New research that analyses flood records of last 73 years reveals that climate change is the major driver of more frequent and less predictable floods in the high mountains of Asia.
The research covers the records of 1,015 floods in high mountains of Asia and has been published in the latest issue of Science Bulletin. It confirms a significant rise in the frequency of floods since 2000 and that temperature rise is driving the increase.
Science Bulletin is an international journal sponsored by the Chinese Academy of Sciences and the National Natural Science Foundation of China.
The research Flood complexity and rising exposure risk in High Mountain Asia under climate change was jointly conducted by Peking University, The International Centre for Integrated Mountain Development (ICIMOD) and University of Colorado. It studies a new inventory of the types, patterns and causes of floods in the region stretching back to 1950.
The research confirms that flood frequency has risen but a major 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 study confirms that planetary heating from the burning of oil, coal, and gas is driving the rise in all four of the main types of floods seen in the region.
The two most common are driven by rain and snowmelt. Less common, but more sudden and highly destructive are those that caused by glacial lake outbursts (GLOFs) and landslide-dammed lake outburst floods (LLOFs).
While population rises and expansion of infrastructure is increasing exposure to risk, temperature rise is the main factor in the rise in the number of floods. “The rules of floods are changing and the window for adaptation is closing,” warned Sonam Wangchuk, one of the report’s authors and a cryosphere specialist of ICIMOD.
Mr Wangchuk said, “A single monsoon cloudburst or glacial collapse can trigger cascading 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.”
Authors emphasise that while climate change is aggravating the risks of all types of floods, there are complex dynamics at play in each type.
Peking University principal investigator of the Cryosphere Dongfeng Li 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 also aggravate the risks from floods, especially urbanisation and land use changes, such as human settlements in flood plains, deforestation, and dams, can all increase vulnerability and reduce natural buffers.