damage by winter storms was examined. Results indicate that by the end of the 21st century (2071-2100), total losses in Europe could increase by 20 to 70% (compared to the reference period 1961-1990). In Switzerland, an average increase in losses due to winter storms by about 20% (0 to 50%, depending on the climate model) is expected (1).

The scenarios for storms are very uncertain. Some models indicate that the frequency of storms is likely to decrease in central Europe. At the same time, the intensity of storms will probably increase (2). Generally the tracks of cyclones and storms are expected to shift polewards, which would reduce the probability of Switzerland being hit (1).

Adaptation strategies

Significant financial resources will be needed for the implementation of measures to adapt to changes in the magnitude of extreme events. However, compared to the estimated cost of inaction (4), adaptation will cost only a fraction and has multiple benefits which are going far beyond the reduction of risk in relation to climate change (1).

Insurance

In Switzerland no forestry insurance is active but a catastrophic fund is in place (8). Studies investigating insurance for storm damage in forests in Switzerland and Germany have shown low enthusiasm among forest owners for insurance under current economic and legal policies (5,6). The main reasons identified are the low economic importance of the forest to many forest owners and low risk awareness or rather underestimation of risks, in light of the long productivity times in forestry (5,7). The disaster relief practice of many states to compensate widely for storm damage decreases the incentive for forest owners to take their own precautions (5).

Artificial protective measures

From 2000 to 2003, the federal government provided funds of CHF 393 million for measures to prevent bark beetle infestation of the remaining stands and to restore destroyed forests. A similar level of support was provided by the cantons. Heavy storms may lead to a loss in the protective functions of forests for downslope areas. The need for temporary artificial protective measures cannot be judged in general terms but must be assessed case by case, depending on the local situation and the potential damage involved. In many cases, leaving the trees lying on the devastated area can ensure sufficient protection for a limited time. Under the present conditions of low demand for wood, this way of managing storm damage has become more common (1).

References

The references below are cited in full in a separate map 'References'. Please click here if you are looking for the full references for Switzerland.

1. Federal Office for the Environment FOEN (Ed.) (2009)
2. Swiss Re (2006), in: Federal Office for the Environment FOEN (Ed.) (2009)
3. Frei et al. (2006), in: Federal Office for the Environment FOEN (Ed.) (2009)
4. Ecoplan (2007), in: Federal Office for the Environment FOEN (Ed.) (2009)
5. Holthausen et al. (2004), in: Gardiner et al. (2010)
6. Hänsli et al. (2002), in: Gardiner et al. (2010)
7. Schwierz et al. (2010), in: Gardiner et al. (2010)
8. Gardiner et al. (2010)
9. Stucki et al. (2014)
10. Imhof (2011), in: Stucki et al. (2014)
11. Usbeck et al. (2010a), in: Stucki et al. (2014)
12. Usbeck et al. (2010b), in: Stucki et al. (2014)