naito_2006.htm

Bulletin of Glaciological Research 23 (2006) 51-61
©Japanese Society of Snow and Ice

Glacier shrinkages and climate conditions around Jichu Dramo Glacier in the Bhutan Himalayas from 1998 to 2003

Nozomu NAITO¹, Yutaka AGETA², Shuji IWATA³, Yoshihiro MATSUDA², Ryohei SUZUKI², KARMA⁴ and Hironori YABUKI⁵
1 Department of Environmental Information Studies, Hiroshima Institute of Technology, Hiroshima 731-5193, Japan
2 Graduate School of Environmental Studies, Nagoya University, Nagoya 464-8601, Japan
3 Department of Geography, Tokyo Metropolitan University, Hachioji, Tokyo 192-0397, Japan
4 Geological Survey of Bhutan, P. O. Box 173, Thimphu, Bhutan
5 Institute of Observational Research for Global Change, Yokosuka, Kanagawa 237-0061, Japan

Abstract

　 Variations of Jichu Dramo Glacier and some other debris-free glaciers as well as the surrounding climate were observed through Japan-Bhutan joint field activities in the autumns of 1998, 1999, and 2003. The annual precipitation around the Jichu Dramo Glacier was estimated to be greater than 1500 mm, based on the record over 340 days in 1998-1999. The surface level of the glacier, which is located in an area strongly influenced by the summer monsoon, was estimated to be rapidly lowering at an approximate rate of 2-3m a^-1 in 1998-2003. This estimate is the first example of surface lowering rates for glaciers in the Bhutan Himalayas. Further, its terminal retreat rate was estimated to be approximately 8m a^-1 in 1998-2003. The terminal retreats of some other debris-free glaciers around Jichu Dramo since the mid-1980s have also been confirmed by comparing them with photos taken previously. Further monitoring of the remarkable glacier shrinkage in Bhutan is essential to assess the general trend of glacier shrinkage in the entire Himalayas.