(Table 2) Mg/Ca and Sr/Ca composition of planktonic foraminifera from ODP Hole 143-865B

To understand the climate dynamics of hypothesized past greenhouse intervals, it is essential to constrain tropical sea-surface temperatures (SST), yet existing proxy records give conflicting results. Here we present the first Mg/Ca-based study of pre-Quaternary SST and investigate early Paleogene (late Paleocene through late middle Eocene; 58.6-39.8 Ma) tropical temperatures, using planktonic foraminifera belonging to the genus Morozovella from Ocean Drilling Program Site 865 on Allison Guyot (western central equatorial Pacific Ocean). Calcification temperatures similar to or warmer than modern tropical SST are calculated using a range of assumptions regarding diagenesis, temperature calibration, and seawater Mg/Ca. Long-term warming is observed into the early Eocene (54.8-49.0 Ma), with peak SST between 51 and 48 Ma and rapid cooling of 4°C beginning at 48 Ma. These findings are inconsistent with the d18O-based SST previously estimated for this site.

Chronology for the EDML ice core from Dronning Maud Land, Antarctica, over the last 150 000 years

A chronology called EDML1 has been developed for the EPICA ice core from Dronning Maud Land (EDML). EDML1 is closely interlinked with EDC3, the new chronology for the EPICA ice core from Dome-C (EDC) through a stratigraphic match between EDML and EDC that consists of 322 volcanic match points over the last 128 ka. The EDC3 chronology comprises a glaciological model at EDC, which is constrained and later selectively tuned using primary dating information from EDC as well as from EDML, the latter being transferred using the tight stratigraphic link between the two cores. Finally, EDML1 was built by exporting EDC3 to EDML. For ages younger than 41 ka BP the new synchronized time scale EDML1/EDC3 is based on dated volcanic events and on a match to the Greenlandic ice core chronology GICC05 via 10Be and methane. The internal consistency between EDML1 and EDC3 is estimated to be typically ~6 years and always less than 450 years over the last 128 ka (always less than 130 years over the last 60 ka), which reflects an unprecedented synchrony of time scales. EDML1 ends at 150 ka BP (2417 m depth) because the match between EDML and EDC becomes ambiguous further down. This hints at a complex ice flow history for the deepest 350 m of the EDML ice core.