A worrying surge in glacial-origin floods is being observed across the Hindu Kush Himalayas, according to new findings from the International Centre for Integrated Mountain Development (ICIMOD). Scientists say that events known as glacial lake outburst floods (GLOFs) sudden releases of water from lakes formed by melting glaciers are becoming alarmingly frequent in the region.
Once rare, such events are now escalating fast. In the early 2000s, GLOFs in the region were expected once every five to ten years. Yet in just the last two months May and June 2025 ICIMOD has documented three: in Nepal’s Limi Valley, Afghanistan’s Andorab Valley, and Pakistan’s Chitral and Hunza regions.
“The acceleration of these types of events is completely unprecedented in the Hindu Kush Himalayan region. We need to delve deeper into the triggers that are resulting in cascading impacts,” said Saswata Sanyal, ICIMOD’s disaster risk reduction lead.
Region under pressure
The Hindu Kush Himalaya spans 3,500 km and covers eight countries Afghanistan, Bangladesh, Bhutan, China, India, Myanmar, Nepal and Pakistan supporting the food, water, and energy needs of nearly two billion people. But as global temperatures rise, this vital region is increasingly threatened by climate-driven hazards.
Glacial lake outburst floods are directly linked to warming. Long-term temperature rise drives the formation and growth of glacial lakes, while short bursts of extreme heat can trigger sudden ice collapses, avalanches or slope failures. Many of these are now tied to melting permafrost frozen ground that, when thawed, destabilizes landscapes and releases water trapped in glacial formations.
New kind of threat: supraglacial lake floods
ICIMOD scientists also warn that recent flood events were triggered not by the typically monitored moraine-dammed lakes but by a new, growing danger supraglacial lakes. These lakes form on the surface of glaciers, especially in areas covered with rock and debris. They start off small, often as meltwater ponds, but can expand quickly and even merge into larger, more volatile water bodies.
A recent flood in Nepal Bhotekoshi Nadi in Rasuwa district was caused by one such supraglacial lake, which was relatively small in December 2024 but grew substantially by June 2025. Traditional hazard assessments often ignore lakes below 0.02 square kilometres, assuming they’re low risk a perception now being challenged by these rapid changes.
According to ICIMOD, Nepal has 25 potentially dangerous glacial lakes, Tibet (China) has 21, and India has identified one. These numbers are based on older assessments that may not reflect the growing threat from smaller or newly formed lakes.
Detection challenges and urgent gaps
Supraglacial lakes are difficult to detect with currently available satellite tools. Freely available platforms like Landsat and Sentinel-2 have limited spatial resolution and often miss smaller or short-lived lakes making dynamic, real-time monitoring a challenge.
ICIMOD is calling for:
•updated glacial lake inventories,
•better tracking of smaller, short-lived ice-dammed lakes,
•improved hazard mapping that accounts for glacier retreat and lake evolution.
Without these, communities living downstream remain highly vulnerable to unpredictable floods that can wipe out homes, livelihoods, and infrastructure with little to no warning.
A stark future warning
If current warming trends continue, the Hindu Kush Himalayan region could see a three-fold increase in GLOF events by 2100. That would mean more frequent disasters hitting a region already on the climate frontlines unless mitigation, monitoring, and early warning systems are urgently scaled up.
For a region on which two billion people depend, the rising risks from glacial-origin floods are no longer distant or theoretical. They are here, accelerating, and increasingly deadly.