Kvartære geosystemer

Clumped isotope thermometry and reconstruction of climate change in the middle Miocene

PhD candidate: Thomas Leutert

PhD candidate: Thomas Leutert

Supervision: Nele Meckler (UiB), Alison Piasecki (UiB), Aradhna Tripati (UCLA)

Project funding: European Research Council

Project period: August 2015 - July 2019

Reliable projections of future climate require a thorough understanding of feedbacks, thresholds and tipping points that determine the sensitivity of the climate system to CO2 forcing. My PhD project focuses on the middle Miocene, which provides a useful test case for studying forcing factors in a warm climate and their responses to rapidly changing boundary conditions. Miocene ocean temperature changes will be reconstructed from foraminifera shells using the carbonate clumped isotope thermometer. This novel temperature proxy is analytically challenging, but circumvents major problems of previous temperature proxies.

In a first study, diagenetic effects on clumped isotope temperatures will be assessed. In combination with further methodological work performed within the clumped isotope group, this will prepare the ground for the application of clumped isotope thermometry to the Mid-Miocene Climate Transition (∼14 Ma), which abruptly terminated the final major warm period in the Earth’s Cenozoic climate evolution. Sea-surface temperatures will be estimated from planktonic foraminifera at different latitudes, whereas changes in ice volume and deep-sea temperature will be derived based on benthic foraminifera from a site in the Indian Ocean. The new paleotemperature dataset will help study fundamental relations between atmospheric CO2, ocean circulation and ice sheet volume, and provide important calibration points to test and improve climate models.

This PhD project is part of the C4T project, which is funded by an ERC Starting Grant and aims at reconstructing Cenozoic ocean temperatures by means of clumped isotope thermometry.