Quantifying the impact of historical and future climate change on windstorm insured loss in Great Britain

• Main Author: Hewston, Richard
• Published: University of East Anglia 2008
• Subjects: 551.6452
• Online Access: http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.446520

Windspeed receives relatively little attention in the literature compared with other meteorological variables, despite affecting many industries. European extratropical cyclones create 70-75% of all European insured losses, with an annual average of £1.5-2bn. This project quantifies the impact of historic and future climate change on wind-related insured loss in the UK, using an observational windspeed dataset established here and RCM model data. A continuous 26-year (1980-2005) record of daily mean 10-metre windspeeds and daily maximum gust speeds (DMGS) at 43 UK Met Office stations is established. Statistically significant decreases in damaging windspeeds, of up to 20%, are found at stations in southern England during that period. Supplemented by dynamically downscaled reanalysis data, statistically significant increases of up to 8% are seen at locations in northern England and in Scotland in the period 1959-2001. An operational windstorm loss model for Great Britain is developed, incorporating socio-economic data to account for the exposure and vulnerability of domestic properties to the windstorm hazard. Damaging windspeeds are found to be those DMGSs exceeding the local 98th percentile. The model captures the variability in losses reasonably well, although losses are markedly underestimated. Impacts of individual storm events dating back to 1959 are quantified using Loss Potentials, which are indicative of insured losses. Annual Loss Potentials reveal no statistically significant temporal trends in the period 1959-2005, although a slight increase is suggested between 1959-1979. Three RCM simulations reveal increases of 15-34% in future (2071-2100) Loss Potentials relative to baseline values. Without adaptation of domestic properties to the future wind regime, these estimates rise to 38-533%. Greatest Loss Potential increases are projected in South East England with adaptation, and in North West England without adaptation. Increases in frequency and intensity of damaging windspeeds in winter, simulated by this three member ensemble, drive the increases in Loss Potentials.