Evaluation of the Evolution of Heatwave Occurrences in Algiers Over the Last Decades Using a Multivariate Heatwave Index

The aim of this work is to evaluate the evolution of heat waves in the city of Algiers over the last few decades, more specifically during the period from 1950 to 2022. Since 1980, heatwaves have become more frequent and intense in various regions worldwide, particularly in Europe, Africa and Asia. The principal human health effects of heatwaves include organs' strain and damage, complications of cardiovascular and kidney diseases, as well as adverse reproductive effects. However, some recent studies have pointed to the association of heatwaves with the thermal stress to which some crops can be subjected, which makes the need to establish objective criteria to define what heatwave episodes are and their temporal evolution, both in the present climate and in the future climate, even greater. Thus, the objective of this study was apply to the city of Algiers a normalized index that could be replicated for any region of the planet, across different temporal scales, that was not dependent on a specific temperature value, that considered the impacts of relative humidity on health risk, that accounted for the persistence of heatwave episodes, and that, moreover, considered the effects of extreme temperatures in an exponential manner. The index was used for evaluating the annual trend of increasing heatwaves on a climate scale in Algiers using ERA 5 data. The results showed an increase of approximately 343% in the heat wave index values for the city when comparing the average index values between the periods 2001–2022 and 1978–2000.