ALBERT

Description: Succession of cold glacials and warm interglacials during the Quaternary results from large global climate responses to variable orbital configurations, accompanied by fluctuating greenhouse gas concentrations. Despite the influences of sea ice and atmospheric and ocean circulations in the Southern Ocean on atmospheric CO2 concentrations and climate, past changes in this region remain poorly documented. Here, we present the 800 ka deuterium excess record from the East Antarctica EPICA Dome C ice core, tracking sea surface temperature in evaporative regions of the Indian sector of the Southern Ocean from which moisture precipitated in East Antarctica is derived. We find that low obliquity leads to surface warming in evaporative moisture source regions during each glacial inception, although this relative temperature increase is counterbalanced by global cooling during glacial maxima. Links between the two regions during interglacials depends on the existence of a temperature maximum at the interglacial onset. In its absence, temperature maxima in the evaporative moisture source regions and in East Antarctica were synchronous. For the other interglacials, temperature maxima in the source areas lag early local temperature maxima by several thousand years, probably because of a change in the position of the evaporative source areas.

Description: Succession of cold glacials and warm interglacials during the Quaternary results from large global climate responses to variable orbital configurations, accompanied by fluctuating greenhouse gas concentrations. Despite the influences of sea ice and atmospheric and ocean circulations in the Southern Ocean on atmospheric CO2 concentrations and climate, past changes in this region remain poorly documented. Here, we present the 800 ka deuterium excess record from the East Antarctica EPICA Dome C ice core, tracking sea surface temperature in evaporative regions of the Indian sector of the Southern Ocean from which moisture precipitated in East Antarctica is derived. We find that low obliquity leads to surface warming in evaporative moisture source regions during each glacial inception, although this relative temperature increase is counterbalanced by global cooling during glacial maxima. Links between the two regions during interglacials depends on the existence of a temperature maximum at the interglacial onset. In its absence, temperature maxima in the evaporative moisture source regions and in East Antarctica were synchronous. For the other interglacials, temperature maxima in the source areas lag early local temperature maxima by several thousand years, probably because of a change in the position of the evaporative source areas.

Description: Processes controlling pore closure are broadly understood yet defining the physical mechanisms driving elemental fractionation remains ambiguous. It has indeed been shown that the pore closure processes lead to a decrease of concentration of small size molecules (e.g. O2, Ar, Ne) in the bubbles. Moreover, ice core δO2/N2 records shows a clear link with local summer solstice insolation and hence makes it a powerful dating tool. However, investigations towards a mechanistic understanding of δO2/N2 and summer solstice insolation suggests local climatic conditions may also be important. We compiled δO2/N2records from several polar ice cores and found a link between δO2/N2 and temperature and/or accumulation rate, in addition to the influence of the summer solstice insolation intensity. Using the Crocus snowpack model, we carry out sensitivity tests to identify the response of near-surface snow properties to changes in insolation, accumulation rate and air temperature.

Description: The drill of the EPICA Dome C ice core has been completed almost 20 years ago. This ice core already provided many reference records for climate and atmospheric greenhouse gase concentrations over the last 800,000 years, hence covering 9 glacial interglacial transitions or glacial terminations. These records combined to records from other archives have already shown the diversity in term of amplitudes and durations of the last 9 glacial terminations occurring in different orbital contexts. Still, the relatively low resolution of the current records hampered a good chronology of the oldest deglaciations as well as the study of the rapid climatic variability at centennial to multi-millennial scale superimposed to the longer term orbital climatic variability. Here, we will present high resolution measurements of water and air isotopes on the EPICA Dome C ice core over the last 800,000 years with a particular focus on glacial terminations. These new data enable to improve the chronology of the EPICA Dome C ice core hence improving the link between orbital forcing and climatic variability, especially for the period between 800,000 years and 200,000 years before present. In addition, our relatively high resolution records (50-300 years) of water and air isotopes enable us to describe on the same chronology the occurrence of millennial scale variability in the low to mid latitudes over the terminations 2, 3, 4 and 5 (occurring between 440,000 and 120,000 years before present) while local climate at the drilling site of EPICA Dome C has a much smoother evolution.