Modeling the impacts of land cover change in Amazonia: a regional climate model (RCM) simulation study

Abstract

SummaryThe numerical regional model (Eta) coupled with the Simplified Simple Biosphere Model (SSiB) was used to investigate the impact of land cover changes on the regional climate in Amazonia. Four 13-month integrations were performed for the following scenarios: (a) no deforestation, (b) current conditions, (c) deforestation predicted for 2033, and (d) large scale deforestation. All initial and prescribed boundary conditions were kept identical for all integrations, except the land cover changes. The results show that during the dry season the post-deforestation decrease in root depth plays an important role in the energy budget, since there is less soil moisture available for evapotranspiration. In all scenarios there was a significant increase in the surface temperature, from 2.0 C in the first scenario, up to 2.8 C in the last one. In both the scenarios (b) and (c), the downward component of the surface solar radiation decreased due to an increase in the cloud cover over the deforested areas, which contributed to a further reduction of the net radiation absorbed at the surface. The cloud mechanism, where an increase in albedo is balanced by an increase in downward solar radiation, was not detected in any of these scenarios. In scenarios (a), (b) and (c), a negative feedback mechanism was observed in the hydrological cycle, with greater amounts of moisture being carried to the deforested areas. The increase in moisture convergence was greater than the reduction in evapotranspiration for both scenarios (b) and (c). This result, and the meso-scale thermodynamic processes caused an increase in precipitation. A different situation was observed in the large-scale deforestation scenario (d): a local increase of moisture convergence was observed, but not sufficiently intense to generate an increase in precipitation; the local evapotranspiration decrease was dominant in this scenario. Therefore, the partial deforestation in Amazonia can actually lead to an increase in precipitation locally. However, if the deforestation increases, this condition becomes unsustainable, leading to drier conditions and, consequently, to reduced precipitation in the region.

Impacts of Land Cover and Greenhouse Gas (Ghg) Concentration Changes on the Hydrological Cycle in Amazon Basin: A Regional Climate Model Study

“…The relation between the increase in surface temperature and deforestation along the highways Belem-Brasilia, Cuiaba-Porto Velho, Manaus-Porto Velho is well indicated in the simulation. These values are close to those obtained by Correia et al (2008) where the authors evaluated the climate changes due to deforestation using the limited area ETA model. Numerical simulations with global circulation and regional model performed by Lean and Rowntree (1997) and Gandu et al (2004), respectively, have shown less significant increase, in the surface temperature, than obtained here.…”

“…The scenario of the 2050 year is elaborated from the dynamic vegetation model Dinamica EGO (SOARES-FILHO et al, 2004). In this study the biome degraded pasture represented the deforestation in the Amazon Basin (CORREIA et al, 2008). Many parameters have been calibrated using measurements taken on forest and pasture sites in the Amazon region (CORREIA et al, 2005).…”

Land Use Change over the Amazon Forest and Its Impact on the Local Climate

“…Four scenarios of LUC over the AMZ were analyzed by Correia, F.W.S. et al [22]: (a) no deforestation, (b) current conditions, (c) deforestation projected for 2033 and (d) large scale deforestation. For this investigation, 13-month integrations were performed using the Eta model (name derived from the Greek letter) coupled to the simplified simple biosphere model (SSiB).…”

Modelling the effects of land‐use/land‐cover changes on the near‐surface atmosphere in southern South America

“…Most of the modelling studies addressing the impacts of LULC changes in South America are centred on tropical regions, particularly deforestation on the Amazon basin and desertification in northeast Brazil (e.g. Nobre et al, 1991;Hahmann and Dickinson, 1997;Baidya Roy and Avissar, 2002;Correia et al, 2007;Costa et al, 2007). Nevertheless, over the last two decades, A&R plans supported through government economic incentives or subsidies have been implemented in Chile, Uruguay, and Argentina (World Bank, 2000).…”