… NCHM study reveals glaciers in Bhutan are more sensitive to climate change

YK Poudel

Three benchmark glaciers, Gangjula, Thana, and Shodug, are witnessing glacial water loss in billion annually, a recent National Centre for Hydrology and Meteorology (NCHM) study showed.

The glaciers fall in the clean type glaciers.

Principal Hydrology and Meteorology Officer at NCHM, Sonam Lhamo, presenting on “From the Cryosphere to the Biosphere: Climate Risks and Vulnerability in Bhutan,” said that glaciers in Bhutan lies in eastern part of Himalayas—more common and sensitive to climate change. “In Bhutan, 45 percent of river flow contribution is from glaciers.”

The report was presented at the two-day symposium titled Road to Dubai: The Bhutan Story at COP28, organised by Bhutan Ecological Society that ended on October 28.

The Gangjula glacier which is the headwater of Phochhu and Punatsangchhu, is 0.3 square Kilometres (sq. Kms), recorded thickness of 96.4 metres in 2019. In between 2004 and 2020, the glacier lost 30 percent of its ice—which is 6.3 billion water loss in 16 years. This has caused annual water loss of 369 million litres. The glacier is expected to be lost within this century.

Similarly, Thana Glacier, the headwater of Chamkharchhu and Manas basin, spanning over 3 Kilometres square with thickness of 210 metres is losing 6 billion litres of water annually, which is 7 percent of the glacial ice. The data with NCHM shows that in between 2016 and 2020, approximately 17 Gigatons of glacial ice is lost.

Shodug glacier, the new benchmark glacier is a head water of Thimchhu, on which monitoring was started in 2001, is 1.4Km square with thickness of 126.6 metres (2021). The glacier mass balance in between 2021 and 2022 was minus 1,762.29 millimetres water per annum.

According to Bhutan Glacial Lake Inventory 2021, Bhutan records 567 glaciers covering 55.04Km square—Phochhu has the maximum.

Of the glaciers, 17 are potentially dangerous—Punatsangchhu has 11, Mangdechhu has 3, Chamkhar chhu has two and one in Kurichhu.

A recent study from the International Centre for Integrated Mountain Development (ICIMOD) reveals that snow-covered areas and snow volumes will decrease in most regions over this decade due to increased temperature and snowline will also decrease.

The study also states that, even if global warming is limited to 1.5 degree Celsius, warming will be at least 0.3 degree higher in Hindu Kush Himalayan regions.

The streamflow is projected to increase until 2050 and decrease in pre-monsoon flow thereafter, risking the hydropower sector, the study also stated.