CO2 HISTORY MATTERS: THE ROLE OF BACKGROUND CLIMATE IN MASS EXTINCTIONS (Invited Presentation)

The study of mass extinctions is invaluable for understanding the effects of sudden perturbations on the different components of the Earth system and its responses, and its impacts and implications for the evolutionary course. Growing interest in extinctions, combined with new field evidence and analytical breakthroughs over recent years has enabled us to zoom into individual events, construct their high-resolution chronologies and proxy records and start untangling their cause mechanisms from consequences. This is fundamental to progressing our knowledge, however, how far can we zoom in without overlooking the wider context? To what extent does the prior background climate state influence the outcome and magnitude of an extinction? For example, how would our understanding of the Permian-Triassic mass extinction change if we were to find the late Permian had low or high background CO₂? We present a new boron isotope-derived record of atmospheric CO₂ spanning the late Permian that we use to establish the pre-extinction climate conditions. We discuss its implications for understanding the carbon cycle perturbations associated with the trigger of the extinction and the CO₂ in its aftermath, and more broadly reflect on the role of background climate as a generalizable component of extinctions.