Beschreibung
The first rise of atmospheric oxygen in Earth’s atmosphere about 2.4 billion years ago certainly marks one of the most profound and longlasting changes in the history of our planet. This Great Oxidation Event (GOE) was accompanied by unparalleled environmental changes, not least including Earth’s first major glaciation. However, the precise sequence of events surrounding the GOE, and the connection between the GOE and the Paleoproterozoic glaciations continues to be intensely debated. The multinational and multidisciplinary initiative GOE-DEEP (Gabon and Oxygenation of Earth – Drilling Early Earth Project) which has been endorsed by ICDP aims at providing new insights into these and other open questions related to the GOE. In this proposal which is connected to GOE-DEEP, we will investigate the Paleoproterozoic glaciations and their connection to the GOE from the point of view of climate physics. This is crucial since this time period has not been investigated in detail with climate models so far, hampering the testing of hypotheses. Uniquely, we will employ a fast Earth-system model which allows simulating the coupled dynamics of ice sheets and the global carbon cycle for the Paleoproterozoic, something which has never been done before. Specifically, we will investigate (1) what it takes to trigger (global) glaciations of the Paleoproterozoic Earth system, (2) the importance of regional ice sheets for the glaciation process, and (3) which of the two competing scenarios (oxidation of methane versus increased weathering) fits to the evidence from the proxy record, including the new data from GOE-DEEP.