Observed change of the standardized precipitation index, its potential cause and implications to future climate change in the Amazon region.

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Observations show that the standard precipitation index (SPI) over the southern Amazon region decreased in the period of 1970-1999 by 0.32 per decade, indicating an increase in dry conditions. Simulations of constant pre-industrial climate with recent climate models indicate a low probability (p=0%) that the trends are due to internal climate variability. When the 23 models are forced with either anthropogenic factors or both anthropogenic and external natural factors, approximately 13% of sampled 30-year SPI trends from the models are found to be within the range of the observed SPI trend at 95% confidence level. This suggests a possibility of anthropogenic and external forcing of climate change in the southern Amazon. On average, the models project no changes in the frequency of occurrence of low SPI values in the future; however, those models which produce more realistic SPI climatology, variability and trend over the period 1970-1999 show more of a tendency towards more negative values of SPI in the future. The analysis presented here suggests a potential anthropogenic influence on Amazon drying, which warrants future, more in-depth, study.





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Li, Wenhong, Rong Fu, Robinson I Negrón Juárez and Katia Fernandes (2008). Observed change of the standardized precipitation index, its potential cause and implications to future climate change in the Amazon region. Philos Trans R Soc Lond B Biol Sci, 363(1498). pp. 1767–1772. 10.1098/rstb.2007.0022 Retrieved from https://hdl.handle.net/10161/14919.

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Wenhong Li

Associate Professor of Climate

Dr. Li's research interests focus primarily on climate dynamics, land-atmosphere interaction, hydroclimatology, and climate modeling. Her current research is to understand how the hydrological cycle changes in the current and future climate and their impacts on the ecosystems, subtropical high variability and change, unforced global temperature variability, and climate and health issues.

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