Lake sediment hydroclimate proxies from the tropical South Pacific reveal large scale changes in the South Pacific convergence zone over the holocene

Sear, David, Hassall, Jonathan, Langdon, Peter, Timmermann, A., Croudace, Ian, Maloney, A. E. ` and J., sachs (2018) Lake sediment hydroclimate proxies from the tropical South Pacific reveal large scale changes in the South Pacific convergence zone over the holocene. Asia Oceania Geosciences Society 15th Annual Meeting, Honolulu, Honolulu, United States. 03 Jun - 05 Aug 2018.

Abstract

The South Pacific Convergence Zone (SPCZ) is one of the largest rain bands on our planet. Its interannual to decadal swings are largely governed by tropical Pacific sea surface temperature anomalies. The dynamics of this important climate feature and its response to external forcings have not been fully understood. Here we present the first continuous, Holocene record of SPCZ variability from Lake Lanoto’o, Samoa, and Atiu, Cook Islands, southwest Pacific. Covering the past 9,500 years, this record reveals massive shifts in the strength and / or position of the SPCZ and corresponding changes in hydroclimate across the South Pacific. The early Holocene (ca. 9,500-6,800 cal yr BP) documents drying near Samoa and a rapid transition thereafter to pluvial conditions beginning at ca. 6,800 cal yr BP and lasting until 2,800 cal yr BP. Thereafter, the hydroclimate regime switched back to a drier state. Our record documents a connection between hitherto undocumented large SPCZ swings and shifts in eastern equatorial Pacific climate conditions, associated with the El Niño-Southern Oscillation (ENSO) phenomenon.

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Contributors

Author: David Sear

Author: Peter Langdon

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