SSP2.2

Earth’s oceans and atmosphere have been subject to numerous variations in oxygen levels throughout their history, including long-term trends towards a more oxygenated environment such as the Great Oxidation Event, and abrupt short-term deoxygenation events during environmental crises associated with Phanerozoic mass extinctions and oceanic anoxic events. Over the past decades, increasingly reducing conditions resulting from anthropogenic activities have also been reported in modern aquatic environments. This session will explore these changes in oxygen levels at the Earth’s surface, and their importance for life on this planet, as evidenced by the sedimentary structures and geochemical compositions of rocks and sediments deposited in marine/lake environments (e.g., trace-fossil imprints and bioturbation, framboidal pyrites, traditional geochemical markers such as redox-sensitive metal concentrations, stable sulphur isotopes, and novel isotope systems such as chromium, molybdenum, uranium etc.). We welcome contributions on the causes and biospheric impacts of oxygenation/deoxygenation events throughout Earth’s history, from the Precambrian to the modern day, and particularly encourage studies highlighting what can be learned from past events analogous to the anticipated 21st century climate changes.