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A comparison of the present and last interglacial in six Antarctic ice cores

Explore causes for regional differences in Antarctic stable isotope records. Understand differences between current and last interglacial periods through ice core data analysis. Investigate orbital contexts, deglacial sequences, and early interglacial dynamics. Examine stable isotope records, moisture origins, and signals of temperature history and elevation changes. Assess potential factors affecting ice core signals and variability. Gain insights into climate mechanisms and past ice sheet geometry impacting Antarctic climates.

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A comparison of the present and last interglacial in six Antarctic ice cores

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  1. A comparison of the present and last interglacial in six Antarcticicecores V. Masson-Delmotte, D. Buiron, A. Ekaykin, M. Frezzotti, H. Gallée, J. Jouzel, G. Krinner, Landais, H. Motoyama, H. Oerter, K. Pol, D. Pollard, C. Ritz, E. Schlosser, L.C. Sime, H. Sodemann, B. Stenni, R. Uemura, F. Vimeux LSCE and LGGE, France - AARI, Russia - ENEA, U. Trieste, Italy - NIPR and U. Ryukyus, Japan - AWI, Germany - Penn State, USA - U. Innsbruck, Austria - BAS, UK - NILU, Norway • Whatcanbe the causes for regionaldifferences in Antarctic stable isotope records? • What are the differencesbetween the current and last interglacial?

  2. Context • Different orbital contexts : excentricity, phase betweenprecession and obliquity • Differentdeglacialcontexts and earlyinterglacialbipolarseesaw EPICA Dome C Greenland Masson-Delmotte et al, PNAS, 2010

  3. Drilling Sites • Seasonality of seaice and « continentality » • Ice flow thinning Masson-Delmotte et al, CP, in press

  4. Origin of Moisture and PrecipitationSeasonality Moistureorigins : largerseasonality for the coastal sites (Taylor Dome and TALDICE) Differencebetweenprecipitationweightedtemperature and annualmeantemperature (ERA40) : largerbias for the inland sites Masson-Delmotte et al, CP, in press

  5. Stable Isotope Records on EDC3 agescale • Site-specific trends • Common to the current and last interglacial • Abrupt drop in d18O during glacial inceptionat EDML and TALDICE (increasedseaicecover?) Masson-Delmotte et al, CP, in press

  6. Common Signals (EOF analysis) • First EOF : temperaturehistory • Second EOF : elevation changes • No trivial relationshipwith the orbital context Masson-Delmotte et al, CP, in press

  7. Site SpecificResiduals • Main possible causes : • Precipitationintermittency • To assesswithclimate model simulations with isotopes (difficult in response to orbital forcing alone) • See the poster of Louise Sime • Site elevation changes • Qualitatively consistent withicesheet model outputs; • Suggestslargerelevation changes thansimulated. Masson-Delmotte et al, CP, in press

  8. 20 yrresolution analyses in EPICA Dome C • Larger variance during MIS5.5 • Significant changes in variance • Shifts in multi-centennial to millennialperiodicities MIS1 MIS1 CenteredδD ‰ Period (ky) Frequency (1/ky)  variability  variability Signal ‰ minus trend  variability  variability Age (ky BP) Holocene MIS5.5 (Resampledevery 20y) CenteredδD ‰ MIS5.5 Running standard Deviation over 3ky MIS5 Transition (Resampled every 20y) Signal ‰ minus trend High variability variability Period (ky) Frequency (1/ky) Running standard Deviation over 3ky Transition  variability highvariability Age (ky BP) Pol et al, EPSL, 2010; CP, 2010; in prep Age (ky BP)

  9. Conclusions and Perspectives • Differencesbetween the current and last interglacial in Antarctica • - Changes in meanstate (common to 6 icecoresin East Antarctica) • - Changes in variability(atDome C) : variance level, power spectrum • Mechanismsresponsible for these changes poorlyunderstood • - climatemodels show verysmallresponse to orbital forcing • - importance of changes in pasticesheetgeometry (WAIS+EAIS) • - oceandynamics, natural(solar, volcanic) forcings (not documented for MIS5.5) • Differencesbetweenicecore records • long term: changes in icesheettopography • short term: precipitationintermittency, moistureorigin (links withseaicecover) • Perspectives: • comparisonswithclimate and icesheet model results • new information on MIS5.5 may come from the NEEM and WAIS icecores

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