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Universidade de Lisboa (2021)

Evolução recente e futura das condições de aridez em Portugal Continental : aplicação de Índices Bioclimáticos

Lopes, Vanessa Filipa Mendes

Titre : Evolução recente e futura das condições de aridez em Portugal Continental : aplicação de Índices Bioclimáticos

Auteur : Lopes, Vanessa Filipa Mendes

Université de soutenance : Universidade de Lisboa

Grade : Mestrado em Geografia Física e Ordenamento do Território 2021

Résumé
In recent years, there has been a growing interest in investigating climate change and its impacts, both now and in the future. In Portugal, numerous works on the theme were also developed, addressing the rising trend of air temperatures, the decrease of rainfall, the frequency of extreme events, among other items. However, the question of aridity and its evolution remains as a lesser discussed topic, despite its importance for various aspects such as biodiversity, culture, economics and even in the way of life, being therefore the theme proposed for the carrying out this work. In this study, the evolution of climate aridity in Mainland Portugal is diagnosed, considering two periods, the recent period defined by the years 1971 to 2015, and the future period, for the span of thirty years between 2041–2070. Climatic projections of regional models produced within the scope of the Euro-Cordex program were used and two levels of greenhouse gas pathways were considered, the well-known scenarios RCP4.5 and RCP8.5. Four aridity climatic indices were adopted, namely the De Martonne Aridity Index, the Emberger Aridity Index, the Bagnouls-Gaussen Aridity Index and the Thornthwaite Aridity Index. In the case of the recent period, there was a tendency for a slight increase of aridity conditions for Mainland Portugal, mainly in the south of the territory. However, this increase was not very significant, although revealed by the four indexes used, resulting in a slight increase in the representation of the most arid classes. For the future period, the simulations indicate a general increase of aridity conditions in Mainland Portugal, with the strongest increases registered in the classes associated with more marked aridity and when considering one of the regional models used (SMHI) and the RCP8.5 scenario. This increase projected for the middle of the century is very significant, and it is anticipated that the worsening of water stress in Portuguese territory may have effects on socioeconomic level, on biodiversity, on the increase of forest fires, among other problems, thus the immediate application of adaptation and mitigation measures in the upcoming years should be a priority.

Mots clés  : Aridez Índices de Aridez Temperatura Precipitação Evapotranspiração Potencial Forçamento Radiativo Modelos Climáticos Cenários RCP

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