Cenozoic proxy constraints on Earth system sensitivity to greenhouse gases

Ring, S. J., Mutz, S. G. and Ehlers, T. A. (2022) Cenozoic proxy constraints on Earth system sensitivity to greenhouse gases. Paleoceanography and Paleoclimatology, 37(12), e2021PA004. (doi: 10.1029/2021PA004364)

Abstract

The long-term extent of the Earth system response to anthropogenic interference remains uncertain. However, the geologic record offers insights into this problem as Earth has previously cycled between warm and cold intervals during the Phanerozoic. We present an updated compilation of surface temperature proxies for several key time intervals to reconstruct global temperature changes during the Cenozoic. Our data synthesis indicates that Earth’s surface slowly cooled by ca. 9°C during the early Paleogene to late Neogene and that continent-scale ice sheets developed after global temperature dropped to less than 10°C above preindustrial conditions. Slow cooling contrasts with the steep decrease in combined radiative forcing from past CO2 concentrations, solar luminosity, and ocean area, which was close to preindustrial levels even as Earth remained in a much warmer state. From this, we infer that the Earth system was less sensitive to greenhouse gas forcing for most of the Cenozoic and that sensitivity must have increased by at least a factor of 2 during the Plio-Pleistocene. Our results imply that slow feedbacks will raise global surface temperatures by more than 3°C in the coming millennia, even if anthropogenic forcing is stabilized at the present-day value (2 W/m2), and that their impact will diminish with further warming.

• Item Type: Articles
• Additional Information: This study was partially supported by the German Science Foundation priority program EarthShape: Earth Surface Shaping by Biota (SPP, 1801) Grants EH329/14-2 and EH329/23-1 to T.A.E and MU4188/3-1 and MU4188/1-1 to S.G.M. We also acknowledge support from the Open Access Publishing Fund of the University of Tübingen. Open Access funding enabled and organized by Projekt DEAL.
• Status: Published
• Refereed: Yes
• Glasgow Author(s) Enlighten ID: Ehlers, Professor Todd A. and Mutz, Dr Rer Nat Sebastian
• Authors: Ring, S. J., Mutz, S. G., and Ehlers, T. A.
• College/School: College of Science and Engineering > School of Geographical and Earth Sciences
• Journal Name: Paleoceanography and Paleoclimatology
• Publisher: American Geophysical Union
• ISSN: 2572-4517
• ISSN (Online): 2572-4525
• Published Online: 01 December 2022
• Copyright Holders: Copyright © 2022 The Authors
• First Published: First published in Paleoceanography and Paleoclimatology 37(12):e2021PA004
• Publisher Policy: Reproduced under a Creative Commons license