Climate change shrinks Bhutan’s glaciers

A database on glaciers and glacial lakes of Bhutan has now been launched 

ICIMOD: Climate change has shrunk glaciers that feed most of the Bhutanese rivers since 1980, International Centre for Integrated Mountain Development (ICIMOD) experts said.

ICIMOD’s Programme Coordinator for Cryosphere Initiative Regional Programme on Cryosphere and Atmosphere, Pradeep Mool, said, “The glacial lakes increased by 8.7 percent while the actual size of the glaciers shrunk by 22 percent between 1980 and 2010.”

Within the same period, the glaciers receded from 860 sq km to 671 sq km in 2010 in Bhutan. These findings from remote sensing were corroborated by field investigation.

A team of ICIMOD scientists including glaciologists went with the Bhutanese counterparts to study causes of the Memari Tsho outburst of June 28.

The team visited four lakes at the source of Mochu including Memari Tsho and concluded that the four lakes should be removed from the list of the potentially dangerous lakes. According to ICIMOD and geology and mines department 2001 inventory, there were 677 glaciers and 2,674 glacial lakes, out of which 24 were considered potentially dangerous.

The investigation found the four lakes at the source of Mochu did not pose any immediate flood risk. According to them, there were no glaciers near these lakes.

ICIMOD, Gross National Happiness Commission, and the Department of Hydro-Met Services (DHMS), Bhutan signed the long-term cryosphere monitoring programme in Bhutan and strengthening capacity of DHMS in October 10 last year.

The experts reported their findings at a recent workshop in Thimphu on the glacial lakes.

There were 2,068 galcial lakes in the country as of last year.

Amochu basin has 50  glacial lakes, Wangchu has 158 lakes, Punatsangchu 803, Manas or Drangmechu 1,049 and Ngeramari eight lakes.

The glacial lakes  cover  100.78 sq km of the mountains in 2014.

“While the glacier changes are more visible at the sub-basin level, the nation as a whole is not very significant,” Pradeep Mool said.

Inventorying glaciers and glacial lakes in the country began from 1999. ICIMOD’s (Dr) Arun Shreshtha said that overall, the most visible evidence is the change in the glacier.

“As glaciers retreat glacial lakes may form and expand and many are observed at elevations of around 4,000m,” he said.

“These events, (as the team found) can be, with certainty, attributed to climate change,” he said. “Glacier changes cannot be attributed to anything else.”

He said that general tendency in the region is that the atmospheric temperature is rising.

“We also observed from other studies that warming is significant in higher altitude compared to lower areas,” he said.

However, he said that lack of monitoring stations at higher altitudes such as those above 4000m limits the scope of their research.

There is also limited research in the area to show the climate change impact on rainfall patterns.

Bhutan makes up one percent of the Hindukush Himalayan range, contributing 1.1 percent of its glaciers. Glaciers occupy 1.7 percent or 671 sq km of the country.

As of 2010, Bhutan had 866 glaciers and the ice reserve according to ICIMOD experts is 47.2 cu km.

Economic affairs minister Norbu Wangchuk launched the database on glaciers and glacial lakes of Bhutan at a workshop on the dissemination of the team’s findings of the Lemthang Tsho outburst in Thimphu last we.

“The database has information from glaciers to events of glacier lake outburst floods in Bhutan,” Pradeep Mool said.

Tshering Palden

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