Abstract

Following the Great Oxidation Event, Earth’s atmosphere has been oxygenated for the past 2.4 billion years, bringing changes to our biosphere which eventually enabled the proliferation of animal life. I use a three-dimensional Earth System Model, which employs coupled physics and chemistry, known as the Whole Atmosphere Community Climate Model (WACCM6), to simulate Earth’s oxygenated paleoclimates. Additionally, I perform simulations of TRAPPIST -1e and Proxima Centauri b (two habitable zone exoplanets) over a range of oxygen (O2) concentrations. I use these simulations as input to the Planetary Spectrum Generator (a radiative transfer suite) to predict telescope observations from these exoplanet scenarios. I will explore how atmospheric O2 influences atmospheric chemistry, planetary habitability, and the observability of biosignature gases in exoplanet atmospheres from afar.