TY - JOUR
T1 - Tropical Pacific climate variability over the last 6000 years as recorded in Bainbridge Crater Lake, Galápagos
AU - Thompson, Diane M.
AU - Conroy, Jessica L.
AU - Collins, Aaron
AU - Hlohowskyj, Stephan R.
AU - Overpeck, Jonathan
AU - Riedinger-Whitmore, Melanie
AU - Cole, Julia
AU - Bush, Mark B.
AU - Whitney, H.
AU - Corley, Timothy L.
AU - Kannan, Miriam Steinitz
N1 - Funding Information:
We thank S. Truebe, M. Miller, N. Dozouville, R. Pepolas, D. Ruiz, A. Tudhope, M. Wilson, C. Chilcot, M. Parrales, and J. Suarez for providing assistance in the field and L. Cruz, E. Rosero, and their crews for ship and logistical support. We are grateful to K. Domanik, S. LeRoy, and C. Routson for their help analyzing samples and the Charles Darwin Research Station and the Galápagos National Park for facilitating all aspects of the project. We also thank W. Kenney and M. Brenner for Pb-210 analyses and the University of Arizona and the National Ocean Sciences AMS facilities for radiocarbon measurements. Finally, we thank Ellen Thomas and Emi Ito for their insightful reviews of the manuscript. This research was supported by the National Science Foundation (NSF) RAPID, P2C2, and Atmospheric and Geospace Sciences Paleoclimate Programs (awards AGS-1256970 and AGS-1561121), the NOAA Climate Program Office, The University of Arizona Department of Geosciences, and the Philanthropic Education Organization. All monitoring data, sediment records, and age models developed here are available at the National Center for Environmental Information (formerly the National Climatic Data Center) paleoclimatology database (https://www.ncdc.noaa.gov/paleo/ study/22274).
Publisher Copyright:
©2017. American Geophysical Union. All Rights Reserved.
PY - 2017/8
Y1 - 2017/8
N2 - Finely laminated sediments within Bainbridge Crater Lake, Galápagos, provide a record of El Niño–Southern Oscillation (ENSO) events over the Holocene. Despite the importance of this sediment record, hypotheses for how climate variability is preserved in the lake sediments have not been tested. Here we present results of long-term monitoring of the local climate and limnology and a revised interpretation of the sediment record. Brown-green, organic-rich, siliciclastic laminae reflect warm, wet conditions typical of El Niño events, whereas carbonate and gypsum precipitate during cool, dry La Niña events and persistent dry periods, respectively. Applying this new interpretation, we find that ENSO events of both phases were generally less frequent during the mid-Holocene (~6100–4000 calendar years B.P.) relative to the last ~1500 calendar years. Abundant carbonate laminations between 3500 and 3000 calendar years B.P. imply that conditions in the Galápagos region were cool and dry during this period when the tropical Pacific E-W sea surface temperature (SST) gradient likely strengthened. The frequency of El Niño and La Niña events then intensified dramatically around 1750–2000 calendar years B.P., consistent with a weaker SST gradient and an increased frequency of ENSO events in other regional records. This strong interannual variability persisted until ~700 calendar years B.P., when ENSO-related variability at the lake decreased as the SST gradient strengthened. Persistent, dry conditions then dominated between 300 and 50 calendar years B.P. (A.D. 1650–1900, ± ~100 years), whereas wetter conditions and frequent El Niño events dominated in the most recent century.
AB - Finely laminated sediments within Bainbridge Crater Lake, Galápagos, provide a record of El Niño–Southern Oscillation (ENSO) events over the Holocene. Despite the importance of this sediment record, hypotheses for how climate variability is preserved in the lake sediments have not been tested. Here we present results of long-term monitoring of the local climate and limnology and a revised interpretation of the sediment record. Brown-green, organic-rich, siliciclastic laminae reflect warm, wet conditions typical of El Niño events, whereas carbonate and gypsum precipitate during cool, dry La Niña events and persistent dry periods, respectively. Applying this new interpretation, we find that ENSO events of both phases were generally less frequent during the mid-Holocene (~6100–4000 calendar years B.P.) relative to the last ~1500 calendar years. Abundant carbonate laminations between 3500 and 3000 calendar years B.P. imply that conditions in the Galápagos region were cool and dry during this period when the tropical Pacific E-W sea surface temperature (SST) gradient likely strengthened. The frequency of El Niño and La Niña events then intensified dramatically around 1750–2000 calendar years B.P., consistent with a weaker SST gradient and an increased frequency of ENSO events in other regional records. This strong interannual variability persisted until ~700 calendar years B.P., when ENSO-related variability at the lake decreased as the SST gradient strengthened. Persistent, dry conditions then dominated between 300 and 50 calendar years B.P. (A.D. 1650–1900, ± ~100 years), whereas wetter conditions and frequent El Niño events dominated in the most recent century.
KW - El Niño–Southern Oscillation (ENSO)
KW - Galápagos archipelago
KW - climate variability
KW - mid-Holocene
KW - monitoring
KW - tropical Pacific Ocean
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U2 - 10.1002/2017PA003089
DO - 10.1002/2017PA003089
M3 - Article
AN - SCOPUS:85029033340
SN - 2572-4517
VL - 32
SP - 903
EP - 922
JO - Paleoceanography and Paleoclimatology
JF - Paleoceanography and Paleoclimatology
IS - 8
ER -