A
Download
1 / 9

A comparison of the present and last interglacial in six Antarctic ice cores - PowerPoint PPT Presentation


  • 68 Views
  • Uploaded on

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

loader
I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.
capcha
Download Presentation

PowerPoint Slideshow about 'A comparison of the present and last interglacial in six Antarctic ice cores' - anitra


An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript
A comparison of the present and last interglacial in six antarctic ice cores

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?


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

Context

  • Different orbital contexts : excentricity, phase betweenprecession and obliquity

  • Differentdeglacialcontexts and earlyinterglacialbipolarseesaw

EPICA

Dome C

Greenland

Masson-Delmotte et al, PNAS, 2010


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

Drilling Sites

  • Seasonality of seaice and « continentality »

  • Ice flow thinning

Masson-Delmotte et al, CP, in press


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

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


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

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


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

Common Signals (EOF analysis)

  • First EOF : temperaturehistory

  • Second EOF : elevation changes

  • No trivial relationshipwith the orbital context

Masson-Delmotte et al, CP, in press


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

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


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

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)


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

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