Wu, Qingbai, and Zhang, Tingjun: Recent permafrost warming on the Qinghai-Tibetan Plateau

Journal of Geophysical Research, Vol. 113 (2008) D13108; doi:10.1029/2007JD009539

Recent permafrost warming on the Qinghai-Tibetan Plateau

Qingbai Wu (State Key Laboratory of Frozen Soil Engineering, Cold and Arid Regions Environmental and Engineering Research Institute, Chinese Academy of Sciences, Lanzhou, China, and National Snow and Ice Data Center, Cooperative Institute for Research in Environmental Sciences, University of Colorado, Boulder, CO, U.S.A.)

Tingjun Zhang (National Snow and Ice Data Center, Cooperative Institute for Research in Environmental Sciences, University of Colorado, Boulder, CO, U.S.A., and Chinese Academy of Meteorological Sciences, China Meteorological Administration, Beijing, China)

(Received 25 October 2007, accepted 1 February 2008, published 9 July 2008.)

Abstract

Permafrost temperature monitoring through 10 boreholes up to 10.7 m depth has been conducted half-monthly from 1996 through 2006 along the Qinghai-Tibetan Highway. The primary results show that the long-term mean annual permafrost temperatures at 6.0 m depth vary from −0.19°C at the Touerjiu Mountains (TM1) site to −3.43°C at Fenghuo Mountain (FH1) site, with an average of about −1.55°C from all 10 sites over the period of their records, indicating permafrost is relatively warm on the Plateau. Mean annual permafrost temperatures at 6.0 m depth have increased 0.12°C to 0.67°C with an average increase of about 0.43°C during the past decade. Over the same period, mean annual air temperatures from four National Weather Service Stations show an increase of about 0.6°C to 1.6°C, generally sufficient to account for the permafrost warming although other factors, such as changes in snow cover and soil moisture conditions, may also play important roles in permafrost warming. Increase in summer rainfall and decrease in winter snowfall may be cooling factors to the underlying soils, offsetting less degree of permafrost warming compared with the magnitude of air temperature increase. Permafrost temperatures at 6.0 m depth increased year-around with most of the increase happened in spring and summer. Winter air temperature has increased 2.9°C to 4.2°C from 1995 through 2005, which may account for significant spring and summer permafrost warming at 6.0 m depth due to three to six month time lag. However, there were no significant trends of air temperature change in other seasons. Further investigation, especially comprehensive monitoring, is needed to better comprehend the physical processes governing the thermal regime of the active layer and permafrost on the Qinghai-Tibetan Plateau.

Key words: permafrost warming, Qinghai-Tibet Plateau

Index Terms: 1823 Hydrology: Frozen ground; 1824 Hydrology: Geomorphology: general (1625); 3322 Atmospheric Processes: Land/atmosphere interactions (1218, 1631, 1843); 1829 Hydrology: Groundwater hydrology.

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Citation: Wu, Q., and T. Zhang (2008), Recent permafrost warming on the Qinghai-Tibetan Plateau, J. Geophys. Res., 113, D13108, doi:10.1029/2007JD009539.

Copyright 2008 by the American Geophysical Union.