Collaborative Research: Pilot Study in Tropical Isotope Dendroclimatology

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The scientific strategy for this research exploits recent breakthroughs in stable isotope dendro-ecology, mass spectrometry, and analytical chemistry to develop chronological and climate proxy data in tropical trees that lack rings. Tree-ring records have shown great potential for long term observations (500 years before present or longer) but are limited in extent because many tropical tree species form rings intermittently or not at all.The ultimate goal of this research is to develop annually resolved proxy estimates of rainfall variability from Indonesia for the past several centuries. These data are expected to directly contribute to observations of past changes in frequency and strength of the El Nino-Southern Oscillation (ENSO) by complementing the existing proxy data network composed of tropical reef corals and extratropical trees. The tropics are an important component of the global climate system, possessing the dynamics and energetics to organize global-scale climatic anomalies on seasonal to interannual time scales. Evidence from models suggests the tropics may be a persistent influence of global climate variability on long time scales. Long-term variability in the tropical climate has the potential to affect the lives of fully a quarter of the world's population primarily through the interruption of seasonally normal precipitation and agricultural patterns. To date the most important archives for seasonal to annual resolution proxy records in the tropics have been derived from measurements from coral reefs and ice cores. They have their limitations, however, as few coral records predate the existing 100-150 year long historical observational record and ice core records, while older, are limited to a few rapidly disappearing tropical ice fields. Prospects for obtaining replicated 300-500 year long records remain challenging but isotope dendroclimatology offers great promise in closing the data gap and, in this manner, offers the potential for broad impact to many scientific fields.