Simulação dos impactos das mudanças climáticas globais na evapotranspiração de referência da bacia amazônica brasileira

Abstract

The intensification of the global warming process caused by the increase in the emission of greenhouse gases (GHG) represents numerous risks for natural ecosystems. Changes in the atmospheric composition can alter climatic variables in several regions of the planet, among them the Brazilian Amazon Basin (BAB). Considered the largest hydrographic basin on the planet, this region influences the climate in other parts of Brazil and Latin America. Therefore, changes in BAB can lead to environmental imbalances in other regions. Among the effects caused by climate change, there are changes in the evapotranspiration patterns, an important regulator of the hydrological cycle. In this article, we simulate future changes in the reference evapotranspiration (ETo) at BAB resulting from a continuous increase in GHG emissions (scenario RCP 8.5). We use the Dinamica EGO environmental modeling platform to implement a spatially explicit model based on the Penman-Monteith method standardized by FAO. The validation was carried out by statistically comparing the results between the simulations and the observations. Thus, we prove that the model closely represents the evapotranspiration process at BAB. The projected seasonality of ETo remained statistically similar to that observed until the year 2050, with an increase in ETo during the dry season and a reduction during the rainy season. ETo showed a spatial distribution pattern with higher values in the eastern portion, extending north-south. This pattern follows the distribution of the temperature and radiation balance values, in addition to coinciding with the spatial arrangement of deforestation. A radiative forcing of 8.5 w / m² across the planet will cause an increase in ETo in the BAB, as a result of the increase in temperature values and the balance of solar radiation. This increase is more evident in the northeast region, progressively extending to the southwest of the basin. Throughout the 21st century, future changes in ETo patterns can pose major problems for agricultural practices and water supply in BAB and other parts of the country. In short, global climate change, reflecting changes in ETo together with the increase in deforestation, they can lead to a deregulation of the water balance. Our results reinforce the need to adopt effective government actions in order to mitigate the effects of the intense GHG emissions.