Michael Schlüter

David Billet

Gerold Wefer

Dierk Hebbeln

Bo B. Jorgensen

Tjeerd C.E. Van Weering

Ocean margins are the transitional zones between the oceans and continents. They represent dynamic systems in which numerous processes shape the environment and result in impacting the utilization and hazard potentials for humans. These processes are influenced by a variety of steering mechanisms, from mountain building and climate on the land to tectonics and sea-level fluctuations in ocean margins. This book examines various aspects of regulation for the long-term development of ocean margins, of the impact of fluids and of the dynamics of benthic life at and below the seafloor in ocean margin systems.

Ocean Margin Systems

Stefan Mulitza

Volker Ratmeyer

The South Atlantic plays a critical role in the couplingofoceanic processes between the Antarctic and the lower latitudes. The Antarctic Ocean, along with the adjacent southern seas, is of substantial importance for global climate and for the distributionofwater masses because itprovides large regions ofthe world ocean with intermediate and bottom waters. In contrast to the North Atlantic, the Southern Ocean acts more as an "information distributor", as opposed to an amplifier. Just as the North Atlantic is influencedby the South Atlantic through the contributionofwarm surface water,the incomingsupply ofNADW - in the area of the Southern Ocean as Circumantarctic Deep Water - influences the oceanography ofthe Antarctic. The competing influences from the northern and southern oceans on the current and mass budget systems can be best studied in the South Atlantic. Not only do changes in the current systems in the eastern Atlantic high-production regions affect the energy budget, they also influence the nutrient inventories, and therefore impact the entire productivity ofthe ocean. In addition, the broad region of the polar front is a critical area with respect to productivity-related circulation since it is the source of Antarctic Intermediate Water. Although theAntarctic Intermediate Watertoday liesdeeper than the water that rises in the upwelling regions, it is the long-term source ofnutrients that are ultimately responsible for the supply oforganic matter to the sea floor and to sediments.

Reconstruction of Material Budgets and Current Systems

The South Atlantic in the Late Quaternary

Gerhard Fischer

Paleoceanographic proxies provide infonnation for reconstructions of the past, including climate changes, global and regional oceanography, and the cycles of biochemical components in the ocean. These prox ies are measurable descriptors for desired but unobservable environmental variables such as tempera ture, salinity, primary productivity, nutrient content, or surface-water carbon dioxide concentrations. The proxies are employed in a manner analogous to oceanographic methods. The water masses are first characterized according to their specific physical and chemical properties, and then related to particular assemblages of certain organisms or to particular element or isotope distributions. We have a long-standing series of proven proxies available. Marine microfossil assemblages, for instance, are employed to reconstruct surface-water temperatures. The calcareous shells of planktonic and benthic microorgan isms contain a wealth of paleoceanographic information in their isotopic and elemental compositions. Stable oxygen isotope measurements are used to detennine ice volume, and MglCa ratios are related to water temperatures, to cite a few examples. Organic material may also provide valuable infonnation, e. g. , about past productivity conditions. Studying the stable carbon isotope composition of bulk organic matter or individual marine organic components may provide a measure of past surface-water CO 2 conditions within the bounds of certain assumptions. Within the scope of paleoceanographic investigations, the existing proxies are continuously evolving and improving, while new proxies are being studied and developed. The methodology is improved by analysis of samples from the water column and surface sediments, and through laboratory experiments.

Examples from the South Atlantic ; with 43 Tables

Use of Proxies in Paleoceanography

Frank Lamy

Fauzi Mantoura

Europe is a continent with a high coast-to-surface ratio, and European seas encompass a broad range of settings and regimes. The sustainable development of living and non-living marine resources, the protection of the marine environment and the provision of marine-based services are critical to economic prosperity and to the quality of life of European citizens. Addressing these concerns, marine-science researchers conducted a workshop reviewing major topics of European marine research. This publication contains overview and thematic background papers, as well as reports and recommendations for future research covering topics such as ocean-climate coupling, biogeochemistry, coastal and shelf processes, and ecosystem functioning/biodiversity.

Marine Science Frontiers for Europe

Examples from the South Atlantic

Wolfgang H. Berger

Karl-Ernst Behre

Eystein Jansen

The global environment is changing rapidly under the impact of human activities, and an important element of this change is related to global c1imate modification. Can the study of c1imate and history help in devising strategies for coping with this change? What might be the type of information most useful in this context? What are the pitfalls awaiting the unwary? These are the kinds of questions that led us to bring together experts from the natural and social sci ences with a strong interest in history, to promote discussion between workers in different disciplines by focussing on a common topic of great interest to society. The meeting was arranged in the framework of a "Hanse Conference" within the interdisciplinary program of the Hanse-Wissenschaftskolleg, a foundation set up to promote interdisciplinary studies in collaboration between the universities ofBremen and Oldenburg. The aim ofthe Hanse Conferences in general is to provide opportunities for experts from different fields of the sciences and humanities to come together and explore the larger framework oftopics of common interest. What unites the partici pants is their desire to look over the fence to neighboring disciplines. Young colleagues who wish to build an interdisciplinary career are particularly welcome. In the Hanse Conference on Climate and History, we have endeavoured to build bridges between the c1imate sciences and the sociological sciences concemed with environmental impacts on human activities. The geological sciences, we feIt, are especially well suited to the purpose because they al ready comprise historical aspects.

Climate Development and History of the North Atlantic Realm

Gerold Wefer

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