Clim. Past Discuss., 5, 1133-1162, 2009
© Author(s) 2009. This work is distributed
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This discussion paper has been under review for the journal Climate of the Past (CP). Please refer to the corresponding final paper in CP.
Sources of holocene variability of oxygen isotopes in paleoclimate archives
A. N. LeGrande and G. A. Schmidt
NASA Goddard Institute for Space Studies and Center for Climate Systems Research, Columbia University, 2880 Broadway, New York, NY 10025, USA

Abstract. Variability in water isotopes has been captured in numerous archives and used to infer climate change. Here we examine water isotope variability over the course of the Holocene using the water-isotope enabled, coupled atmosphere-ocean general circulation model, GISS ModelE-R. Eight Holocene time slices, mostly 1000 years apart are simulated using estimated changes in orbital configuration, greenhouse gases, and ice sheet extent. We find that water isotopes in the model match well with those captured in proxy climate archives in ice cores, ocean sediment cores, and speleothems. The climate changes associated with the water isotope changes, however, are more complex than simple modern analog interpretations. In particular, water isotope variability in Asian speleothems is linked to alterations in landward water vapor transport, not local precipitation, and ice sheet changes over North America lead to masking of temperature signals in Summit, Greenland. Salinity-seawater isotope variability is complicated by inter-ocean basin exchanges of water vapor. Water isotopes do reflect variability in the hydrologic cycle, but are better interpreted in terms of regional changes rather than local climate variables.

Citation: LeGrande, A. N. and Schmidt, G. A.: Sources of holocene variability of oxygen isotopes in paleoclimate archives, Clim. Past Discuss., 5, 1133-1162, doi:10.5194/cpd-5-1133-2009, 2009.
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