(TibetanReview.net, Sep10’24) – The largest lake in Tibet Autonomous Region (TAR), located in Nagchu (Chinese: Naqu) prefecture-level city, has expanded to spill over into another lake and they could merge by 2030 as a result of climate change, reported the scmp.com Sep 10, citing scientists monitoring them.
The TAR’s largest inland lake, Siling (Tibetan: Serling Tso), has spilled over into another nearby salt lake, Bange (Drangkhog Tso), for the first time in more than 4,000 years, after decades of rising water levels driven by climate change, the report said.
Siling is located in the city’s Shentsa (Chinese: Xainza) and Palgon (Baingoin) counties while Drangkhog is in the city’s Shentsa county.
The report cited scientists monitoring the two lakes – which are about 6km (4 miles) apart – as saying they could merge, with significant possible implications for people living nearby.
The report said a team from the Institute of Tibetan Plateau Research at the Chinese Academy of Sciences published their analysis of the changes at Siling lake in the peer-reviewed Science Bulletin in July.
Siling has significantly expanded in the past two decades. It covered an area of some 1,640 sq km (630 sq miles) in the 1970s, but by 2023 the lake had swollen to 2,445 sq km (945 sq miles), Lei Yanbin, a professor with the institute and lead author of the study, has said.
The report noted that Siling and nearby lake Bange – once a source of borax – have been part of separate watersheds with no hydrological connection for more than 4,000 years but potentially as far back as 8,200 years ago, when glaciers melted and sea levels rose.
“While Bange [lake’s] water level decreased by about 1 metre [3 feet] over the last decade, Siling [lake’s] rose by 4 metres [13 feet],” Lei has written.
Siling was stated to have spilled over into an ancient riverbed between the two lakes in Sep 2023, breaking up a provincial road and forming a channel that was 200 metres at its widest and nearly 2 metres deep.
“The outburst flood … will lead to the rapid expansion of Bange,” Lei has said in a statement released by the institute.
“Satellite data revealed that within a month of the overflow, Bange’s area had increased by more than 10%.”
Lei has said the immediate cause of the overflow was a continued rise in water levels over the past 20 years, noting that it had risen by more than 13 metres from 1998 to 2023. Increased rainfall in the area in August and September last year was stated to have pushed the water levels to the point where the lake spilled over.
He sees rapid climate change on the Tibetan Plateau as being responsible for driving the problem.
Song Chunqiao, a professor at the academy’s Nanjing Institute of Geography and Limnology, has said the impact of climate change is being seen across the Himalayan region. He has said there were 11 such events between 2000 and 2018, and the most severe one in 2011 had put the railway between Qinghai and TAR at risk.
Lei’s team was stated to have also observed unprecedented expansion of lakes in the central Tibetan Plateau from 2017 to 2018, when the water levels of five lakes rose by between 1.4 metres and 2.8 metres. It expects Siling’s water levels to continue rising – potentially by another 16.8 metres by 2100.
The team members have said that even under the most conservative scenario for emissions growth, the lake is predicted to expand and it could merge with Bange around 2030.
Noting that the change could affect people living near the lakes, Lei has urged authorities to identify potential hazards from the expansion of inland lakes on the Tibetan Plateau caused by climate change.
“Real-time monitoring and early warnings for critical lake water level changes are needed to protect surrounding roads, bridges and villages from emerging threats,” he has said in the statement.
The Tibetan Plateau, known as “Asia’s water tower”, has more than 1,000 lakes and is the source of 10 major rivers in Asia that provide water resources to about 2 billion people in downstream countries, the scmp.com report noted.