Scientists say climate change may have intensified catastrophic Nepal flood | Ukraine news - #Mezha

The disaster unfolded in seconds, as a collapsing mountain unleashed a chain reaction that overwhelmed valleys and left rescuers facing an unprecedented challenge.

The catastrophic flood on the border between Nepal and China in late August was likely the result not of a single extreme event, but of a complex sequence of natural processes. Their impact may have been amplified by decades of global warming caused by the burning of fossil fuels. This was the conclusion reached by more than 20 international scientists.

As reported by CNN

A rock-and-ice avalanche destroyed towns, roads, and bridges in narrow mountain valleys. At least 1,300 people were killed in the disaster, while more than 5,000 remain missing. After the rescue operations ended, Nepal moved on to rebuilding the affected areas.

On August 26, a mass of rock and ice approximately 600 meters wide broke away from Langtang Lirung. It traveled about 2,100 meters before crashing into the river channel, releasing energy comparable to that of a magnitude 5.2 earthquake.

The impact was so powerful that the ice melted almost instantly. The flow swept up water-saturated debris and likely crashed into ice buried beneath the valley. This created a flood wave that raced more than 32 kilometers downstream at high speed.

This was an unprecedented disaster for the Himalayas.

– Walter Immerzeel

How climate change may have intensified the flood in Nepal

Scientists from the international World Weather Attribution (WWA) network, which studies the influence of climate change on extreme weather events, suggest that the slope may have been primed for collapse by the magnitude 7.8 earthquake that struck in April 2015. At the time, a rock-and-ice avalanche occurred on the southern side of the mountain, potentially weakening the slope. Landslides became more frequent in the area afterward.

The researchers believe that several factors acted simultaneously. The freezing level in the Himalayas is rising by more than 98 meters per decade. Warming weakens high-altitude permafrost, which holds together ice, rocks, sand, and soil. Its thawing reduces the strength of the rock and allows water to penetrate the mountain slope more easily.

The condition of the Langtang Lirung glacier may also have played an additional role. Over the past several decades, particularly since 2010, it has thinned and retreated substantially. Meltwater may have seeped into cracks and further weakened the slope.

Weather conditions may also have heightened the danger. An exceptionally large amount of snow fell in the region during the autumn, particularly in October and early November. At the same time, July and August were the warmest on record in the area, which may have caused substantial ice melt.

Historical data and climate models indicate that July and August temperatures in the area are now approximately 1.5 degrees Celsius higher than they would have been without the influence of climate change. The average annual temperature has risen by 2 degrees, significantly exceeding the global average.

At the same time, scientists found no similarly clear link between global warming and an increase in snowfall or precipitation. Assessing this connection is complicated by the Himalayas’ difficult terrain and the limited number of meteorological observations.

There is no doubt that human-caused climate change played a role in creating the conditions for this disaster.

– Friederike Otto

Why an early warning might not have saved lives

The authors of the analysis noted that the collapse was exceptional in its scale, speed, and complexity, with no obvious precedent in the region. In their view, none of the existing early-warning systems could have provided enough time to evacuate the population.

Friederike Otto stressed that events of this magnitude exceed society’s ability to adapt to natural hazards. Without rapid cuts to emissions from fossil-fuel burning, similar disasters may occur more frequently.