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Continental ice sheets are a key component of the Earth’s climate system, but their internal dynamics need to be further studied. Since the last deglaciation, the northern Eurasian Fennoscandian Ice Sheet (FIS) has been connected to the Black Sea (BS) watershed, making this basin a suitable location to investigate former ice-sheet dynamics. Here, from a core retrieved in the BS, we combine the use of neodymium isotopes, high-resolution elemental analysis, and biomarkers to trace changes in sediment provenance and river runoff. We reveal cyclic releases of meltwater originating from Lake Disna, a proglacial lake linked to the FIS during Heinrich Stadial 1. Regional interactions within the climate–lake–FIS system, linked to changes in the availability of subglacial water, led to abrupt drainage cycles of the FIS into the BS watershed. This phenomenon raised the BS water level by ∼100 m until the sill of the Bosphorus Strait was reached, flooding the vast northwestern BS shelf and deeply affecting the hydrology and circulation of the BS and, probably, of the Marmara and Aegean Seas.

This study is a synthesis of gas-related features in recent sediments across the western Black Sea basin. The investigation is based on an extensive seismic dataset, and integrates published information from previous local studies. Our data reveal widespread occurrences of seismic facies indicating free gas in sediments and gas escape in the water column. The presence of gas hydrates is inferred from bottom-simulating reflections (BSRs). The distribution of the gas facies shows (1) major gas accumulations close to the seafloor in the coastal area and along the shelfbreak, (2) ubiquitous gas migration from the deeper subsurface on the shelf and (3) gas hydrate occurrences on the lower slope (below 750 m water depth). The coastal and shelfbreak shallow gas areas correspond to the highstand and lowstand depocentres, respectively. Gas in these areas most likely results from in situ degradation of biogenic methane, probably with a contribution of deep gas in the shelfbreak accumulation. On the western shelf, vertical gas migration appears to originate from a source of Eocene age or older and, in some cases, it is clearly related to known deep oil and gas fields. Gas release at the seafloor is abundant at water depths shallower than 725 m, which corresponds to the minimum theoretical depth for methane hydrate stability, but occurs only exceptionally at water depths where hydrates can form. As such, gas entering the hydrate stability field appears to form hydrates, acting as a buffer for gas migration towards the seafloor and subsequent escape.

Decades of seabed mapping, reflection profiling, and seabed sampling reveal that throughout the past two million years the Black Sea was predominantly a freshwater lake interrupted only briefly by saltwater invasions coincident with global sea level highstand. When the exterior ocean lay below the relatively shallow sill of the Bosporus outlet, the Black Sea operated in two modes. As in the neighboring Caspian Sea, a cold climate mode corresponded with an expanded lake and a warm climate mode with a shrunken lake. Thus, during much of the cold glacial Quaternary, the expanded Black Sea's lake spilled into to the Marmara Sea and from there to the Mediterranean. However, in the warm climate mode, after receiving a vast volume of ice sheet meltwater, the shoreline of the shrinking lake contracted to the outer shelf and on a few occasions even beyond the shelf edge. If the confluence of a falling interior lake and a rising global ocean persisted to the moment when the rising ocean penetrated across the dividing sill, it would set the stage for catastrophic flooding. Although recently challenged, the flood hypothesis for the connecting event best fits the full set of observations.

During the last glacial phase the Black Sea basin was isolated from the world's oceans due to the lowering of global sea-levels. As sea-levels rose during the latest glacial and early Holocene period, the Black Sea was once again connected to the eastern Mediterranean via the Dardanelles-Marmara-Bosporus seaway. In recent years, trace element and stable isotope analyses of ostracod assemblages have yielded important details regarding the hydrological evolution of the Black Sea during these events. Despite this focus on the geochemical signatures of the ostracods, little if any attention has been paid to the taxonomic composition of the ostracod assemblages themselves and there are notably few publications on the sub-littoral fauna of this important water body. We present a summary of the most abundant ostracod taxa of the Black Sea during the late glacial to early Holocene phase (dominated by the Candonidae, Leptocytheridae and Loxoconchidae) and chart their response to the subsequent environmental changes in the early Holocene with the pre-connection, low salinity 'lacustrine' fauna being replaced by one with a more Mediterranean aspect. Many of these taxa are illustrated using SEM for the first time, providing an important initial step in establishing taxonomic stability within Black Sea ostracod studies and noting faunal similarities with neighbouring areas, such as the Caspian Sea.

The Black Sea semi-enclosed basin is bounded by Europe, Asia Minor and the Caucasus and is ultimately connected to the Atlantic Ocean via the Mediterranean and Aegean seas and various straits. The Bosporus Strait connects it to the Sea of Marmara, and the Dardanelles Strait connects it to the Aegean Sea region of the Mediterranean. For about 15 years the sedimentary systems of the northwestern part of the Black Sea extending from the continental shelf and slope down to the deep-sea zone have been studied using geophysical and coring techniques. These results provide a robust record of water-level fluctuations in the Black Sea since the Last Glacial Maximum (LGM) and thereby shed new light on its disputed aspects. The deep-sea fan studies demonstrate that the last channel-levee system on the Danube fan developed during the LGM with a water level about 120 m.

Over the last 15 years marine scientists in Europe have come together to work on a range of scientific problems related to the geological, physical, chemical, and biological processes that control the functioning of the ocean margin system, the most important area for our natural marine resources. These projects have been commissioned due to the increasing need to understand the offshore environment, especially since its exploitation by the hydrocarbon, telecommunication cable, and fishing industries is increasing rapidly. The most recently funded projects have been brought together by two overarching projects that create clusters of related science activities. The EU-funded OMARC (Ocean Margin Deep Water Research Consortium) project links 13 EU-funded projects on continental margins. The European Science Foundation (ESF)-funded EUROMARGINS (for example Slope Stability on Europe's Passive Continental Margins) program includes 14 projects that study a range of European margin settings from the active margins of the Mediterranean Seas to the passive high-latitude margins of the Northeast Atlantic.

This chapter gives an overview of the environmental changes to the European shelf and its marginal seas during the Late Pleistocene to the Middle Holocene. It first explains the regional tectonics of Europe. The age of the consolidation of the basement together with the plate tectonic setting serves as the main parameters determining coastal formation. Next, the chapter reviews the fluctuation of glacial and interglacial stadia as an effect of orbital parameters of the Earth around the Sun. In addition, it examines eustatic change during the Last Glacial Cycle (LGC). The chapter also describes the development of the Baltic Sea, the North Sea and the Atlantic shelf, based on numerical sea-level scenarios constrained by observational data. Finally, it explains the basics of the ECHO-G global climate model, together with an overview of Late Holocene changes in European climate with special attention to wind forces.