Estimating sea ice extent from continental ice cores

Scientist with ice core
Processing an ice core in the field (Photo: Tas van Ommen)

A shallow ice core was collected inland of Davis at Wilhelm II Land. The ice core spans a 15 year period, from 1984 to 1999.

The core was analysed for a chemical marker, MSA, which is produced by biological activity within the sea ice. It was found that the concentration of MSA in this ice core allows us to estimate the amount (or extent) of the sea ice, and therefore changes in sea ice extent through time.

Ice core records can extend many thousands of years, however, the results we have found from this very recent time period has provided good reason to return to Wilhelm II Land to retrieve a deeper ice core to further this research:

  • The concentration of the biological marker, MSA, shows a relationship to the sea ice extent in the surrounding ocean sector (60–120°E) for the time period 1984 to 1999.
  • It confirms a recently developed technique for estimating sea ice extent using an ice core drilled at Law Dome, near Casey.
  • It gives us reason to return to get a deeper core to confirm the sea ice decline [presented in Curran and others, 2003]. To investigate this recent decline (over the last 50 years or so), we require an 80–100m core (approximately 8–9 days of drilling).
  • This is an important contribution to international research and an index of sea ice will be built from a network of cores around Antarctica.
    • This research will be planned at an International Trans-Antarctic Scientific Expedition (ITASE) workshop in 2008 (possibly associated with the next SCAR Open Science Conference or other similar forum).