Data synthesis
We are synthesizing records that span the whole or part of the EPICA EDC2 time frame (the last c. 800 kyr), using the EDC2 deuterium record and the new Lisiecki/Raymo stack of benthic δ18O as templates. These records have timescales that have been obtained objectively, but with assumptions (for example ice core glaciological timescales and orbitally-tuned marine scales) that will be tested using absolute dates that are being measured in some archives, especially U/Th dating. A suite of approaches will be used to tie different datasets to these reference sequences and to each other.
We will synthesise sufficient data to provide time series appropriate for both forcing and testing the model simulations. The datasets are grouped as follows:
- Climate forcing agents
(a) Orbital forcing (available by calculation)
(b) Greenhouse gases CO2 and CH4 (from ice cores)
(c) Solar and volcanic forcing (becoming available for some periods from ice cores during the period of this proposal) - Climate response variables (especially temperature and ice volume) from:
(a) Marine benthic and planktonic δ18O (plus Ca/Mg, alkenones for specific periods)
(b) δD and δ18O in ice (plus accumulation rates) - Other climate related variables:
(a) Pollen records (from terrestrial and paired marine cores)
(b) Sea ice (from marine diatoms and ice core sea salt) - Biogeochemical and ocean circulation variables:
(a) Marine productivity and nutrient utilization (from δ13C and Cd/Ca)
(b) Ocean stratification and ventilation (from Pa/Th)
(c) Carbonate compensation depth (CCD)
(d) Chemical weathering (from Ca accumulation rate in marine sediments)
(e) Southern Ocean iron input from EPICA dust and Fe fluxes.