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

极端气候，如严重、长期的干旱或洪水，可能会产生深远的生态和社会经济后果。全球气候变化预计将增加印度夏季风(ISM)领域区域气候极端事件的频率和强度。现有的古气候数据表明，热带和温带强迫可能在几十年甚至几个世纪内持续高发，导致区域水文变化和生态制度转变。特别是喜马拉雅西北地区，由于年降水量的增加和冬季(西风)降水与例如AO/NAO和ENSO的非平稳联系及其对这一生态脆弱地区经济福祉的严重影响而引起关注。目前，具有历史强迫的多模式集合平均对2001-2005年气温和降水的模拟是合理的，但各预报模式之间仍然存在较大的差异。因此，喜马拉雅西北部的长期(古)气候数据不仅在区域尺度上很重要，而且对了解印度次大陆上持续的极端气候也很重要。在这种跨学科的协调努力中，我们的目标是利用气候敏感地区的湖泊(沉积物岩芯)的多重代理方法，对ISM领域的全新世气候变异性进行全面的描述。三项密切相关的建议旨在：(I)重建以区域极端事件为重点的全新世时空ISM；(Ii)使用跨学科、多代理的方法来确定极端事件对生态系统的影响；(Iii)利用区域模式、数据分析和建模来确定气候极端事件背后的驱动力；以及(Iv)使人类和气候对生态系统的影响脱钩。这些可能为全新世极端事件提供类比；(Ii)根据对马纳斯巴尔湖(印度喜马拉雅西北部)的集水区、现代湖泊沉积物和岩心的多代理调查，建立完整的全新世古气候(古水文)趋势和生产力变化的记录；(Iii)利用区域氧同位素断面的组合来确定全新世极端事件期间可能的降雨源；(Iv)确定气候/水文变化和人为影响对马纳斯巴尔湖湖泊生产力的影响；(V)确定气候引起的湖泊制度变化的领先和滞后。

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.