Decadal to Orbital Scale Climate Change in the Indian Ocean Region: Precipitation Isotopic Perspectives from East Africa and Indonesia

Konecky, Bronwen L.

Full Metadata

Overview

Year:: 2014
Contributor:: Konecky, Bronwen L (creator); Russell, James (Director); Prell, Warren (Reader); Huang, Yongsong (Reader); Fischer, Karen (Reader); Vuille, Mathias (Reader); Brown University. Geological Sciences (sponsor)
Genre:: theses
Subject:: paleoclimate; East Africa; biomarkers; climate change; tropical climate; Indian Ocean region; Paleoclimatology; Paleolimnology; Stable isotopes; Biochemical markers; Climatic changes; Africa, Eastern; Indonesia; Indian Ocean Region
Extent:: 27, 209 p.
DOI: https://doi.org/10.7301/Z0DJ5D05

Files

Description

Abstract:: Climate variability in the Indian Ocean region affects the livelihoods of billions of people. Paleoclimate reconstructions can provide critical insights into the fundamental oceanic-atmospheric processes that drive long-term variations in rainfall in this region, and how these processes might respond to global climate change. In this dissertation, I use stable isotopes of leaf wax compounds preserved in lake sediments to reconstruct climatic and ecological changes in East Africa and Indonesia, two sides of the Indian Ocean. I focus on two time periods – the late Pleistocene (particularly the past 60,000 years) and the Common Era (the past 2,000 years) – to investigate climate variability under a range of mean climate states and timescales, from decadal (tens of years) to orbital (tens of thousands of years). I find that the reconstructed precipitation D/H ratio (δDprecip), when adequately constrained with other geochemical and lithological tracers, can track a variety of important climate processes in the Indian Ocean region. On multi-decadal to centennial timescales, reconstructed δDprecip illuminates how variations in the intensity of the Indian and Australasian Monsoons and their relationship to remote sea surface temperatures affected droughts and pluvials in East Africa and southwestern Indonesia. On millennial to orbital timescales, and particularly under the glacial boundary conditions of the late Pleistocene, reconstructed δDprecip reveals that rainfall in East Africa and central Indonesia was driven by major changes the locus, strength, and spatial extent of tropical convergence. When compared with isotope-enabled General Circulation Model experiments, it becomes clear that on climatic and paleoclimatic timescales, the relationships between tropical atmospheric circulation and continental rainfall are not always stable. Spatial and temporal patterns in reconstructed δDprecip help to evaluate several competing hypotheses for climatic changes, and allow for an informed assessment of the circulation changes that accompanied major tropical climatic transitions in East Africa and Indonesia during the late Pleistocene, the Holocene, and the 20th century. These findings are not only critical for understanding this poorly-studied region’s climatic history, but are also critical for applying these lessons to questions facing the region during the 21st century.
Notes:: Thesis (Ph.D. -- Brown University (2014)

Content

Access Conditions

Rights: In Copyright
Restrictions on Use: Collection is open for research.

Citation

Konecky, Bronwen L., "Decadal to Orbital Scale Climate Change in the Indian Ocean Region: Precipitation Isotopic Perspectives from East Africa and Indonesia" (2014). Earth, Environmental and Planetary Sciences Theses and Dissertations. Brown Digital Repository. Brown University Library. https://doi.org/10.7301/Z0DJ5D05

Relations

Collection:

Earth, Environmental and Planetary Sciences Theses and Dissertations

Theses and Dissertations for the Earth, Environmental and Planetary Sciences department.
...