Clim. Past Discuss., 9, 525-582, 2013
© Author(s) 2013. This work is distributed
under the Creative Commons Attribution 3.0 License.
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This discussion paper has been under review for the journal Climate of the Past (CP). Please refer to the corresponding final paper in CP.
Albedo and heat transport in 3-dimensional model simulations of the early Archean climate
H. Kienert, G. Feulner, and V. Petoukhov
Potsdam Institute for Climate Impact Research, Telegrafenberg A62, 14473 Potsdam, Germany

Abstract. At the beginning of the Archean eon (ca. 3.8 billion yr ago), the Earth's climate state was significantly different from today due to the lower solar luminosity, smaller continental fraction, higher rotation rate and, presumably, significantly larger greenhouse gas concentrations. All these aspects play a role in solutions to the "faint young Sun problem" which must explain why the ocean surface was not fully frozen at that time. Here, we present 3-dimensional model simulations of climate states that are consistent with early Archean boundary conditions and have different CO2 concentrations, aiming at an understanding of the fundamental characteristics of the early Archean climate system. We focus on three states: one of them is ice-free, one has the same mean surface air temperature of 288 K as today's Earth and the third one is the coldest stable state in which there is still an area with liquid surface water (i.e. the critical state at the transition to a "snowball Earth"). We find a reduction in meridional heat transport compared to today which leads to a steeper latitudinal temperature profile and has atmospheric as well as oceanic contributions. Ocean surface velocities are largely zonal, and the strength of the atmospheric meridional circulation is significantly reduced in all three states. These aspects contribute to the observed relation between global mean temperature and albedo, which we suggest as a parameterisation of the ice-albedo feedback for 1-dimensional model simulations of the early Archean and thus the faint young Sun problem.

Citation: Kienert, H., Feulner, G., and Petoukhov, V.: Albedo and heat transport in 3-dimensional model simulations of the early Archean climate, Clim. Past Discuss., 9, 525-582, doi:10.5194/cpd-9-525-2013, 2013.
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