New Mis 19 Epica Dome C High Resolution Deuterium Data: Hints For A Problematic Preservation Of Climate Variability At Sub-Millennial Scale In The "Oldest Ice"

Marine Isotope Stage 19 (MIS 19) is the oldest interglacial period archived in the EPICA Dome C ice core (similar to 780 ky BP) and the closest "orbital analogue" to the Holocene - albeit with a different obliquity amplitude and phase with precession. New detailed deuterium measurements have been conducted with a depth resolution of 11 cm (corresponding time resolution of similar to 130 years). They confirm our earlier low resolution profile (55 cm), showing a relatively smooth shape over the MIS 20 to MIS 18 time period with a lack of sub-millennial climate variability, first thought to be due to this low resolution. The MIS 19 high resolution profile actually reveals a strong isotopic diffusion process leading to a diffusion length of at least similar to 40 cm erasing sub-millennial climate variability. We suggest that this diffusion is caused by water-veins associated with large ice crystals at temperatures above -10 degrees C, temperature conditions in which the MIS 19 ice has spent more than 200 Icy. This result has implications for the selection of the future "oldest ice" drilling site. (C) 2010 Elsevier B.V. All rights reserved.