Warnings must cross borders before disasters do

On 26 August 2026, a large rock–ice collapse on Nepal’s Langtang Lirung massif initiated the Gyirong–Rasuwagadhi transboundary cascade. The disaster reveals three clocks governing mountain risk: long-term preconditioning, minute-scale physical cascading and institutional response. Science cannot predict every collapse, but it can connect source monitoring, event detection, impact-based warning and pre-authorized action into a warning chain that outruns the hazard. Such capacity should become shared public-safety infrastructure for mountain societies.