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Atmospheric CO 2 decrease led to Greenland glaciation in the Late Pliocene

Atmospheric CO 2 decrease led to Greenland glaciation in the Late Pliocene. D.J. Lunt, G.L. Foster, A.M. Haywood, E.J. Stone. Motivation Experimental Design Results Conclusions Future Work / Implications. The Causes of Northern Hemisphere Glaciation?. Zachos et al, Nature, 2001.

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Atmospheric CO 2 decrease led to Greenland glaciation in the Late Pliocene

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  1. Atmospheric CO2 decrease led to Greenland glaciation in the Late Pliocene D.J. Lunt, G.L. Foster, A.M. Haywood, E.J. Stone • Motivation • Experimental Design • Results • Conclusions • Future Work / Implications

  2. The Causes of Northern Hemisphere Glaciation? Zachos et al, Nature, 2001

  3. The Causes of Northern Hemisphere Glaciation? 5 main hypotheses • Closure of Panama Seaway • Tectonic Uplift • Termination of ‘Permanent El Nino’ • Decrease in CO2 • Oribital variations

  4. The Causes of Northern Hemisphere Glaciation? 5 main hypotheses • Closure of Panama Seaway • Tectonic Uplift • Termination of ‘Permanent El Nino’ • Decrease in CO2 • Oribital variations Ruddiman, p163

  5. The Causes of Northern Hemisphere Glaciation? 5 main hypotheses Bartoli et al, 2005 • Closure of Panama Seaway • Tectonic Uplift • Termination of ‘Permanent El Nino’ • Decrease in CO2 • Oribital variations

  6. The Causes of Northern Hemisphere Glaciation? 5 main hypotheses • Closure of Panama Seaway • Tectonic Uplift • Termination of ‘Permanent El Nino’ • Decrease in CO2 • Oribital variations

  7. The Causes of Northern Hemisphere Glaciation? 5 main hypotheses • Closure of Panama Seaway • Tectonic Uplift • Termination of ‘Permanent El Nino’ • Decrease in CO2 • Oribital variations Ruddiman and Kutzbach, 1989

  8. The Causes of Northern Hemisphere Glaciation? 5 main hypotheses Japsen and Chalmers, 2000 Parrish et al, 2007 • Closure of Panama Seaway • Tectonic Uplift • Termination of ‘Permanent El Nino’ • Decrease in CO2 • Oribital variations

  9. The Causes of Northern Hemisphere Glaciation? 5 main hypotheses • Closure of Panama Seaway • Tectonic Uplift • Termination of ‘Permanent El Nino’ • Decrease in CO2 • Oribital variations

  10. The Causes of Northern Hemisphere Glaciation? 5 main hypotheses Molnar and Cane, 2002 • Closure of Panama Seaway • Uplift of Rockies • Termination of ‘Permanent El Nino’ • Decrease in CO2 • Oribital variations

  11. The Causes of Northern Hemisphere Glaciation? 5 main hypotheses e.g. Wara et al, 2005 • Closure of Panama Seaway • Uplift of Rockies • Termination of ‘Permanent El Nino’ • Decrease in CO2 • Oribital variations

  12. The Causes of Northern Hemisphere Glaciation? 5 main hypotheses • Closure of Panama Seaway • Uplift of Rockies • Termination of ‘Permanent El Nino’ • Decrease in CO2 • Oribital variations

  13. The Causes of Northern Hemisphere Glaciation? 5 main hypotheses • Closure of Panama Seaway • Uplift of Rockies • Termination of ‘Permanent El Nino’ • Decrease in CO2 • Oribital variations

  14. The Causes of Northern Hemisphere Glaciation? 5 main hypotheses 380ppmv mean, 425ppmv max Raymo et al, 1996 • Closure of Panama Seaway • Uplift of Rockies • Termination of ‘Permanent El Nino’ • Decrease in CO2 • Oribital variations

  15. The Causes of Northern Hemisphere Glaciation? 5 main hypotheses 400ppmv to 280ppmv • Closure of Panama Seaway • Uplift of Rockies • Termination of ‘Permanent El Nino’ • Decrease in CO2 • Oribital variations

  16. Spinup of GCM simulations…

  17. GCM results… Panama ENSO Rockies CO2 Temp Precip

  18. Ice sheet model results…

  19. Ice sheet model results…

  20. Ice sheet model results…

  21. Ice sheet model results…

  22. Ice sheet model results…

  23. The Causes of Northern Hemisphere Glaciation? 5 main hypotheses From Berger and Loutre, 1991 • Closure of Panama Seaway • Uplift of Rockies • Termination of ‘Permanent El Nino’ • Decrease in CO2 • Oribital variations

  24. The Causes of Northern Hemisphere Glaciation? 5 main hypotheses Maslin et al, 1998 • Closure of Panama Seaway • Uplift of Rockies • Termination of ‘Permanent El Nino’ • Decrease in CO2 • Oribital variations

  25. The Causes of Northern Hemisphere Glaciation? 5 main hypotheses • Closure of Panama Seaway • Uplift of Rockies • Termination of ‘Permanent El Nino’ • Decrease in CO2 • Oribital variations

  26. Ice sheet model results…(2) Extent of ‘cold orbit’ ice sheet

  27. Conclusions • Enhancement of Greenland glaciation in the late Pliocene driven by decrease in atmospheric CO2 • Greenland ice sheet waxed and waned on orbital timescales prior to 3 Ma. • ENSO and tectonic forcing factors, with or without orbital trigger, did not play an important role in Greenland glaciation. Future Work / Implications • Improvement of CO2 records of the pre-ice core era. • Improvement of IRD records in North Atlantic (including provenance). • Need for transient model simulations (using fully coupled Earth System Models). • Strong dependence on CO2 has obvious implications for future ice sheet stability.

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