IP1: Reconstructing ISM and westerlies influence on Holocene hydrology, productivity and regime shifts in NW Himalaya.

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Climate extremes, like severe, prolonged droughts or floods can have profound ecological and socio-economic consequences. Global climate change is expected to increase both the frequency and the intensity of regional climate extremes in the Indian Summer Monsoon (ISM) realm. Available palaeoclimate data demonstrate that tropical and extratropical forcings may show a persistently high frequency of occurrence over decades or even centuries, resulting in regional hydrology changes and ecological regime shifts. NW Himalayan region in particular has drawn attention due to increasing annual precipitation and non-stationary link of winter (westerlies) precipitation with e.g. AO/NAO and ENSO and their critical impact on the economic wellbeing of this ecologically fragile region. At present the multi-model ensemble mean simulations of temperature and precipitation with historical forcing for the period 2001–2005 are reasonable, but large differences continue to persist among the predictive models. Thus, long term (palaeo)climate data from NW Himalaya is important not just on regional scale but also to understand persistent climate extremes over the larger Indian subcontinent. Within this interdisciplinary coordinated effort, we aim to develop a comprehensive picture of Holocene climate variability over the ISM realm using a multiproxy approach on lakes (sediment cores) from climatically sensitive regions. Three closely interrelated proposals aim to (i) reconstruct spatiotemporal Holocene ISM with focus on regional extreme events; (ii) use an interdisciplinary, multiproxy approach to identify the impact of extreme events on the ecosystem; (iii) use regional patterns, data analyses and modelling to identify the forcings underlying climate extremes; and (iv) decouple human and climate impact on ecosystem.IP1 aims to (i) identify regional extreme events in the meteorological period triggered by known forcings, and reconstruct precipitation pathways and moisture sources using the HYSPLIT model for these periods. These may potentially provide analogues for Holocene extreme events; (ii) develop a record of well dated Holocene palaeoclimate (palaeohydrological) trends and productivity changes based on multiproxy investigations of catchment, modern lake sediments, and cores from Lake Manasbal (NW Himalaya, India); (iii) use a combination of regional oxygen isotope transects to identify likely precipitation sources during Holocene extreme events; (iv) identify the impact of climate/hydrological changes and anthropogenic impact on lacustrine productivity in Lake Manasbal; (v) identify leads and lags in climate induced regime shifts in the lake.