2. Ice-Age Cycles 2 Lisiecki and Raymo (2005) http://commons.wikimedia.org/wiki/File:Five_Myr_Climate_Change.png

3. Orbital Control 3 AuthorsYear Orbital control of LGM Timing of LGM Joseph Adhémar 1842longer winter (duration)~10 ka James Croll1860s weaker insolation in winter (Intensity) ~ 10ka Milutin Milankovic 1930s weaker insolation in summer (Intensity) ~22 ka Hays, Imbrie, Shackleton 1976 Confirmed Milankovic theory with 450 kyr oxygen isotope records from the sediments of the Southern Ocean

4. Problem of SH-lead 4 “Fly in the ointment”

5. Recent hypotheses for the SH-control of ice age cycles 5

6. 6 2007 2009

7. 2008

9. Data-model comparison: testing mechanisms of the last deglaciation 9 IPCC-type coupled climate model High-res proxy data Loutre, M. F. (2003)

10. Model: CCSM3 (T31_gx3v5) + dynamic vegetation ATM 3.75(lon) x 3.75(lat) x 26(level) OCN ~3 (lon/lat) x 25 (level) Peak performance: 120 model years per day 21,000 years in 6 months Data storage: over 300 TB INCITE Supercomputing Support 10

11. TraCE simulations Transient boundary conditions Orbital forcing GHGs Ice sheets Meltwater forcing (AMOC) 11

12. Five simulations Simulation ALL (ORBIT+GHG+Ice sheets+AMOC) Simulation ORB (ORBIT) Simulation GHG (GHG) Simulation ICE (Ice sheets) Simulation MOC (AMOC) 12

13. 13 Ice sheet changes (once per 500 years) He 2011

14. 14

15. 15

16. Transient simulation of the last deglaciation Simulation ALL 16

17. 17

18. 18

19. 19

20. 20

21. 21

22. TraCE simulation of the SH deglaciation

24. Bipolar seesaw early deglacial warming in the SH (Simulation ALL vs. single forcing simulations) 24

25. bipolar seesaw (19-17 ka) 25

26. Deglacial CO 2 rise synchronous deglacial warming and eventually reach and sustain complete deglaciation (Simulation ALL vs. single forcing simulations) 26

27. CO 2 -induced global warming (17-15 ka) 27

28. Mechanism of the terminations What’s causing the deglacial CO 2 rise? 28

29. Heinrich events & deglacial CO 2 rise 29

30. Deglacial CO 2 rise due to Southern Ocean processes

31. NH meltwater Early warming of the Southern Ocean deglacial CO2 rise 31

32. Large NH Ice sheets at LGM NH meltwater Early warming of the Southern Ocean deglacial CO 2 rise 32 2006

33. 2010