Senckenberg Research

Sensitivity studies for tipping points

The aim of the work package is to investigate whether the water budget of the catchment area of the Qaidam lake (China) was balanced during specific time segments within the last 2.7 Ma, thus providing quasi-stable conditions which were not irreversibly disturbed by global climate fluctuations. Furthermore, it shall be studied why the Qaidam lake experienced about 600 ka ago an abrupt change and was no longer able to maintain its earlier, much greater extent for a longer time. In particular, it will be analyzed whether tipping points can be identified with respect to large-scale atmospheric circulation that led to this irreversible change in the Qaidam lake. It is assumed that there are additional tipping points which prevent a long-term adjusted water balance in the catchment area in the case of a specific minimum lake expansion, since recycling of the rainfall within the catchment area was no longer sufficient to ensure the long-term stability of Lake Qaidam during dry periods.

General circulation models (GCM) as well as regional climate models (RCM) are carried out to simulate the atmospheric circulation. These simulations are the basis for the investigation of global atmospheric drivers, which can lead to the formation of tipping points in Tibetan lakes. Such global drivers may be orbital variations, glacial and interglacial variations as well as land surface changes (e.g., vegetation and ice cover, land-sea extent), which occurred in the past 2.7 Ma. Simulations at different time-slices are used to identify certain significant climate conditions in the past. It is planned to model the current state (as a control simulation), the middle Holocene (~ 6 ka), the Last Glacial Maximum (~ 21 ka) and the preglacial world, represented by a Pliocene simulation (~ 3 Ma).