Geochemistry of karst deposits in Borneo detailing hydroclimate variations in the Warm Pool across the late Pleistocene
Variability in the tropical ocean-atmospheric system causes global scale climate anomalies, most evident in the El Niño-Southern Oscillation’s coupled climate feedbacks. Despite being an area of high interest, many questions still remain regarding the west Pacific warm pool’s response to external fo...
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Georgia Institute of Technology
2014
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Online Access: | http://hdl.handle.net/1853/52277 |
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ftgeorgiatech:oai:smartech.gatech.edu:1853/52277 2023-05-15T16:30:42+02:00 Geochemistry of karst deposits in Borneo detailing hydroclimate variations in the Warm Pool across the late Pleistocene Carolin, Stacy Anne Cobb, Kim M. Earth and Atmospheric Sciences Lynch-Stieglitz, Jean Webster, Peter J. 2014-08-27T13:38:40Z application/pdf http://hdl.handle.net/1853/52277 en_US eng Georgia Institute of Technology Western tropical Pacific Oxygen isotopes U-series dating Abrupt climate change Glacial-interglacial cycles Hydrology Hydroclimate Stalagmites Karst system Warm pool Late pleistocene Glacial period Dissertation 2014 ftgeorgiatech 2018-09-18T19:51:37Z Variability in the tropical ocean-atmospheric system causes global scale climate anomalies, most evident in the El Niño-Southern Oscillation’s coupled climate feedbacks. Despite being an area of high interest, many questions still remain regarding the west Pacific warm pool’s response to external forcing, particularly its response to increases in anthropogenic greenhouse gases. Paleoclimate reconstructions coupled with model simulations provide insight into the tropical Pacific’s role in past climate variability necessary to the development of robust climate projections. Most paleoclimate records, however, still lack the resolution, length, and chronological control to resolve rapid variability against a background of orbital-scale variations. Here we present stalagmite oxygen isotope (δ18O) reconstructions from Gunung Mulu National Park (4oN, 115oE ), in northern Borneo, that provide reproducible centennial-scale records of western Pacific hydrologic variability that are precisely U/Th-dated and continuous throughout most of the late Pleistocene (0-160 thousand years ago, kybp). The record comprises an entire glacial-interglacial cycle, which allows us to investigate orbital-scale climate forcings and compare two well-dated glacial terminations in the western tropical Pacific. The ice- volume-corrected δ18O records suggest that glacial boundary condtions, which include significantly lower atmospheric carbon dioxide levels, did not drive significant changes in Mulu rainfall δ18O. Similarly, Borneo stalagmite δ18O is poorly correlated to either global sea level shifts or Sunda Shelf areal exposure is not evident. The Borneo record does vary in phase with local mid-fall equatorial insolation, suggesting that precessional forcing may impart a strong influence on hydroclimate variability in the warm pool. This is best illustrated across Glacial Termination II, when the oscillation of equatorial fall insolation is large and out of phase with ice sheet decay. We also use a subset of well-dated, high-resolution stalagmite δ18O records from Mulu to investigate millennial-scale climate variability during Marine Isotope Stages 3-5 (30-100kybp). We find that regional convection likely decreased during the six massive iceberg discharges defined in the North Atlantic sediment records (“Heinrich events”). The inferred drying (increased stalagmite δ18O) during Heinrich events is consistent with a southward shift of the Intertropical Convergence Zone – the dominant paradigm to explain global climate anomalies originating in the north Atlantic (ref). However, any hydrologic variability related to Dansgaad-Oeschgar (D/O) events, millennial-scale sawtooth temperature anomalies of the last glacial period first evident in the Greenland ice records, is notably absent in the stalagmite records. . The Mulu stalagmite record’s absence of D/O signal, however, is in marked contrast to the regional west Pacific marine records and suggests D/O events and Heinrich events may be characterized by fundamentally different climate mechanisms and feedbacks. Ph.D. Doctoral or Postdoctoral Thesis Greenland Ice Sheet North Atlantic Georgia Institute of Technology: SMARTech - Scholarly Materials and Research at Georgia Tech Greenland Pacific Sunda ENVELOPE(-6.982,-6.982,62.205,62.205) |
institution |
Open Polar |
collection |
Georgia Institute of Technology: SMARTech - Scholarly Materials and Research at Georgia Tech |
op_collection_id |
ftgeorgiatech |
language |
English |
topic |
Western tropical Pacific Oxygen isotopes U-series dating Abrupt climate change Glacial-interglacial cycles Hydrology Hydroclimate Stalagmites Karst system Warm pool Late pleistocene Glacial period |
spellingShingle |
Western tropical Pacific Oxygen isotopes U-series dating Abrupt climate change Glacial-interglacial cycles Hydrology Hydroclimate Stalagmites Karst system Warm pool Late pleistocene Glacial period Carolin, Stacy Anne Geochemistry of karst deposits in Borneo detailing hydroclimate variations in the Warm Pool across the late Pleistocene |
topic_facet |
Western tropical Pacific Oxygen isotopes U-series dating Abrupt climate change Glacial-interglacial cycles Hydrology Hydroclimate Stalagmites Karst system Warm pool Late pleistocene Glacial period |
description |
Variability in the tropical ocean-atmospheric system causes global scale climate anomalies, most evident in the El Niño-Southern Oscillation’s coupled climate feedbacks. Despite being an area of high interest, many questions still remain regarding the west Pacific warm pool’s response to external forcing, particularly its response to increases in anthropogenic greenhouse gases. Paleoclimate reconstructions coupled with model simulations provide insight into the tropical Pacific’s role in past climate variability necessary to the development of robust climate projections. Most paleoclimate records, however, still lack the resolution, length, and chronological control to resolve rapid variability against a background of orbital-scale variations. Here we present stalagmite oxygen isotope (δ18O) reconstructions from Gunung Mulu National Park (4oN, 115oE ), in northern Borneo, that provide reproducible centennial-scale records of western Pacific hydrologic variability that are precisely U/Th-dated and continuous throughout most of the late Pleistocene (0-160 thousand years ago, kybp). The record comprises an entire glacial-interglacial cycle, which allows us to investigate orbital-scale climate forcings and compare two well-dated glacial terminations in the western tropical Pacific. The ice- volume-corrected δ18O records suggest that glacial boundary condtions, which include significantly lower atmospheric carbon dioxide levels, did not drive significant changes in Mulu rainfall δ18O. Similarly, Borneo stalagmite δ18O is poorly correlated to either global sea level shifts or Sunda Shelf areal exposure is not evident. The Borneo record does vary in phase with local mid-fall equatorial insolation, suggesting that precessional forcing may impart a strong influence on hydroclimate variability in the warm pool. This is best illustrated across Glacial Termination II, when the oscillation of equatorial fall insolation is large and out of phase with ice sheet decay. We also use a subset of well-dated, high-resolution stalagmite δ18O records from Mulu to investigate millennial-scale climate variability during Marine Isotope Stages 3-5 (30-100kybp). We find that regional convection likely decreased during the six massive iceberg discharges defined in the North Atlantic sediment records (“Heinrich events”). The inferred drying (increased stalagmite δ18O) during Heinrich events is consistent with a southward shift of the Intertropical Convergence Zone – the dominant paradigm to explain global climate anomalies originating in the north Atlantic (ref). However, any hydrologic variability related to Dansgaad-Oeschgar (D/O) events, millennial-scale sawtooth temperature anomalies of the last glacial period first evident in the Greenland ice records, is notably absent in the stalagmite records. . The Mulu stalagmite record’s absence of D/O signal, however, is in marked contrast to the regional west Pacific marine records and suggests D/O events and Heinrich events may be characterized by fundamentally different climate mechanisms and feedbacks. Ph.D. |
author2 |
Cobb, Kim M. Earth and Atmospheric Sciences Lynch-Stieglitz, Jean Webster, Peter J. |
format |
Doctoral or Postdoctoral Thesis |
author |
Carolin, Stacy Anne |
author_facet |
Carolin, Stacy Anne |
author_sort |
Carolin, Stacy Anne |
title |
Geochemistry of karst deposits in Borneo detailing hydroclimate variations in the Warm Pool across the late Pleistocene |
title_short |
Geochemistry of karst deposits in Borneo detailing hydroclimate variations in the Warm Pool across the late Pleistocene |
title_full |
Geochemistry of karst deposits in Borneo detailing hydroclimate variations in the Warm Pool across the late Pleistocene |
title_fullStr |
Geochemistry of karst deposits in Borneo detailing hydroclimate variations in the Warm Pool across the late Pleistocene |
title_full_unstemmed |
Geochemistry of karst deposits in Borneo detailing hydroclimate variations in the Warm Pool across the late Pleistocene |
title_sort |
geochemistry of karst deposits in borneo detailing hydroclimate variations in the warm pool across the late pleistocene |
publisher |
Georgia Institute of Technology |
publishDate |
2014 |
url |
http://hdl.handle.net/1853/52277 |
long_lat |
ENVELOPE(-6.982,-6.982,62.205,62.205) |
geographic |
Greenland Pacific Sunda |
geographic_facet |
Greenland Pacific Sunda |
genre |
Greenland Ice Sheet North Atlantic |
genre_facet |
Greenland Ice Sheet North Atlantic |
_version_ |
1766020433798234112 |