What do Paleoclimate . records tell us about . WAIS stability?

1. What Do West Antarctic Ice Cores Say About Rapid Ice Flow? What do Paleoclimate . records tell us about . WAIS stability? Ken Taylor Richard Alley Ed Brook Howard Conway Jeff Severinghaus Paul Mayewski Jim White

2. Byrd vs SDM Warmer Colder White & Brook

3. Byrd vs SDM Warmer Colder White & Brook

4. 15 ka Byrd vs SDM 22 ka Warmer Colder White & Brook

5. Byrd vs SDM Warmer Colder White & Brook

6. kkks • Must be local change at Siple Dome because: • 1) Change does not show up at Byrd • 2) Proxies of distant climate (Dexcess and chemistry) do not show significant changes Gas records Siple Dome Records

7. kkks Disrupted stratigraphy • Must be local change at Siple Dome because: • 1) Change does not show up at Byrd • 2) Proxies of distant climate (Dexcess and chemistry) do not show significant changes Gas records Siple Dome Records

8. Regional Climate Change: Would see something at Byrd and in other climate proxies from SDM.

9. Regional Climate Change: Would see something at Byrd and in other climate proxies from SDM. Mishandling of Core: Gas record/Deuterium record offset is correct

10. Regional Climate Change: Would see something at Byrd and in other climate proxies from SDM. Mishandling of Core: Gas record/Deuterium record offset is correct Folded Stratigraphy: No suitable ice to fold into record

11. Regional Climate Change: Would see something at Byrd and in other climate proxies from SDM. Mishandling of Core: Gas record/Deuterium record offset is correct Folded Stratigraphy: No suitable ice to fold into record Ice Flow Overrode Siple Dome Change in record is too abrupt No other ice with right characterisitics

12. Regional Climate Change: Would see something at Byrd and in other climate proxies from SDM. Mishandling of Core: Gas record/Deuterium record offset is correct Folded Stratigraphy: No suitable ice to fold into record Ice Flow Overrode Siple Dome Change in record is too abrupt

13. Interpretation 1: Elevation of Siple Dome Changed  Lapse Rate 22 ka B.P. 6oC warming, ~200 years 600 m elevation decrease at SDM 15 ka B.P. 3.5oC warming < 1,000? years 350 m elevation decrease at SDM Ice Flow Modeling: Rapid 350 m decrease of Siple Dome at 15 ka (Price et. al., 2007) Atmospheric Modeling: Elevation of ice streams has large influence on temperature at Summit of Siple Dome (Monaghan & Bromwich, 2006)

14. Interpretation 1: Elevation of Siple Dome Changed  Lapse Rate 22 ka B.P. 6oC warming, ~200 years 600 m elevation decrease at SDM 15 ka B.P. 3.5oC warming < 1,000? years 350 m elevation decrease at SDM Ice Flow Modeling: Rapid 350 m decrease of Siple Dome at 15 ka (Price et. al., 2007) Atmospheric Modeling: Elevation of ice streams has large influence on temperature at Summit of Siple Dome (Monaghan & Bromwich, 2006)

15. Interpretation 2: Elevation of Ice Streams Changed  Air Flow Changed Current situation Paleo situation BYRD BYRD SDM SDM Atmospheric Modeling:Elevation of ice streams has large influence on temperature at Summit of Siple Dome (Monaghan & Bromwich, 2006) Ice Sheet Model:Siple Dome was a bump (Dave Pollard)

16. Some combination of: 1) Changes in SDM surface elevation. (lapse rate) 2) Changes in ice stream elevation. (air flow patterns/katabatic winds) At 15 ka and 22 ka there were large and rapid drawn downs of ice on the Siple Coast.

17. What caused ice draw down? Sea level rise Sub-ice flood Ice shelf collapse Ice stream internal dynamics

18. ocean Explaination 16 m Hanebuth 12 m Yokoyama Sea Level The Siple Dome events precede the step increases in sea level. Siple: White et al

19. What caused ice draw down? Sea level rise Sub-ice flood Ice shelf collapse Ice stream internal dynamics

20. ` Eastern Ross Sea Mosola & Anderson, 2006 Slope Gullies Sub-ice water system

21. What caused ice draw down? Sea level rise Sub-ice flood Ice shelf collapse Ice stream internal dynamics

22. Siple Dome • MAP SHOWING • Tdome, SDM, BYRD, Moulton, OCEAM COres Ross Ice Shelf Roosevelt Island http://lima.usgs.gov/access.php BYRD BYRD BYRD

23. Siple Dome • MAP SHOWING • Tdome, SDM, BYRD, Moulton, OCEAM COres Ross Ice Shelf Roosevelt Island http://lima.usgs.gov/access.php BYRD BYRD BYRD

24. Ice Shelf Thickness Water Temperature Bathymetry Siple and Shirase Coasts are most vulnerable David Holland

25. Ice Shelf Thickness Water Temperature Bathymetry Siple and Shirase Coasts are most vulnerable David Holland

26. Ice Shelf Thickness Water Temperature Bathymetry Siple and Shirase Coasts are most vulnerable David Holland

27. Ice Shelf Thickness Water Temperature Bathymetry Siple and Shirase Coasts are most vulnerable David Holland

28. ` Eastern Ross Sea Mosola & Anderson, 2006 Iceberg furrows at 650 m No sub-ice shelf deposits Rapid retreat of grounded ice

29. Siple Dome • MAP SHOWING • Tdome, SDM, BYRD, Moulton, OCEAM COres Ross Ice Shelf Roosevelt Island http://lima.usgs.gov/access.php BYRD BYRD BYRD

30. What caused ice draw down? Sea level rise Sub-ice flood Ice shelf collapse Ice stream internal dynamics

31. Siple Coast ice had large and rapid changes at 15 ka and 22 ka Basal flooding Break up of a portion of the Ross Ice Shelf Ice stream internal dynamics

33. Amanda Mosola & John Anderson Andy Monaghan, Dave Brom

34. * Ignore this age; the simulation is for 15 ka From dave pollard pollard@essc.psu.edu