Regional trends in maximum and minimum surface air temperatures in Pernambuco Brazil from 1961 to 2024
摘要
The semi-arid Northeast of Brazil is one of the most vulnerable regions to climate change, characterized by strong thermal and hydrological variability. The intensification of warming in this region, coupled with urban expansion and changes in land use, highlights the need for detailed regional analyses to understand the local warming mechanisms and their socio-environmental impacts. In this context, this study investigated the temporal dynamics of maximum and minimum air temperatures in the state of Pernambuco, Brazil, with the aim of characterizing thermal patterns and identifying warming trends between 1961 and 2024, highlighting the climatic and geographical particularities of the municipalities of Cabrobó (Sertão Semiárido, western interior of the state); Garanhuns (Agreste Semiárido, central interior); Surubim (Agreste tropical, north-central, bordering the Zona da Mata) and the Metropolitan Region (Eastern Coast). Daily historical series of maximum and minimum air temperatures (Tmax, Tmin) from the National Institute of Meteorology stations were used for the period 1961–2024 (civil years). The research included characterization analyses, anomalies, and statistical trend tests (Mann-Kendall and Theil-Sen), as well as change-point detection (Pettitt test). Seasonal, decadal, and climatological average (1961–1990; 1991–2020) comparisons were performed. The results revealed significant and widespread warming across all regions for Tmin and Tmax (+ 0.018–0.031 °C.year⁻¹), with a 95% confidence level, indicating increases greater than 1,0 °C over 50 years. The 1990s stood out as a turning point, with marked warming, especially after the strong El Niño event of 1997–1998. The last decade (2011–2020) was the most critical, concentrating the largest positive anomalies. Regional analysis revealed distinct patterns: in the semi-arid Sertão (Cabrobó), peaks in Tmax (up to 40.4 °C) and a higher rate of change (+ 0.028–0.031 °C.year⁻¹) were observed; in the Agreste region (Garanhuns and Surubim), the increase in Tmin indicated progressively warmer nights, compromising nighttime recovery (+ 0.018–0.026 °C.year⁻¹) and greater thermal amplitudes (12.5 °C between Tmin and Tmax); and on the coast (Recife), the consistent increase in Tmin may reflect the effects of urbanization and the occurrence of urban heat islands (+ 0.014–0.024 °C.year⁻¹). Seasonal assessments highlighted more intense warming during the transition from summer to autumn (March to May). These findings indicate significant and non-linear warming, with a change in the thermal regime starting in the 1990s, especially after the 1997–1998 El Niño event. The intensification of warming in recent decades highlights the growing influence of anthropogenic and regional factors on the local climate, emphasizing the need to strengthen meteorological monitoring and adaptation policies on a regional scale.