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A new Holocene lake sediment archive from Samoa (tropical South Pacific) reveals millennial scale changes in ENSO driven precipitation

A new Holocene lake sediment archive from Samoa (tropical South Pacific) reveals millennial scale changes in ENSO driven precipitation
A new Holocene lake sediment archive from Samoa (tropical South Pacific) reveals millennial scale changes in ENSO driven precipitation
El Niño-Southern Oscillation (ENSO) is the strongest source of interannual climate variability on the planet. Its behaviour leads to major hydro-climate impacts around the world, including flooding, drought, and altering cyclone frequency. Simulating ENSO behaviour is difficult using climate models, as it is a complex non-linear system, and hence predicting its future variability under changing climate is challenging. Using palaeoclimate data thus allows an insight into long-term ENSO behaviour against a range of different forcings throughout the Holocene. To date long, coherent, high resolution records from lake sediment archives have been limited to the Pacific Rim. We present new data from the closed crater Lake Lanoto'o, on Upolu Island, Samoa, located within the tropical South Pacific. The lake sediment record extends back into the early Holocene with an average sedimentation rate 0.4mm a-1. We demonstrate a strong correspondence between precipitation at the study site and measures of the Southern Oscillation Index (SOI)1. We compare geochemical proxies of precipitation to a long-term reconstruction of the SOI2. The resulting proxy SOI record extends over the last 9000 years, revealing scales of change in ENSO that match those recorded from sites located on the Pacific rim3,4. A major period of La-Nina dominance occurs around 4.5ka BP before abruptly switching to El-Nino dominance around 3.2ka. Thereafter, phases of El-Nino - La Nina dominance, alternate every c. 400yrs. The results point to prolonged phases of enhanced or reduced precipitation - conditions that may influence future population resilience to climate change, and may also have been triggers for the colonisation of more remote eastern Polynesia. 1. http://www.cgd.ucar.edu/cas/catalog/climind/SOI.signal.annstd.ascii. 2. Yan, H. et al. (2011) Nature Geoscience, 4, p.611. 3. Conroy J. L. et al. (2008) Quaternary Science Reviews, 27, p.1166 4. Moy, C. M. et al. (2002) Nature, 420, p.162
Sear, David
ccd892ab-a93d-4073-a11c-b8bca42ecfd3
Hassall, Jonathan
17b719cf-5b7b-496a-8bf7-96c57618baca
Langdon, Peter
95b97671-f9fe-4884-aca6-9aa3cd1a6d7f
Croudace, Ian
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Maloney, A. E. `
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Sachs, Julian P.
22b7dd0e-f300-491e-94df-8f226c14980c
Sear, David
ccd892ab-a93d-4073-a11c-b8bca42ecfd3
Hassall, Jonathan
17b719cf-5b7b-496a-8bf7-96c57618baca
Langdon, Peter
95b97671-f9fe-4884-aca6-9aa3cd1a6d7f
Croudace, Ian
24deb068-d096-485e-8a23-a32b7a68afaf
Maloney, A. E. `
61b7b468-9323-4859-9aea-6370e20903fd
Sachs, Julian P.
22b7dd0e-f300-491e-94df-8f226c14980c

Sear, David, Hassall, Jonathan, Langdon, Peter, Croudace, Ian, Maloney, A. E. ` and Sachs, Julian P. (2015) A new Holocene lake sediment archive from Samoa (tropical South Pacific) reveals millennial scale changes in ENSO driven precipitation. American Geophysical Union, Fall Meeting 2015, United States. 14 - 18 Dec 2015.

Record type: Conference or Workshop Item (Paper)

Abstract

El Niño-Southern Oscillation (ENSO) is the strongest source of interannual climate variability on the planet. Its behaviour leads to major hydro-climate impacts around the world, including flooding, drought, and altering cyclone frequency. Simulating ENSO behaviour is difficult using climate models, as it is a complex non-linear system, and hence predicting its future variability under changing climate is challenging. Using palaeoclimate data thus allows an insight into long-term ENSO behaviour against a range of different forcings throughout the Holocene. To date long, coherent, high resolution records from lake sediment archives have been limited to the Pacific Rim. We present new data from the closed crater Lake Lanoto'o, on Upolu Island, Samoa, located within the tropical South Pacific. The lake sediment record extends back into the early Holocene with an average sedimentation rate 0.4mm a-1. We demonstrate a strong correspondence between precipitation at the study site and measures of the Southern Oscillation Index (SOI)1. We compare geochemical proxies of precipitation to a long-term reconstruction of the SOI2. The resulting proxy SOI record extends over the last 9000 years, revealing scales of change in ENSO that match those recorded from sites located on the Pacific rim3,4. A major period of La-Nina dominance occurs around 4.5ka BP before abruptly switching to El-Nino dominance around 3.2ka. Thereafter, phases of El-Nino - La Nina dominance, alternate every c. 400yrs. The results point to prolonged phases of enhanced or reduced precipitation - conditions that may influence future population resilience to climate change, and may also have been triggers for the colonisation of more remote eastern Polynesia. 1. http://www.cgd.ucar.edu/cas/catalog/climind/SOI.signal.annstd.ascii. 2. Yan, H. et al. (2011) Nature Geoscience, 4, p.611. 3. Conroy J. L. et al. (2008) Quaternary Science Reviews, 27, p.1166 4. Moy, C. M. et al. (2002) Nature, 420, p.162

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More information

Published date: December 2015
Venue - Dates: American Geophysical Union, Fall Meeting 2015, United States, 2015-12-14 - 2015-12-18

Identifiers

Local EPrints ID: 432461
URI: http://eprints.soton.ac.uk/id/eprint/432461
PURE UUID: 4f589c7d-7f4b-4a66-a458-35757f087929
ORCID for David Sear: ORCID iD orcid.org/0000-0003-0191-6179
ORCID for Peter Langdon: ORCID iD orcid.org/0000-0003-2724-2643

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Date deposited: 16 Jul 2019 16:30
Last modified: 13 May 2020 00:29

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Contributors

Author: David Sear ORCID iD
Author: Jonathan Hassall
Author: Peter Langdon ORCID iD
Author: Ian Croudace
Author: A. E. ` Maloney
Author: Julian P. Sachs

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