Climate change could turn parts the Amazon rainforest into savanna
Shifts in climate have significantly affected tropical rainforests in the past and there is growing concern among scientists involved with the Large Scale Biosphere/Atmosphere Experiment in Amazonia that climate change, when with combined large-scale deforestation, could turn extensive parts of the Amazon rainforest into savanna.
Past climate change has caused fluctuations in the extent of tropical rainforests (http://rainforests.mongabay.com/0304.htm, ). Many scientists believe that much of the Amazon reverted to savanna and montane forest during the past ice age -- a transition that could be worsened by increasing deforestation in the region.
Recent studies using NASA satellite data suggest that deforestation in the Amazon can affect regional climate. Researchers found that during the Amazon dry season there was a distinct pattern of higher rainfall and warmer temperatures over deforested regions (http://www.mongabay.com/external/Deforestation_Affects_Climate.htm). The loss of forest cover means there is less heat absorption by vegetation, resulting in less moisture being taken up into the atmosphere. In the long run, this can result in reduced rainfall and contribute to a positive feedback loop which encourages further replacement of rainforest with savanna (* in the long term this shift may have positive effects for global biodiversity, but in the short-term it could be devastating to human populations). Furthermore, savanna vegetation is more susceptible to fires, which in themselves may alter regional climate by inhibiting cloud formation.