Bioclimatic shifts and land use options for Viticulture in Portugal

Abstract

Land use, plays a relevant role in the climatic system. It endows means for agriculture practices thus contributing to the food supply. Since climate and land are closely intertwined through multiple interface processes, climate change may lead to significant impacts in land use. In this study, 1-km observational gridded datasets are used to assess changes in the Köppen–Geiger and Worldwide Bioclimatic (WBCS) Classification Systems in mainland Portugal. As such, two past periods were analyzed: 1950–1979 and 1990–2019. A compound bioclimatic-shift exposure index (BSEI) is defined to identify the most exposed regions to recent climatic changes. The temporal evolution of land cover with vineyards between 1990 and 2018, as well as correlations with areas with bioclimatic shifts, are also analyzed. Results show an increase of 18.1% in the Warm Mediterranean with hot summer (Csa) climate in Portugal. This increase was followed by a 17.8% decrease in the Warm Mediterranean with warm summer (CSb) climate. Moreover, the WBCS Temperate areas also reveal a decrease of 5.11%. Arid and semi-arid ombrotypes areas increased, whilst humid to sub-humid ombrotypes decreased. Thermotypic horizons depict a shift towards warmer classes. BSEI highlights the most significant shifts in northwestern Portugal. Results show that vineyards have been displaced towards regions that are either the coolest/humid, in the northwest, or the warmest/driest, in the south. As vineyards in southern Portugal are commonly irrigated, options for the intensification of these crops in this region may threaten the already scarce water resources and challenge the future sustainability of these sectors. As similar problems can be found in other regions with Mediterranean-type climates, the main outcomes from this study can be easily extrapolated to other countries worldwide.