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Wednesday’s furious flash floods and landslides on the Nepal-Tibet border show how closely interconnected the Himalayan region is as an ecological disaster zone. An extreme event in the mountains can affect communities far away, across national borders. What happens in one part of the Himalayas cannot be regarded as any one country’s problem. The danger extends across the region.

For India, the concern is immediate and geographical. The Tibetan-origin Lhende river, where the flooding initiated, forms the Bhote Koshi in Nepal, which flows downstream as the Trishuli and the Narayani, which flows farther into India as the Gandak. What happens in the upper reaches of the river system can affect people downstream. The Himalayan rivers make cooperation on disasters a practical necessity, whatever the political circumstances.

The latest floods also point to a changing pattern of Himalayan risk. No rain fell when flooding occurred. The trigger appears to have been a glacier collapse and an ice-rock avalanche, followed by a temporary blockage and the sudden release of water and debris. This differs from the familiar picture of flooding and shows why disaster warnings in the mountains have to look beyond rainfall.

Weather forecasts will need to be backed by closer monitoring of glaciers, unstable slopes and other sources of sudden flooding. In the mountains, such events can develop rapidly, leaving little time to evacuate. Climate change must be part of this discussion, with continuously evaluated evidence. The broader changes in the Himalayas are clear. The region is warming and its glaciers are rapidly losing ice. These changes make it important to understand how risks are evolving rather than assume that past patterns will always hold.