Abstract ID: 420

Climatic impacts due to concurrently land cover changes over Amazon basin and Northeast semi-arid region of Brazil - A simulation modeling study.

Tropical South American biomes have been going through a high level of environmental degradation, with large areas transformed from closed forests to croplands and pasture as well as with visible land cover degradation over (caatinga) vegetation region located in Northeast of Brazil (NEB). Numerous modeling studies have demonstrated that the land use changes described above influence climate, and may trigger feedback mechanisms which may lead to new vegetation distributions and atmospheric circulation patterns. However, such modeling studies set up only individual biome changes, for instance, the replacement of the Amazon forest by savannas, pasture or croplands, and caatinga by deserts. However, Amazon forest and caatinga vegetation are experiencing human pressures togheter and because of that do not impact the climate system separately but at the same time. Considering this two-biome replacement scenario, we use the Center of Climate Studies and Weather Forecasting (CPTEC) general circulation model coupled with SSiB land surface scheme to simulate the regional climate responses after Amazon forest and caatinga are converted at the same time into savanna and desert, respectively (AN experiment). We compare AN anomalies to the linear sum of individual-biome-replacement anomalies taken from savannization and desertification alone. Results show that, despite the fact that annual means present weak significant differences and may have a secondary role, seasonally, during drier months (June-October), AN simulation presents stronger impacts on both precipitation and temperature within Amazon basin and NEB than does the linear sum of individual biome conversions. Simulation results suggest that, considering seasonal timescales, there might be synergy processes acting when two biomes are replaced togheter and this concept should be taken into account when aggregating climatic effects of two or more land cover conversions.

Session:  Feedbacks to Climate - Effects of deforestation on regional and global climate.

Presentation Type:  Poster