Uncertainty of typhoon extreme wind speeds in Hong Kong integrating the effects of climate change

Abstract

To assess the influence of climate change on the estimates of extreme wind speeds induced by typhoons, the present study employs a Monte Carlo simulation approach to forecast the extreme wind speeds in the proximity of Hong Kong when the sea surface temperatures rise as projected by various climate change models according to the Representative Concentration Pathway (RCP) 8.5. In addition, the present study shows the first attempt to quantitatively assess the uncertainty buried in the prediction of the extreme wind speed in association with typhoons taking the rise in sea surface temperatures, and therefore climate change, into consideration. It is found that climate change leads, with high confidence, to the increase in extreme wind speeds brought about by typhoons. From the numerical simulation, it is found that the mean wind speeds associated with typhoons impacting Hong Kong rise from 10.8 m/s (1961–1990) to 12.4 m/s (2051–2080), and the extreme wind speed is 47.5 m/s during 2051–2080 under the RCP 8.5 climate scenario, which is 21.2% higher than that corresponding to the period of 1961–1990. As for the quantification of uncertainties in the extreme wind estimates, the inter-quartile ranges for the sea surface temperatures projected by various climate models in July and October are 9.5% and 8.2% in 2050, respectively, and go up to 9.6% and 9.9% in 2080. The extreme wind speeds with 50 years return period show inter-quartile ranges of 14.2% in 2050, and the value decreases to 12.8% in 2080.