MASS EXTINCTIONS AND CLOSE CALLS: USING EXPERIMENTAL EARTH SYSTEM AND ECOLOGICAL MODELLING TO UNDERSTAND WHAT MAKES A CATASTROPHIC EXTINCTION

Ancient warming events are commonly proposed as deep-time analogues for modern climate change. However, comparisons are complicated by potentially critical differences in the rate and magnitude of warming, and changes in key Earth system boundary conditions such as continental configuration. These differences make it difficult to compare ancient extinctions to the modern biodiversity crisis, and to mechanistically understand why some ancient warming events resulted in more severe marine extinctions than others. The synergistic effects of ocean warming and deoxygenation have been proposed as a key physiological mechanism for driving extinction in marine animals across hyperthermals through time, emphasizing the importance of spatially explicit palaeoceanography to provide direct links between climate and animal physiology.

We first investigate ocean oxygenation responses to different rates and magnitudes of global warming under different Mesozoic–Cenozoic continental configurations using a dynamic application of the cGENIE Earth system model. Then, we use integrated macroecological and ecophysiological modelling approaches to simulate how the combined physiological impacts of marine oxygen, temperature, and productivity dynamics control the ability of marine organisms to track their physiological niches in response to warming. Using this integrated modeling framweork, we investigate why well-characterized Mesozoic–Cenozoic hyperthermal events resulted in markedly different marine biodiversity responses. By appling our dynamic, coupled Earth system and ecological model approach as an experimental tool, we provide a new quantitative framework for mechanistically comparing ancient warming events, and evaluating their applicability as analogues for modern and future global change.