Precise chronology and feedbacks on past glacial terminations

Glacial terminations reflect the greatest magnitude and most widespread abrupt natural climate change of the last million years, but the exact nature of the orbital triggers and carbon cycle and ocean circulation feedbacks remain uncertain. Only the most recent deglaciation event has been dated independently with ¹⁴C, but prior glacial terminations are beyond the range of ¹⁴C. Speleothems from Northern Spain feature more complete growth histories through glacial terminations than those from more northern locations in Europe, and can therefore provide complete records of the glacial/interglacial transitions which are absolutely dated with U/Th decay series

In the Pyrenees of northeastern Spain, the strong imprint of temperature on stalagmite geochemistry has enabled characterization of the Termination III deglaciation and the millennial structure of the most recent deglaciation (collaboration with Carlos Perez, Miguel Bartholome and Ana Moreno, Instituto Pireneico de Ecologia in Zaragoza Spain, and Isabel Cacho, University of Barcelona).  

In contrast to the temperature-dominated signals in the Pyrenees, stalagmites in coastal regions of northwestern Spain record well the isotopic changes arising from release of glacial meltwater into the North Atlantic. They feature abrupt climate changes that can be correlated with marine sediment records of deglaciation. Our current focus in this region is on stalagmites covering Termination II, III, and IV, with interpretations supported by multi-stalagmite calibration during Termination I.  

This project has been supported by the OPERA project of the Spanish Science Ministry (2014-2017), and is currently supported by ETH internal funding. ETH Masters Projects (Kost, 2018) contribute to this work.  

Publications

external pageStoll, Heather; Perez, Carlos; Cacho, Isabel; Moreno, Ana; Iglesias, Miguel; Edwards, R. Lawrence; Cheng, Hai. (2018) Chronlogy for deglaciation during Termination II from stalagmites in NW Spain. EGUcall_made

external pagePérez-Mejías, C., Moreno, A., Sancho, C., Bartolomé, M., Stoll, H., Cacho, I., Edwards, R. L. (2017). Abrupt climate changes during Termination III in Southern Europe. Proceedings of the National Academy of Sciences, 114(38), 10047-10052.call_made

external pageBartolomé, M., Moreno, A., Sancho, C., Stoll, H. M., Cacho, I., Spötl, C., Belmonte, Á., Edwards, R. L., Cheng, H., and Hellstrom, J. C. (2015). Hydrological change in Southern Europe responding to increasing North Atlantic overturning during Greenland Stadial 1. Proceedings of the National Academy of Sciences 112, 6568-6572.call_made