Beschreibung: Deep ocean circulation has been considered relatively stable during interglacial periods, yet little is known about its behavior on submillennial time scales. Using a subcentennially resolved epibenthic foraminiferal d13C record we show that North Atlantic Deep Water (NADW) influence was strong at the onset of the last interglacial period and then interrupted by several prominent, centennial-scale reductions. These NADW transients occurred during periods of increased ice rafting and southward expansions of polar water influence, suggesting that a buoyancy threshold for convective instability was triggered by freshwater and circum-Arctic cryosphere changes. The deep Atlantic chemical changes were similar in magnitude to those associated with glaciations, implying that the canonical view of a relatively stable interglacial circulation may not hold for conditions warmer/fresher than at present.

Beschreibung: The mid-Pliocene (3.3-3.0 million years ago) is an important possible analogue to future, warmer-than-present climates. This interval is the most recent period in Earth's history of sustained global warmth, when atmospheric CO2 concentrations were comparable to the early 21th century, global ice volume was reduced and sea-levels were significantly higher than at present. Relatively few deep ocean temperature records exist from this time interval, but some available data suggest that large differences in temperatures existed between different deep ocean basins. This is in contrast to the modern ocean, which is relatively isothermal across the various basins at similar depth. In order to verify the possibility of a large temperature gradient between the deep Pacific and deep North Atlantic oceans, we generated new benthic foraminiferal carbonate clumped isotope (Δ47) and Mg/Ca bottom water temperatures from Pacific ODP Site 849 and North Atlantic IODP Site U1308. We find that the deep North Atlantic was significantly warmer (by 4°C) and likely more saline than the deep Pacific throughout our study interval, suggesting inefficient heat and salt transport from the Atlantic into the deep Pacific at this time. Our records also cover the enigmatic Marine Isotope Stage (MIS) M2 glacial event at 3.3 Ma, which represents the largest positive oxygen isotope excursion of the Pliocene prior to the intensification of Northern Hemisphere glaation.This event has been cited as a possible failed attempt at establishing Northern Hemisphere glacial-interglacial cycles. The amplitute of cooling observed in our temperature records suggest that much of the observed change in benthic δ18O can be attributed to cooling of the deep ocean rather than a substantial growth of ice on land. This data set contains final calculated bottom water temperatures from Δ47 from both study sites; Mg/Ca, Mn/Ca and Fe/Ca ratios and calculated Mg/Ca bottom water temperatures from both study sites and new stable isotope data from Site U1308.

Beschreibung: This dataset contains temperatures calculated from carbonate clumped isotope measurements performed on mid-Pliocene benthic foraminifera from Ocean Discovery Program (ODP) Site 849 in the Equatorial East Pacific (0°11'N, 110°31'W).

Beschreibung: This dataset contains the results of trace element analysis (Mg/Ca, Fe/Ca and Mn/Ca ratios in mmol/mol) of the benthic foraminifer Oridorsalis umbonatus from Ocean Discovery Program (ODP) Site 849 in the Equatorial East Pacific (0°11'N, 110°31'W). Trace element ratios were analyzed using a Agilent Inductively Coupled Plasma-Optical Emission Spectrometer (ICP-OES) 720. Mg/Ca data was normalised to the ECRM752-1 standard. Temperatures calculated using the O. umbonatus-specific calibration by Lear et al. (2002). For temperature calculation, raw Mg/Ca ratios were adjusted to account for past variation in seawater Mg/Ca using estimates of seawater Mg/Ca from Evans et al. (2016).

Beschreibung: This dataset contains temperatures calculated from carbonate clumped isotope measurements performed on mid-Pliocene benthic foraminifera from Integrated Ocean Drilling Program (IODP) Site 303-U1308 in the North Atlantic (49°52'N, 24°14'W, water depth: 3871 m).

Beschreibung: This dataset contains the results of trace element analysis (Mg/Ca, Fe/Ca and Mn/Ca ratios in mmol/mol) of the benthic foraminifer Oridorsalis umbonatus from Integrated Ocean Drilling Program (IODP) Site U1308 in the North Atlantic (49°52'N, 24°14'W, water depth: 3871m).Trace element ratios were analyzed using a Agilent Inductively Coupled Plasma-Optical Emission Spectrometer (ICP-OES) 720. Mg/Ca data was normalised to the ECRM752-1 standard. The dataset also contains stable isotope measurements (δ18O and δ13C) from the benthic foraminifers Cibicidoides mundulus and Cibicidoides wuellerstorfi. Stable isotope measurements were performed using a Finnigan MAT 253 mass spectrometer coupled to a Kiel IV carbonate device. Values are reported in (‰ PDB). Temperatures calculated using the O. umbonatus-specific calibration by Lear et al. (2002). For temperature calculation, raw Mg/Ca ratios were adjusted to account for past variation in seawater Mg/Ca using estimates of seawater Mg/Ca from Evans et al. (2016).