HR: 16:55h
AN: PP14A-04 INVITED    [Abstracts]
TI: Southeast Asian Mega-Droughts of the Past 5 Centuries from Tree Rings and Historical Records
AU: * Buckley, B M
EM: bmb@ldeo.columbia.edu
AF: Lamont-Doherty Earth Observatory, 61 Route 9W, Palisades, NY 10964-1707, United States
AB: The need for understanding the natural range of climate variability in the monsoon regions of Asia - among the worldês most heavily populated and most dependent on agriculture - is critical for making sound planning decisions in the face of expected hydrological changes associated with global climate change. As part of a US National Science Foundation-funded project (Tree Ring Reconstructions of Asian Monsoon Climate Variability) we have produced climate-responsive tree-ring records from tropical Asia that span the past five centuries. We find compelling evidence for 18th century decadal-scale summer monsoon droughts that span from India to Vietnam. Historical records corroborate that periods of severe drought occurred across much of the region during this time, while speleothem and coral records suggest multiple decadal-scale droughts for much of the Little Ice Age period in India, and elevated Sea Surface Temperature (SST) during the 18th century for much of the tropical Pacific, respectively. Tropical Pacific SST anomalies are seen as one key component to monsoon variability over the study region, with El Ni?o and La Ni?a like conditions resulting in rainfall reductions and increases, respectively, with corresponding opposite-sign anomalies across much of western North America. Persistent anomaly trends in the SST fields can result in the kinds of decadal-scale variability our studies suggest, although this is not the entire story. We explore the role of the Interdecadal Pacific Oscillation (IPO), first defined in 1999 as a Pacific-wide measure of variability that is physically distinct from both the Pacific Decadal Oscillation (PDO) and the El Ni?o Southern Oscillation (ENSO), in contributing to protracted –mega-droughts" in the region related to weakening monsoon strength, as suggested by recent research. Interestingly, near-millennium-aged conifers from Vietnam and Laos have been located and much longer records are now being constructed. Of great interest is the period of the late 14th and early 15th centuries when a very week monsoon is thought to have occurred, possibly contributing to the demise of the Angkor Wat civilization in Cambodia.
DE: 0429 Climate dynamics (1620)
DE: 0473 Paleoclimatology and paleoceanography (3344, 4900)
DE: 0498 General or miscellaneous
SC: Paleoceanography and Paleoclimatology [PP]
MN: 2007 Fall Meeting