Trends in heat and cold wave risks for the Italian Trentino-Alto Adigeregion from 1980 to 2018

Heat waves (HWs) and cold waves (CWs) can have considerable impact onpeople. Mapping risks of extreme temperature at local scale, accounting forthe interactions between hazard, exposure, and vulnerability, remains achallenging task. In this study, we quantify risks from HWs and CWs for theTrentino-Alto Adige region of Italy from 1980 to 2018 at high spatialresolution. We use the Heat Wave Magnitude Index daily (HWMId) and the ColdWave Magnitude Index daily (CWMId) as the hazard indicators. To obtain HWsand CW risk maps we combined the following: (i) occurrence probability maps of the hazardobtained using the zero-inflated Tweedie distribution (accounting directlyfor the absence of events for certain years), (ii) normalized populationdensity maps, and (iii) normalized vulnerability maps based on eightsocioeconomic indicators. The methodology allowed us to disentangle thecontributions of each component of the risk relative to total change inrisk. We find a statistically significant increase in HW hazard andexposure, while CW hazard remained stagnant in the analyzed area over thestudy period. A decrease in vulnerability to extreme temperature spells isobserved through the region except in the larger cities where vulnerabilityincreased. HW risk increased in 40 % of the region, with the increasebeing greatest in highly populated areas. Stagnant CW hazard and decliningvulnerability result in reduced CW risk levels overall, except for the fourmain cities where increased vulnerability and exposure increased risklevels. These findings can help to steer investments in local riskmitigation, and this method can potentially be applied to other regionswhere there are sufficient detailed data.