ALBERT

Description: Earth's climate cooled markedly during the Late Miocene from 12 to 5 million years ago, with far-reaching consequences for global ecosystems. However, the driving forces of these changes remain controversial. A major obstacle to progress is the uncertainty over the role played by greenhouse gas radiative forcing. Here we present boron isotope compositions for planktonic foraminifera, which record carbon dioxide change for the interval of most rapid cooling, the Late Miocene Cooling event between 7 and 5 Ma. Our record suggests that CO₂ declined by some 100 ppm over this two-million year-long interval to a minimum at approximately 5.9 Ma. Having accounted non-CO₂ greenhouse gasses and slow climate feedbacks, we estimate global mean surface temperature change for a doubling of CO₂ - Equilibrium Climate Sensitivity - to be 3.9˚C (1.8–6.7 ˚C at 95% confidence) based on comparison of our record of radiative forcing from CO₂ with a record of global mean surface temperature change. We conclude that changes in CO₂ and climate were closely coupled during the latest Miocene and that Equilibrium Climate Sensitivity was within range of estimates for the late Pleistocene, other intervals of the Cenozoic, and the 21st century as presented by the Intergovernmental Panel on Climate Change.

Description: We present a sedimentary record from a marine core, KL11, taken from the central Red Sea, spanning the last ca. 210 kyr. The core was recovered at 18°44.5' N and 39°20.6' E from a water depth of 825 m during RV Meteor expedition M5/2 in 1987. We combine high-resolution grain size, clay mineral and geochemical data, together with Nd and Sr isotope data to identify provenance and reconstruct changes in aridity/humidity through time.

Description: 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.

Description: 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).

Description: 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).

Description: 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).

Description: 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).

Description: This dataset contains clumped isotope, and stable carbon and oxygen isotope data from benthic foraminifera from IODP Expedition 320 Sites U1334 and U1333, and ODP Site 1218, in the eastern equatorial Pacific Ocean. The clumped isotope data were used to reconstruct deep ocean temperatures from ~35 Ma to ~33 Ma, across the Eocene-Oligocene Transition. Data in this dataset are provided as averaged stable isotope and temperature data, whereby each individual temperature represents the average of a minimum of 30 measurements of aliquots of monospecific benthic foraminifera sourced from multiple (n = 11-34) closely spaced samples.

Description: This dataset contains clumped isotope, and stable carbon and oxygen isotope data from benthic foraminifera from ODP Site 1218, in the eastern equatorial Pacific Ocean. The clumped isotope data were used to reconstruct deep ocean temperatures from ~35 Ma to ~33 Ma, across the Eocene-Oligocene Transition. Data in this dataset are provided as averaged stable isotope and temperature data, whereby each individual temperature represents the average of a minimum of 30 measurements of aliquots of monospecific benthic foraminifera sourced from multiple (n = 11-34) closely spaced samples.

Description: The major Cenozoic shift from a shallow (~3‒4 km) to deep (~4.5 km) calcite compensation depth (CCD) occurred at the Eocene-Oligocene Transition (EOT; ~34 Ma), suggesting a strong relationship between calcium carbonate (CaCO3) cycling and Antarctic glaciation. To further investigate the linkages between these two events, detailed records of deep-sea carbonate content, and bulk sediment and benthic foraminiferal stable isotope records are needed. This dataset contains bulk sediment stable isotope and carbonate content records from eight sites in the eastern equatorial Pacific (ODP Leg 199 and IODP Expedition 320). These records were used to reconstruct the depth of the calcite compensation depth (CCD) across the Eocene-Oligocene Transition. The projected depth of the CCD is included in this dataset. In addition, this dataset contains a monospecific epifaunal benthic foraminiferal stable isotope stratigraphy from IODP Expedition 320 Site U1334, in the eastern equatorial Pacific, across the Eocene-Oligocene Transition.