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AP photo NEW DELHI: The frequency of floods in High Mountain Asia (HMA) has increased significantly since 2000 due to climate change, according to a new study. The study, conducted by a team of scientists including environment expert Sonam Wangchuk, analysed 1,015 floods since 1950. Since 1950, the region's average temperature has shown a steady rise, warming at a rate of 0.
3 degrees Celsius per decade. Meanwhile, precipitation patterns have changed in complex ways, both in terms of location and timing, the scientists said. They said this rapid warming, combined with shifting rainfall patterns, is affecting the region's water cycle and increasing flood risks.
"In terms of temporal trends, the frequency of recorded flood events since 2000 has generally increased compared to the earlier period, with pluvial floods and snowmelt floods exhibiting a more considerable rise," the authors said. "The study confirms that flood frequency has risen, but a key additional finding is a rise in the unpredictability in the timing of floods: while most events continue to occur during monsoon, there is a marked rise in the number of floods happening outside these times," the International Centre for Integrated Mountain Development (ICIMOD) said in a statement. HMA, also known as the 'Asian Water Tower', is the largest source of frozen water outside the polar regions.
It feeds 10 major rivers that support over 2 billion people downstream. Due to its high altitude and vast ice cover, HMA is extremely sensitive to climate change. Earlier studies show that temperatures in this region are rising at twice the global average, altering rainfall patterns.
This has increased the risk of floods, especially glacial lake outburst floods (GLOFs), which are becoming more common. For example, in the summer of 2023, monsoon-triggered floods in the southern Himalayas of India, Nepal and Pakistan killed over 1,500 people. The ICIMOD said the study confirms that burning oil, coal and gas is increasing the frequency of floods in the region.
The most common types of floods are caused by heavy rain and melting snow. Less frequent but far more sudden and destructive are GLOFs and landslide-dammed lake outburst floods (LLOFs). While population growth and expanding infrastructure are increasing exposure to flood risks, rising temperatures remain the main factor behind the increase in all four types of floods, the ICIMOD said.
"The rules of floods are changing and the window for adaptation is closing," warned Wangchuk. He cautioned that a single monsoon cloudburst or glacial collapse could trigger devastating disasters, overwhelming unprepared regions. "We should prioritise real-time monitoring of floods in vulnerable valleys, restrict infrastructure projects in high-risk zones and strengthen data-sharing agreements between High Mountain Asia nations to address transboundary threats," he said.
The authors said that while climate change is worsening all types of floods, each type has unique triggers. Report author Dongfeng Li, principal investigator of the Cryosphere and River Lab at Peking University, said, "While pluvial and snowmelt floods result from extreme rainfall, snowmelt floods are driven by rising temperatures and increased soil moisture. In contrast, GLOFs and LLOFs are shaped by complex interactions between climate, glaciers, and topography.
" Human activities are making flood risks worse. Rapid urbanisation, deforestation and construction in flood-prone areas are reducing natural buffers and increasing vulnerabilities, he said..
