Agricultural expansion dominates climate changes in southeastern Amazonia: the overlooked non-GHG forcing

The contribution of tropical deforestation to changes in the surface energy balance and water recycling strongly depends on which land uses replace forests. Here, we quantify how recent (2000-2010) transitions among common land uses (i.e. forests, croplands, and pastures) altered the water and energy balance of the 176,892 km² upper Xingu watershed in southeast Amazonia. Our spatial-temporal analyses of several satellite data revealed that forest-to-crop and forest-to-pasture transitions decreased net surface radiation (18% and 12%, respectively) and latent heat (32% and 24%), while increasing sensible heat (6% and 9%, respectively). Integrated over the entire upper Xingu, during the 2000s expansion of croplands and pastures into forests reduced evapotranspiration by 7 km³ and 25.5 km³, and warmed regional land surface temperatures by 0.07°C and 0.2°C, respectively. Regional pasture-to-crop transitions further reduced evapotranspiration (2.5 km³) and increased temperature (0.03 ºC). Such regional climate changes could reduce precipitation1,2, triggering negative feedbacks on forest and agricultural productivity3. Our results indicate that, at regional scales, private and public protected forests may play a critical role in buffering against climate changes caused by tropical land use change.

SILVERIO Divino V;  BRANDO Paulo M.;  MARCIA Macedo;  BECK Pieter;  BUSTAMANTE Mercedes;  COE Michael T; 

2015-10-28

IOP Publishing

JRC92619

1748-9326,   

http://iopscience.iop.org/article/10.1088/1748-9326/10/10/104015/meta,    https://publications.jrc.ec.europa.eu/repository/handle/JRC92619,   

10.1088/1748-9326/10/10/104015,