Climate change raises risk of 'catastrophic' events as Nepal-Tibet flood death toll mounts

Scientists have warned that landslides and glacial collapses, like those responsible for this week's devastating flooding in Nepal and Tibet, are likely to become more frequent due to climate change. A massive surge of water and debris swept away people, roads, and buildings, resulting in over 600 deaths, primarily in Nepal but also a few in Tibet.

Rescue operations persist, though they are occasionally halted by the threat of further flooding, as the lakes in the region could overflow. The catastrophic event is believed to have originated on the Langtang Lirung peak in Nepal, situated just 15km from the Nepal-China border where the floods struck.

Himalayan glaciers are "retreating like crazy" as the climate warms, according to Mike Searle, a professor of earth sciences at the University of Oxford. Alongside the retreat of glaciers, the thawing of mountain permafrost poses a significant risk. The ice that secures shattered rock surfaces melts, leading to landslides from the mountains.

Dr Richard Waller, a senior lecturer in physical geography at Keele University, explains that this event was a result of a perfect storm of factors, including rapid warming, which allowed water to enter the glacier through crevasses, lubricating it and enabling it to slide more easily along the rock.

Another contributing factor is the ongoing growth of the mountains due to tectonic activity, which makes the glaciers steeper and more prone to collapse. The enormous waves of water that caused such devastation were likely not the direct result of the glacier collapse. Instead, debris probably formed a dam in the river, creating a lake that took two days to fill before breaching its dam and causing catastrophic floods.

Dr Waller hopes that the devastation caused by this week's events will lead to detailed hazard mapping to identify other areas at risk of similar disasters, allowing for early warnings and potential disaster prevention. He contrasts this situation with the evacuation of the Swiss village of Blatten in May 2022, which was successfully evacuated a week before it was destroyed by a glacial collapse and landslide.

Currently, only the Khumbu glacier on the slopes of Mount Everest is being monitored in detail. The affected regions are particularly vulnerable due to their location in river valleys. Prof Searle suggests building roads and houses higher up to reduce risks, although steep valley sides make this challenging.

Immediate aid is desperately needed, especially for UN organizations. The reduction of USAID funding has had a disastrous impact on impoverished countries like Nepal. Dr Ethan Lee, a postdoctoral researcher in glacial modelling at the University of Sheffield, emphasizes that while this event cannot be directly attributed to climate change, warming does have a destabilizing effect that can be compounded by other factors.

He notes that this phenomenon has been observed in previous disasters, such as the 2021 Uttarakhand flood in northeastern India and the 2022 Marmolada glacial collapse in Italy. Dr Diana Francis, an associate professor at Khalifa University, explains that glaciers in mountainous regions are more sensitive to climate change than those in polar regions, as they lack the protective buffer of sea ice.

She recommends global mapping of populated areas in regions prone to glacial collapses to enable the implementation of risk reduction measures.