The Ice Isotope Record from Siple Dome, Antarctica A. Schilla, J.W.C. White, R. Alley, M. Bender, E. Brook, E. Steig, K. Taylor

Regional Similarities.... Broad Antarctic Climate Signal: Siple fits Broad Antarctic Climate Signal: Siple fits

Regional Similarities.... Broad Antarctic Climate Signal: Siple fits Broad Antarctic Climate Signal: Siple fits ~ Similar A1-A7 warm events (after Blunier and Brook, 2001), but timing and relative magnitudes differ ~ Similar A1-A7 warm events (after Blunier and Brook, 2001), but timing and relative magnitudes differ A1 A2 A3 A4 A5 A6 A7 ? ?

Regional Similarities.... Siple and Byrd: agree very well for at least last ~10ka Siple and Byrd: agree very well for at least last ~10ka

Regional Variation.... Milankovitch cycle strengths seem to vary among cores Milankovitch cycle strengths seem to vary among cores

Regional Variation.... Milankovitch cycle strengths seem to vary among cores Milankovitch cycle strengths seem to vary among cores Timing of termination differs among cores Timing of termination differs among cores

Regional Variation.... Milankovitch cycle strengths seem to vary among cores Milankovitch cycle strengths seem to vary among cores Timing of termination differs among cores Timing of termination differs among cores Rapid event at termination in Siple ice Rapid event at termination in Siple ice

Regional Variation.... Neither core has a final age- model yet Neither core has a final age- model yet Siple and Taylor: opposed throughout Holocene?  At least for last ~6ka Siple and Taylor: opposed throughout Holocene?  At least for last ~6ka

What Does Siple Dome Tell Us About WAIS?

What did WAIS Look Like During the LIG? Siple Dome Ice  Inconclusive Siple Dome Ice  Inconclusive Drop in isotopes + “funny” gases at ~100ka  Siple Dome overrun by ice from higher up on ice sheet?? Drop in isotopes + “funny” gases at ~100ka  Siple Dome overrun by ice from higher up on ice sheet??

How Long has Siple Been a Dome? Siple and the surrounding Ice Streams have probably existed for ≥ 100ka From:

Elevation Changes Between Byrd and Siple Dome? Relative Holocene elevation change between Siple and Byrd could only be ~50m (Δ‰ only ~0.5; with a lapse rate of ~ -1‰/100m) barring a very precise coordination of elevation and associated climate change Relative Holocene elevation change between Siple and Byrd could only be ~50m (Δ‰ only ~0.5; with a lapse rate of ~ -1‰/100m) barring a very precise coordination of elevation and associated climate change

Divergence Across the Ross Ice Shelf Opposition between Siple and Taylor  storm track modulation by ENSO/ASL?? Opposition between Siple and Taylor  storm track modulation by ENSO/ASL??

ASL/ENSO Influence.... Moisture flux during (a) 1980 (normal year) and (b) 1982 (El Nino year). From Cullather et al., Moisture flux during (a) 1980 (normal year) and (b) 1982 (El Nino year). From Cullather et al., Did ENSO variability really increase in the mid-Holocene (e.g., per Clement et al., 2000, Rodbell et al. 1999, Moy et al. 2000)? Did ENSO variability really increase in the mid-Holocene (e.g., per Clement et al., 2000, Rodbell et al. 1999, Moy et al. 2000)? a) b)

Dating Issues.... Age relationship between Taylor Dome and Siple, Byrd is crucial for picking apart ENSO/ASL story Age relationship between Taylor Dome and Siple, Byrd is crucial for picking apart ENSO/ASL story Were Siple and Taylor opposed only for late Holocene, or for entire Holocene? Were Siple and Taylor opposed only for late Holocene, or for entire Holocene? How much dating room is there with Taylor? How much dating room is there with Taylor?

Summary WAIS during LIG: Siple Dome ice = inconclusive WAIS during LIG: Siple Dome ice = inconclusive Siple Dome and surrounding ice streams ≥ 100ka Siple Dome and surrounding ice streams ≥ 100ka Siple and Byrd either have very little relative elevation change, or Byrd climate and elevation change ~ cancelled out Siple and Byrd either have very little relative elevation change, or Byrd climate and elevation change ~ cancelled out Taylor and Siple ages are key to Taylor-Siple Holocene story, and therefore part of the Holocene ENSO story Taylor and Siple ages are key to Taylor-Siple Holocene story, and therefore part of the Holocene ENSO story