Last Glacial multi-decadal to millennial-scale precipitation variability inferred from Puerto Rican speleothems
- 1Institute of Environmental Physics, University of Heidelberg, Germany
- 2Institute of Earth Sciences, Heidelberg University, Germany
- 3Institute for Geosciences, University of Mainz, Germany
- 4Department of Marine Sciences, University of Puerto Rico, Mayagüez, Puerto Rico
- 5Earth and Environmental Systems Department, Indiana State University, Terre Haute, Indiana, USA
- 6Institute of Geology, University of Innsbruck, Austria
- 7Department of Geology, University of Puerto Rico, Mayagüez, Puerto Rico
- 8Max Planck Institute for Chemistry, Climate Geochemistry Department, Mainz, Germany
The high sensitivity of climate variability to the mean position of the intertropical convergence zone at different time scales is well known. However, due to a lack of absolutely dated high-resolution proxy records, the long-term changes in the tropical Atlantic oceanic and atmospheric circulation system prior to the late Holocene are still not well constrained. Paleo climate reconstructions and model studies suggest a very complex response of the northern hemispheric tropical rain belts in the western tropical Atlantic depending on the nature of the forcing, surface type and surrounding continent-ocean configuration.
Here we present a high resolution multi-proxy speleothem record from Cueva Larga (Puerto Rico) covering the last Glacial between 46 and 15 ka BP. Precise 230Th/U-dating reveals growth rates between 50 up to more than 1000 µm/year which allow for the investigation of multi-decadal to millennial scale variability in the stable isotope (δ18O and δ13C) and elemental records.
The analysed proxies document a pronounced response of regional precipitation to abrupt centennial to millennial scale climatic excursions across the last Glacial, such as Heinrich Stadials and Dansgaard/Oeschger oscillations. Here, we observe a strong agreement between our paleo-precipitation reconstruction and climate proxy records which are indicative of the strength of the Atlantic meridional overturning circulation and northern hemispheric temperature changes. The coherence of speleothem δ18O values with sedimentary 231Pa/230Th also on sub-millennial timescales supports a persistent link of regional precipitation variability to ocean circulation variability. Spectral analysis further suggests that multi-decadal to centennial variability persisted in the western tropical Atlantic hydro-climate not only during stadial and interstadial conditions, but also during the last Glacial maximum, supporting the hypothesis that the Atlantic low-latitude regions respond to internal modes of climate variability on these time scales regardless of the global climate state.
The compilation of our dataset from Puerto Rico with other paleo-precipitation records allows for the reconstruction of past changes in position, strength and extent of the intertropical convergence zone in the western tropical Atlantic and reveal the existence of spatio-temporal gradients in response to millennial to orbital climate change.
How to cite: Warken, S., Vieten, R., Winter, A., Spötl, C., Miller, T., Frank, N., Jochum, K. P., Mielke, A., Schandl, J., Schröder-Ritzrau, A., Mangini, A., and Scholz, D.: Last Glacial multi-decadal to millennial-scale precipitation variability inferred from Puerto Rican speleothems, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-19591, https://doi.org/10.5194/egusphere-egu2020-19591, 2020.
