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[1] 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 U 37 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.

The upper Holocene marine section from a kasten core taken from the oxygen minimum zone off Karachi (Pakistan) at water depth 700 m contains continuously laminated sediments with a sedimentation rate of 1.2 mm/yr and a unique record of monsoonal climatic variability covering the past 5000 years. Our chronostratigraphy is based on varve counts verified by conventional and AMS14C dating. Individual hemipelagic varve couplets are about 0.8–1.5 mm thick, with light-colored terrigenous laminae (A) deposited mainly during the winter monsoon alternating with dark-colored laminae (B) rich in marine organic matter, coccoliths, and fish debris that reflect deposition during the high-productivity season of the late summer monsoon (August–October). Precipitation and river runoff appear to control varve thickness and turbidite frequency. We infer that precipitation decreased in the river watershed (indicated by thinning varves) after 3500–4000 yr B.P. This is about the time of increasing aridification in the Near East and Middle East, as documented by decreasing Nile River runoff data and lake-level lowstands between Turkey and northwestern India. This precipitation pattern continued until today with precipitation minima about 2200–1900 yr B.P., 1000 yr B.P., and in the late Middle Ages (700–400 yr B.P.), and precipitation maxima in the intervening periods. As documented by spectral analysis, the thickness of varve couplets responds to the average length of a 250-yr cycle, a 125-yr cycle, the Gleissberg cycle of solar activity (95 yr), and a 56-yr cycle of unknown origin. Higher frequency cycles are also present at 45, 39, 29–31, and 14 yr. The sedimentary gray-value also shows strong variability in the 55-yr band plus a 31-yr cycle. Because high-frequency cyclicity in the ENSO band (ca. 3.5 and 5 yr) is only weakly expressed, our data do not support a straightforward interaction of the Pacific ENSO with the monsoon-driven climate system of the Arabian Sea.

[1] Water column stratification increased at climatic transitions from cold to warm periods during the late Quaternary and led to anoxic conditions and sapropel formation in the deep eastern Mediterranean basins. Highresolution data sets on sea-surface temperatures (SST) (estimated from U 37 O seawater depletion of eastern Mediterranean surface waters at the transition is between 0.5 and 3.0%, and in all but one case exceeded the depletion seen in a western Mediterranean core. The depletion in d 18O seawater is most pronounced at sapropel bases, in agreement with an initial sudden input of monsoon-derived freshwater. Most sapropels coincide with warming trends of SST. The density decrease by initial freshwater input and continued warming of the sea surface pooled fresh water in the surface layer and prohibited deep convection down to ageing deep water emplaced during cold and arid glacial conditions. An exception to this pattern is ''glacial'' sapropel S6; its largest d 18 O seawater depletion (3%) is almost matched by the depletion in the western Mediterranean Sea, and it is accompanied by surface water cooling following an initially rapid warming phase. A second period of significant isotopic depletion is in isotope stage 6 at the 150 kyr insolation maximum. While not expressed as a sapropel due to cold SST, it is in accord with a strengthened monsoon in the southern catchment.

Abstract. Eight time slices of surface-water paleoceanography were reconstructed from stable isotope and paleotemperature data to evaluate late Quaternary changes in density, current directions, and sea-ice cover in the Nordic Seas and NE Atlantic. We used isotopic records from 110 deep-sea cores, 20 of which are accelerator mass spectrometry (AMS)-14C

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To elucidate the vegetation dynamics in the Aegean region during the last 20 kyr, we have studied terrestrial palynomorphs in marine core GeoTü SL152 (Mount Athos Basin, northern Aegean Sea) at centennial-scale (125 to 300 yr) resolution. The robust chronology of the core allows us to reliably date signals of short-term vegetation change in the Aegean region. For the Pleniglacial interval until ~14.6 kyr BP, our data document steppe vegetation, suggesting dry climatic conditions in the borderlands of the Aegean Sea. Subaerially exposed parts of the shelf were probably colonized by Pinus-dominated vegetation until shelf areas were flooded during Lateglacial sea-level rise. The final, rapid decrease of Pinus pollen percentages between ~14 and ~13 kyr BP appears to be connected to meltwater pulse MWP-1A. The Lateglacial interstadial complex (ie, Meiendorf, Bølling and Allerød) is characterized by the spread of oak trees, but also by the continuous presence of steppe elements, indicating only slightly increased humidity. The Younger Dryas chronozone was the driest interval of the past 20 kyr. Insufficient humidity was most likely also responsible for the ~2.0 kyr delay in Holocene reforestation in the Aegean region relative to western Greece. During the Holocene, the vegetation was repeatedly affected by centennial-scale episodes of reduced moisture availability. Radiocarbon-based age models of previously published pollen records imply strong discrepancies in vegetation development in the Aegean region, but there are reasons to doubt the accuracy of these age models. Here we use the well-dated pollen record from marine core SL152 and biostratigraphic correlation to propose revised chronologies for several published terrestrial pollen records. This re-assessment yields a spatiotemporally consistent pattern of vegetation dynamics in the borderlands of the Aegean Sea.

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