Triggering a Climate Change Dominated "Anthropocene": Is It Common among Exocivilizations?

We seek to model the coupled evolution of a civilization and its host planet through the era when energy harvesting by the civilization drives the planet into new and adverse climate states. In this way, we ask if triggering "Anthropocenes" of the kind humanity is experiencing might be a generic feature of planet-civilization evolution. This question has direct consequences for both the study of astrobiology and the sustainability of human civilization. Furthermore, if Anthropocenes prove fatal for some civilizations then they can be considered as one form of a "Great Filter" and are therefore relevant to discussions of the Fermi Paradox. In this study, we focus on the effects of energy harvesting via combustion and vary the planet's initial chemistry and orbital radius. We find that in this context, the most influential parameter dictating a civilization's fate is their host planet's climate sensitivity, which quantifies how global temperatures change as CO₂ is added to the atmosphere. Furthermore, this is in itself a function of the planet's atmospheric CO₂ level, so planets with low levels of CO₂ will have high climate sensitivities and high probabilities of triggering climate change. Using simulations of the coupled nonlinear model combined with semi-analytic treatments, we find that most planets in our initial parameter space experience diminished growth due to climate effects, an event we call a "climate-dominated Anthropocene."