The southern Red Sea is a key region for investigating the effect of climate forces on a semi-closed basin. Detailed micropaleontological (planktic foraminifera) and isotopic (δ18Ο, δ13C) analyses along with reconstructions of sea surface temperature and salinity on a sediment core from the Farasan banks revealed the imprints of sea level changes and the South Asian Monsoon on the area. Comparison with surrounding records provided insights on the Red Sea-Gulf of Aden (GoA)-Northwestern Arabian Sea (NWArS) water exchange pattern over the last 30 ka. During glacial sea-level lowstand, flow of water from the GoA prevented hypersalinity in the southern Red Sea. Deglacial sea level rise improved water mass exchange between the NWArS, GoA and the entire Red Sea, resulting in relatively similar surface water conditions during the early Holocene when sea-level rise slowed. Thus, sea level change is the major driver of Red Sea δ18O variability. Southwest Monsoon (SWM), which was dominant during the late glacial and Early–Middle Holocene, enhanced surface productivity in the southern Red Sea. Northeast Monsoon (NEM) dominated around Heinrich stadial 1, as indicated by a nearly aplanktonic zone that was probably caused by restricted GoA inflow and low productivity.

Northern and southern hemispheric influences—particularly changes in Southern Hemisphere westerly winds (SSW) and Southern Ocean ventilation—triggered the stepwise atmospheric CO2 increase that accompanied the last deglaciation. One approach for gaining potential insights into past changes in SWW/CO2 upwelling is to reconstruct the positions of the northern oceanic fronts associated with the Antarctic Circumpolar Current. Using two deep-sea cores located ~600 km apart off the southern coast of Australia, we detail oceanic changes from ~23 to 6 ka using foraminifer faunal and biomarker alkenone records. Our results indicate a tight coupling between hydrographic and related frontal displacements offshore South Australia (and by analogy, possibly the entire Southern Ocean) and Northern Hemisphere (NH) climate that may help confirm previous hypotheses that the westerlies play a critical role in modulating CO2 uptake and release from the Southern Ocean on millennial and potentially even centennial timescales. The intensity and extent of the northward displacements of the Subtropical Front following well-known NH cold events seem to decrease with progressing NH ice sheet deglaciation and parallel a weakening NH temperature response and amplitude of Intertropical Convergence Zone shifts. In addition, an exceptional poleward shift of Southern Hemisphere fronts occurs during the NH Heinrich Stadial 1. This event was likely facilitated by the NH ice maximum and acted as a coup-de-grâce for glacial ocean stratification and its high CO2 capacitance. Thus, through its influence on the global atmosphere and on ocean mixing, “excessive” NH glaciation could have triggered its own demise by facilitating the destratification of the glacial ocean CO2 state.

Upper water column dynamics in the eastern Arabian Sea were reconstructed in order to investigate changes in the activity of the South Asian / Indian monsoon during the early Pleistocene (c. 1.5–2.7 Ma). We used planktic foraminiferal assemblage records combined with isotopic (δ18O and δ13C) data, Mg/Ca-based sea surface temperatures and seawater δ18O records to estimate changes in surface water conditions at International Ocean Discovery Program (IODP) Site U1457. Our records indicate two distinct regimes of monsoon-induced changes in upper water structure during the periods c. 1.55–1.65 Ma and c. 1.85–2.7 Ma. We infer that a more stratified upper water column and oligotrophic mixed layer conditions prevailed during the period 1.85–2.7 Ma, which may be due to overall weaker South Asian / Indian winter (NE) and summer (SW) monsoon circulations. The period 1.55–1.65 Ma was characterized by enhanced eutrophication of the mixed layer, which was probably triggered by intensified winter (NE) monsoonal winds. The long-term trend in hydrographic changes during 1.55–1.65 Ma appears to be superimposed by short-term variations, probably reflecting glacial/interglacial changes. We suggest that an intensification of the South Asian / Indian winter monsoon circulation occurred between ∼1.65 Ma and 1.85 Ma, which is most likely due to the development of strong meridional and zonal atmospheric circulations (i.e. Walker Circulation and Hadley Circulation) because of strong equatorial East–West Pacific temperature gradients.

Planktic foraminiferal census data, faunal sea surface temperatures (SSTs) and oxygen isotopic and lithic records from a site in the northeast Atlantic were analyzed to study the interglacial dynamics of Marine Isotope Stage (MIS) 11, a period thought to closely resemble the Holocene on the basis of orbital forcing. Interglacial conditions during MIS 11 persisted for approximately 26 ka. After the main deglacial meltwater processes ceased, a 10- to 12-ka-long transitional period marked by significant water mass circulation changes occurred before surface waters finally reached their thermal maximum. This SST peak occurred between 400 and 397 ka, inferred from the abundance of the most thermophilic foraminiferal species and was coincident with lowest sea level according to benthic isotope values. The ensuing stepwise SST decrease characterizes the overall climate deterioration preceding the increase in global ice volume by ∼ 3 ka. This cooling trend was followed by a more pronounced cold event that began at 388 ka, and that terminated in the recurrence of icebergs at the site around 382 ka. Because the water mass configuration of early MIS 11 evolved quite differently from that of the early Holocene, there is little evidence that MIS 11 can serve as an appropriate analogue for a future Holocene climate, despite the similarity in some orbital parameters.

A deep-sea sediment core covering the last 20 ka and located between the Polar and the Arctic fronts in the marginal ice zone (MIZ) of the central Fram Strait has been investigated for changes in paleoceanography and calcium carbonate preservation. The reconstruction is based on the distribution patterns of planktic foraminifera, mean shell weight and the degree of fragmentation of their shells, stable isotopes and other geochemical and sedimentological data. The results show that the planktic foraminifera shells are poorly preserved throughout most of the record. Only the intervals comprising the early Holocene from 10.8 to ~ 8 cal ka BP and the last 800 yr show improved preservation of CaCO3. The dissolution correlated with the extent of Arctic water and the associated marginal ice zone (MIZ) and high organic productivity. Dissolution of planktic foraminifera is generally high during the late deglaciation, mid and late Holocene prior to ~ 800 cal yr BP. The abundance of small subpolar species increases in the surface sediments dating from the last century, which could be interpreted as a large and significant surface water warming. However, this apparent high-magnitude warming seems to be overestimated due to preservation changes in the youngest sediments.