The John Joly Memorial Lecture 2025

Isabel Patricia Montañez is the Chancellor’s Leadership Distinguished Professor in the Dept. of Earth and Planetary Sciences, University of California, Davis. Her research focuses on reconstructing the evolution of atmospheric CO2 through time including times of past perturbations to global carbon cycling and investigating the linkages to climate and ecosystems, in particular, during periods of warming and major transitions from glaciated to non-glaciated conditions.

Paleo-CO2 reconstructions are integral to understanding the evolution of Earth system processes and their interactions given that atmospheric CO2 concentrations are intrinsically linked to planetary function. Past periods of major climate change, within both greenhouse and icehouse states, provide unique insights into the response of land-atmosphere-ocean interactions to warming induced climate change, in particular for times of pCO2 comparable to those projected for our future. How well the past can inform the future, however, depends on how well paleo-CO2 estimates can be constrained. In this talk, I will first address present-day CO2 in the context of the geologic past and what it suggests about our future and then discuss approaches to and challenges of reconstructing paleo-CO2 concentrations. I will then introduce a path forward to advance the science of paleo-CO2 reconstruction and to build a next-generation CO2 record for the past 400 million years. This will include approaches to modernizing published paleo-CO2 records so that they meet modern proxy theory and the modeling tools that are being developed to provide quantitative, data-driven CO2 reconstructions. To illustrate the potential of high temporal-resolution and modernized paleo-CO2 records to advance our understanding of how Earth surface processes and ecosystems responded to changing atmospheric CO2 concentrations in the past, I will share our work reconstructing CO2-climate-ecosystem interactions and feedbacks in the marine and terrestrial realms during a time (Late Paleozoic Ice Age) when CO2 fluctuated within the range of levels during the last ice age to those projected by socio-economic emission scenarios for this century, including CO2-driven abrupt warmings that led to major changes in environmental conditions.

Lecture will be followed by wine and cheese reception from 6pm - 8pm in the Main Foyer, Museum Building, on Trinity's Main Campus

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Host or Publisher Discipline of Geology, Trinity College Dublin, The University of Dublin