A Terrestrial Indo-Pacific Warm Pool Temperature Reconstruction Enables a Mechanistic Understanding of Climate Changes in the Tropics
Abstract
Sea surface temperature (SST) reconstructions from the Indo-Pacific Warm Pool (IPWP) indicate a 3-4°C increase in temperature from the Last Glacial Maximum (LGM) to the Holocene. However, SST reconstructions show the onset of warming ranging from ~20.4-17.9 ka and differ in their trends during the Holocene. These data discrepancies limit our understanding of the causes and amplitude of regional temperature change, and the couplings between temperature and the hydrological cycle. Reconstructions of terrestrial temperature from southeast Asia do not exist, preventing comparison to SST reconstructions. A terrestrial temperature reconstruction from a lake sediment core from Lake Towuti located on Sulawesi Island, Indonesia can provide mechanistic insight into changing IPWP temperature, including the magnitude and timing of deglacial and Holocene temperature change. Here we apply the TEX86 paleotemperature proxy, based on the fractional abundances of isoprenoidal glycerol dialkyl glycerol tetraethers (GDGTs) to reconstruct temperature over the past 30,000 years. Our record indicates a ~5°C temperature increase from the LGM to the Holocene. The 5°C temperature change is one degree less than the 4°C change observed in tropical East Africa, suggesting possible differences in climate forcings in the two tropical regions. The onset of the deglacial warming occurs at ~16.7 ka, as indicated by Bayesian change point analysis. The timing of the onset of warming indicated in the Lake Towuti temperature record lags behind the onset of increasing carbon dioxide in Antarctica, providing support for increased atmospheric carbon dioxide concentrations causing the initial warming in the tropics after the LGM, rather than a slowing of Atlantic Meridional Overturning Circulation as previous studies suggest. Temperature appears to increase over the Holocene similarly to carbon dioxide in Antarctica; however, the trend is not significant at a significance level of 0.05. Our temperature reconstruction indicates a lower amplitude increase in temperature from the LGM to the Holocene than records show in tropical East Africa, deglacial warming occurring after the onset of warming estimated from SST reconstructions, and an insignificant increase in temperature over the Holocene.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2020
- Bibcode:
- 2020AGUFMPP026..07P
- Keywords:
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- 1626 Global climate models;
- GLOBAL CHANGE;
- 1637 Regional climate change;
- GLOBAL CHANGE;
- 4901 Abrupt/rapid climate change;
- PALEOCEANOGRAPHY;
- 4934 Insolation forcing;
- PALEOCEANOGRAPHY