Cloudfree Archean Explanation for High Surface Temperatures

Returning to an earlier discussion of the DMS/CCN story (see chapter 1), if indeed there was much lower production of CCNs in the Archean, as a result of the absence of DMS production by eucaryotic algae, with no other source comparable with today's, the surface albedo could have been as low as 0.1. A naive calculation of this effect on surface temperature gives increases on the order of 30°C. However, taking into account the new steady-state in the silicate-carbonate cycle brings this increase down to a more modest increment of 5 to 10°C relative to the constant surface albedo case for the Archean (Volk 1998 computed a similar result). Given the likelihood that other CCN sources may have been more important in the Archean (e.g., from stratospheric oxidation of H2S), the tentative conclusion is that albedo variations are unlikely to explain the high apparent surface temperatures in the first two thirds of Earth history.

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