As one of the world's best-known mountain rescue helicopter pilots, Gerold Biner is used to spotting things on glaciers that shouldn't be there. Flying under the north face of the Matterhorn last summer, he saw at the edge of the ice that flows beneath the mountain some equipment, clearly abandoned. Inside the clothing were bones, and a name tag with one word: Conville.

When the remains arrived at the laboratory of forensic pathologist Bettina Schrag, she put the name into Google and discovered the website of a charity set up in memory of a young British climber who disappeared after falling from high on the Matterhorn in 1979. "As soon as I saw the email was from a Swiss pathology laboratory," says his sister, Melissa, "I knew they'd found Jonathan."

Now is a boom time for glacier archaeology, a small silver lining among the gathering storm of climate change. As glaciers retreat, chance discoveries are revealing that, along with the remains of recent tragedies, there are signs that our ancient ancestors spent much more time in the mountains than we thought.

Since the discovery in 1991 of a mummified body dubbed Ötzi emerging from the ice on the border between Austria and Italy, archaeologists have found other sites and remains, including hundreds of artefacts stretching back 5,000 years at the remote Schniderjoch pass, at 2,750m in the Swiss Alps.

But alongside academic interest in Europe's retreating glaciers, the final resting places of climbers are also being revealed, posing difficult questions about how to deal with the remains, and reawakening the emotional turmoil that a sudden death leaves behind.

Bettina Schrag is based in Sion, and her area of responsibility takes in the northern side of the Matterhorn and its surrounding peaks above the town of Zermatt. It's a magnet for mountaineers from all over the world. Around 250 people are missing in the area, most of them climbers and hikers.

When Jonathan Conville died aged 27, a few days after spending Christmas with his parents and sisters, he was a man who had turned his life around. He'd left Marlborough College under a cloud and at his next school developed a drug habit. His final report dismissed him as "dirty, uncouth, idle and self-indulgent".

"He went travelling after he left school," says another sister, Katrina Taee. "In Nepal he ended up living in a monastery. He sent us a photo of himself, bald and wearing robes. My dad asked why he'd sent us a picture of a monk; I had to tell him it was Jonathan. Whatever happened to him there changed his path."

Back in Britain, Conville quit drugs, stopped smoking and hardly drank. He joined the Parachute Regiment, developed a passion for outdoor adventure, learned to ski and climb, and became obsessively fit. "When he was stationed at Aldershot, he'd run home to Odiham for Sunday lunch," says Melissa. "That's 10 miles."

After a tour in Northern Ireland he left the army and studied to be an outdoor instructor, eventually working for the Outward Bound Trust at Loch Eil. "He'd found his role in life," Melissa says.

He was reunited there with his childhood friend David Tidmarsh. Together they took on harder and harder challenges in Scotland and then the Alps. When Tidmarsh suffered an injury that winter, Conville teamed up with a teenage Dutchman called Frans Heusdens.Having given up near the summit in the face of bad weather, Conville fell to his death as he and Heusdens were descending to an emergency shelter high on the mountain. Heusdens was eventually rescued from there by helicopter. Conville's mother, Anne, saw a news report of a death in the Alps. "She guessed it was him," Katrina recalls.

As a way to make sense of their son's death, Anne and her husband, Michael, supported a charity set up by Jonathan's uncle, the actor David Conville, Tidmarsh and another friend from the Parachute Regiment, Andrew Don. In the last 34 years, the Jonathan Conville Trust has put thousands of young climbers through subsidised training courses, in conjunction with Plas y Brenin, the national mountain centre in Snowdonia.

"Every member of a family has a different experience of grief," Katrina says. "Our dad, despite being a mild man, exploded. Our mum imploded. She never got over it. At the time, I became super calm. I didn't realise it was shock. I also didn't understand how terrible it is for parents to lose a child."

Her mother slept in Jonathan's bed among his childhood things, before burning everything six months after his death. " She couldn't believe he was dead," Melissa says. "The fact that there was no body and no funeral made that harder. For months she thought maybe Jonathan had escaped. It wasn't so important for us that there was a body to bury. To us he was a free spirit in the place he loved."

Having lived with the loss for most of their adult lives, the discovery of their brother's remains was a greater shock than they had expected. "I felt almost angry," Katrina says. "The discovery reawakened the grief and emotions. It was raw, even brutal. People were saying how wonderful, but it wasn't at first. The glacier had spat him out. There was nothing romantic about this."

Three days after Schrag's email, the sisters flew to Switzerland to identify their brother's equipment and give DNA samples. One of Conville's hands, just like that of Ötzi the iceman, had been preserved by the ice. "It was so poignant,' Katrina says. 'There was a mummified hand, with nails and skin, and cupped, like it was waiting to be held. It was 34 years on, and I was holding my brother's hand. It was bittersweet but so wonderful."

Katrina, a grief counsellor, says her brother's death was a factor in her choice of career, and the discovery of his remains has revealed a great deal to her about the grieving process. "Our story is hopeful. As you get older and family becomes more important, I feel his loss more. It would have been great to have a big brother. It's been difficult finding him. We will always grieve, but it does feel like an ending.

For more information about the Jonathan Conville Memorial visit jcmt.org.uk