Extreme precipitation events are one of the most consequential components of climate change for society. The El Niño-Southern Oscillation (ENSO) is the dominant mode of precipitation variability in the tropics and causes severe flooding and drought in many socioeconomically vulnerable regions. It remains unclear how tropical rainfall extremes and ENSO are changing in response to anthropogenic forcing, demanding that we investigate the relationships between precipitation, ENSO, and external forcing in the past. Lake sediment records have provided benchmark records of extreme flood events from the eastern tropical Pacific, where paleofloods have been interpreted to reflect El Niño events during the last millennium. However, the connections between flooding and ENSO variability in this region are uncertain, and the eastern Pacific can only capture precipitation events driven by El Niño, not La Niña. Thus, it is unclear how the ENSO system and tropical rainfall extremes have changed in the recent past. Here, we reconstruct flood events during the past millennium using a lake sediment record from East Java, Indonesia, which can provide insight into flooding driven by La Niña. We detect flood frequency variations in the western tropical Pacific that are highly coherent with records from the eastern part of the basin over the past millennium. Our findings demonstrate that heavy rainfall and flooding occurs more frequently on both sides of the tropical Pacific during periods of warmer Northern Hemisphere mean temperatures, implying that ENSO-driven rainfall extremes could intensify in the near future.
Bibliographical noteFunding Information:
We thank the Government of the Republic of Indonesia and the Ministry of Research, Technology, and Higher Education (RISTEK) for permission and assistance in conducting field research. We thank Candace Bousquet for laboratory assistance, Baylor Fox-Kemper for helpful discussions, and Tom Cronin and two anonymous reviewers for improving the quality of this manuscript. This material is based upon work supported by the US National Science Foundation [grant number 0902845 ], the National Geographic Society [grant number 8083-06 ], and the National Oceanic and Atmospheric Administration Climate Change Data and Detection program [grant number NA09OAR4310090 ]. Any use of trade, product or firm names is for descriptive purposes only and does not imply endorsement by the U.S. government.
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- La Niña
- Pacific Ocean