Climate change and heatwaves in the main coastal cities of the Basque Country

Abstract

In this paper we analyse the probabilistic behaviour of heatwaves (HWs) in the main coastal cities of the Basque Country (Bayonne, Bilbao and Donostia-San Sebastian) in the twentyfirst century. We estimate HW behaviour using data from eight climate circulation models under two representative concentration pathways (RCP 8.5 and RCP 4.5). We model HWs according to three factors: number per annum, duration and intensity, including correlations, and find very different results for each climate model. This highlights the problem of using a single model. Under RCP 8.5, we find an expected mean excess over the 30C temperature threshold of 4.19C for Bayonne, 4.05C for Bilbao and 4.14C for Donostia-San Sebastian in 2100. These expected values are based on incomplete information, so we also calculate several risk measures.