14-4 Mega-climate Regimes and Macroevolutionary Vulnerability

Session: Interdisciplinary Paleontology: New approaches to solving complex paleontological problems (Part II)

Presenting Author:

Corinne Myers

Authors:

Myers, Corinne E¹, Sudakow, Ivan², Spiridonov, Andrej³, Stankevič, Robertas⁴, Feulner, Georg⁵, Livina, Valerie⁶

(1) Earth and Planetary Sciences, University of New Mexico, Albuquerque, New Mexico, USA, (2) Applied Mathematics, School of Mathematics and Statistics; The Open University, Milton Keynes, United Kingdom, (3) Department of Geology and Mineralogy, Vilnius University, Vilnius, Lithuania, (4) Department of Geology and Mineralogy, Vilnius University, Vilnius, Lithuania, (5) Earth System Analysis, Potsdam Institute for Climate Impact Research (PIK), Potsdam, Germany, (6) National Physics Laboratory, Teddington, United Kingdom,

Abstract:

The Phanerozoic has experienced significant changes in both biodiversity and the abiotic environments in which they thrive; however, identifying causal connections between the two continues to be challenging. Using stable isotope and pCO2 proxy records, we characterize five recurring, long-lived mega-climate states separated by comparatively sharp boundaries. We explore the mechanics of these mega-climate states with a climate-carbon cycle dynamical model that includes an excitable carbon cycle, temperature-dependent weathering, and impulsive inputs (e.g., carbon injection from large igneous province emplacement) that are coupled with a simple energy-balance model including ice-albedo feedbacks and logarithmic greenhouse gas forcing. We compare these to a macroevolutionary vulnerability index derived from Phanerozoic records of generic biodiversity to identify the behavior of biospheric stress in the context of mega-climate regimes and their transitions. Results suggest that Phanerozoic biodiversity and its relationship with global climate is hierarchical – whereas we observe an overall positive trend between macroevolutionary vulnerability and global temperature records across the  whole Phanerozoic, within individual mega-climate states the relationship is more variable and subject to noise. Macroevolutionary vulnerability appears higher near mega-climate transitions than within a given regime. Macroevolutionary vulnerability is notably higher during the early Paleozoic hothouse compared to the significantly lower vulnerability observed in the Cenozoic icehouse. In this context, mega-climate states may be interpreted to set a baseline macroevolutionary stress landscape within which short-timescale and event-specific environmental perturbations create variability in the biosphere’s vulnerability to extinction.

Geological Society of America Abstracts with Programs. Vol. 58, No. 4, 2026

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