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Climate of the Past An interactive open-access journal of the European Geosciences Union
https://doi.org/10.5194/cp-2017-146
© Author(s) 2017. This work is distributed under
the Creative Commons Attribution 4.0 License.
Research article
24 Nov 2017
Review status
This discussion paper is a preprint. It is a manuscript under review for the journal Climate of the Past (CP).
A Stalagmite Test of North Atlantic SST and Iberian Hydroclimate Linkages over the Last Two Glacial Cycles
Rhawn F. Denniston1, Amanda N. Houts1,a, Yemane Asmerom2, Alan D. Wanamaker3, Jonathon A. Haws4, Victor J. Polyak2, Diana L. Thatcher3, Sestsen Altan-Ochir1, Alyssa C. Borowske1,b, Sebastian F. M. Breitenbach5, Caroline C. Ummenhofer6, Frederico T. Regala7, Michael M. Benedetti8, and Nuno Bicho9 1Department of Geology, Cornell College, Mount Vernon, Iowa 52314, USA
2Department of Earth and Planetary Sciences, University of New Mexico, Albuquerque, New Mexico 87131, USA
3Department of Geological and Atmospheric Sciences, Iowa State University, Ames, Iowa 50011, USA
4Department of Anthropology, Louisville University, Louisville, Kentucky 40208, USA
5Institute for Geology, Mineralogy, and Geophysics, Ruhr-University Bochum 44801, Germany
6Department of Physical Oceanography, Woods Hole Oceanographic Institution, Woods Hole, Massachusetts 02543, USA
7Associação de Estudos Subterrâneos e Defesa do Ambiente, Torres Vedras, Portugal
8Department of Geography and Geology, University of North Carolina Wilmington, Wilmington, North Carolina 28403, USA
9Center for Archaeology and Evolution of Human Behaviour, Universidade do Algarve, Faro, Portugal
acurrent address: Department of Earth Sciences, University of New Hampshire, Durham, New Hampshire 03824, USA
bcurrent address: Department of Ecology and Evolutionary Biology, University of Connecticut, Storrs, Connecticut 06269, USA
Abstract. Close coupling of Iberian hydroclimate and North Atlantic sea surface temperature (SST) during recent glacial periods has been identified through the analysis of marine sediment and pollen grains co-deposited on the Portuguese continental margin. These reconstructions have lacked a directly-dated, site-specific record of continental Iberian climate spanning multiple glacial cycles as a point of comparison. Here we present a high-resolution, multi-proxy (δ13C, δ234U, and growth dynamics) stalagmite record of hydroclimate from two caves in western Portugal across the majority of the last two glacial cycles (~230 ka). At orbital and millennial scales, stalagmite-based proxies of hydroclimate covaried with sea surface temperature (SST), with positive carbon isotope excursions and/or growth hiatuses indicating reduced effective moisture coincident with suppressed SST during major ice-rafted debris events and Greenland stadials, in agreement with changes in palynological reconstructions of continental climate. The Portuguese stalagmite record also reveal intervals during which the magnitudes of hydroclimate changes appear to have been somewhat decoupled from SST.

Citation: Denniston, R. F., Houts, A. N., Asmerom, Y., Wanamaker, A. D., Haws, J. A., Polyak, V. J., Thatcher, D. L., Altan-Ochir, S., Borowske, A. C., Breitenbach, S. F. M., Ummenhofer, C. C., Regala, F. T., Benedetti, M. M., and Bicho, N.: A Stalagmite Test of North Atlantic SST and Iberian Hydroclimate Linkages over the Last Two Glacial Cycles, Clim. Past Discuss., https://doi.org/10.5194/cp-2017-146, in review, 2017.
Rhawn F. Denniston et al.
Rhawn F. Denniston et al.
Rhawn F. Denniston et al.

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Short summary
The sediment deposited off the coast of Portugal includes the remains of marine organisms and pollen washed to sea from Iberia. Analysis of both the pollen and the ocean sediments has revealed that the type and density of vegetation on land changed in concert with shifts in ocean temperature over centuries to tens of millennia. The research presented here tests these relationships across the last two glacial periods using a series of climate-sensitive stalagmites from western Portugal.
The sediment deposited off the coast of Portugal includes the remains of marine organisms and...
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