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Impacts of greenhouse gases and deforestation in Amazon Basin climate extreme indices

Adriane Lima Brito*, José Augusto P. Veiga, Francis Wagner S. Correia, Alessandro A. Michiles, Vinícius Buscioli Capistrano, Sin Chan Chou, André de Arruda Lyra, Gustavo Medeiros

*Corresponding author:

ABSTRACT: Aiming to evaluate and understand the relative and, mainly, combined impacts of increasing greenhouse gases and deforestation, on extreme precipitation events in the Amazon Basin, numerical experiments with the regional Eta model forced from the boundary conditions of the global HadGEM2-ES model were carried out. To quantify these impacts, four numerical experiments were performed with the Eta regional model forced from the initial conditions of the HadGEM2-ES global model, they are: i) Control Experiment (CTRL); ii) RCP8. 5 scenario; iii) DEFOREST scenario, ; iv) RCP8.5+DEFOREST scenario. To analyze changes in extreme rainy events associated with the increase in greenhouse gases, deforestation, and the combined effect, anomalies were calculated from the sensitivity and control experiments. In the RCP8.5 scenario, there was an increase in the maximum number of consecutive dry days (CDD), a reduction in the maximum number of consecutive wet days (CWD), a reduction in total annual precipitation (PRCPTOT), and an increase in the maximum precipitation accumulated in five consecutive days (RX5Day). The DEFOREST scenario evidenced an increased CDD, and reduction in the other indices (CWD, PRCPTOT, and RX5Day). Furthermore, the RCP8.5+DEFOREST scenario exhibited an increased CDD, and a reduction in the other indices (CWD, PRCPTOT, and RX5Day), but with more intense increases and reductions than observed in the DEFOREST scenario. In general, towards the end of the 21st century, the three scenarios would increase the drought period, mainly on the boundary between the Brazilian states of Amazonas and Pará.