(Table 2) Radiocarbon ages of eastern equatorial Pacific sediment cores

We use planktonic oxygen isotope (d18O) records spanning the last 30,000 years (kyr) to constrain the magnitude and spatial pattern of glacial cooling in the upwelling environment of the eastern equatorial Pacific (EEP). Fourteen new downcore d18O records were obtained from surface-dwelling planktonic foraminifera Globigerinoides sacculifer and Globigerinoides ruber in eight cores from the upwelling tongue of the EEP. All sites have sedimentation rates exceeding 5 cm/kyr and, with one exception, lie above the modern depth of the foraminiferal lysocline. Sites directly underlying the cool band of upwelling immediately south of the equator record mean late Holocene (LH)-Last Glacial Maximum (LGM) d18O amplitudes ranging between 1.0 and 1.3 per mil. We estimate that mean sea surface temperatures (SST) in this region during the LGM were on average 1.5 ± 0.5°C lower than the LH. Larger d18O amplitudes are observed in sites north of the equator, indicating a spatial pattern of reduced meridional SST gradient across the equator during the LGM. This result is supported by comparison of Mg/Ca SST reconstructions from two sites straddling the equator. We interpret the reduction of this gradient during the LGM as evidence for a less intense cold tongue-Intertropical Convergence Zone (ITCZ) frontal system, a more southerly position of the ITCZ, and weaker southeast equatorial trades in the EEP.

Geographic distribution of dinoflagellate cysts in surface sediments

Dinoflagellate cysts are useful for reconstructing upper water conditions. For adequate reconstructions detailed information is required about the relationship between modern day environmental conditions and the geographic distribution of cysts in sediments. This Atlas summarises the modern global distribution of 71 organicwalled dinoflagellate cyst species. The synthesis is based on the integration of literature sources together with data of 2405 globally distributed surface sediment samples that have been preparedwith a comparable methodology and taxonomy. The distribution patterns of individual cyst species are being comparedwith environmental factors that are knownto influence dinoflagellate growth, gamete production, encystment, excystment and preservation of their organic-walled cysts: surface water temperature, salinity, nitrate, phosphate, chlorophyll-a concentrations and bottom water oxygen concentrations. Graphs are provided for every species depicting the relationship between seasonal and annual variations of these parameters and the relative abundance of the species. Results have been compared with previously published records; an overview of the ecological significance as well as information about the seasonal production of each individual species is presented. The relationship between the cyst distribution and variation in the aforementioned environmental parameters was analysed by performing a canonical correspondence analysis. All tested variables showed a positive relationship on the 99% confidence level. Sea-surface temperature represents the parameter corresponding to the largest amount of variance within the dataset (40%) followed by nitrate, salinity, phosphate and bottom-water oxygen concentration, which correspond to 34%, 33%, 25% and 24% of the variance, respectively. Characterisations of selected environments as well as a discussion about how these factors could have influenced the final cyst yield in sediments are included.

Pollen profiles from a Late Palaeolithic site in the community of Bad Buchau-Kappel, Baden-Wuerttemberg, Germany

Excavations were carried out in a Late Palaeolithic site in the community of Bad Buchau-Kappel between 2003 and 2007. Archaeological investigations covered a total of more than 200 m**2. This site is the product of what likely were multiple occupations that occurred during the Late Glacial on the Federsee shore in this location. The site is situated on a mineral ridge that projected into the former Late Glacial lake Federsee. This beach ridge consists of deposits of fine to coarse gravel and sand and was surrounded by open water, except for a connection to the solid shore on the south. A lagoon lay between the hook-shaped ridge and the shore of the Federsee. This exposed location provided optimal access to the water of the lake. In addition, the small lagoon may have served as a natural harbor for landing boats or canoes. Sedimentological and palynological investigations document the dynamic history of the location between 14,500 and 11,600 years before present (cal BP). Evidence of the deposition of sands, gravels and muds since the Bølling Interstadial is provided by stratigraphic and palynological analyses. The major occupation occurred in the second half of the Younger Dryas period. Most of the finds were located on or in the sediments of the ridge; fewer finds occurred in the surrounding mud, which was also deposited during the Younger Dryas. Direct dates on some bone fragments, however, demonstrate that intermittent sporadic occupations also took place during the two millennia of the Meiendorf, Bølling, and Allerød Interstadials. These bones were reworked during the Younger Dryas and redeposited in the mud. A 14C date from one bone of 11,600 years ago (cal BP) places the Late Palaeolithic occupation of the ridge at the very end of the Younger Dryas, which is in agreement with stratigraphic observations. Stone artifacts, numbering 3,281, comprise the majority of finds from the site. These include typical artifacts of the Late Palaeolithic, such as backed points, short scrapers, and small burins. There are no bipointes or Malaurie-Points, which is in accord with the absolute date of the occupation. A majority of the artifacts are made from a brown chert that is obtainable a few kilometers north of the site in sediments of the Graupensandrinne. Other raw materials include red and green radiolarite that occur in the fluvioglacial gravels of Oberschwaben, as well as quartzite and lydite. The only non-local material present is a few artifacts of tabular chert from the region near Kelheim in Bavaria. A unique find consists of two fragments of a double-barbed harpoon made of red deer antler, which was found in the Younger Dryas mud. It is likely, but not certain, that this find belongs to the same assemblage as the numerous stone artifacts. Although not numerous, animal bones were also found in the excavations. Most of them lay in sediments of the Younger Dryas, but several 14C dates place some of these bones in earlier periods, including the Meiendorf, Bølling, and Allerød Interstadials. These bones were reworked by water and redeposited in mud sediments during the Younger Dryas. As a result, it is difficult to attribute individual bones to particular chronological positions without exact dates. Species that could be identified include wild horse (Equus spec.), moose or elk (Alces alces), red deer (Cervus elaphus), roe deer (Capreolus capreolus), aurochs or bison (Bos spec.), wild boar (Sus scrofa), as well as birds and fish, including pike (Esox Lucius).

(Table 1) Age determination of Arctic Ocean sediment cores

Accelerator mass spectrometer 14C dated stable isotope data from Neogloboquadrina pachyerma in cores raised from the Mendeleyev Ridge and slope provide evidence for significant influx of meltwater to the western Arctic Ocean during the early part of marine oxygen isotope stage 1 (OIS 1) and during several intervals within OIS 3. The strongest OIS 3 meltwater event occurred before ca. 45 ka (conventional radiocarbon age) and was probably related to the deglaciation at the beginning of OIS 3. Major meltwater input to the western Arctic Ocean during the last deglaciation coincides closely with the maximum rate of global sea-level rise as determined from the Barbados sea-level record, demonstrating a strong link between the global record and changes in the central Arctic Ocean. OIS 2, which includes the last glacial maximum, is very condensed or absent in the cores. Abundance and d13C values for N. pachyderma in the middle part of OIS 3 are similar to modern values, indicating high productivity and seasonal ice-free areas along the Arctic margin at that time. These records indicate that the Arctic Ocean was a source of heat and moisture to the northern polar atmosphere during parts of OIS 3.

Surface sediment data, CaCO3 and TOC

Modern sedimentary total organic carbon (TOC) content as a proxy for surface water export production was mapped on the shelf and on the upper continental slope of the Benguela upwelling system using 137 core tops. Shelf maxima in TOC can be correlated with maxima in surface water productivity. On the slope, high TOC contents are observed offshore from sites of strong modern upwelling. Estimates of modern TOC mass accumulation rates (MAR) show that approximately 85% of the total is accumulating on the shelf. TOC MAR were calculated, mapped, and budgeted for the Holocene and for the Last Glacial Maximum (LGM) using 19 sediment cores from the continental slope. During the LGM, centers of deposition and production have migrated offshore with respect to their Holocene positions. TOC accumulation on the continental slope was approximately 84% higher during the LGM than during the Holocene, possibly reflecting enhanced productivity. The TOC distribution patterns and sediment echo sounding data suggest that undercurrents strongly influence the sedimentation off Namibia. Winnowing and focusing result in great lateral heterogeneity of sedimentation rates and sediment properties. Individual cores therefore do not necessarily reflect general changes in export production. These results highlight the need for detailed regional studies based on a large number of sediment cores for highly heterogeneous high-productivity areas in order to derive general statements on total fluxes.

Dinoflagellate cyst accumulation rates of ODP Hole 146-893A from Santa Barbara Basin

The dinoflagellate cyst record from Ocean Drilling Program Hole 893A, Santa Barbara Basin, southern California, is examined at millennial-scale resolution for the past 40 kyr. Changes in cyst abundance, composition of cyst assemblages, and their diversity reflect major shifts in climate and ocean circulation in the region over this time interval. Throughout the sequence, dinoflagellate cyst assemblages are dominated by heterotrophic dinoflagellates. Brigantedinium spp. and other upwelling-related taxa such as Echinidinium and Protoperidinium americanum are abundant, indicating the continued influence of coastal upwelling on the basin during the late Quaternary. A significant increase in cyst accumulation rates is seen during the Holocene and, to a lesser extent, during shorter warming events such as Bolling/Allerod and Dansgaard-Oeschger interstadials, implying enhanced marine productivity during these periods. Cyst diversity is high during the Holocene. An increase in abundance of cysts produced by autotrophic dinoflagellates in the late Holocene suggests enhanced input of warm, nutrient-rich waters. In contrast, cyst assemblages from the Last Glacial Maximum exhibit a relatively low diversity and an increase in the cysts of heterotrophic dinoflagellates, in particular Selenopemphix nephroides. The presence of this taxon in association with Brigantedinium spp. implies substantial cooling of surface waters in the Santa Barbara Basin at that time.

Atlantic 231Pa/230Th and biogenic opal compilation of the Holocene and the LGM

The strength and geometry of the Atlantic meridional overturning circulation is tightly coupled to climate on glacial-interglacial and millennial timescales, but has proved difficult to reconstruct, particularly for the Last Glacial Maximum. Today, the return flow from the northern North Atlantic to lower latitudes associated with the Atlantic meridional overturning circulation reaches down to approximately 4,000 m. In contrast, during the Last Glacial Maximum this return flow is thought to have occurred primarily at shallower depths. Measurements of sedimentary 231Pa/230Th have been used to reconstruct the strength of circulation in the North Atlantic Ocean, but the effects of biogenic silica on 231Pa/230Th-based estimates remain controversial. Here we use measurements of 231Pa/230Th ratios and biogenic silica in Holocene-aged Atlantic sediments and simulations with a two-dimensional scavenging model to demonstrate that the geometry and strength of the Atlantic meridional overturning circulation are the primary controls of 231Pa/230Th ratios in modern Atlantic sediments. For the glacial maximum, a simulation of Atlantic overturning with a shallow, but vigorous circulation and bulk water transport at around 2,000 m depth best matched observed glacial Atlantic 231Pa/230Th values. We estimate that the transport of intermediate water during the Last Glacial Maximum was at least as strong as deep water transport today.

Comparison of glacial/interglacial carbonate concentrations in Atlantic sediments

To assess the regional effects of glaciation on sedimentation in the Atlantic Ocean we compare sediment types, distributions, and rates between Recent (core top) and last glacial maximum (LGM: ~18,000 years B.P.) stratigraphic levels. Based upon smear slides and carbonate analyses in 178 cores we find that glacial age carbonate content is generally lower than Recent. During both the Recent and LGM, carbonate content shows an east/west asymmetry with western basins exhibiting lower carbonate values. Input of ice-rafted detritus into the North Atlantic during LGM time interrupts this topographic control on carbonate distribution considerably farther south than at present; in the South Atlantic this effect is minor. Comparison of LGM and Recent sediment distributions indicates that the LGM seafloor was dominated by biogenic oozes, calcareous clays, and clays, while the Recent is dominated by biogenic oozes and marls. Coarse-grained detritus is much more prevalent in LGM sediments, derived not only from glacial input but also from fluvial and aeolian sources. Sedimentation rates, calculated from LGM to Recent sediment thickness in cores, are <4 cm/1000 yr for most of the ocean. Higher rates are typical of the continental margin off the Amazon River, the North American Basin, and a small region off west equatorial Africa.

(Supporting Information) 14Cage plateau tuning of local Atlantic sediment cores

Modeling studies predict that changes in radiocarbon (14C) reservoir ages of surface waters during the last deglacial episode will reflect changes in both atmospheric 14C concentration and ocean circulation including the Atlantic Meridional Overturning Circulation. Tests of these models require the availability of accurate 14C reservoir ages in well-dated late Quaternary time series. We here test two models using plateau-tuned 14C time series in multiple well-placed sediment core age-depth sequences throughout the lower latitudes of the Atlantic Ocean. 14C age plateau tuning in glacial and deglacial sequences provides accurate calendar year ages that differ by as much as 500-2500 years from those based on assumed global reservoir ages around 400 years. This study demonstrates increases in local Atlantic surface reservoir ages of up to 1000 years during the Last Glacial Maximum, ages that reflect stronger trades off Benguela and summer winds off southern Brazil. By contrast, surface water reservoir ages remained close to zero in the Cariaco Basin in the southern Caribbean due to lagoon-style isolation and persistently strong atmospheric CO2 exchange. Later, during the early deglacial (16 ka) reservoir ages decreased to a minimum of 170-420 14C years throughout the South Atlantic, likely in response to the rapid rise in atmospheric pCO2 and Antarctic temperatures occurring then. Changes in magnitude and geographic distribution of 14C reservoir ages of peak glacial and deglacial surface waters deviate from the results of Franke et al. (2008) but are generally consistent with those of the more advanced ocean circulation model of Butzin et al. (2012).

Age models, accumulation rates, and grain size distributions of sediment cores from the northern subtropical Atlantic

The terrigenous sediment proportion of the deep sea sediments from off Northwest Africa has been studied in order to distinguish between the aeolian and the fluvial sediment supply. The present and fossil Saharan dust trajectories were recognized from the distribution patterns of the aeolian sediment. The following timeslices have been investigated: Present, 6,000, 12,000 and 18,000 y. B. P. Furthermore, the quantity of dust deposited off the Saharan coast has been estimated. For this purpose, 80 surface sediment samples and 34 sediment cores have been analysed. The stratigraphy of the cores has been achieved from oxygen isotopic curves, 14C-dating, foraminiferal transfer temperatures, and carbonate contents. Silt sized biogenic opal generally accounts for less than 2 % of the total insoluble sediment proportion. Only under productive upwelling waters and off river mouths, the opal proportion exceeds 2 % significantly. The modern terrigenous sediment from off the Saharan coast is generally characterized by intensely stained quartz grains. They indicate an origin from southern Saharan and Sahelian laterites, and a zonal aeolian transport in midtropospheric levels, between 1.5 an 5.5 km, by 'Harmattan' Winds. The dust particles follow large outbreaks of Saharan air across the African coast between 15° and 21° N. Their trajectories are centered at about 18° N and continue further into a clockwise gyre situated south of the Canary Islands. This course is indicated by a sickle-shaped tongue of coarser grain sizes in the deep-sea sediment. Such loess-sized terrigenous particles only settle within a zone extending to 700 km offshore. Fine silt and clay sized particles, with grain sizes smaller than 10- 15 µm, drift still further west and can be traced up to more than 4,000 km distance from their source areas. Additional terrigenous silt which is poor in stained quartz occurs within a narrow zone off the western Sahara between 20° and 27° N only. It depicts the present dust supply by the trade winds close to the surface. The dust load originates from the northwestern Sahara, the Atlas Mountains and coastal areas, which contain a particularly low amount of stained quartz. The distribution pattern of these pale quartz sediments reveals a SSW-dispersal of dust being consistent with the present trade wind direction from the NNE. In comparison to the sediments from off the Sahara and the deeper subtropical Atlantic, the sediments off river mouths, in particular off the Senegal river, are characterized by an additional input of fine grained terrigenous particles (< 6 µm). This is due to fluvial suspension load. The fluvial discharge leads to a relative excess of fine grained particles and is observed in a correlation diagram of the modal grain sizes of terrigenous silt with the proportion of fine fraction (< 6 µm). The aeolian sediment contribution by the Harmattan Winds strongly decreased during the Climatic Optimum at 6,000 y. B. P. The dust discharge of the trade winds is hardly detectable in the deep-sea sediments. This probably indicates a weakened atmospheric circulation. In contrast, the fluvial sediment supply reached a maximum, and can be traced to beyond Cape Blanc. Thus, the Saharan climate was more humid at 6,000 y B. P. A latitudinal shift of the Harmattan driven dust outbreaks cannot be observed. Also during the Glacial, 18,000 y. B. P., Harmattan dust transport crossed the African coast at latitudes of 15°-20° N. Its sediment load increased intensively, and markedly coarser grains spread further into the Atlantic Ocean. An expanded zone of pale-quart sediments indicates an enhanced dust supply by the trade winds blowing from the NE. No synglacial fluvial sediment contribution can be recognized between 12° and 30° N. This indicates a dry glacial climate and a strengthened stmospheric circulation over the Sahelian and Saharan region. The climatic transition pahes, at 12, 000 y. B. P., between the last Glacial and the Intergalcial, which is compareable to the Alerod in Europe, is characterized by an intermediate supply of terrigenous particles. The Harmattan dust transport wa weaker than during the Glacial. The northeasterly trade winds were still intensive. River supply reached a first postglacial maximum seaward of the Senegal river mouth. This indicates increasing humidity over the southern Sahara and a weaker atmospheric circulation as compared to the glacial. The accumulation rates of the terrigenous silt proportion (> 6 µm) decrcase exponentially with increasing distance from the Saharan coast. Those of the terrigenous fine fraction (< 6 µm) follow the same trend and show almost similar gradients. Accordingly, also the terrigenous fine fraction is believed to result predominantly from aeolian transport. In the Atlantic deep-sea sediments, the annual terrigenous sediment accumulation has fluctuated, from about 60 million tons p. a. during the Late Glacial (13,500-18,000 y. B. P, aeolian supply only) to about 33 million tons p. a. during the Holocene Climatic Optimum (6,000-9,000 y. B. P, mainly fluvial supply), when the river supply has reached a maximum, and to about 45 million tons p. a. during the last 4,000 years B. P. (fluvial supply only south of 18° N).

Database of the GLAMAP project

A uniform chronology for foraminifera-based sea surface temperature records has been established in more than 120 sediment cores obtained from the equatorial and eastern Atlantic up to the Arctic Ocean. The chronostratigraphy of the last 30,000 years is mainly based on published d18O records and 14C ages from accelerator mass spectrometry, converted into calendar-year ages. The high-precision age control provides the database necessary for the uniform reconstruction of the climate interval of the Last Glacial Maximum within the GLAMAP-2000 project.

Glacial North Atlantic: Sea surface conditions reconstructed by GLAMAP 2000

The response of the tropical ocean to global climate change and the extent of sea ice in the glacial nordic seas belong to the great controversies in paleoclimatology. Our new reconstruction of peak glacial sea surface temperatures (SSTs) in the Atlantic is based on census counts of planktic foraminifera, using the Maximum Similarity Technique Version 28 (SIMMAX-28) modern analog technique with 947 modern analog samples and 119 well-dated sediment cores. Our study compares two slightly different scenarios of the Last Glacial Maximum (LGM), the Environmental Processes of the Ice Age: Land, Oceans, Glaciers (EPILOG), and Glacial Atlantic Ocean Mapping (GLAMAP 2000) time slices. The comparison shows that the maximum LGM cooling in the Southern Hemisphere slightly preceeded that in the north. In both time slices sea ice was restricted to the north western margin of the nordic seas during glacial northern summer, while the central and eastern parts were ice-free. During northern glacial winter, sea ice advanced to the south of Iceland and Faeroe. In the central northern North Atlantic an anticyclonic gyre formed between 45° and 60°N, with a cool water mass centered west of Ireland, where glacial cooling reached a maximum of >12°C. In the subtropical ocean gyres the new reconstruction supports the glacial-to-interglacial stability of SST as shown by CLIMAP Project Members (CLIMAP) [1981]. The zonal belt of minimum SST seasonality between 2° and 6°N suggests that the LGM caloric equator occupied the same latitude as today. In contrast to the CLIMAP reconstruction, the glacial cooling of the tropical east Atlantic upwelling belt reached up to 6°-8°C during Northern Hemisphere summer. Differences between these SIMMAX-based and published U37[k]- and Mg/Ca-based equatorial SST records are ascribed to strong SST seasonalities and SST signals that were produced by different planktic species groups during different seasons.

Investigation of N. pachyderma from the North Atlantic

The shells of the planktonic foraminifer Neogloboquadrina pachyderma have become a classical tool for reconstructing glacial-interglacial climate conditions in the North Atlantic Ocean. Palaeoceanographers utilize its left- and right-coiling variants, which exhibit a distinctive reciprocal temperature and water mass related shift in faunal abundance both at present and in late Quaternary sediments. Recently discovered cryptic genetic diversity in planktonic foraminifers now poses significant questions for these studies. Here we report genetic evidence demonstrating that the apparent 'single species' shell-based records of right-coiling N. pachyderma used in palaeoceanographic reconstructions contain an alternation in species as environmental factors change. This is reflected in a species-dependent incremental shift in right-coiling N. pachyderma shell calcite d18O between the Last Glacial Maximum and full Holocene conditions. Guided by the percentage dextral coiling ratio, our findings enhance the use of d18O records of right-coiling N. pachyderma for future study. They also highlight the need to genetically investigate other important morphospecies to refine their accuracy and reliability as palaeoceanographic proxies.