Análise de projeções das mudanças climáticas sobre precipitação e temperatura nas regiões hidrográficas brasileiras para o século XXI

Abstract

In order to obtain information about the possible impacts on the precipitation and temperature fields regime in the Brazilian hydrographic regions, due to the increase in greenhouse gas emissions, this study aimed to analyze the projections resulting from nine models participating in the Coordinated Regional Climate Downscaling Experiment (CORDEX), considering the scenarios RCP4.5 and RCP8.5 for the 21st century. The models used were CCCma-CanESM2, CSIRO-Mk3-6-0, ICHEC-EC-EARTH, IPSL-CMSAMR, MIROC5, HadGEM2-ES, MPI-M-ESM, NCC-NorESM1-M, and NOAA-GFDL-ESM2M. The anomalies and trends of the mean annual rainfall and temperature fields in the period from 2006 to 2095 were analyzed. All models projected temperature increases in all regions. For the RCP8.5 scenario, the temperature anomaly indicated an increase of up to 1.58ºC in the Amazonian hydrographic region. Precipitation is also expected to increase in some hydrographic regions. The median of anomalies suggested increases of between 10 and 30% in the Eastern Atlantic, Western Northeast Atlantic, Eastern Northeast Atlantic, Paraguay, Parnaiba, Tocantins-Araguaia, and San Francisco. Negative anomalies were identified in the Southeast and mainly in the South of Brazil, indicating reductions in precipitation. The Man-Kendall-Sen test suggested a possible intensification of the annual rainfall regime in most hydrographic regions, except those in the South Atlantic, Parana, and Uruguay. In both scenarios, the test showed no trend in the South Atlantic region by most models. All models showed a significant positive trend for temperature in both scenarios and in all regions. The highest and lowest warming trends were observed in the North and South of the country, respectively.