A satellite's-eye-view of the Tibetan Plateau. Image from NASA's Terra satellite. Photo credit- NASA
Glaciers & Rivers
Glacial runoff from these regions feeds the largest rivers in Asia, including Yarlung Tsangpo (Brahmaputra), Drichu (Yangtze), Machu (Yellow), Zachu (Mekong), Macha Khabab (Ganges) and Sengye Khabab (Indus River) and more. Referred to as 'The Water Tower of Asia’, the Tibetan Plateau is the head region to major rivers that flow into India, Bangladesh, China, Nepal, Pakistan, Thailand, Burma and Vietnam. For China alone, 30 percent of its fresh water supply is met from the rivers flowing from Tibet. For many generations, this Plateau has met the basic necessities to sustain life and flourish human civilizations beyond its vast border. From the arid plains of Pakistan and India to the rice paddies of southern Vietnam, from the great Tonlesap lake of Cambodia to the North China plain, these rivers bring life and joy to millions of peoples.
The glacier-fed rivers originating from the Tibetan Plateau make up the largest river run-off from any single location in the world. Perhaps the most critical region in which the melting glaciers will negatively affect water supply (in the next few decades) will be China and parts of Asia, including India and Bangladesh.
Zachu or Mekong River, originating from Mount Thangla is the bloodline for the Mekong-region countries. This river flows from the central Tibet through Yunnan Province in China and then flowing through Laos, Thailand, Cambodia and finally ending its journey in Vietnam. This river directly supports approximately 70 million common peoples along its basin from fisherman to farmers.
Permafrost: The frozen soils
The presence or absence of the permafrost layer entails major variations in the soil’s physical structure, determining, to a large extent, the hydrological and nutritional status of the soil, which in turn, is pivotal in determining the vegetative coverage, plant community structure and productivity. Unlike the ones that are widespread in the Arctic and boreal regions of Northern Hemisphere, the permafrost prevailing on the Tibetan Plateau (1.3 to 1.6 million km2) are alpine permafrost. This type of permafrost are featured by warm permafrost and rich ground ice and are among the most sensitive to climate change and are particularly vulnerable to warming temperature. The alpine permafrost on Tibetan Plateau stores about 12,300 Million tonnes of Carbon.
Alpine Grasslands and Meadows
Tibet’s rangeland (Tib: Jhangthang), from the Northern Plateau of upper Tibet to the extreme eastern edge of the plateau, with an average altitude of 4000 to 5000 meters, covers approximately 70 percent of the total area of the Tibet’s area. The types of rangeland vary from alpine meadows and mountain scrub to mountain sparse wood and mountain desert, which helps sustain domestic herds and nurture a wide variety of wildlife species.
These rangelands and its cold alpine grassland soils are the major carbon sink and house a greater organic carbon pool. During the growing season, the alpine meadows appears to absorb ‘or’ take up CO2 at the rate of (1840 – 3050) mg/m2.day. Studies showed that total Soil Organic Carbon storage (sampled from the top 1 meter soil) in the alpine grasslands of TP was estimated about 7400 Million tonnes of Carbon.
For many generations, pastoral nomadism on these rangelands has been the best and the only option to live successfully. Over the time, Tibetan pastoral nomads has skillfully introduced domestic herds and maintained an extraordinary biodiversity of grasses and sedges, enabling human life to flourish at the Third pole.
Wetlands and wetland areas as carbon sequesters
Statistics of the natural wetlands (excluding lakes and floodplains) area by geographic regions in China revealed that Tibetan Highland holds over 51 percent of total natural wetlands. These wetlands are dominated by Salt Marsh, Peat land and Freshwater Marsh. These wetlands tend to trap carbon-rich sediments from watershed sources.
The Wetlands in Tibet play a major role in regulating the flow of rivers and also are the major carbon stores. They act like sponge, absorbing water during the summer when the water is in excess and releasing it in the winter when the runoff is short.
Much effort is needed on the ground in Tibet to restore wetlands, adapt farm and pastureland, and preserve forests before the impacts of climate change makes it more difficult to save ecosystems. Through state and people working together, desertification may also be reversed. The fate of future developments and social security of the lower riparian countries relies on how well the resources are managed in Tibet.