Anne‐Sofie Ahm

The temporal relationship between global glaciations and the Great Oxidation Event (GOE) suggests that climate change played an important role in Earth's oxygenation. The potential role of temperature is captured by the stratigraphic proximity between glacial deposits and sediments containing mass‐independent fractionation of sulfur isotopes (MIF‐S). We use a time‐dependent one‐dimensional photochemical model to investigate whether temperature changes associated with global glaciations can drive oscillations in atmospheric O 2 levels and MIF‐S production across the GOE. We find that extreme climate change can cause atmospheric O 2 to oscillate between pre (<10 −6 times the present atmospheric level, PAL) and post‐GOE (>10 −5 PAL) levels. Post‐glacial hot‐moist greenhouse climates lead to post‐GOE O 2 levels because the abundant H 2 O vapor and oxidizing radicals drive the depletion of reduced species. This pattern is generally consistent with the MIF‐S signal observed in the sedimentary record, suggesting a link between global glaciations and O 2 oscillations across the GOE.