Snowball Earth: Asynchronous coupling of sea‐glacier flow with a global climate model. Issue 10 (20th May 2017)

• Record Type: Journal Article
• Authors: Pollard, D.; Kasting, J. F.; Zugger, M. E.
• Is Part Of: Journal of geophysical research. Volume 122:Issue 10(2017)
• Page Start: 5157
• Page End: 5171
• Publication Date: 2017-05-20
• Subjects: Snowball Earth -- sea glacier -- climate model; Atmospheric physics -- Periodicals; Geophysics -- Periodicals; 551.5
• DOI: 10.1002/2017JD026621
• Languages: English
• ISSNs: 2169-897X

Abstract

Abstract: During Snowball Earth episodes of the Neoproterozoic and Paleoproterozoic, limited amounts of tropical open ocean (Jormungand), or tropical ocean with thin ice cover, would help to explain (1) vigorous glacial activity in low latitudes, (2) survival of photosynthetic life, and (3) deglacial recovery without excessive buildup of atmospheric CO2 . Some previous models have suggested that tropical open ocean or thin‐ice cover is possible; however, its viability in the presence of kilometer‐thick sea glaciers flowing from higher latitudes has not been demonstrated conclusively. Here we describe a new method of asynchronously coupling a zonal sea‐glacier model with a 3‐D global climate model and apply it to Snowball Earth. Equilibrium curves of ice line versus CO2 are mapped out, as well as their dependence on ocean heat transport efficiency, sea‐glacier flow, and other model parameters. No climate states with limited tropical open ocean or thin ice are found in any of our model runs, including those with sea glaciers. If this result is correct, then other refugia such as cryoconite pans would have been required for life to survive. However, the reasons for the differences between our results and others should first be resolved. It is suggested that small‐scale convective dynamics, affecting fractional snow cover in low latitudes, may be a critical factor accounting for these differences. Key Points: A method for asynchronously coupling a sea‐glacier model with a global climate model is described No Jormungand or tropical thin ice states are found for Snowball Earth Fractional snow cover and small‐scale dynamics may influence Snowball Earth results