Description: Das Projekt "Rekonstruktion und Modellierung der Langzeitdynamik von Oekosystemen" wird vom Umweltbundesamt gefördert und von Eidgenössische Anstalt für Wasserversorgung, Abwasserreinigung und Gewässerschutz, Abteilung für Umweltphysik durchgeführt. How can we extract from the sediment record of a lake information about the influence of climate on terrestrial and lacustrine ecosystems as well as information about the nature of the endogenous dynamics of these ecosystems? What are the uncertainties associated with this information? What is the relevance for policy makers? Irrespective of location, mean air temperatures in Switzerland have increased by about 1 oC over the last hundred years. Lake surface water temperatures are undergoing a secular increase at a similar rate. In deep lakes, this implies a long-term increase in thermal stability and a prolongation of summer stagnation. Also, ice covered lakes in Switzerland exhibit a secular trend to earlier break-up. The secular trend apparent in the Swiss air and water temperature data over the last 50 yr does not appear in air temperature data from central England, despite a great similarity in shorter-term temporal structures. Thus, secular air and water temperature increases may be more a regional than a continent-wide phenomenon. Since secular increases in mean air temperature in lowland areas are due to nighttime warming, this is also likely to be true of lake temperatures. Complementary information: Although the existence of secular trends in air temperature over the last hundred years, both globally and regionally, is well documented, the response of lake water temperature to recent climatic changes has been largely neglected. Long-term meteorological records show that surface air temperatures in Switzerland have been increasing persistently at an average rate of about 0.01 Koyr-1 since the end of the 19th century, which is about 50-100 percent greater than the global rate of increase. Since air and water temperatures can be viewed as indicators of essentially the same climatic trends, although with different response times, an increase in the temperature of surface waters over the same period of time is also be expected. In deep lakes, only temperatures in the upper water layers appear to be undergoing a long-term increase. This is causing a general increase in thermal stability, a reduction in the duration of winter circulation and a prolongation of the summer stratification period. Decreases hypolimnetic oxygen concentrations and an upward extension of the anoxic zone are likely to result.
Types:
SupportProgram
Origin: /Bund/UBA/UFORDAT
Tags: England ? Seen ? Schweiz ? Abwasserreinigung ? Pflanzensamen ? Sauerstoff ? Seensediment ? Wassertemperatur ? Binnengewässer ? Eis ? Lufttemperatur ? Oberflächenwasser ? Naturwissenschaft ? Messdaten ? Monitoring ? Oberflächengewässer ? Terrestrisches Ökosystem ? Daten ? Sauerstoffgehalt ? Wasserversorgung ? Gewässerschutz ? Sediment ? Flachland ? Modellierung ? Langzeituntersuchung ? Sedimentdynamik ? Ökosystem ? Datenerhebung ? Klima ? Zirkulation ? Klimawandel ? Klimawirkung ? Gebiet ? Globale Aspekte ? See [Binnengewässer] ? Dynamische Analyse ? Temperaturerhöhung ? environmental dynamics ?
License: cc-by-nc-nd/4.0
Language: Deutsch
Time ranges: 1993-01-01 - 1995-12-31
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