Kvartærgeologi & Paleoklima

Plio-Pleistocene deep sea temperature evolution

Anna Hauge Braaten


The last ~5.3 million years (Ma) represents a key interval in the climatic history of our planet. Over this time, Earth transitioned from a globally warm Pliocene (5.3-2.6 Ma) to a cooler Pleistocene (2.6-0.011 Ma) characterized by intensive Northern Hemisphere glacial-interglacial cycles. In the Pliocene, atmospheric CO2 concentrations were comparable to today (~400 ppm), but a very different climate state persisted. Areas of the Arctic were up to 10-19 °C warmer than at present, ice-sheet extent was significantly reduced and sea-level stood ~20 meters higher than today.

Our understanding of how the climate system has operated under periods of elevated CO2 concentrations in the past is vital for our ability to accurately predict future climate change. Despite decades of research, a full understanding of the processes that caused, maintained, and ultimately terminated the warm conditions of the Pliocene is still missing.

This PhD project aims to reconstruct ocean temperatures for key intervals over the past ~5 Ma, with a particular focus on the mid-Pliocene and Plio-Pleistocene transition. Using carbonate clumped isotope thermometry, which produces temperatures that are independent of seawater composition and is also likely free of species-specific effects, we can bypass many of the uncertainties related to existing records. Results will further our understanding of Plio-Pleistocene deep sea temperature evolution, climate sensitivity and ocean circulation patterns.