Quantifying Last Glacial Earth System Interactions

Project description
There is currently no consensus on the causal linkages between the climate system processes that together shaped Earth's ice age climate. Processes in the North Atlantic (NA) region, including meltwater release or sea-ice dynamics, are considered a key influence on the iconic Dansgaard-Oeschger (D-O) oscillations evident in a wide range of paleoclimate reconstructions. Another prominent feature of the glacial climate system is the 'bipolar see-saw', the idea that reduced heat transport to the NA during D-O cold events caused warming in the Southern Hemisphere (SH). Although the Northern Hemisphere (NH) is thought to have driven the SH in this case, a prominent influence in the opposite direction has also been suggested. The carbon cycle plays a key role in the climate system by shifting carbon between atmospheric, oceanic, and terrestrial reservoirs. Ice core records show considerable millennial and centennial scale variability in atmospheric CO2 and CH4 concentrations that can be linked to the D-O fluctuations and associated climate system changes. The goal of this project is to quantify the strength and directionality of causal relationships directly from glacial climate records. To avoid the problem of relative age uncertainty in paleoclimate reconstructions, this project will target high-resolution records of CO2, CH4, and proxies for temperature and atmospheric dust from the Antarctic WAIS Divide (WD) ice core. Causal analyses will be done using CausalityTools.jl and its associated software ecosystem, featuring tools for dynamical systems reconstruction, entropy-based causal estimators, and surrogate techniques for hypothesis testing. By combining the WD data with Greenland ice core records of temperature, this project can test specific hypotheses on the relative influence of SH and NH processes on glacial CO2 variations. If the WD results are encouraging and time permits, the analyses can optionally be expanded to include NA proxy records of ocean circulation and iceberg influence, to test a wider set of proposed hypotheses on the role of NH processes in the glacial climate system.

Proposed course plan during the master's degree (60 ECTS):
Autumn: 
GEOV222/10
SDG207/10
GEOV230/10
GEOV205/10

Spring: 
GEOV302/10
GEOV331/5
GEOV328/5

External data
Published paleoclimate data from ice cores and marine sediments

Field, lab and analysis
Causal analyses will be done using CausalityTools.jl and its associated software ecosystem, featuring tools for dynamical systems reconstruction, entropy-based causal estimators, and surrogate techniques for hypothesis testing.