Reconstructing causal interactions from last ice age paleoclimate records

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 and marine sediment 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.

Supervisors

Main supervisor: Bjarte Hannisdal, GEO-UiB
Co-supervisor: Jo Brendryen, GEO-UiB

Project description

The goal of this project is to quantify the strength, directionality and time scale of causal relationships directly from glacial climate records. Analyses will be done using the JuliaDynamics software ecosystem, featuring tools for inferring networks of causal relationships from time series. The project will analyse NA proxy records of ocean circulation and iceberg influence along with high-resolution records of CO2, CH4, and proxies for temperature and atmospheric dust from the Antarctic WAIS Divide (WD) ice core. By combining the WD data with NA records and 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.

Field-, lab- and analysis work

This project will use published paleoclimate data from ice cores and marine sediments. Causal analyses will be done using open-source high-performance software. The project is expected to also perform CT scanning of NA sediment cores to quantify ice-rafted debris.

Proposed course plan

GEOV222 Paleoclimatology (10 ECTS - fall)
GEOV230 Glacial geology and geomorphology (10 ECTS - fall)
GEOV231 Marine Geological Field-and Laboratory Course (10 ECTS - spring)
GEOV302 Data analysis in Earth Science (10 ECTS - spring)
GEOV342 The Geochemical Toolbox (10 ECTS - spring)
GEOV324 Polar palaeoclimate (5 ECTS - fall)
GEOV331 Paleoceanography (5 ECTS - spring)

Last updated: 23.06.2026