500 YEARS OF CLIMATE IN THE AMAZON, THE SPECTER OF MULTI-YEAR DROUGHT, AND IMPLICATIONS FOR MANAGEMENT

The Amazon Rainforest is a carbon sink and a center of biodiversity, and as such plays a critical role in the global climatological and ecological systems. In the last decade, two widespread single year droughts alerted us to sensitivity of the Amazonian ecosystem. Both droughts were deemed once in a century events and exposed the limited perspective of the 30-year satellite record, paucity of ground-based measurements, and the need for longer records. We have analyzed sediments from Lake Ayauchi, a permanent, closed basin lake located in the Western Amazon basin, to improve understanding of past climate and hydrology. Using temperature and moisture sensitive proxies including grain size, elemental concentration, magnetic susceptibility and biomarker measurements, we have identified several multi-year hydrological events that occurred during the past ~500 years. Identifying and characterizing these events extends the climatological baseline of observations, quantifies historical variability in the Amazon Basin, and will help us to understand hydrological changes that may occur in a warming world. Our results highlight the possibility that multi-year drought events can occur in the Amazon, and thus such events need to be taken into consideration in carbon management and biodiversity conservation efforts.