Spatiotemporal Evolution of Hydroclimatic Variables in the Brazilian Semi‐Arid Region Through the Aridity Index and Susceptibility to Desertification

ABSTRACT Climate change intensifies temperatures and alters precipitation patterns, impacting water availability and increasing desertification. This article assesses the spatiotemporal evolution of the Brazilian semi‐arid region (1961–2020) using the aridity index (AI). It investigates susceptibility to desertification and the behaviour of climatic variables influencing these processes. The study covers the Brazilian Northeast (NEB) and the states of Minas Gerais and Espírito Santo, which are also affected by the region's overall spatial patterns with regions with similar climatic patterns. The climatic variables analysed during the period from 1961 to 2020, based on Brazilian Daily Weather Gridded Data (BR‐DWGD), were: maximum air temperature ( T max ), minimum air temperature ( T min ), precipitation ( P ), potential evapotranspiration (ET) and the Thornthwaite aridity index. The Mann–Kendall test was used for trend analysis, in combination with land‐cover analysis of satellite imagery. The temporal analysis revealed a statistically significant trend of warming and increased aridity in the region. There is an observed expansion of areas where T max exceeds 31°C and T min exceeds 19°C, associated with increased ET and reduced P . The conversion of native vegetation into agricultural areas, linked to rising ET, is evident and warrants further investigation regarding the crops implemented over time. Seasonal analysis of the series and investigation of extreme events, as well as ocean variability, are also recommended as modulating factors of regional climatic changes.