Observed Changes of Köppen Climate Zones in Spain since 1951: Cambios observados en las zonas climáticas de Köppen en España desde 1951

Despite of having been originally formulated more than one hundred years ago, the Köppen classification is still nowadays the climate classification most widely used in climatological studies. Based on the empirical relationship between climate and vegetation, this climate classification provides an efficient and easy way to describe climate conditions and their seasonality by using a simple but ecologically meaningful classification scheme. This study examines the temporal evolution of the Köppen climate classification in Spain for the period 1951-2020, using high-resolution gridded datasets of monthly mean temperature and precipitation with 1 x 1 km spatial resolution. Climate classification maps for consecutive 30-year reference periods are compared, and the temporal evolution of each climate type in Spain is analysed, showing a progressive expansion of the arid climate zones and a contraction of the cold climate zones along the study period.