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The δ13C composition of Cibicidoides wuellerstorfi and other Cibicidoides spp is an important tool to reconstruct past changes in the deep ocean carbon cycle. The species are expected to match the δ13C of ambient dissolved inorganic carbon (DIC), although it has been recognized that substantial offsets can occur. Here, I present a compilation of modern δ13C and δ18O data for named Cibicidoides species in combination with fully resolved carbonate chemistry at each core location. The data show for C. wuellerstorfi that the offset from the expected value in both carbon (∆13C) and oxygen (∆18O) is correlated with seawater carbonate chemistry. The result is comparable to, but not identical with, published culture experiments in which marine organisms were grown under variable pH‐conditions. Overall, ∆13C in C. wuellerstorfi correlates positively with carbonate saturation, [DIC], and temperature. The three variables together explain 47.1% of the variation in ∆13C. The trend for ∆18O is similar, except that the effect of temperature has been removed through correction with a published δ18O‐temperature equation. Up to 35% of the remaining variation in ∆18O can be explained by ambient carbonate chemistry. Data for other named Cibicidoides species are broadly similar, but are too sparse for a detailed analysis. The results indicate that strongly negative ∆13C occurs predominantly in the deep Atlantic in response to a combination of low [DIC], low temperature, and undersaturation within the lysocline. Implications for paleoceanographic reconstructions are discussed. Key Points: The offset between the measured and expected δ13C and δ18O of Cibicidoides wuellerstorfi correlates with seawater carbonate chemistryNegative ∆13C occurs mainly in the deep Atlantic due to a combination of low temperature, under‐saturation, and low to intermediate dissolved inorganic carbon [ABSTRACT FROM AUTHOR]

Archaeology has yet to capitalise on the opportunities offered by bioarchaeological approaches to examine the impact of the 11th-century AD Norman Conquest of England. This study utilises an integrated multiproxy analytical approach to identify and explain changes and continuities in diet and foodways between the 10th and 13th centuries in the city of Oxford, UK. The integration of organic residue analysis of ceramics, carbon (δ13C) and nitrogen (δ15N) isotope analysis of human and animal bones, incremental analysis of δ13C and δ15N from human tooth dentine and palaeopathological analysis of human skeletal remains has revealed a broad pattern of increasing intensification and marketisation across various areas of economic practice, with a much lesser and more short-term impact of the Conquest on everyday lifestyles than is suggested by documentary sources. Nonetheless, isotope data indicate short-term periods of instability, particularly food insecurity, did impact individuals. Evidence of preferences for certain foodstuffs and cooking techniques documented among the elite classes were also observed among lower-status townspeople, suggesting that Anglo-Norman fashions could be adopted across the social spectrum. This study demonstrates the potential for future archaeological research to generate more nuanced understanding of the cultural impact of the Norman Conquest of England, while showcasing a method which can be used to elucidate the undocumented, everyday implications of other large-scale political events on non-elites. [ABSTRACT FROM AUTHOR]

The Antarctic Circumpolar Current (ACC) dominates the transfer of heat, salt, and tracers around the Southern Ocean (SO), driving the upwelling of carbon-rich deep waters around Antarctica. Paleoclimate reconstructions reveal marked variability in SO circulation; however, few records exist coupling quantitative reconstructions of ACC flow with tracers of SO upwelling spanning multiple Pleistocene glacial cycles. Here, we reconstruct near-bottom flow speed variability in the SO south of Africa, revealing systematic glacial-interglacial variations in the strength and/or proximity of ACC jets. These are superimposed by warmer-than-present "super-interglacials," whereby extreme slowdown in the midlatitude ACC (41°S) is opposed by faster flow at higher latitudes (>54°S), implying poleward strengthening of the ACC. Coupled with reconstructions of the subsurface-deep stable carbon isotope gradient, we show that the reorganization of ACC coincides with the upwelling of isotopically light deep waters around Antarctica, likely contributing to the interglacial rise in atmospheric carbon dioxide (CO2) levels. [ABSTRACT FROM AUTHOR]