The Tibetan Plateau is after the Arctic and Antarctic the third largest reservoir of fresh water in form of ice and is therefore referred to as the Earth's “Third Pole”. Almost one third of the world's population is dependent on the water supply from the plateau. According to the IPCC report, future climate change will have a particularly large impact on the region and affect the water cycle, water resources, ecology and the economy. In order to assess future climate scenarios on the basis of models, it is crucial to understand the intensity and the timing of hydrogeological interactions on long-term time scales. To accomplish this, the sediment sequence of Lake Nam Co, which is located 4700 m above sea level and has a depth of approxomately 125 m, is investigated. With an area of nearly 2000 m², it is almost four times the size of Lake Constance. In contrast to much younger and often incomplete climate archives of the Tibetan Plateau, the sedimentary sequence of Nam Co contains continuous information on climate history going back to probably more than one million years. The investigation of this sequence will cover several cycles of glacial and interglacial stages.

LIAG completed geophysical downhole measurements at two boreholes in the central area of the lake as part of the ICDP project “The Nam Co Drilling Project, Tibet (NamCore)”. This involved logging the sediment layers with several instruments to a depth of more than 360 m below lake floor. Time series analysis and cyclostratigraphy will be applied to create a time-depth scale from the acquired data. Multivariate statistics will help to understand the complexity of the data sets and to characterize the sediment properties which allow conclusions about the past depositional environments.

All information on depositional age and lithology will be combined to derive statements on the relationship between aridity and precipitation in the past and to interpret these in the context of global climate development.