Subdecadal paleoceanographic and paleoclimatic reconstructions of Late Holocene oceanographic conditions of the Eastern Mediterranean based on organic walled dinoflagellate cysts

Abstract

The current abrupt rise in global temperature within the last century has resulted in major concern about future climate change. Although it is obvious that anthropogenic activities influence climate, natural processes steer climate as well. This has resulted in intensive discussions in the academic community and general society alike about to what extent these natural processes might be responsible for the present change of climate. Unfortunately, to date, the character and influence of the natural forcing mechanisms are far from clear. One way to improve our understanding on climate mechanisms is to compare climatic and environmental change prior to the human induced increase in greenhouse gasses with those of the last 150 years. For this, long, continuous, well dated, high temporal resolution records have to be studied covering both pre-industrial and industrial climate change. To date, such records are extremely rare but recently unique sediment cores have been recovered from the Golfo di Taranto (Eastern Mediterranean) that fulfil these requirements. This thesis reports the results of marine palynological investigations on these sediments notably of the dinoflagelate cyst content. Dinoflagellate cyst associations are very useful to reconstruct past changes in marine environment, especially in coastal regions. The thesis presents detailed high temporal resolution information about the climate and oceanographic history of three different time intervals during last 2000 years. It forms a basis for solving the question to what extent natural versus anthropogenic factors influence the environmental and climate change in the study region. The good match between dinocyst based reconstructions and those from other proxy records as well as to environmental and climate information derived from historical sources subscribes that dinoflagellate cyst can be very useful and reliable indicators for reconstructing past environmental and climate change on high temporal resolution which forms a prerequisite to obtain insight into the mechanisms that force the present day global temperature rise.