Understanding the change in the periodicity of glacial to interglacial cycles during the Mid-Pleistocene Transition
The new Beyond Epica deep ice core will enable the paleoclimate community to address major scientific questions on the role of ice sheet size and greenhouse gas concentrations on the dynamics of past climate changes. In particular, a key challenge is to understand why the periodicity of glacial to interglacial cycles changed from 41 to 100 thousand of years during the so-called Mid-Pleistocene Transition, between 0.8 and 1.2 Ma, while at the same time the orbital forcing given by astronomical parameters keeps the same periodicity.
Key paleoclimatic records over the past 1.5 Myr. (a) Antarctic climate (Jouzel et al. Science 2007) and (b) atmospheric CO2 concentrations Bereiter et al. GRL 2015) infered from Antarctic deep ice cores; (c) Marine benthic foraminifera δ18O indicative of ice sheet volume changes (Lisiecki and Raymo, Paleoceanography 2005); (d) 65°N summer insolation.
Analysis of deep ice core: scientific and technical challenges
In addition to the logistical challenges associated with the drilling of a ~3km-long ice core in extreme climatic conditions, large technological and scientific challenges need to be tackled in order to exploit this unique archive in the field and back in the laboratory.
As the new climatic records between 0.8 and 1.5 Ma will be located at the bottom of the ice core and hence, the ice will be extremely thinned (1 m of ice covering 10 000 years). Thus, an optimal analysis of this precious ice for getting the best scientific outputs require to develop new techniques to analyse precisely very small quantity of ice.
Besides, it will be important to quantify the potential effects that may affect the quality of climate records contained in the deepest ice for the interpretation of the data.
Moreover, the results related to atmospheric greenhouse gas concentration changes and climate change will have to be confronted to climate model simulations in order to progress on the physical processes.
The specific main scientific objectives of DEEPICE are to:
- Develop novel techniques required for the analyses of precious samples of the 1.5 Ma Beyond Epica deep ice core to obtain the highest possible resolution records of climate and environment ever possible;
- Document surface climate parameters in the remote East Antarctic plateau, where weather data are very rare and instrumentation deployment is difficult;
- Quantify potential effects that may affect the quality of climate records in the deepest ice;
- Document past ice sheet dynamics and flow in East Antarctica in relationship to climate change;
- Study and document the past climate dynamics in Antarctica on short and long timescales with the ultimate aim to improve predictions on the future climate and the state of the Antarctic ice-sheet;
- Communicate state-of-the-art research on climate change with a focus on the role of Antarctica in the climate system.