Nepal Disaster Shows Danger of Living on Melting Ground

A massive mud tsunami recently struck Nepal, killing many people and leaving thousands more missing. The disaster hit mountain communities in the Himalayas, one of the world's most rugged regions. Dozens of bridges were washed away and large stretches of road were destroyed, making it very hard for rescue teams to reach survivors. Scientists say the disaster is a warning about what a warming climate can do to mountain areas around the world.

Scientists have been warning for years that rising temperatures are making the Himalayas more dangerous. The ground itself is shifting, and the risk of deadly floods and landslides is growing. Professor Umesh Haritashya, a glacier expert from the University of Dayton, is part of an international team studying the disaster. He says it is hard to ask people to simply leave their homes, but communities need to understand the dangers they face.

The Himalayas are sometimes called the 'third pole' because the region holds more ice and snow than anywhere else on Earth outside the Arctic and Antarctic. There are more than 55,000 glaciers spread across the Himalayan, Karakoram, and Hindu Kush mountain ranges. The area is warming faster than the global average, causing these glaciers to melt and shrink. As the ice melts, it forms large lakes held back only by loose rock and dirt, which can break apart without much warning.

Professor Haritashya's research has found more than 1,466 glacial lakes in the region. Most of these lakes formed because of rising temperatures since the mid-1900s. When the barriers holding these lakes back become weak, they can suddenly burst and release huge amounts of water. An avalanche or rockfall crashing into a lake can also cause a giant wave that triggers a deadly flood, called a glacial lake outburst flood, or GLOF.

There is another hidden danger beneath the ground. Much of the Himalayan region sits on permafrost, which is ground that stays frozen all year long. Ice inside the soil and rock acts like glue, holding everything together. As temperatures rise, this ice melts, and the slopes can become dangerously unstable.

As temperatures rise, the line where the ground stays frozen is moving higher and higher up the mountains. This means more slopes are becoming unstable as the ice inside them melts away. Scientists worry about what happens when several of these problems occur at the same time. A warming climate can melt glaciers, create unstable lakes, and weaken slopes — and when those things combine, the result can be catastrophic.

Melting permafrost is also damaging roads, buildings, and bridges across cold regions of the world. When the ice inside frozen soil melts, the ground becomes weak and uneven, and it can sink, crack, or collapse. Glaciologist Adrian McCallum from the University of the Sunshine Coast describes the changing ground this way: 'It becomes part liquid, part solid, part soup.' Countries from North America to Asia are all facing this growing problem.

Climate historian Ruth Gamble has studied the Himalayas and Tibet for more than ten years. She says the warming climate is also changing how rain and snow fall in the region. The area is fed by two weather systems — a summer monsoon and a winter snow cycle — and both are now shifting in ways that make extreme weather more likely. Instead of gentle, steady rainfall, storms are now dumping huge amounts of water all at once.

Dr. Gamble has studied historical records going back to 603 CE that show floods and landslides have always happened in this region. But she says these events used to be rare — now they are happening every single year. The burning of fossil fuels is driving the temperature increases that cause these events, and experts say things will keep getting worse until emissions reach zero.

Experts agree that the world must do more to help mountain communities adapt to these changes. Climate activist Shreya K.C. from Kathmandu says Nepal should not have to pay for a crisis it did little to cause. Professor Haritashya says this is a global problem that needs a global solution — one that goes beyond the borders of any single country. He believes the world owes these communities a responsibility to act.