TUMBLE - the tipping question ...

... for Antarctica, Greenland, monsoon and overturning

Scientific Objective

Some parts of the climate system are particularly sensitive already to relatively small changes in background climate. Among the most relevant for human society are the great ice sheets on Greenland (GIS) and West-Antarctica (WAIS) through their role for global sea level rise and the Asian monsoon as a basis of livelihood for more than a billion people. Here we propose to investigate the stability of each of these tipping elements as well as their inter-linkage through another possibly vulnerable system, the Atlantic overturning circulation (THC), and the intertropical convergence zone (ITCZ).

Research questions

• Is the West Antarctic ice sheet stable under global warming?
• Are monsoon circulations capable of multi-stability?
• What is the future of the Greenland Ice Sheet (GIS) and what is the probability of its irreversible melt-back under different global warming scenarios?
• Can a wind-driven Atlantic overturning be inherently unstable?
• How could GIS melting affect stability of Antarctic ice sheet and thermohaline circulation?
• How does it feed back onto tropical monsoon circulations?

Project members (and their expertise within the project)

• Torsten Albrecht (ice shelf calving)
  
• Reinhard Calov (Greenland ice sheet modeling)
  
• Andrey Ganopolski (land ice climate interaction)
  
• Marianne Haseloff (ice sheet / ice shelf transitions zone)
• Hendrik Kienert (Atlantic overturning and sea surface elevation)
  
• Anders Levermann (climate dynamics)
  
• Maria Martin (Antarctic ice sheet modeling)
• Arathy Menon (monsoon dynamics)
  
• Matthias Mengel (stability of North Atlantic subpolar gyre)
  
• Friederike Otto (basal ice shelf melting)
  
• Vladimir Petoukhov (monsoon dynamics)
• Stefan Rahmstorf (ocean dynamics)
• Alex Robinson (Greenland surface mass balance)
  
• Jacob Schewe (ocean circulation and monsoon dynamics)
• Carl Friedrich Schleussner (large-scale ocean circulation)
  
• Ricarda Winkelmann (Antarctic ice loss)
  

Former members

• Tore Hattermann
• Johannes Fürst

Publications

20. M. Haseloff, M. Martin, T. Albrecht, R. Winkelmann, A. Levermann; Grounding line hysteresis: mechanism and influence of buttressing ice shelves; Geophysical Research Letters, (2010), in preparation.

19.  J.J. Fürst and A. Levermann; Minimal model of a wind- and mixing-driven overturning circulation; Climate Dynamics, (2010), in preparation.

18. J. Schewe and A. Levermann; Abrupt monsoon failure - mechanism for sustained 'dry state' in comprehensive climate model; (2010), in preparation.

17.  M. Martin, R. Winkelmann, M. Haseloff, T. Albrecht, E. Bueler, C. Khroulev, A. Levermann; Dynamic simulation of Antarctic land ice with the Potsdam Parallel Ice Sheet Model PISM-PIK; Climate Dynamics,  (2010), in preparation.

16.  A. Levermann, T. Albrecht, R. Winkelmann, M. Martin, M. Haseloff; Universal dynamic calving law implies potential for abrupt ice-shelf retreat; Nature,  (2010), under review.

15. A. Born and A. Levermann; The 8k event: abrupt transition of the subpolar gyre towards a modern North Atlantic circulation; G-cubed, (2010), submitted.

14. F. E. L. Otto and A. Levermann; Levity - complementing climate policy strategies; Climatic Change Letters, (2010), submitted.

13. A. Robinson, R. Calov, A. Ganopolski; An efficient regional energy-moisture balance model for simulation of the Greenland Ice Sheet response to climate change; The Cryosphere Discussions, 3 (2009), 729-764.

12. A. Levermann and J. Mignot; Scaling relations for upper and bottom overturning cells in the Atlantic; Climate Dynamics, (2010), in revision.

11.  M. Montoya, A. Born, A. Levermann; Reversed North Atlantic gyre dynamics in glacial climate; Climate Dynamics, (2010), in press.

10.  A. Levermann and J.J. Fürst; Atlantic pycnocline theory scrutinized using a coupled climate model; Geophysical Research Letters, (2010), in revision.

9.  B. Marzeion and A. Levermann; Stratification-dependent mixing may increase sensitivity of a wind-driven Atlantic overturning to surface freshwater flux; Geophysical Research Letters, 36 (2009), L20602.

8.  A. Levermann, J. Schewe, V. Petoukhov, H. Held; Basic mechanism for abrupt monsoon transitions; Proceedings of the National Acadamie of Sciences, (2009), DOI 10.1073/PNAS.0901414106.

7.  T. Hattermann and A. Levermann; Response of Southern Ocean circulation to global warming may enhance basal ice shelf melting around Antarctica; Climate Dynamics, (2010), DOI: 10.1007/s00382-009-0643-3. .

6.  J. Schewe and A. Levermann; The role of meridional density gradients for a wind-driven overturning; Climate Dynamics, (2009), published online, DOI: 10.1007/s00382-009-0572-1.

5. H. Goelzer, A. Levermann, S. Rahmstorf
Two-way coupling of an ENSO model to the global climate model CLIMBER-3α
Ocean Modeling, 29 (2009), 94-101

4.  B. Marzeion, A. Levermann, J. Mignot; Sensitivity of North Atlantic subpolar gyre and overturning to stratification-dependent mixing: response to global warming; Climate Dynamics, (2009), published online, DOI: 10.1007/s00382-008-0521-4.

3. A. Born, A. Levermann, J. Mignot
Sensitivity of the Atlantic ocean circulation to a hydraulic overflow parameterisation in a coarse resolution model: response of the subpolar gyre
Ocean Modeling, 27 (2009), 130-142.

2.  M. Montoya and A. Levermann; Surface wind stress threshold for glacial Atlantic overturning; Geophysical Research Letters, 35 (2008), L03608. » Supporting online material. » Highlighted in EOS, February 2008

1.  A. Levermann and A. Born; Bistability of the Atlantic subpolar gyre in a coarse resolution climate model;Geophysical Research Letters, 34 (2007), L24605.