Vortragsreihe Ökologie und Umweltforschung SS 2014

Paleoenvironmental change on the roof of the world

Hydrological processes on the Tibetan Plateau, the so-called “Water Tower of Asia”, are directly influencing the lives of millions of people in adjacent regions since the Tibetan Plateau feeds the seven major rivers of Asia providing freshwater to a large portion of the population. In addition to that, these rivers provide sediments for megadeltas representing both, fertile farmland and home to millions of people. Climate Change has strongly affected and will further affect the progradation and retreat of these megadeltas fed by rivers originating from the Tibetan Plateau. Very rapid lake level changes reflect hydrological variations which seem to have occurred rather simultaneously at various sites on the Tibetan Plateau. One major shift occurred about 2000 years ago. This observation is probably linked to a shift in the precipitation regime and hence to a change in the monsoon system which in turn influences the above mentioned water supply. This major shift to a weak monsoon and hence to drier conditions can be detected on large parts of the Tibetan Plateau. Clear co-variations with ENSO and a potential socio-cultural impact on the migration decision of the Romani population at the same time can be observed. Although, recent observations indicate a lake level rise in many lakes on the Tibetan Plateau and hence more moisture a similar shift to drier conditions today would be harmful to large portions of the world’s population. Based on this Late Holocene interpretation of various proxies an exceptional sedimentary record continuously spanning the past 24,000 years from Lake Nam Co will also be presented. During this time span extreme hydrological variations can be observed on the Tibetan Plateau partly responsible for lake levels of up to 200 m above the recent ones. Additionally, the post Glacial intensification of the monsoon as well as major shifts in the regional atmospheric circulation systems and their global teleconnections can be traced.

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Invited by Michael Zech, Geomorphology

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