Heat wave and cold spell changes in Iberia for a future climate scenario

This study investigates the impacts of climate change scenario on summer heat waves' (HWs) and winter cold spells' (CSs) characteristics for 12 locations over the Iberian Peninsula (IP). These characteristics are duration, recovery factor and intensity. Two future time slices of the chosen scenario are studied, namely, the periods 2046-2065 and 2081-2100 which are compared with a reference climate for the recent-past (1986-2005). The RCP8.5 greenhouse gas emission scenario is considered. The minimum and maximum daily temperature were obtained for these periods through regional model simulations using the Weather and Research Forecast (WRF) model forced with the MPI-ESM-LR model. The model was validated against EOBS and SPAIN02 datasets. The model shows 90th/10th percentile temperature (i.e. thresholds to identify HW/CS) biases. Therefore, HW/CS numbers and properties were evaluated using the model's respective thresholds. HW/CS numbers and characteristics were also compared between the model and EOBS derived data. Probability density functions (PDFs) of the duration, recovery factor and intensity show significant changes in the mean and variance for the summer HWs. Differences, between future and recent-past climate in the extremes are evaluated by the 95th percentile which show an increase in the duration and intensity of the HWs for the future time slices. Very few CSs were detectable in the mid-term future (2046-2065) and none in the long-term future (2080-2100), except for Barcelona. For most locations, the CS for the future are of smaller duration and intensity. The PDF of the recovery factor suggests smaller absolute differences between the minimum and maximum temperature during winter which is also confirmed by the percentile analysis. The increase in the duration and intensity of HWs is greater in the long-term future than in the mid-term future, pointing for a warmer IP with more and longer HWs towards the end of the XXI century.