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https://doi.org/10.5194/egusphere-2026-679
© Author(s) 2026. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
https://doi.org/10.5194/egusphere-2026-679
© Author(s) 2026. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
24 Feb 2026
| 24 Feb 2026
Status: this preprint is open for discussion and under review for Climate of the Past (CP).
Amplified cooling of Snowball Earth from a salt–albedo feedback
Abstract. It is believed that the atmospheric circulation on Snowball Earth produced a net ablation zone exposing bare sea ice. Under sufficiently low temperatures, salt begins to precipitate out of sea ice, forming a lag deposit of crystals with high albedo as the ice sublimates. This could have resulted in a salt–albedo feedback that has not previously been included in modeling studies of Snowball Earth. We implement a salt-albedo feedback in a simple climate model and show that, once initiated, this mechanism could have intensified global cooling in the initial phase of Snowball Earth. Our results suggest that salt precipitation may have played a role in shaping the early climate of Snowball Earth.
How to cite. Samuelsberg, A., Jakobsen, P. K., and Rypdal, M.: Amplified cooling of Snowball Earth from a salt–albedo feedback, EGUsphere [preprint], https://doi.org/10.5194/egusphere-2026-679, 2026.
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Aksel Samuelsberg
CORRESPONDING AUTHOR
Department of Mathematics and Statistics, UiT - The Arctic University of Norway
Per Kristen Jakobsen
Department of Mathematics and Statistics, UiT - The Arctic University of Norway
Martin Rypdal
Department of Mathematics and Statistics, UiT - The Arctic University of Norway
Short summary
In this work we implement a feedback mechanism with proposed relevance for Snowball Earth in a simple climate model, a salt-albedo feedback. Our results show that this mechanism could have amplified cooling during the initial phase of Snowball Earth, suggesting it may have played an overlooked role in the climate evolution of Snowball Earth.
In this work we implement a feedback mechanism with proposed relevance for Snowball Earth in a...
GENERAL COMMENT: This paper investigates the effect of extremely bright ice resulting from the presence of salt deposits under Snowball Earth conditions. Such ice, no characterized by an exceptionally high albedo, would amplify global cooling because it forms in low-latitude regions, which receive the highest levels of solar insolation. Consequently, the temperature of the Snowball Earth state would be even lower, making the exit from this climatic state more difficult.
This effect is quantified using an energy balance model (EBM) in which the albedo is determined solely by the surface albedo (cloud effects are not included), with ice properties varying as a function of temperature and the presence or absence of snow cover.
The paper presents novel results using a clear methodology to address a specific Snowball Earth–related problem. None of the issues identified during the review raise concerns about the validity of the results presented.
SPECIFIC COMMENTS (ordered by importance)
Surface conditions formalism. The formalism used to describe the surface conditions (lines 28–44) is limited to temperature and the absence of snow (P–E < 0). However, the results of Jason C. Goodman (2006) clearly show that surface water is primarily of meteoric origin and therefore very low in salinity, except between approximately 0–3° latitude (see meteoric ice vs. marine ice, Fig. 2 in the paper).
This important point is only briefly mentioned (line 110) and the appropriate reference is not cited. The relevant study is:
Goodman, J. C. (2006), Through thick and thin: Marine and meteoric ice in a “Snowball Earth” climate, Geophysical Research Letters, 33, L16701. https://doi.org/10.1029/2006GL026840.
Given the importance of this issue for the process investigated in the manuscript, this point deserves more attention and should be discussed in greater detail.
Additional Figure
A figure similar to that presented by Goodman (Fig. 3), showing solar radiation, albedo, and temperature, would be useful. This figure could distinguish two cases: with and without the salt crust. It could also serve as an opportunity to summarize the boundary conditions used in the model (e.g., absence of continents, no-clouds, solar constant used, etc.).
Figure 1 X-axis addition
For Fig. 1, adding a second X-axis corresponding to CO₂ concentration would be useful, in addition to the radiative forcing. This can be easily computed at first order using the relationship provided by:
Kiehl, J. T., & Dickinson, R. E. (1987), A study of the radiative effects of enhanced atmospheric CO₂ and CH₄ on early Earth surface temperatures, Journal of Geophysical Research: Atmospheres, 92(D3), 2991–2998. https://doi.org/10.1029/JD092iD03p02991
Addressing these points would further strengthen the paper, particularly the discussion of marine ice (salt deposits) vs meteoric ice.