Combined impacts due to deforestation and the forest fires in the Amazonia and the global climate change on the future climate of South America: a modelling study

Abstract:

Since the late 1980s a large number of numerical experiments with atmospheric general circulation models has been used to assess the impacts of deforestation on global and regional climate, and one of the main motivations is the Amazon rainforest. In the same way, in the last decade several studies have shown that a higher concentration of CO₂ in the atmosphere could lead changes in climate in the Amazon region. In this study we performed new analyses to quantify how deforestation, fire and the increase in atmospheric CO2 concentration may combine to affect the climate in Amazonia during this century. For the projection of land use was considered a spatially explicit land use scenario from Aguiar et al. (2013). The scenario was built using LuccME generic modelling framework and the potential of change considering the proximity to previously deforested areas and also spatial drivers (roads and protected areas). In order to quantify the response of Brazilian Earth System Model, with INLAND-IBIS surface model, to climate change, deforestation and forest fire we performed a suite of simulations in two main categories: 1) the model was running under historical and RCP8.5 greenhouse gas concentration, and 2) the model was forced by the same configuration in 1 but also considering the effects of deforestation and forest fire in Amazon. In summary, the most important changes occur in the East/Northeast and South of the Amazonia and are more evident when are considered all effects (climate change, deforestation and fire). The results show warmer near-surface air temperature in all cases compared to the control case. This relative warming of the deforested land surface is consistent with the reduction in evapotranspiration, the lower leaf area and the lower surface roughness length. There is a reduction in annual precipitation in both cases mainly over eastern/northeastern Amazonia. The reduction in precipitation occurs mainly during the dry season (June-November) in both cases, and there is an increase in dry season length that is more evident when are considered all effects. In summary, we conclude that the synergistic combination of deforestation and climate change resulting from global warming may lead to important impacts that add considerably to the vulnerability of tropical forest ecosystems in the region.