Variable sequence of events during the past seven terminations in two deep-sea cores from the Southern Ocean

The relationships among internally consistent records of summer sea-surface temperature (SSST), winter sea ice (WSI), and diatomaceous stable isotopes were studied across seven terminations over the last 660 ka in sedimentary cores from ODP sites 1093 and 1094. The sequence of events at both sites indicates that SSST and WSI changes led the carbon and nitrogen isotopic changes in three Terminations (TI, TII and TVI) and followed them in the other four Terminations (TIII, TIV, TV and TVII). In both TIII and TIV, the leads and lags between the proxies were related to weak glacial mode, while in TV and TVII they were due to the influence of the mid-Pleistocene transition. We show that the sequence of events is not unique and does not follow the same pattern across terminations, implying that the processes that initiated climate change in the Southern Ocean has varied through time

Sea ice working group (SIP)

The sea ice is a crucial component of the polar climate system, and has an impact on albedo, heat and gas ex- change, primary productivity and car- bon export, atmospheric and ocean circulation, freshwater budget, ocean stratification, and deep water mass for- mation. It is therefore critical that it is correctly specified as a forcing or pre- dicted as a feedback in modeling stud- ies

Late Quaternary Distribution of the Cycladophora davisiana Radiolarian Species: Reflection of Possible Ventilation of the North Pacific Intermediate Water during the Last Glacial Maximum

A comparison of micropaleontological data on the distribution of the Cycladophora davisiana radiolarian species in the surface sediment layer and the Late Quaternary sediments from the Subarctic Pacific and Far East marginal seas allowed conclusions concerning the possible conditions and occurrence of intermediate waters during the last glacial maximum. We used the modern data on the C. davisiana species, which is a micropaleontological indicator of the cold oxygen-rich upper intermediate water mass, which is now forming only in the Sea of Okhotsk. The high amount of C. davisiana in sediments of the last glacial maximum may point to the possible formation and expansion of the ventilated intermediate water in the most part of the Subarctic paleo-Pacific: the Bering Sea, the Sea of Okhotsk, within the NW Gyre, and in the Gulf of Alaska

Overview of Glacial Atlantic Ocean Mapping (GLAMAP 2000)

GLAMAP 2000 presents new reconstructions of the Atlantic's sea surface temperatures (SST) at the Last Glacial Maximum (LGM), defined at both 21,500–18,000 years B.P. (“Last Isotope Maximum”) and 23,000–19,000 years B.P. (maximum glacial sea level low stand and orbital minimum of solar insolation; EPILOG working group; see Mix et al. [2001]). These reconstructions use 275 sediment cores between the North Pole and 60°S with carefully defined chronostratigraphies. Four categories of core quality are distinguished. More than 100 core sections provide a glacial record with subcentennial- to multicentennial-scale resolution. SST estimates are based on a new set of almost 1000 reference samples of modern planktic foraminifera and on improved transfer-function techniques to deduce SST from census counts of microfossils, including radiolarians and diatoms. New proxies also serve to deduce sea ice boundaries. The GLAMAP 2000 SST patterns differ significantly in crucial regions from the CLIMAP [1981] reconstruction and thus are important in providing updated boundary conditions to initiate and validate computational models for climate prediction

Spatial distribution of the coccolithophore Emiliania huxleyi in the Pacific Ocean sector of the Antarctic Ocean: new data for paleoembiromental reconstruction and characterization of biostratigraphic events

A specific biometric study of coccoliths of Emiliania huxleyi has been accomplished on 25 surface water samples from the eastern Pacific sector of the Southern Ocean. In all samples, E. huxleyi is the most abundant taxon, accounting always more than 85% of the assemblage. An automatic analysis of E. huxleyi was carried out, in order to characterize and compare specimens from this region with other described. The data show that all E. huxleyi specimens corresponds with the Type C (Young y Westbroek, 1991), and no major variations occur between samples recovered under influence of PF and SAF. On the other hand, this is the southernmost record of E. huxleyi in the Pacific Ocea

The Atlantic Ocean at the last glacial maximum: 1. Objective mapping of the GLAMAP sea-surface conditions

Recent efforts of the German paleoceanographic community have resulted in a unique data set of reconstructed sea-surface temperature for the Atlantic Ocean during the Last Glacial Maximum, plus estimates for the extents of glacial sea ice. Unlike prior attempts, the contributing research groups based their data on a common definition of the Last Glacial Maximum chronozone and used the same modern reference data for calibrating the different transfer techniques. Furthermore, the number of processed sediment cores was vastly increased. Thus the new data is a significant advance not only with respect to quality, but also to quantity. We integrate these new data and provide monthly data sets of global sea-surface temperature and ice cover, objectively interpolated onto a regular 1°x1° grid, suitable for forcing or validating numerical ocean and atmosphere models. This set is compared to an existing subjective interpolation of the same base data, in part by employing an ocean circulation model. For the latter purpose, we reconstruct sea surface salinity from the new temperature data and the available oxygen isotope measurements