Mutual influence between human activities and climate change in the Tibetan Plateau during recent years
Introduction
The Tibetan Plateau (or Qinghai-Xizang Plateau, hereafter TP) with an average elevation of more than 4000 m above sea level (a.s.l.) and area of about 2.3 million km2 is of immense importance both to climate and to ecosystems of the Asian continent and even the whole world. Although adequate knowledge of climate change over the TP is still insufficient, which is partly due to the lack of sufficient observational data, research on the climate change in the TP has received more and more attention in the literature since mid-1970s (e.g. Lin and Zhao, 1996, Tang et al., 1998, Zheng and Zhu, 2000, Zheng et al., 2000). Many studies show there is strong evidence that the TP exerts profound thermal and dynamical influences on the local weather and climate as well as on atmospheric circulation (e.g. Manabe and Terpstra, 1974, Yeh and Gao, 1979, Yanai et al., 1992) and some studies suggest that the TP is one of the most sensitive areas to respond to global climate change (e.g. Zhang et al., 1996, Liu and Chen, 2000). Recent work by analyzing the temperature series of 97 stations carried out by Liu and Chen (2000) showed that the main portion of the TP has experienced statistically significant warming since the mid-1950s, especially in winter. The linear rates of temperature increase over the TP during the period 1955–1996 are about 0.16 °C/decade for the annual mean and 0.32 °C/decade for the winter mean, which exceed those for the Northern Hemisphere and the same latitudinal zone in the same period. However, its cause has not been clarified. There is no work dealing with the possible interaction between climate change in the TP and human activities such as grazing. Most of the work concerning climate change in the TP attempt to link the climate change to atmospheric circulations or global warming related to the atmosphere greenhouse gases (e.g. Lin and Wang, 1994, Yin et al., 2000, Liu and Chen, 2000, Liu and Yin, 2001).
It is well known that there is a vast expanse of grassland on the TP. The complex terrain and variable boundary conditions of the TP create unique weather and climatic characteristics as described in some Chinese and English literatures (e.g., Yeh and Gao, 1979, Gao et al., 1984, Domros and Peng, 1988, Tang et al., 1998, Zheng et al., 2000). Despite its harsh climatic conditions, millions of people make use of this vast area through the management of the rangelands that provide the feed for a variety of livestock on which people depend for their daily survival. Six of the largest rivers of the world originate from the TP and provide the much-needed irrigation water that feed the agricultural fields of hundreds of millions of farmers in the downstream regions. Climate impact on human activities and human impact on climate change in the TP have great importance not only to the local area but also to the whole Asian continent and even to the whole world. Some recent biome simulation work on the TP and their responses to global climate change has suggested that there would be a great change in vegetation and permafrost distribution and a significant increase in net primary production on the TP under changed climate with a CO2 concentration increasing Zhang et al., 1996, Ni, 2000.
The purpose of this study is to examine the relationship between human activities and climate change in the TP in recent years.
Section snippets
Data and methods
Due to the unique environment and social economic development situation, agricultural land (total of grazing land, farmland, forestry and orchard) is about 62% of the total TP and undeveloped land is 34%. Of the agriculture land, grazing land occupies about 80% and forestry about 19% (Wu and Yang, 2000). The annual statistic livestock production and meat production were therefore used for indicating the human activities. Monthly mean surface air temperature and precipitation data from most
Increase in livestock and meat production
Fig. 2 shows the annual variation of production numbers of livestock in Tibet and Fig. 3 shows the meat production variation in Tibet from 1978 to 1999. It can be seen that the production of sheep in Tibet has increased 106% and that of cattle 249% since 1978. Increases in beef and mutton production in Tibet are about 297% and 133%, respectively. Total meat production (beef, mutton and pork) has increased 212%. For other region of the TP, meat production has increased about 220% and number of
Discussion and conclusions
Livestock husbandry in the TP is still performed a primitive natural nomadic manner. There is even no artificial grassland field on the TP and no feed import from outside of TP. Production of livestock largely depends on the natural grass and water condition, and the efficiency of animal husbandry practices. Therefore, increase in production of livestock or meat means increased feed or plant biomass use on the TP. One to three times increase in production of livestock means that there should be
Acknowledgements
The authors wish to thank Dr. Y. Tang from National Institute for Environmental Studies, Japan for his helpful comments. This study was supported through The Global Environment Research Fund of Ministry of Environment, the Japanese Government.
References (27)
The climatic impact of a Sonoran vegetation discontinuity
Clim. Change
(1988)The impact of summer rainfall on the temperature gradient along the United States–Mexico border
J. Appl. Meteorol.
(1989)Impact of desertification on regional and global warming
Bull. Am. Meteorol. Soc.
(1991)- et al.
Impacts of land degradation on historical temperature records from the Sonoran Desert
Clim. Change
(1998) - et al.
Surface albedo and the Sahel drought
Nature
(1984) - et al.
The Climate of China
(1988) Is it a global change impact that the climate is becoming better in the western part of the arid region of China?
Theor. Appl. Climatol.
(1996)- et al.
Climate change and agricultural activities in the Taklimakan Desert, China in recent years
J. Arid Land Stud.
(1996) - et al.
Tibet Climate (in Chinese)
(1984) - et al.
Recent and future climate change in East Asia
Int. J. Climatol.
(1994)