Climate is the set of average atmospheric conditions that characterizes a region. It directly influences the majority of human activities, especially agriculture. Climate classification systems (CCSs) are important tools in the study of agriculture, enabling knowledge of the climatic characteristics of a region. Thus, we aimed to perform the climatic characterization of the State of Paraná using the methods proposed by Köppen and Geiger (1928), modified by Trewartha (1954) (KT), Thornthwaite (1948) (TH) and Camargo (1991) and modified by Maluf (2000) (CM), using data from the European Center for Medium-Range Weather Forecast (ECMWF) model. The results of spatial interpolation (virtual stations) were performed using the Kriging method in spherical shape with one neighbour and resolution of 0.25°. The CCSs displayed the ability to separate the warm and dry from cold and wet regions. The most predominant climates were Cfa (temperate humid with hot summers), C₁rA'a' (sub-humid with little water deficiency, megathermal) and ST-UMi (humid subtropical with dry winter), according to KT, TH and CM, respectively. CM is an intermediate CCS between KT and TH.

Analyses and climate forecasts indicate significant changes in climate elements, particularly the global mean temperature, and variations in rainfall patterns, which can have profound effects on ecosystems and agriculture. This study aims to assess the impacts of climate change on the Brazilian territory using the Köppen-Geiger (1936) climate classification. Climate data were analyzed at 4,942 locations, encompassing municipalities in Brazil from 1989 to 2019. These data were obtained from the NASA/POWER platform and complemented with monthly temperature and rainfall projections from the BCC-CSM1-1 model, part of the CMIP5 (Coupled Model Intercomparison Project Phase 5), under four emission scenarios (RCP 2.6, RCP 4.5, RCP 6.0, and RCP 8.5) for the periods 2041-2060 and 2061-2080. The findings reveal a temperature increase across all scenarios, with RCP 8.5 indicating the most significant rise, reaching 4.30 and 5.42 °C for the periods 2041-2060 and 2061-2080, respectively. Additionally, the least rainy month of the year exhibits precipitation values exceeding 60 mm, leading to the dominance of the tropical climate typology “A” in 82.94% of the current climate assessment. In contrast, under climate change scenarios, reductions in areas with typical temperate climate “C” and expansions in arid climate “B” and tropical climate classes were observed compared to the present climate pattern. Notably, the BSh class has a prevalence of 6.09% and 8.16% for the periods 2041-2060 and 2061-2080, respectively. The observed climate changes signal potential challenges for the preservation of species in Brazil, as higher temperatures may hinder their adaptability to drier and warmer conditions. As a result, careful measures and strategies are needed to address the implications of these changes in the coming decades.