December 16, 2016
Landsat image comparison of the Laigu Glacier in 1988 and 2015. The red arrow indicates the 1988 terminus and the yellow arrow the 2015 terminus location. The purple dots in 2015 indicate the snowline.
Laigu (Lhagu) Glacier, China is in the Kangri Karpo Mountains of the Southeast Tibet Plateau and drains into the Salween River. This is the largest glacier in its region at 32 km in length. The glacier terminates in an expanding proglacial lake, Laigu Lake. Here we examine changes in Landsat imagery from 1988 to 2015 to identify response to climate change. Wang and others (2011) note that glacial lakes have expanded from 1970-2009 by 19% and the area that is glacier covered has decline by 13% during the 1970-2009 period in the nearby Boshula Range. At the AGU this week research based on Landsat imagery indicates a 20% per decade velocity decline on the glacier (Landsat Science, 2016).
In 1988 Laigu Glacier terminated in the proglacial lake that was 2 km across from north to south and 1.3 km from east to west. By 2001 the lake had expanded to 1.6 km from east to west. The transient snow line is at 4300 m. In November, 2014 the snowline is at 4700 m. In October, 2015 the snowline is at 4700 m again. The glacier has retreated 1900 m from its 1988 terminus along the southern shore of the expanding lake and 900 m along the northern shore. The expansion of the lake along the southern shore is evident in the 2004 and 2014 Google Earth segmented image below, note the pink arrows. The high snowline indicate a reduced accumulation, which reduces the flux into the ablation zone, this is evident in the reduced glacier velocity noted by Dehecq (2016). The reduced velocity will lead to a continued retreat of the glacier and expansion of the lake. This region has experienced a sustained rise in summer temperatures (Wang and others, 2011). The snowlines remaining high into November indicates warmer conditions in the post summer monsoon season also. The high snowlines and lake expansion due to glacier retreat is a familar story in the region, Chutanjima Glacier and Menlung Glacier.
Landsat image comparison of the Laigu Glacier in 2001. The red arrow indicates the 1988 terminus and the yellow arrow the 2015 terminus location. The purple dots in 2001 indicate the snowline.
Landsat image comparison of the Laigu Glacier in 2014. The red arrow indicates the 1988 terminus and the yellow arrow the 2015 terminus location. The purple dots in 2014 indicate the snowline.
Summer temperature rise form Wang and others (2011).