154 EUROPE/Holocene Figure 10 Preliminary curve of relative sea level change for western Pomerania, shaded area: interval of ‘data confidence’, solid line: local trend for western Pomerania, dashed line: estimated trend, for the time span between 6000 and 4500 years BP tectonically controlled local uplift is assumed Note: Ages are given here in 14C years BP (From Harff J, Frischbutter A, Lampe R, and Meyer M (2001) Sea level change in the Baltic Sea: interrelation of climatic and geological processes In: Gerhard LC, Harrison WE, and Hanson BM (eds.) Geological perspectives of global climate change Tulsa, Oklahoma, American Association of Petroleum Geologists in collabor ation with the Kansas Geological Survey and the AAPG Division of Environmental Geosciences: 231 250 Reprinted by permission of the AAPG whose permission is required for further use.) volcanism (e.g., the eruption of Vesuvius in ad 79 described by Pliny the Younger), earthquakes (e.g., the disastrous one of Lisboa in ad 1755) or floods along rivers and seashores On the other hand, changing social conditions also induced dramatic changes of their natural environment Once human activity stopped or declined, the surrounding environment developed depending on its natural stability Robust ecosystems changed back to a state similar to the original one being controlled by the natural conditions An example for such processes is the re-forestation after depopulation during the Thirty Years’ War (1618–1648 ad) in central Europe In other cases, human activity led to irreversible effects on the ecosystem’s stability when the social structures collapsed During the Roman period there was a land use maximum partly on metastable soils Here, terraces were maintained, preventing soil erosion After the invasion of eastern nomads, the land was partly abandoned and soil erosion started at a greater extent and in the worst case, barren badlands were the final result Therefore, maximum erosion is not connected with maximum land use, but with subsequent phases in different cultural environments Generally, when judging human impact on the natural environment, it is often regarded only as negative However, in contrast, the creation of new metastable ecosystems more diverse than before, particularly in the early phases of the Holocene, would not have been possible without human activity Human Activity and Environmental Conservation During the last 500 years, human impact on the European environment have become much more important than the natural conditions Particularly