The Amazon rainforest experienced a once-in-a-century drought in 2005. The drought was concentrated especially in western and southwestern Amazonia, where rainfall remained unusually low during the dry season and river levels fell sharply.
Scientists linked the event mainly to unusually warm sea-surface temperatures in the tropical North Atlantic, rather than the El Niño pattern associated with many earlier Amazon droughts. Rivers and lakes in parts of Peru, Bolivia and Brazil became extremely shallow, disrupting transportation, fishing and local livelihoods.
The drought also affected the forest’s role in the carbon cycle. Instead of absorbing carbon dioxide as it normally does, drought-stressed vegetation and fires helped turn parts of the Amazon into a temporary carbon source. Satellite studies found that some intact forest areas became greener during the short drought, a reminder that the Amazon’s response is complex.
A common mix-up is 2010: that later drought was more spatially extensive and, in some respects, more severe, but the event first widely described as “once in a century” occurred in 2005.