The drought that descended upon the Amazon River basin in 2005 was an extraordinary event. Its more visible effects were well documented in the mainstream media (see here, here, here, and here for a few examples). There were reports of rivers that had turned to mudflats, boats that became stranded whilst waterways evaporated, and thousands of fish that perished amidst receding currents. At the time, the media attributed the lack of rainfall in the Amazon to climate change, deforestation, and abnormally warm sea surface temperatures in the North Atlantic Ocean. But from a scientific perspective, the true causes and effects of the drought would require methodical analysis to understand.
In 2008, a careful analysis of climatic data surrounding the 2005 drought event was published in Environmental Research Letters by a team of scientists lead by Ning Zeng of the University of Maryland. These figures (from Zeng 2008) illustrate two key events that occurred in 2005, an abnormally dry Amazon River basin and an abnormally worm tropical North Atlantic Region.
Figure (a) illustrates just how dry the Amazon basin was in 2005 as compared to mean rainfall measurements for the region over the preceding 25 years (1979-2005). Where the shaded areas are the darkest brown, rainfall deficits were the most pronounced. The regions where the drought was the most devastating were in the western and southern parts of the Amazon basin. Figure (b) shows the abnormally warm sea surface temperatures in the North Atlantic region, with the more elevated temperatures marked by increasingly darker shades of red.
Find out more:
- Y. Malhi, J. T. Roberts, R. A. Betts, T. J. Killeen, W. Li, C. A. Nobre (2008). Climate Change, Deforestation, and the Fate of the Amazon Science, 319 (5860), 169-172 DOI: 10.1126/science.1146961
- O. L. Phillips et al. (2009). Drought Sensitivity of the Amazon Rainforest Science, 323 (5919), 1344-1347 DOI: 10.1126/science.1164033
- Ning Zeng, Jin-Ho Yoon, Jose A Marengo, Ajit Subramaniam, Carlos A Nobre, Annarita Mariotti, J David Neelin (2008). Causes and impacts of the 2005 Amazon drought Environmental Research Letters, 3 (1) DOI: 10.1088/1748-9326/3/1/014002
Photo © Luiz Arag„o. Brazil nut leaves carpet the forest floor in 2005 dry season, Caxiuana, Brazil.