Efeitos da mudança de uso e cobertura do solo e do aumento na concentração de gases de efeito estufa no microclima da região metropolitana de Manaus

Abstract

The Amazon is one of the most important biomes in Brazil, as much for its immense territorial extension (about 5 million km² (~ 60%) of Brazilian territory), and for its rich biodiversity of fauna and flora. Nevertheless, it performs essential environmental services such as: carbon storage, availability of fresh water, source of moisture for remote regions, among other services. Faced with the need to understand how the change in land use and land cover and the constant increase in greenhouse gases (GHGs) affect the Amazonian climate, the present study sought to elucidate how these factors modify the climate of the Metropolitan Region of Manaus (MRM). For this, the evolution of deforestation and the expansion of urban areas in the MRM for the period from 2017 to 2100 was simulated based on the historical trends of change in land use and land cover. The analysis of these simulations indicated that: 1) if the deforestation rate maintains the historical trend, the MRM may present an increase of around 140% in the deforested area by 2100; 2) the urban area of the MRM may present an increase above 500% by the end of the 21st century. The MRM land use and land cover maps for the years 2017 and 2100 and the current and future climate conditions (RCP 8.5) derived from the global model were used as the initial and boundary conditions of the Regional Climate Model (RCM). The results showed that changes in land use and land cover produced local changes in the components of the radiation and energy balance, in surface temperature and in the spatial pattern of precipitation. Analyzing the influence of these variables on the daily cycle of two different areas (one that suffered urban expansion and the other that suffered an increase in deforestation) it was noticed that the daily cycle of precipitation increased after the time of maximum precipitation (at 14:00 local time) over the urban area. The increase in GHGs produced significant changes in the components of the radiation and energy balances resulting in a positive surface temperature anomaly (~ 10 °C) and a strong negative precipitation anomaly (~ 50%). These results were slightly intensified in the experiment that combines the increase in the concentration of greenhouse gases with the change in land use and land cover. In conclusion, it was found that the microclimate of the RMM is more sensitive to the increase in GHGs than to the local change in land use and land cover. The results of this study show that the change in land use and cover, in a relatively small region when compared to the total area of the Amazon basin, slightly modifies the surface radiation balance, precipitation and temperature on a local scale. In contrast, the climate of the RMM is significantly affected by the increase in GHGs. Our results can help in the implementation of strategic and development policies in the municipalities that are part of the RMM to minimize such effects.