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Logotyp för Naturhistoriska riksmuseet
Logotyp för Naturhistoriska riksmuseet

Ice-rafted granitic dropstone in Miocene marine sediment core, Weddell Sea. Photo credit: IODP/Michelle Penkrot

Tracking past growth and collapse of the Antarctic ice sheet

This project investigates the stability of the Antarctic ice sheet during a warm climatic interval in the mid-Miocene, c. 17 to 15 million years ago. This period offers a useful analogue to Earth’s likely future trajectory under current global warming scenarios. Mid-Miocene warm climate was followed by an abrupt transition to a cooler global climate, which is also investigated.

Forskningsområden: Geovetenskap

Forskningsämnen: Antarktis, Geologiska och förhistoriska händelser, Inlandsisar

Forskningsområden: Geovetenskap

Forskningsämnen: Antarktis, Geologiska och förhistoriska händelser, Inlandsisar

Project overview

Project period: 2019 – 2024

Participating departments from the museum: Department of Geosciences, GEO

To trace the onshore source(s) of ice-rafted debris, a range of detrital provenance techniques are employed, including U-Pb and trace-element analysis of accessory minerals (apatite, rutile, zircon), and in-situ Rb-Sr and Pb-isotope analysis of rock forming phases (biotite, K-feldspar, plagioclase). These are applied to offshore marine sediment cores, mostly collected as part of the International Ocean Discovery Program (and predecessor programs).


The Antarctic ice-sheet (AIS), since the time of its major expansion into a permanent ice sheet during the Late Eocene - Early Oligocene, has experienced a dynamic history of alternating retreat-expansion cycles in response to global climate variation (and on geological timescales, changes in underlying topography). This variability was especially pronounced during the Miocene, as documented globally by a wealth of indirect evidence from geochemical, isotopic, and sedimentological proxies (e.g., δ18O fluctuations), as well as limited direct evidence from drill cores recovered from ice-sheet marginal sediments.

These data have been used to argue for a major retreat in the size of the AIS as a response to the Mid-Miocene Climate Optimum, characterised by a peak in global temperatures and a rise in sea level, followed by a major Antarctic ice-sheet expansion and stabilisation during the Mid-Miocene Climate Transition (MMCT), characterised by rapid cooling of ca. 6-7 °C in the high-latitude Southern Ocean between ca. 14.2 to 13.8 Ma.

Antarctic ice-sheet instability during the MMCT is recorded by ice-rafted debris in numerous horizons of marine sediment cores obtained around the Antarctic margin. This rafted debris reflects iceberg calving during times of ice-sheet instability. The objective of this project is to determine the location of iceberg calving sites, particularly around the Weddell Sea, in order to identify ice-sheet sectors characterised by repeated instability. These data can be used to evaluate reconstructions from the latest generation of paleo-ice sheet models, which in turn can be used to predict future ice-sheet responses to anthropogenic climate change.


  • Science Foundation Ireland (grant number 18/SIRG/5559) (
  • European Consortium for Ocean Research Drilling (

Project manager

Chris Mark

Senior Curator



Resarch Areas: Geosciences

Research Subjects: Historical and Geological Events, Inland Ice , Antarctica

Page manager: Ellen Kooijman