Climate Tipping Phenomena in Nonautonomous Paleoecosystems

IMSI - October 2023
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IMSI Interdisciplinary Research Cluster – Climate Tipping Phenomena in Nonautonomous Paleoecosystems
The NSF-funded Institute for Mathematical and Statistical Innovation (IMSI) hosted an Interdisciplinary Research Cluster (IRC) entitled, “Climate Tipping Phenomena in Nonautonomous Paleoecosystems,” June 20-30, 2023, at the University of Chicago.
This IRC focused on developing a conceptual theoretical framework for describing tipping points and regime shifts in a coupled global climate-biota system taking into account the temporal heterogeneity of the processes involved.  The particular focus was the origin and timing of potential extinction triggers. There is evidence in the fossil record that the global ecosystems’ response to a trigger (e.g., a bolide collision or increases in factors such as atmospheric carbon dioxide) can be diverse, leading to a considerable biodiversity loss (i.e., a mass extinction) in some cases but having a relatively small effect in others. A consistent theory for understanding this variability is lacking. This IRC made progress on bridging this gap by bringing together an interdisciplinary group of researchers who applied modern mathematical methods of modelling and data analysis to better understand the mechanisms of mass extinction events in Earth history.
Specifically, the IRC examined historical paleontological data (i.e., the fossil record), which has been the time series scientists have used to identify mass extinction events in the past.  Historic atmospheric carbon dioxide is estimated geologically from core samples.  A mass extinction event can be thought of as a tipping point in which the normally balanced rate of species extinction and the appearance of new species suddenly goes out of balance, and the extinction rate rises significantly above the background rate. Today, atmospheric carbon dioxide and extinctions are observed in real time, and scientists have concluded that both are increasing faster now than in the past.  Applying concepts and tools from rate induced tipping point theory (R-tipping), the IRC has found that there is a strong case to be made that carbon forcing is causing the increasing rate of extinction, thus pushing extinction into a new dynamical regime with a much stronger response to the rate of carbon increase (i.e., the system now is less robust to further increases in carbon cycle change, as compared to previous mass extinction events – see Figure 1).  This exciting, and troubling, discovery is the first empirical evidence of R-tipping in environmental systems, in particular in Earth history.   

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