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

Voigt, Aiko; Abbot, Dorian S.; Pierrehumbert, Raymond T.; Marotzke, Jochem

doi:10.5194/cp-7-249-2011

Cited by 102 publications

(130 citation statements)

References 46 publications

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“…In some general circulation models, various authors also have found this characteristic to prevail (e.g. Lewis et al, 2007;Voigt and Marotzke, 2010;Voigt et al, 2011). However, in other models, it is found that a state with tropical open-water may be stable even if the sea ice edge reaches as low as 10 • latitude (Chandler and Sohl, 2000;Baum and Crowley, 2001;Pierrehumbert et al, 2011;Abbot et al, 2011;Yang et al, 2012a,b).…”

mentioning

confidence: 99%

The initiation of modern soft and hard Snowball Earth climates in CCSM4

Yang

Peltier

2012

Clim. Past

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Abstract. Geochemical and geological evidence has suggested that several global-scale glaciation events occurred during the Neoproterozoic Era in the interval from 750-580 million years ago. The initiation of these glaciations is thought to have been a consequence of the combined influence of a low level of atmospheric carbon dioxide concentration and an approximately 6 % weakening of solar luminosity. The latest version of the Community Climate System Model (CCSM4) is employed herein to explore the detailed combination of forcings required to trigger such extreme glaciation conditions under present-day circumstances of geography and topography. It is found that runaway glaciation occurs in the model under the following conditions: (1) an 8-9 % reduction in solar radiation with 286 ppmv CO 2 or (2) a 6 % reduction in solar radiation with 70-100 ppmv CO 2 . These thresholds are moderately different from those found to be characteristic of the previously employd CCSM3 model reported recently in Yang et al. (2012a,b), for which the respective critical points corresponded to a 10-10.5 % reduction in solar radiation with 286 ppmv CO 2 or a 6 % reduction in solar radiation with 17.5-20 ppmv CO 2 . The most important reason for these differences is that the sea ice/snow albedo parameterization employed in CCSM4 is believed to be more realistic than that in CCSM3. Differences in cloud radiative forcings and ocean and atmosphere heat transports also influence the bifurcation points. These results are potentially very important, as they are to serve as control on further calculations which will be devoted to an investigation of the impact of continental configuration.We demonstrate that there exist "soft Snowball" Earth states, in which the fractional sea ice coverage reaches approximately 60-65 %, land masses in low latitudes are covered by perennial snow, and runaway glaciation does not develop. This is consistent with our previous results based upon CCSM3. Although our results cannot exclude the possibility of a "hard Snowball" solution, it is suggested that a "soft Snowball" solution for the Neoproterozoic remains entirely plausible.

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confidence: 99%

The initiation of modern soft and hard Snowball Earth climates in CCSM4

Yang

Peltier

2012

Clim. Past

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“…Lewis et al, 2007;Peltier et al, 2007;Peltier, 2010, 2011;Pierrehumbert et al, 2011). Several recent studies with fully coupled atmosphere-ocean models have suggested that the CO 2 threshold is quite strongly model dependent, ranging from 17.5-20 ppmv in CCSM3 (Yang et al, 2012a,b), 86 ppmv in MIROC-lite (Oka et al, 2010), 70-100 ppmv in CCSM4 (Yang et al, 2012c), to 278 ppmv in ECHAM5/MPI-OM (Voigt and Marotzke, 2010;Voigt et al, 2011), when there is a 6 % reduction in solar luminosity. For deglaciation is assumed, simulations with different models have also suggested different thresholds (Hyde et al, 2000;Tajika, 2003;Pierrehumbert, 2004Pierrehumbert, , 2005Le Hir et al, 2007).…”

Section: Introductionmentioning

confidence: 99%

Radiative effects of ozone on the climate of a Snowball Earth

Yang

Peltier

2012

Clim. Past

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Abstract. Some geochemical and geological evidence has been interpreted to suggest that the concentration of atmospheric oxygen was only 1-10 % of the present level in the time interval from 750 to 580 million years ago when several nearly global glaciations or Snowball Earth events occurred. This low concentration of oxygen would have been accompanied by a lower ozone concentration than exists at present. Since ozone is a greenhouse gas, this change in ozone concentration would alter surface temperature, and thereby could have an important influence on the climate of the Snowball Earth. Previous works that have focused either on initiation or deglaciation of the proposed Snowball Earth has not taken the radiative effects of ozone changes into account. We address this issue herein by performing a series of simulations using an atmospheric general circulation model with various ozone concentrations.Our simulation results demonstrate that, as ozone concentration is uniformly reduced from 100 % to 50 %, surface temperature decreases by approximately 0.8 K at the Equator, with the largest decreases located in the middle latitudes reaching as high as 2.5 K. When ozone concentration is reduced and its vertical and horizontal distribution is simultaneously modulated, surface temperature decreases by 0.4-1.0 K at the Equator and by 4-7 K in polar regions. These results here have uncertainties, depending on model parameterizations of cloud, surface snow albedo, and relevant feedback processes, while they are qualitatively consistent with radiative-convective model results that do not involve such parameterizations and feedbacks. These results suggest that ozone variations could have had a moderate impact on the climate during the Neoproterozoic glaciations.

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“…More energy leaves the atmosphere at the top than enters at the bottom, yet the snowball planet does not cool off, implying that there is a small spurious heat source in the model atmosphere. This discrepancy, which may be a surface diagnostic bug rather than a true model error, was noted by Voigt et al (2011) and should not significantly affect our results, since we only compare time variations in thermal emission. We simply renormalize the snowball simulation's thermal emission to the time-averaged absorbed power in Sections 3 and 4 of this paper.…”

Section: Time-averaged Power Budgetmentioning

confidence: 88%

“…A detailed description of the GCM is given in Voigt et al (2011), and references therein. We use topof-atmosphere (TOA) incident stellar flux, outgoing longwave radiation, and reflected light, each of which is outputted every two hours at each grid point.…”

Section: Global Climate Modelsmentioning

confidence: 99%

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Thermal Phases of Earth-Like Planets: Estimating Thermal Inertia From Eccentricity, Obliquity, and Diurnal Forcing

Cowan

Voigt

Abbot

2012

ApJ

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In order to understand the climate on terrestrial planets orbiting nearby Sun-like stars, one would like to know their thermal inertia. We use a global climate model to simulate the thermal phase variations of Earth analogs and test whether these data could distinguish between planets with different heat storage and heat transport characteristics. In particular, we consider a temperate climate with polar ice caps (like the modern Earth) and a snowball state where the oceans are globally covered in ice. We first quantitatively study the periodic radiative forcing from, and climatic response to, rotation, obliquity, and eccentricity. Orbital eccentricity and seasonal changes in albedo cause variations in the global-mean absorbed flux. The responses of the two climates to these global seasons indicate that the temperate planet has 3× the bulk heat capacity of the snowball planet due to the presence of liquid water oceans. The obliquity seasons in the temperate simulation are weaker than one would expect based on thermal inertia alone; this is due to cross-equatorial oceanic and atmospheric energy transport. Thermal inertia and cross-equatorial heat transport have qualitatively different effects on obliquity seasons, insofar as heat transport tends to reduce seasonal amplitude without inducing a phase lag. For an Earth-like planet, however, this effect is masked by the mixing of signals from low thermal inertia regions (sea ice and land) with that from high thermal inertia regions (oceans), which also produces a damped response with small phase lag. We then simulate thermal light curves as they would appear to a high-contrast imaging mission (TPF-I/Darwin). In order of importance to the present simulations, which use modern-Earth orbital parameters, the three drivers of thermal phase variations are (1) obliquity seasons, (2) diurnal cycle, and (3) global seasons. Obliquity seasons are the dominant source of phase variations for most viewing angles. A pole-on observer would measure peak-to-trough amplitudes of 13% and 47% for the temperate and snowball climates, respectively. Diurnal heating is important for equatorial observers (∼5% phase variations), because the obliquity effects cancel to first order from that vantage. Finally, we compare the prospects of optical versus thermal direct imaging missions for constraining the climate on exoplanets and conclude that while zero-and one-dimensional models are best served by thermal measurements, second-order models accounting for seasons and planetary thermal inertia would require both optical and thermal observations.

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

Cited by 102 publications

References 46 publications

The initiation of modern soft and hard Snowball Earth climates in CCSM4

The initiation of modern soft and hard Snowball Earth climates in CCSM4

Radiative effects of ozone on the climate of a Snowball Earth

Thermal Phases of Earth-Like Planets: Estimating Thermal Inertia From Eccentricity, Obliquity, and Diurnal Forcing

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