The drivers and magnitude of the Cenozoic change in global mean surface temperature

Montag 01.07.2024, 11:00 → 12:00 Europe/Berlin

8A-002 - Hörsaal Ostufer / Lecture Hall East (GEOMAR - Standort Ostufer / GEOMAR - East Shore)

Speaker: Dr. David Evans, School of Ocean and Earth Science, University of Southampton, Southampton, UK

Hybrid  - Zoom: https://geomar-de.zoom.us/j/84289388604?pwd=dGlpeTBUd1Nxem5Ec3dRYXh4NFpOUT09

Abstract               
Cenozoic climate change was characterised by a long-term cooling trend from the greenhouse warmth of the early Eocene to the late Pleistocene ice ages. In this talk, I will tackle three key questions: 1) How can we accurately and precisely reconstruct the magnitude of this change? 2) How much cooling has occurred and what does it tell us about climate sensitivity? and 3) What drove this change? To do so, I will explore how deep ocean temperature records can be used as a robust proxy for global mean surface temperature, and build on this to derive a new high-resolution record of Cenozoic climate change, using both empirical evidence and climate model output to demonstrate the Earth system processes at play that mean that this appears to be a fruitful approach. Following this, I will show how reconstructions of changes in the major ion composition of seawater point towards these being an important but under-recognised climate driver in and of themselves, to the extent that the observed magnitude of change of the concentration of calcium in seawater may be capable of driving the entirety of the Cenozoic temperature and CO2 decline.