Greenhouse gas emissions have already caused the Amazon to dry
Rhett A. Butler, mongabay.com
February 27, 2008
Analyzing a decline in SPI, a widely used drought index, since 1970 and comparing it with climate simulations from the Intergovernmental Panel for Climate Change's (IPCC) Fourth Report, researchers led by Wenhong Li of the Georgia Institute of Technology report that climate models that exclude recent emissions of greenhouse gases cannot explain declining precipitation levels in the Amazon. The results suggest that the "observed SPI trend exceeds the range of the natural climate variability", implying that the recent towards a drier climate is part of the result of anthropogenic emissions.
Looking towards the future, Li and colleagues forecast increasing incidence of drought in the region.
"For the twenty-first century, those models realistically simulating the changes of the SPI in the twentieth century suggest an overall shift of the SPI towards more frequent and/or intense dry events, and probably stronger extreme dry events over the Amazon as anthropogenic forcing continues to increase," the authors conclude.
Wenhong Li et al. (2008). Observed change of the standardized precipitation index, its potential cause and implications to future climate change in the Amazon region [FREE OPEN ACCESS]. Phil. Trans. R. Soc. B, DOI: 10.1098/rstb.2007.0026
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