Vulnerabilities – Trends of storm frequency and intensity in the past

There has been no long–term trend in the frequency of severe gales since 1881, but decadal average gale activity was greatest in the 1990s (1). Recent storm intensity is similar to that experienced at the start of the twentieth century, so present storminess may simply be an expression of natural climate variability (2).

Vulnerabilities – Future storm frequency and intensity

Winter storms that hit the UK between 1987 and 1998 each cost between 200 million to over 2 billion Euros (3). Future extreme wind storm events are expected to be one of the most significant of the climate change impacts for the insurance industry because of the associated claims for business disruption, utility and transport infrastructure damage and domestic property damage (4).

More hurricanes

Model simulations (based on a climate change scenario showing 1°C less global warming than the SRES A1B scenario) suggest that tropical hurricanes might become a serious threat for Western Europe in the future (6). An increase in severe storms of predominantly tropical origin reaching Western Europe is anticipated as part of 21st global warming. An eastward extension of the development region of tropical storms is projected. In the current climate, the main genesis region for hurricanes is confined to the western tropical Atlantic, where sea surface temperatures are above the threshold (27°C) required for tropical cyclones to develop. Future tropical storms that reach western European coasts (and cause hurricane-force storms) predominantly originate from the eastern part of the tropical Atlantic. This is because climate warming in the eastern tropical Atlantic causes sea surface temperatures to rise well above the 27°C threshold. In addition to an increase in the frequency of severe winds (Beaufort 11–12), a shift is projected of the season of highest occurrence from winter to autumn (6). Scientists stress that both natural variability and human influences (including climate change) play a role in determining the frequency, strength and trajectory of hurricanes on the Atlantic Ocean (8). 

After their formation, tropical cyclones move in a north-westerly direction. When they reach the mid-latitudes they are caught by the predominant westerly winds, thereby veering their track in a north-easterly direction, with the possibility of reaching Western Europe. Geometrically, this likelihood increases if their genesis region in the tropical Atlantic is further to the east. In addition, the shorter travel distance in the mid-latitudes will enable the “tropical” characteristics of hurricanes to be better preserved along their journey to Western Europe. Hence, the likelihood of these storms maintaining their strength when reaching Western Europe will increase, because there is simply less time for them to dissipate (7).

Adaptation strategy

An insurance stakeholder view is that there is a clear lesson here for adaptation strategies. Storms in London are likely to become more severe and frequent, but as buildings in London have been designed for relatively benign weather conditions, theyare likely to be more vulnerable to storm damage. This needs to be taken into account when revising the Building Regulations. It will also be necessary to have more stringent control through inspections on the quality of construction and the resilience of buildings to storms or floods (4).

In the United Kingdom insurance coverance (in % of forest area) is 10%. There is a UK woodland scheme in place which consists of 200,000 ha insured for fire, and fire & wind. The woodland scheme represents about 66%  of insured woodlands in England, Wales and Scotland (5).

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 the United Kingdom.

1. Kersey et al. (2000)
2. Hall et al. (2006)
3. ABI (2003); Munich Re (2002), both in: WWF (2006)
4. London Climate Change Partnership (2002)
5. Gardiner et al. (2010)
6. Haarsma et al. (2013)
7. Hart and Evans (2001), in: Haarsma et al. (2013)
8. Rosen (2017)