Renowned Nepalese mountaineer Nirmal Purja and his team looked poised for a successful ascent of Broad Peak in Pakistan’s Karakoram Range before an avalanche swept them away.The climbers had been missing since July 30, when an avalanche struck the expedition at an altitude of 6,600 metres. The incoming wall of snow threw the climbers 1,000 feet down, the GPS tracker attached to their bodies revealed.A rescue operation was launched by local authorities and three bodies were recovered on Friday. The expedition seemed to be a lesser challenge for Purja, who had ascended eighth-thousanders 57 times. Eighth-thousanders refer to the 14 mountains in the Himalayas and the Karakoram range, which exceed 8,000 metre altitude.Broad Peak is the 12th highest at 8,047 metres. Suggesting a departure from expected trends, experts say that avalanches of such nature shouldn’t be occurring in July.ALSO READ | Nirmal Purja, mountaineering legend, among 10 climbers killed in Broad Peak avalanche“There is a particular period —February to April— which is the highest avalanche risk period because after the high snowfall during the winter months from December to January. According to studies, generally, avalanches take place between February and April,” Dr Hasan Raja Naqvi, an Assistant Professor of geography at New Delhi’s Jamia Millia Islamia told The Indian Express.Naqvi said the impact of climate change is clearly visible in the Western Himalayas, which is bearing the brunt of the changing weather events.According to a report by the scientists at the Institute for Environmental Sciences at the University of Geneva, there has been an increase in avalanche occurrence in recent decades in Western Himalayas.Story continues below this adApart from frequent avalanches, weather events like snow blizzards, intense snowfall and extreme precipitation remain challenges at the high altitude. In order to reduce risk, mountaineers often resort to ascending critical patches on high mountains during night hours.Overcrowding at the Himalayas has also posed several challenges for the climbers.“While I was climbing Everest, a lot of people died because of slow-moving climbers. Even if I’m fast, but somebody ahead of me is slow and I am actually dying because of him as my oxygen is running out,” says Rizza Alee, who attempted to climb Mount Everest in 2019, the same year Nirmal Purja was on ‘Project Possible’, where he became the first climber to summit all 14 eight-thousanders in just 6 months and 6 days.ALSO READ | Nims Purja’s last message before Broad Peak avalanche: ‘I ask for nothing but safe passage’“There’s only one rope. You have to be clipped to that rope and can’t overtake. If you try to overtake, you can die if you slip,” he added. Eleven people died in the spring season of Everest that year, he remembers.Story continues below this adWhile the footfall on Everest and its neighbouring peaks like Lhotse or Makalu have made them more explored, Karakoram, on the other hand, remains remote.The terrain is difficult and weather is unpredictable.Climbers call 8,000 altitudes the “death Zone”, where the body stops working because of the lack of oxygen. At high altitude, people start experiencing High Altitude Cerebral Edema (HACE), where lack of oxygen results in brain swelling, and High-Altitude Pulmonary Edema (HAPE), where fluid builds up in the lungs.“I had to turn down at 800 meters before the summit as my oxygen regulator broke. I could see the summit, but I turned back,” Alee said.“I could have easily summited Everest, but I would have definitely died on my way back.”