In the cold dawn of 1 August 2008, 31 climbers from eight separate international expeditions set off for the final day's ascent of K2 in northern Pakistan – a near-perfect pyramid which, though smaller than Everest, has lured the best climbers for decades. Less than 48 hours later, 11 climbers would be dead, in one of the worst tragedies in Himalayan history, a story told in my book No Way Down. The edge of a gigantic ice shelf sheared off, sending blocks of ice down the mountain that killed one climber and swept away the network of fixed ropes the teams needed to get down. Trapped in darkness in the so-called death zone, where body and mind gradually break down due to lack of oxygen, the mountaineers had to climb down without ropes or stay overnight in the plummeting temperatures.
The human cost of climbing and exploration is borne not just by the mountaineers who die or are injured but also by the families they leave behind. Of the 11 who died, eight were married or had long-term partners, others had girlfriends, and six had children. One had grandchildren, and the first child of one of the climbers, a young Nepalese Sherpa, was born back in Kathmandu hours before he died.
Two years on from that terrible day on K2, the repercussions are still being felt. I talked to three of the families to find out how they are.
Cecilie Skog and Rolf Bae
While other climbers' spouses resented the months they spent away from home and the risks they took, Cecilie Skog and Rolf Bae were both accomplished mountaineers – she was the first woman to stand at both poles and on the tallest peaks in every continent. They often climbed together and shared a passion for the outdoors.
They had met on Mount Elbrus in Russia, in 2003, and married in 2007, just over a year before the ascent of K2. They had moved in together in Stavanger, in Norway, and started a business leading other expeditions.
Cecilie felt ready to have children and they had discussed it. She thought she could return to working as a nurse and when they climbed, they could take their children with them to the mountains. But Rolf wasn't ready to settle down. He died on the mountain, swept away by an ice avalanche, yards in front of Cecilie.
Cecilie was the first to arrive at K2 in 2008. When Rolf arrived later he brought her a present – a colourful plastic inflatable sofa for their tent, where they socialised with other teams by the warmth of a gas heater, watching DVDs on Rolf's laptop.
Cecilie reached the summit on August 1 but Rolf turned back, tired and perhaps suffering from altitude sickness. He waited for his wife and they began to descend together. Then, Rolf ventured out under a huge ice cliff and was swept into the void as the ice collapsed. Cecilie composed herself and gradually continued to descend. The next day she got to the base of the mountain – helped, she was convinced, by Rolf's voice whispering to her. She telephoned Rolf's parents in Norway to tell them their son was dead. He was their only child. "It's OK," Rolf's father assured her. "We only have you now. You must get down safely."
Back home in Norway, she couldn't face the apartment she had shared with Rolf, and moved in with his parents. She continued to rely on their support and the support of her friends as she struggled to come to terms with what had happened.
She also continued to travel – to Greenland not long after K2 and last winter to the south pole with an American adventurer, Ryan Waters. Those trips began to help her get over Rolf's death, she says. She will not give up her life in the wilderness.
This year, she came to New York, where we met. I was struck that she had brought her climbing harness – she spent many days climbing the walls in a sports centre in Manhattan, and bouldering in Central Park. "It is very easy to sit here and say we should not have done it," she told me. "But I am glad that Rolf was able to live the life he did. One thing that he taught me: You should not just sneak after your dreams. You should grab them with both hands and hold them really tight and try to live them."
Next year, she plans to travel back to K2 with Rolf's father to set up a monument to Rolf. But she will never climb K2 again or any of the Earth's tallest, most dangerous peaks. She will miss the exhilaration. "But I have decided that's not for me now. I don't know if I could tell my mum that I am going back. I could not look her in the eye and say that. One of the hardest things on an expedition is knowing people are sitting at home scared and waiting for you to come back."
Hugues d'Aubarède
Hugues d'Aubarède was a 61-year-old Frenchman from Lyon with a partner, two daughters and two grandchildren. He had already tried twice to reach the summit of K2 and thought this would be his last chance.
Hugues came to climbing late in life, but his infatuation began in 1972 when he glimpsed the summit of Kilimanjaro from an aeroplane as he travelled on military service. He never forgot it but his wife didn't approve of climbing, so he got on with his life as an insurance agent. But in 1993, they divorced – and a year later, aged 47, he travelled with his new partner, Mine, to Kilimanjaro.
In 2004, Hugues became the 56th Frenchman to climb Everest. Sometimes he climbed with his daughters, but they never went with him to the Himalayas or other very high mountains. His absences caused friction. Mine and his daughters, worried that one day he might not return. His younger daughter, Constance, was getting married in September 2008 and she wanted him back safely and on time. She sent Hugues a bottle of Chartreuse on K2 and a note with the latest wedding news. She warned her father not to be late – she didn't want to walk to the altar alone. On K2, he kept in touch with the family almost daily. A friend in Lyon, Raphäele Vernay, kept a blog for him, taking down the messages he called in on a satellite phone. Hugues took comfort, he said, reading in his sleeping bag the text messages friends and family sent.
From the summit, Hugues called Mine and promised it would be his last climb. He was right, but not in the way he intended: after an ice avalanche swept away the ropes, he tried to descend a steep gully and fell to his death.
Five months later, I travelled to Lyon and spent several days with his family. I found a yearning for understanding and a strong sense of loss. I listened to stories of Hugues' passion for the mountains and glimpsed the fascinating alter ego he had constructed through his pursuit of distant peaks – as if he had stepped out of his life as an insurance agent into one of exotic adventure. "He was a very closed person but he became a lot more accessible," one friend said.
But as well as love, I witnessed anger that he spent so many months away from his family, and in the end had given his life. In fact, Mine refused to talk to me at first, before consenting to spend hours describing Hugues. His 31-year-old daughter Julia remained silent, carefully listening to my questions to others about her father's death, while Hugues's grandchild played at her knees.
Constance refused to meet me to talk about her father. "It was difficult for all of us to relive again this dreadful day," Mine explained in a recent email. "Two years afterwards we miss him a lot, as on the first day."
I also contacted Julia recently to ask how she had coped: "I find that these disappearances are hard to accept," she wrote. "It is quite difficult to have nothing, no body, no accurate story, no funeral, no farewell."
When her two children are older, she said, she would like to take them to K2 and visit the Gilkey Memorial at the base camp where all the climbers who have died on K2 are remembered. She went on: "I always understood the passion that animated my father about this mountain, and others, and I think it is great that he was able to realise his dreams. He was a great father and even though I miss him very much, I am just happy that he did not go earlier!"
Alberto Zerain
Alberto Zerain was one of Spain's best climbers. Aged 46 on that ascent of K2, he was the first to reach the summit on 1 August, at 3pm. On his way down, he passed the other teams going up, and made it to the safety of one of the lower camps. He survived – in fact, he slept through the tragedy unfolding above him. But his wife Patricia had no idea he was safe. The Basque climber had taken a satellite telephone to the mountain but the battery was dead. As news of the deaths was carried by the world's media, she could only sit at home and wait.
I visited Alberto and Patricia – a teacher and translator – in the village where they live with their sons 40 miles outside Bilbao. Andoni and Jon, then 15 and 12, were not interested in climbing, Alberto said, only football. When they were young, Alberto eased off on mountaineering. "I needed to be home to help with the kids, or it's a lot of work for Patti. I am very casero, a homebody. I like to be at home."
More recently, he had started to travel again. After K2 he was planning to go to Kanchenjunga, another terrifying peak in the Himalayas – Patricia glanced over uneasily when he talked about his plans to spend more months away from home and his family.
Her anxiety at the time of the K2 disaster was entirely understandable. "I had no idea she had had such a hard time until I got back," Alberto said.
We talked for hours about his trip and watched a homemade film of his K2 expedition. Afterwards, we drove to a restaurant for a late lunch. He is a gentle, polite man who bonded most strongly on the mountain with the Pakistani high-altitude porters.
I spoke to Patricia again last month. Alberto was away from home again, this time on Everest. He had not been put off by the disaster on K2. She still finds his absences hard. "I understand that it is a very important thing for him to do what he really loves doing," she said. "But it means he is not at home with me and my children. It is still hard, even after all these years."
Patricia copes by keeping busy with her job and the children. Her sons seem less affected, perhaps because Alberto has been doing this for as long as they can remember. "But they are still always asking, 'How is Daddy?'"
Graham Bowley is a reporter on the New York Times. His book about the K2 accident, No Way Down, is published by Viking, £9.99. To order a copy for £7.99 with free UK p&p go to theguardian.com/bookshop or call 0330 333 6846