The Last Glacial Maximum was cool and dry over the Indo-Pacific Warm Pool (IPWP), a key region driving global oceanic-atmospheric circulation. Both low- and high-latitude teleconnections with insolation, ice sheets, and sea level have been suggested to explain the pervasive aridity observed in paleoecological and geomorphic data. However, proxies tracking the H- and O-isotopic composition of rainfall (e.g., speleothems, sedimentary biomarkers) suggest muted aridity or even wetter conditions than the present, complicating interpretations of glacial IPWP climate. Here we use multiproxy reconstructions from lake sediments and modern rainfall isotopic measurements from central Indonesia to show that, contrary to the classical "amount effect," intensified Australian-Indonesian monsoon circulation drove lighter H- and O-isotopic composition of IPWP rainfall during the LGM, while at the same time, dry conditions prevailed. Precipitation isotopes are particularly sensitive to the apparent increase in monsoon circulation and perhaps also decreased moisture residence time implied by our data, explaining contrasts among proxy records while illuminating glacial IPWP atmospheric circulation, a key target for climate models.
Bibliographical noteFunding Information:
We wish to thank Sinyo Rio for onsite precipitation collection, Rafael Tarozo, Angel Mojarro, Lily Cohen, and Kassandra Costa for laboratory assistance, David Noone for helpful discussions, and PT Vale Indonesia for local meteorological station data. This material is based upon work supported by the National Science Foundation under Grant Number NSF-EAR-0902845 to J. Russell, and an NSF Graduate Research Fellowship to B. Konecky.
© 2016 Elsevier B.V.
Copyright 2016 Elsevier B.V., All rights reserved.
- Indo-Pacific Warm Pool climate
- Leaf wax hydrogen isotopes
- Pleistocene paleoclimate
- Precipitation isotopes
- The Australian-Indonesian summer monsoon
- The Last Glacial Maximum
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