|Abstract or Summary
- The recovery of a 1.5 million yr long ice core from
Antarctica represents a keystone of our understanding of
Quaternary climate, the progression of glaciation over this
time period and the role of greenhouse gas cycles in this progression.
Here we tackle the question of where such ice may
still be found in the Antarctic ice sheet. We can show that
such old ice is most likely to exist in the plateau area of the
East Antarctic ice sheet (EAIS) without stratigraphic disturbance
and should be able to be recovered after careful pre-site
selection studies. Based on a simple ice and heat flow
model and glaciological observations, we conclude that positions
in the vicinity of major domes and saddle position on the East Antarctic Plateau will most likely have such old
ice in store and represent the best study areas for dedicated
reconnaissance studies in the near future. In contrast to previous
ice core drill site selections, however, we strongly suggest
significantly reduced ice thickness to avoid bottom melting.
For example for the geothermal heat flux and accumulation
conditions at Dome C, an ice thickness lower than but
close to about 2500 m would be required to find 1.5 Myr old
ice (i.e., more than 700 m less than at the current EPICA
Dome C drill site). Within this constraint, the resolution of
an Oldest-Ice record and the distance of such old ice to the
bedrock should be maximized to avoid ice flow disturbances, for example, by finding locations with minimum geothermal
heat flux. As the geothermal heat flux is largely unknown for
the EAIS, this parameter has to be carefully determined beforehand.
In addition, detailed bedrock topography and ice
flow history has to be reconstructed for candidates of an
Oldest-Ice ice coring site. Finally, we argue strongly for rapid
access drilling before any full, deep ice coring activity commences
to bring datable samples to the surface and to allow
an age check of the oldest ice.
- Fischer, H., Severinghaus, J., Brook, E., Wolff, E., Albert, M., Alemany, O., Arthern, R., Bentley, C., Blankenship, D., Chappellaz, J., Creyts, T., Dahl-Jensen, D., Dinn, M., Frezzotti, M., Fujita, S., Gallee, H., Hindmarsh, R., Hudspeth, D., Jugie, G., Kawamura, K., Lipenkov, V., Miller, H., Mulvaney, R., Parrenin, F., Pattyn, F., Ritz, C., Schwander, J., Steinhage, D., van Ommen, T., and Wilhelms, F.: Where to find 1.5 million yr old ice for the IPICS "Oldest-Ice" ice core, Climate of the Past, 9, 2489-2505. doi:10.5194/cp-9-2489-2013, 2013.