Coeval Drying Across the Central Tropical Pacific Over the Last Millennium

D.A. Wyman, J.L. Conroy, M.R. Osburn, A.R. Atwood

Research output: Contribution to journalArticlepeer-review

Abstract

Hydroclimatic variability in the tropical Pacific reflects large-scale ocean-atmosphere processes that imprint on global climate, but tropical Pacific hydroclimate variability over the last millennium remains uncertain. Here we present a multi-proxy reconstruction from a lacustrine sediment record on Kiritimati Atoll that spans the last millennium. A lake salinity reconstruction from the δ2H values of total lipid extracts, combined with changes in sediment mineralogy and the stable isotopic composition of inorganic carbonates, indicate the presence of several distinct hydrologic regimes on Kiritimati, including a period of persistent aridity from 960–1030 CE, shorter episodes of aridity from 1030–1370 CE, and extreme aridity throughout the latter half of the last millennium, from 1370–1970 CE, that drove complete evaporation of the lake. A period of wetter, variable conditions defines recent decades. Compound-specific lipid biomarker δ2H values indicate that shifts in microbial community structure occurred in the past, from a community dominated by photoautotrophic and chemoautotrophic organisms in more arid periods to a more metabolically diverse community in the recent period. Comparison of this record with nearby sediment records from Washington Island reveals a similar pattern of aridity through the last millennium, followed by wetter conditions in the modern period. These coherent changes in hydroclimate in the central Pacific are inconsistent with a migration of the Pacific Intertropical Convergence Zone within these latitudes. Rather, past aridity was caused by reduced El Niño-Southern Oscillation variability, observed through the low-pass filter of lacustrine records, or by multidecadal to multi-century strengthening of the Pacific Walker Circulation. © 2021. American Geophysical Union. All Rights Reserved.
Original languageEnglish (US)
Article numbere2021PA004311
Number of pages15
JournalPaleoceanography and Paleoclimatology
Volume36
Issue number7
DOIs
StatePublished - 2021

Bibliographical note

Funding Information:
This work was funded by NSF EAR 1602590 to JLC and LacCore support to DAW. The authors thank the Environmental Ministry of the Republic of Kiribati for the research permit to complete this work. We thank M. Higley, C. Karamperidou, N. Murray, and N. Meghani for assistance with field work, the Osburn Lab for training and assistance with biomarker measurements, and A. Masterson for hydrogen isotopic measurements.

Funding Information:
This work was funded by NSF EAR 1602590 to JLC and LacCore support to DAW. The authors thank the Environmental Ministry of the Republic of Kiribati for the research permit to complete this work. We thank M. Higley, C. Karamperidou, N. Murray, and N. Meghani for assistance with field work, the Osburn Lab for training and assistance with biomarker measurements, and A. Masterson for hydrogen isotopic measurements.

Publisher Copyright:
© 2021. American Geophysical Union. All Rights Reserved.

Keywords

  • biomarker
  • hydroclimate
  • lake
  • salinity
  • stable isotope
  • tropical Pacific

Continental Scientific Drilling Facility tags

  • K2014

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