DOCTORAL CANDIDATE
Franka Neumann

SUPERVISORS
Dr Emilie Capron, Université Grenoble Alpes (UGA)
Dr. Frédéric Parrenin, Université Grenoble Alpes (UGA)
Dr. Taryn Noble, University of Tasmania (UTAS)
Dr Joel Pedro, University of Tasmania (UTAS)
Dr. Andy Menking, University of Tasmania (UTAS)

Paleoclimatology, Glaciology

Past warm periods (referred to as interglacials) are relevant in the context of the current and future global climate change since they represent a natural laboratory to study processes within the Earth system and to understand the impact of a warm climate on its vulnerable components. In particular, the interglacial referred to as Marine Isotopic Stage 11 (MIS 11) that occurred about 410 thousand years ago is one of the most prominent past interglacials during which global sea level was 9-13 m higher than today. Thus, MIS 11 is a unique period of climate to investigate the impact of climate warming on the polar ice sheets and ocean circulation. Numerous paleoclimatic records from different natural archives (e.g. polar ice cores, marine sediments and cave speleothems) cover this period. Each archive has its own specific characteristics, providing a different view of past climates and information on different components of the Earth system (e.g. cryosphere, ocean, vegetation). To interpret these climate records and identify the sequence of changes in different parts of the world, precise dating of the natural archives is essential. However, it is challenging to achieve that far back in time and it results that most climatic records are attached to large dating uncertainties of several millennia. The current lack of global-scale data compilation relying on a robust temporal framework across MIS 11 prevents a refined characterisation on the sequence of climate changes in different parts of the world. It also hinders the identification of the climate mechanisms and feedbacks during this period.

In this context, the present PhD project aims at constructing a global-scale compilation of climatic data (e.g. sea and air surface temperatures, oceanic circulation intensity, sea level, hydrological cycle) from different types of natural archives covering MIS 11 to provide the spatio-temporal picture of climate variations across this past warm time interval and to progress on our understanding of the forcing processes.

In order to achieve this, an important task will be to produce a common and robust chronology between the selected paleoclimatic records. For that purpose, a probabilistic dating model will be used. This tool enables to date jointly numerous climate records from different archives, accounting for various types of chronological constraints and providing also quantitative estimates of the uncertainties attached to the produced age scales. This dating effort will be essential to characterize eventually the amplitude of the climate warming during Marine Isotopic Stage 11, its spatial and temporal evolution, and more broadly, the sequences of events between climate, ocean circulation and polar ice sheets.

Also, the new results will be used to evaluate Earth System Model simulations run across MIS 11 in order to identify with those physics-based tools the climate forcing and feedbacks at play during this interglacial. Overall, these results will provide (i) a better understanding of the impacts of a warm climate on the vulnerable components of the Earth system and (ii) testbeds for evaluating how well Earth System Models simulate warm climates, contributing to improving future climate projections.