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Sea-ice Dynamics Strongly Promote Snowball Earth Initiation and Destabilize Tropical Sea-ice Margins : Volume 8, Issue 6 (21/12/2012)

By Voigt, A.

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Book Id: WPLBN0004006409
Format Type: PDF Article :
File Size: Pages 14
Reproduction Date: 2015

Title: Sea-ice Dynamics Strongly Promote Snowball Earth Initiation and Destabilize Tropical Sea-ice Margins : Volume 8, Issue 6 (21/12/2012)  
Author: Voigt, A.
Volume: Vol. 8, Issue 6
Language: English
Subject: Science, Climate, Past
Collections: Periodicals: Journal and Magazine Collection (Contemporary), Copernicus GmbH
Historic
Publication Date:
2012
Publisher: Copernicus Gmbh, Göttingen, Germany
Member Page: Copernicus Publications

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Abbot, D. S., & Voigt, A. (2012). Sea-ice Dynamics Strongly Promote Snowball Earth Initiation and Destabilize Tropical Sea-ice Margins : Volume 8, Issue 6 (21/12/2012). Retrieved from http://ebook2.worldlibrary.net/


Description
Description: Max Planck Institute for Meteorology, Hamburg, Germany. The Snowball Earth bifurcation, or runaway ice-albedo feedback, is defined for particular boundary conditions by a critical CO2 and a critical sea-ice cover (SI), both of which are essential for evaluating hypotheses related to Neoproterozoic glaciations. Previous work has shown that the Snowball Earth bifurcation, denoted as (CO2, SI)*, differs greatly among climate models. Here, we study the effect of bare sea-ice albedo, sea-ice dynamics and ocean heat transport on (CO2, SI)* in the atmosphere–ocean general circulation model ECHAM5/MPI-OM with Marinoan (~ 635 Ma) continents and solar insolation (94% of modern). In its standard setup, ECHAM5/MPI-OM initiates a~Snowball Earth much more easily than other climate models at (CO2, SI)* ≈ (500 ppm, 55%). Replacing the model's standard bare sea-ice albedo of 0.75 by a much lower value of 0.45, we find (CO2, SI)* ≈ (204 ppm, 70%). This is consistent with previous work and results from net evaporation and local melting near the sea-ice margin. When we additionally disable sea-ice dynamics, we find that the Snowball Earth bifurcation can be pushed even closer to the equator and occurs at a hundred times lower CO2: (CO2, SI)* ≈ (2 ppm, 85%). Therefore, the simulation of sea-ice dynamics in ECHAM5/MPI-OM is a dominant determinant of its high critical CO2 for Snowball initiation relative to other models. Ocean heat transport has no effect on the critical sea-ice cover and only slightly decreases the critical CO2. For disabled sea-ice dynamics, the state with 85% sea-ice cover is stabilized by the Jormungand mechanism and shares characteristics with the Jormungand climate states. However, there is no indication of the Jormungand bifurcation and hysteresis in ECHAM5/MPI-OM. The state with 85% sea-ice cover therefore is a soft Snowball state rather than a true Jormungand state. Overall, our results demonstrate that differences in sea-ice dynamics schemes can be at least as important as differences in sea-ice albedo for causing the spread in climate models' estimates of the Snowball Earth bifurcation. A detailed understanding of Snowball Earth initiation therefore requires future research on sea-ice dynamics to determine which model's simulation is most realistic.

Summary
Sea-ice dynamics strongly promote Snowball Earth initiation and destabilize tropical sea-ice margins

Excerpt
Abbot, D. S. and Pierrehumbert, R. T.: Mudball: Surface dust and Snowball Earth deglaciation, J. Geophys. Res., 115, D03104, doi:10.1029/2009JD012007, 2010.; Abbot, D. S., Voigt, A., and Koll, D.: T}he {J}ormungand {G}lobal {C}limate {S}tate and {I}mplications for {N}eoproterozoic {G}laciations, {J. {G}eophys. {R}es., 116, D18103, doi:10.1029/2011JD015927, 2011.; Brandt, R. E., Warren, S. G., Worby, A. P., and Grenfell, T. C.: S}urface albedo of the antarctic sea ice zone, {J. {C}limate, 18, 3606–3622, doi:10.1175/JCLI3489.1, 2005.; Budyko, M. I.: {E}ffect of solar radiation variations on climate of {E}arth, {T}ellus, 21, 611–619, 1969.; Chandler, M. A. and Sohl, L. E.: C}limate forcings and the initiation of low-latitude ice sheets during the {N}eoproterozoic {V}aranger glacial interval, {J. {G}eophys. {R}es., 105, 20737–20756, 2000.; Evans, D. A. D.: S}tratigraphic, geochronological, and paleomagnetic constraints upon the {N}eoproterozoic climatic paradox, {A}m. {J. {S}ci., 300, 347–433, doi:10.2475/ajs.300.5.347, 2000.; Feltham, D. L.: Sea Ice Rheology, {A}nn. {R}ev. {F}luid {M}ech., 40, 91–112, doi:10.1146/annurev.fluid.40.111406.102151, 2008.; Ferreira, D., Marshall, J., and Rose, B.: C}limate determinism revisited: multiple equilibria in a complex climate model, {J. {C}limate, 24, 992–1012, doi:10.1175/2010JCLI3580.1, 2011.; Fortuin, J. P. F. and Kelder, H.: A}n ozone climatology based on ozonesonde and satellite measurements, {J. {G}eophys. {R}es., 103, 31709–31734, doi:10.1029/1998JD200008, 1998.; Lubick, N.: {P}alaeoclimatology: {S}nowball fights, {N}ature, 417, 12–13, doi:10.1038/417012a, 2002.; Godderis, Y., Donnadieu, Y., Dessert, C., Dupre, B., Fluteau, F., Francois, L. M., Meert, J., Nedelec, A., and Ramstein, G.: Coupled modeling of global carbon cycle and climate in the Neoproterozoic: links between Rodinia breakup and major glaciations, Comptes Rendus Geosci., 339, 212–222, doi:10.1016/j.crte.2005.12.002, 2007.; Goodman, J. C. and Pierrehumbert, R. T.: G}lacial flow of floating marine ice in {S}nowball {E}arth, {J. {G}eophys. {R}es., 108, 3308, doi:10.1029/2002JC001471, 2003.; Gough, D. O.: {S}olar interior structure and luminosity variations, {S}olar {P}hysics, 74, 21–34, doi:10.1007/BF00151270, 1981.; Hibler, W. D.: D}ynamic thermodynamic sea ice model, {J. {P}hys. {O}ceanogr., 9, 815–846, 1979.; Hoffman, P. F., Kaufman, A. J., Halverson, G. P., and Schrag, D. P.: A {N}eoproterozoic snowball earth, {S}cience, 281, 1342–1346, doi:10.1126/science.281.5381.1342, 1998.; Hyde, W. T., Crowley, T. J., Baum, S. K., and Peltier, W. R.: {N}eoproterozoic 'snowball {E}arth' simulations with a coupled climate/ice-sheet model, {N}ature, 405, 425–429, doi:10.1038/35013005, 2000.; Kennedy, M. J., Christie-Blick, N., and Sohl, L. E.: {A}re {P}roterozoic cap carbonates and isotopic excursions a record of gas hydrate destabilization following {E}arth's

 

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