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Shri Ashtapad Maha Tirth - II
1. Introduction The Tibetan Plateau, frequently referred to as the Earth's "third pole”, is one of the major drivers of global climate [1-3]. With a mean altitude of -5000 m a.s.l. and an area of more than one million km2, it is the highest and largest plateau of the Earth. Over the past 70 million years the tectonic formation of the Tibetan Plateau has modulated the climate and switched on the monsoon system. Since its formation, the Tibetan Plateau, its vegetation, and temperature difference between plateau and ocean, represent a major controlling factor of the monsoonal climate of East Asia and Africa (Fig.1).
Winter Monsoon
Westerlies
Southwest Asian
Monsoon
East Asian Monsoon
Fig.1: Scheme of the principle atmospheric circulation patterns in the area of the Tibetan Plateau.
There is also evidence for teleconnections between the Asian monsoonal system, climate oscillations in the North Atlantic, and the El Nino-Southern Oscillation during the Quaternary [4-9]. Because of its high elevation and extreme continentality, the Tibetan Plateau responds like a delicate sensor to environmental change, and this response can in turn cause drastic shifts and modifications, especially in the hydrological cycle. The sensitivity to global warming of the Tibetan Plateau, for example, is underlined by ice core data suggesting that the large-scale, plateau-wide 20th-century warming trend appears to be amplified at higher elevations [10]. This causes significant environmental changes, demonstrated for example in glacier extent, in the depth and persistence of permafrost, in vegetation cover, and in ecologic diversity. Together with the Himalayas, the Tibetan Plateau forms the headwater area of a series of major rivers, mostly fed by melt waters that provide half of humanity with water for drinking, irrigation and the production of electric power [11,12]. Similar to the polar regions, it provides high resolution archives of global and regional climate evolution, and, in addition, offers an excellent opportunity to study responses and interactions of climate and ecosystems to past and present external forcing and internal feedback mechanisms. It is thus a spectacular field laboratory Tibetan Plateau: Formation-Climate-Ecosystems
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