A long-term health check
At the headwaters of the Urumqi River, scientists at the Tianshan Glaciological Station have maintained one of the world's longest and most detailed health charts for a glacier. The subject is Urumqi Glacier No. 1, a valley glacier that has been under continuous observation since 1959. This extensive record makes it an reference point for the World Glacier Monitoring Service. Researchers here track the glacier's "mass balance," an annual accounting of ice accumulation from snowfall versus ice loss, known as ablation, from melting.
The data reveals a persistent and accelerating decline. Between 1959 and 2010, the glacier's mass balance showed a decreasing trend of -14.5 mm per year. The loss has intensified dramatically in recent decades. One study noted that the average mass balance was -136.4 mm per year between 1959 and 1996, but this loss jumped to -663.9 mm per year from 1997 to 2010. From 1962 to 2018, the glacier's total area shrank by 19.3%. The rate of this shrinkage after 1994 was about three times faster than in the period between 1962 and 1986. The accelerated melt is linked to rising summer temperatures. The glaciers in the wider Eastern Tian Shan region lost 22% of their area between 1990 and 2015.