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: The mechanisms leading to the emergence of strong 100,000-year ice age cycles at the end of the Middle Pleistocene Transition (MPT), ~670-800 ka, encompassing Marine Isotope Stage (MIS) 19, 18 and 17, are still not fully understood. This period is associated with anomalously warm North Atlantic sea surface temperatures enhancing moisture production and transport to northern hemisphere ice-sheets. However, the most relevant processes explaining the progressive ice accumulation during the end of MPT remain unclear yet, partly due to the poor knowledge of the Eurasian environments and atmospheric climate. New marine-terrestrial climatic records from the IODP Site U1385 (south-west Iberian margin) and their comparison with loess records from the Chinese Plateau reveal a nearly synchronous, long-term warming and wetting trend in the two subtropical regions from MIS 19 to 17. Mediterranean forest cover and winter precipitation were stronger during the MIS 18 glacial compared to the MIS 19 interglacial and significantly correlated with oceanic moisture production off Iberia, also suggested by iLOVECLIM climate model simulation. Likewise, the strengthening of the East Asian Summer monsoon was associated with the increasing thermal gradient between the tropical and polar West North Pacific Ocean enhancing moisture production off eastern Eurasia from MIS 19 to 17. These findings provide supporting evidence for a nearly-continuous supply of oceanic moisture from the mid-latitude North Atlantic and tropical West North Pacific to higher latitudes through the westerlies, which might have critically contributed to the accelerated expansion of Eurasian and North American ice-sheets at the end of the MPT.