How climate shapes the world, why science is an art, and why free data access and international collaborations are essential

Ulf Büntgen

On Wednesday 28 May 2025, at 15:24 local time, a substantial part of the Birch glacier in the Lötschen valley of the Swiss Alps detached and triggered a catastrophic rock-ice avalanche that obliterated most of the village of Blatten and nearby settlements (Büntgen et al., 2025a). An estimated 20 million tonnes of ice and rock travelled at a speed of up to 200 km per hour over 1200 m vertical distance to the valley floor and then nearly 200 m up the opposite slope of the valley. Preserved in Switzerland’s collective memory as the largest and most devastating ever monitored rock-ice avalanches, the Blatten disaster reveals the urgent need to improve research-based policy guidance for detecting, preventing, and managing multi-hazard cascades in steep terrain, including avalanches, debris flows, and glacial lake outburst floods. While continuous monitoring and effective risk management prevented mass casualties, most parts of the world lack the means and expertise to establish such early warning systems. This policy brief addresses the increasingly critical challenges that climate brings as it shapes our data-driven and globalised world, recommending pathways forward for policymakers to include harnessing both data and global cooperation.

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