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Project Progress

Kasting spent 8 months of this year on sabbatical at JPL/Caltech working with Vikki Meadows’ NAI group. I will describe those efforts separately as part of Vikki’s report. My work with Penn State was divided into three parts: 1) coupled ecosystem/atmosphere modeling of the Archean Earth with my graduate student, Pushker Kharecha, 2) modeling of Snowball Earth with climate modeler David Pollard, and 3) modeling of BIF deposition with my graduate student, Shawn Goldman. In Project 1, we showed that an anaerobic ecosystem on the early Earth should have produced methane at approximately the same rate as today’s combination aerobic/anaerobic ecosystem. This strengthens the argument that methane could have been an important factor in warming the climate of early Earth and offsetting the fainter young Sun. In project 2, we showed that “thin-ice” solutions can be found in the tropics, either globally or locally, despite the flow of sea ice from the poles to the equator. This provides a possible explanation for how photosynthetic algae and other light-dependent organisms survived the Snowball Earth episodes of the Late Proterozoic. In Project 3, we made a preliminary attempt to show that hematite-rich banded iron-formations (BIFs) could have formed in an anoxic environment. We argued that H₂ consumption by iron-reducing bacteria could have kept oxygen fugacities in iron-rich sediments below the crossover point between hematite and magnetite.