Samples from eight cedar trees in Bolivia have helped shed light on the seasonal rainfall in the Amazon basin over the past century, say researchers.
A study led by UK-based scientists said the data from the trees provided a key tool to assess the natural variation in the region's climate system.
It suggested that tree-rings from lowland tropical cedar provided a natural archive of rainfall data.
The findings appear in the Proceedings of the National Academy of Sciences.
"Climate models vary widely in their predictions for the Amazon, and we still do not know whether the Amazon will become wetter or dryer in a warmer world," said co-author Manuel Gloor from the University of Leeds.