Abstract
Variations in the location and strength of convection in the Western Pacific Warm Pool (WPWP) have a profound impact on the distribution and amount of global rainfall. Much of the variability in WPWP convection is attributed to variations in the El Niño-Southern Oscillation, for which the long-term trends and forcing mechanisms remain poorly understood. Despite the importance of WPWP convection to global climate change, we have very few paleohydrological reconstructions from the region. Here we present a new paleolimnologic and paleohydrologic record spanning the past 1,400 years using a multi-proxy dataset from Lake Logung, located in East Java, Indonesia that provides insights into centennial-scale trends in warm pool hydrology. Organic matter δ13C data indicate that East Java became wetter over the last millennium until ca. 1800 Common Era (CE), consistent with evidence for the southward migration of the Intertropical Convergence Zone (ITCZ) during this time. Superimposed on this long-term trend are four decade- to century-scale droughts, inferred from organic matter δ13C and calcite abundance data. They are centered at 1030, 1550, 1830, and 1996 CE. The three more recent droughts correlate with hydrologic anomalies documented in other proxy records from the WPWP region on both sides of the equator, and the two most recent droughts correlate in time with historically documented periods of multiple, intense El Niño events. Thus, our record provides strong evidence that century-scale hydrologic variability in this region relates to changes in the Walker Circulation. Human activity within the lake catchment is apparent since 1860 CE.
| Original language | English (US) |
|---|---|
| Pages (from-to) | 125-139 |
| Number of pages | 15 |
| Journal | Journal of Paleolimnology |
| Volume | 47 |
| Issue number | 1 |
| DOIs | |
| State | Published - Jan 1 2012 |
Bibliographical note
Funding Information:funded by NOAA award NA09OAR4310107 and a National Geographic Society research grant to J. Russell.
Funding Information:
We present a new, high-resolution drought record from the climatically important WPWP region. Our data suggest enhanced anthropogenic activity within the catchment of Lake Logung began circa 1860 CE. Prior to that time, variations in the lake sediment composition likely reflect the response of lacustrine sedimentation processes to climate forcing. Our record documents four droughts during the past 1,400 years that occurred from 930 to 1130, 1460–1640, 1790–1860, and 1985–2008 CE, superimposed on a long-term trend toward wetter conditions in East Java throughout the past millennium. We suggest that while this long-term pattern likely results from ITCZ migration, the spatial relationships between the higher-frequency droughts documented in our record and the hydrological trends observed in reconstructions from other sites in the WPWP region are consistent with patterns in hydrology associated with ENSO dynamics. This interpretation is supported by the co-occurrence of drought with historically documented regional drought associated with a failure of the Southeast Asian monsoon during El Niño events.
Keywords
- Drought
- ENSO
- Indonesia
- ITCZ
- Lake Logung
- Western Pacific Warm Pool
