Journal cover Journal topic
Climate of the Past An interactive open-access journal of the European Geosciences Union
© Author(s) 2017. This work is distributed under
the Creative Commons Attribution 4.0 License.
Research article
16 Jun 2017
Review status
This discussion paper is a preprint. A revision of this manuscript was accepted for the journal Climate of the Past (CP) and is expected to appear here in due course.
Temperature and mineral dust variability recorded in two low accumulation Alpine ice cores over the last millennium
Pascal Bohleber1,2,3, Tobias Erhardt4,5, Nicole Spaulding1, Helene Hoffmann2, Hubertus Fischer4,5, and Paul Mayewski1 1Climate Change Institute, University of Maine, Orono, Maine, USA
2Institute of Environmental Physics, Heidelberg University, Heidelberg, Germany
3Institute for Interdisciplinary Mountain Research, Austrian Academy of Sciences, Innsbruck, Austria
4Climate and Environmental Physics, Physics Institute, University of Bern, Bern, Switzerland
5Oeschger Centre for Climate Change Research, University of Bern, Bern, Switzerland
Abstract. Among ice core drilling sites in the European Alps, the Colle Gnifetti (CG) glacier saddle is the only one to offer climate records back to at least 1000 years. This unique long-term archive is the result of an exceptionally low net accumulation driven by wind erosion and rapid annual layer thinning. To-date, however, the full exploitation of the CG time series has been hampered by considerable dating uncertainties and the seasonal summer bias in snow preservation. Using a new core drilled in 2013 we extend annual layer counting, for the first time at CG, over the last 1000 years and add additional constraints to the resulting age scale from radiocarbon dating. Based on this improved age scale, and using a multi-core approach with a neighboring ice core, we explore the potential for reconstructing long-term temperature variability from the stable water isotope and mineral dust proxy time series. A high and potentially non-stationary isotope/temperature sensitivity limits the quantitative use of the stable isotope variability thus far. However, we find substantial agreement comparing the mineral dust proxy Ca2+ with instrumental temperature. The temperature-related variability in the Ca2+ record is explained based on the temperature-dependent snow preservation bias combined with the advection of dust-rich air masses coinciding with warm temperatures. We show that using the Ca2+ trends for a quantitative temperature reconstruction results in good agreement with instrumental temperature and the latest summer temperature reconstruction derived from other archives covering the last 1000 years. This includes a Little Ice Age cold period as well as a medieval climate anomaly. In particular, part of the medieval climate period around 1100–1200 AD stands out through an increased occurrence of dust events, potentially resulting from a relative increase in meridional flow and dry conditions over the Mediterranean.

Citation: Bohleber, P., Erhardt, T., Spaulding, N., Hoffmann, H., Fischer, H., and Mayewski, P.: Temperature and mineral dust variability recorded in two low accumulation Alpine ice cores over the last millennium, Clim. Past Discuss.,, in review, 2017.
Pascal Bohleber et al.
Pascal Bohleber et al.


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Short summary
The Colle Gnifetti (CG) glacier is the only drilling site in the European Alps offering ice core records back to some 1000 years. We aim to fully exploit these unique long-term records by establishing a reliable long-term age scale and an improved ice core proxy interpretation for reconstructing temperature. Ultimately we are able to present the first CG record of temperature-related variability over the last millennium and discuss our reconstruction with respect to other proxy evidence.
The Colle Gnifetti (CG) glacier is the only drilling site in the European Alps offering ice core...