The impact of atmospheric and oceanic heat transports on the sea-ice-albedo instability during the Neoproterozoic

Donnadieu, Yannick; Ramstein, Gilles; Fluteau, Frédéric; Roche, Didier M.; Ganopolski, A.

doi:10.1007/s00382-003-0378-5

Cited by 46 publications

(17 citation statements)

References 39 publications

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“…Moreover, the comparison of the Snowball Earth bifurcation point between models is rendered difficult by the use of different continents and albedo values. Despite these issues, our study demonstrates that Snowball Earth initiation for Marinoan total solar irradiance (94% of the present-day value) in the most sophisticated climate model hitherto applied is possible at similar or even higher carbon dioxide levels than in simpler models without ocean dynamics (Donnadieu et al, 2004;Micheels and Montenari, 2008;Chandler and Sohl, 2000;Pollard and Kasting, 2004). This implies that models that calculate ocean heat transport dynamically are not necessarily more resistant to Snowball Earth initiation than models that do not incorporate ocean dynamics but use a specified ocean heat transport.…”

Section: Discussionmentioning

confidence: 76%

Initiation of a Marinoan Snowball Earth in a state-of-the-art atmosphere-ocean general circulation model

et al. 2011

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Abstract.We study the initiation of a Marinoan Snowball Earth (∼635 million years before present) with the state-of-the-art atmosphere-ocean general circulation model ECHAM5/MPI-OM. This is the most sophisticated model ever applied to Snowball initiation. A comparison with a preindustrial control climate shows that the change of surface boundary conditions from present-day to Marinoan, including a shift of continents to low latitudes, induces a globalmean cooling of 4.6 K. Two thirds of this cooling can be attributed to increased planetary albedo, the remaining one third to a weaker greenhouse effect. The Marinoan Snowball Earth bifurcation point for pre-industrial atmospheric carbon dioxide is between 95.5 and 96% of the present-day total solar irradiance (TSI), whereas a previous study with the same model found that it was between 91 and 94% for presentday surface boundary conditions. A Snowball Earth for TSI set to its Marinoan value (94% of the present-day TSI) is prevented by doubling carbon dioxide with respect to its preindustrial level. A zero-dimensional energy balance model is used to predict the Snowball Earth bifurcation point from only the equilibrium global-mean ocean potential temperature for present-day TSI. We do not find stable states with sea-ice cover above 55%, and land conditions are such that glaciers could not grow with sea-ice cover of 55%. Therefore, none of our simulations qualifies as a "slushball" solution. While uncertainties in important processes and parameters such as clouds and sea-ice albedo suggest that the Snowball Earth bifurcation point differs between climate models, our results contradict previous findings that Snowball Earth initiation would require much stronger forcings.

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Section: Discussionmentioning

confidence: 76%

Initiation of a Marinoan Snowball Earth in a state-of-the-art atmosphere-ocean general circulation model

et al. 2011

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“…Using sensitivity experiments with climate models of different complexity, modelers analyzed the various processes that might have initiated (e.g., Chandler and Sohl, 2000;Donnadieu et al, 2004a) or terminated (e.g., Pierrehumbert, 2004) the Neoproterozoic glaciation. These climate modeling studies focused on the role of a reduced solar luminosity and a different confi guration of the Earth's orbit, the effects of different concentrations of atmospheric carbon dioxide, the relevance of the paleogeography and/ or paleo-orography and changed land surface cover, and the ocean (e.g., Chandler and Sohl, 2000;Hyde et al, 2000;Poulsen et al, 2001Poulsen et al, , 2002Donnadieu et al, 2003Donnadieu et al, , 2004aDonnadieu et al, , 2004bPoulsen, 2003;Pierrehumbert, 2004;Poulsen and Jacob, 2004;Romanova et al, 2006). One could think that models give a consistent view on the Neoproterozoic because they are based on (more or less) unalterable physical principles.…”

Section: Introductionmentioning

confidence: 99%

A snowball Earth versus a slushball Earth: Results from Neoproterozoic climate modeling sensitivity experiments

Micheels

Montenari

2008

Geosphere

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The Neoproterozoic was characterized by an extreme glaciation, but until now there has been no consensus as to whether it was a complete glaciation (snowball Earth) or a less severe glaciation (slushball Earth). We performed sensitivity experiments with an Earth model of intermediate complexity for this period of dramatic global cooling. Our simulations focus on the climate response on a cool versus a cold ocean, on a desert versus a glacier land surface, and on a lower versus a higher CO 2 concentration. All Neoproterozoic model experiments represent much colder conditions than today and widespread glaciation. In case of an initial forcing representing a snowball Earth, the model maintains its complete glaciation, and temperatures are as low as -45 °C in equatorial latitudes. At the poles, the snowball experiments demonstrate annual average temperatures of <-70 °C. If the initial model forcing is more moderate (slushball Earth), polar temperatures are <-50 °C, but temperatures in low latitudes stay well above the freezing point of water, and therefore ice-free ocean areas remain. Based on our simulations, we are able to observe that global climate reacts less sensitively to reductions of atmospheric CO 2 during times with increased glaciations. Our results suggest that the development of glaciers on land contributes signifi cantly to intense ice coverage of the oceans. Because simulations initialized without complete ice cover do not reach the global glaciation condition, we conclude that our simulations support the rather moderate scenario of a slushball Earth than the extreme snowball Earth hypothesis. The experimental design and the model might, however, limit the interpretation of our results.

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“…The CLIMBER-2 model has been fully described in [Petoukhov et al, 2000] and successfully simulates the last glacial/interglacial cycle [Ganopolski et al, 1998b;Ganopolski andRahmstorf, 2001;Ganopolski et al, 1998a] as well as earlier climates [Donnadieu et al, 2004b]. Briefly, the atmos pheric module is a 2.5-dimensional statistical-dynamical model and has a resolution of 10° in latitude and approxi mately 51° in longitude (7x18 grid).…”

Section: The Climate Model and The Experimentsmentioning

confidence: 99%

“…The model also includes a thermodynamic sea-ice model. More details on the changes and on the limits of the CLIMBER-2 model when simulating very different climates, such as the Neoprotero zoic one, than the present-day one can be found in Donnadieu et al [2004b].…”

Section: The Climate Model and The Experimentsmentioning

confidence: 99%

Global Tectonic Setting and Climate of the Late Neoproterozoic: A Climate-Geochemical Coupled Study

Donnadieu¹,

Ramstein²,

Goddéris³

et al. 2013

The Extreme Proterozoic: Geology, Geochemistry, and Climate

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Whereas the snowball Earth hypothesis seems to account for most of the major fea tures of the Neoproterozoic glacial records, the causes that drove the Earth into a snowball state remain largely open to debate. Most of the mechanisms leading to the initiation of a snowball Earth are based on the existence of the unusual preponder ance of land masses in the tropics. However, the time of the youngest Neoprotero zoic glaciation is characterised by a rather widely distributed geography from low-to-high latitudes. In the absence of reliable knowledge of Neoproterozoic topog raphy, two series of coupled ocean-atmosphere climate model simulations were car ried out with a Late Neoproterozoic paleogeography (580 Ma) and solar luminosity reduced by 6% relative to today, the first one with flat continents and the second one with mountain ranges that mimic the Pan-African Orogen occurring at this time. Those climatic simulations coupled to the long-term carbon cycle have allowed to better constrain the atmospheric pC0 2 and the associated climate by the time of the youngest late Proterozoic glaciation. The Pan-African Orogen runs result in a snow accumulation pattern compatible with a regional-scale glaciation more less exten sive while the no relief runs do not succeed in initiating any glaciation. These results could give additional support to the inferences from many authors that some of the glacial deposits originally attributed to a snowball-like glaciation could in fact be the consequence of a more localised glaciation due to the important orogen occurring at the end of the Neoproterozoic.

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The impact of atmospheric and oceanic heat transports on the sea-ice-albedo instability during the Neoproterozoic

Cited by 46 publications

References 39 publications

Initiation of a Marinoan Snowball Earth in a state-of-the-art atmosphere-ocean general circulation model

Initiation of a Marinoan Snowball Earth in a state-of-the-art atmosphere-ocean general circulation model

A snowball Earth versus a slushball Earth: Results from Neoproterozoic climate modeling sensitivity experiments

Global Tectonic Setting and Climate of the Late Neoproterozoic: A Climate-Geochemical Coupled Study

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