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HIMPAC Forscher Gruppe Seminar

  Seminars & Colloquia

18 Nov 2010, 14.30 hrs, in Haus H (VR2) GFZ Potsdam

Vegetation vis-à-vis climate change during

Holocene in the Himalaya

 

Dr. A. Bhattacharya
Birbal Sahni Institute of Palaeobotany
53, University Road, Lucknow-226 007, India

For the understanding of the monsoon dynamics and long-term relationship between climate of the Himalayan and other regions, a long climatic record is a prerequisite. Since instrumental data is short, we need to reconstruct climate through analyses of various proxy records. Among the catalogue of proxies, pollen offers a broad perspective of palaeoclimate and significantly helps in understanding the long-term palaeoclimate of the Himalaya. Analysis of temporal variation vegetation during the Holocene from sites close to glaciers of the Himalayan region will be useful in understating the climatic changes vis a vis fluctuation of glaciers of the region.  Pollen assemblage of this alpine  region above tree line is characterized by deposition of pollen from local taxa (alpine vegetation) as well as extra local taxa (trees growing at lower elevations comprising both conifers and broad-leaved taxa). A good amount of pollen (both local and extra local) in sediments suggests that site was much closer to tree line and the area itself had  good vegetation cover under amelioration of climate (warm-moist). Alternatively, an increase of local taxa especially steppe elements in the pollen spectra suggests existence of cooler-drier climate. Based on this principle past alpine vegetation of the Himalaya has been interpreted spatio-temporally in terms of broad climate changes. In the Northwest Himalayan region, climate was warm-moist during major part of the Holocene with short phases of interruption of cooler and drier phases around 8.3-7.3 ka BP, 6 - ~3 ka BP and 850 years BP. In contrary, data from the Northeast Himalaya is available only for Late Holocene. It reveals warm and moist climate around 1,800 years BP, similar to condition prevailing at present. Subsequently, further amelioration of climate has been recorded around 1,100 years BP (~AD 985) that corresponds to medieval warm period. Around 550 years BP (~AD 1400) a trend towards cooler and comparatively less moist climate might be the impact of Little Ice Age. This is followed by an amelioration of climate comparable to present day climatic condition.

 

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