The bitter-sweet return to Nepal made him think of New Zealand father and son Marty and Denali Schmidt every day. The men died in July.

''Marty climbed in Nepal a lot, but the mountains give me happiness so there are no difficulties,'' Warner said.

On this trip Warner has been climbing waterfall ice in the Rolwaling Valley.

''Frozen waterfalls also give these amazing lines to climb, hundreds of metres at times of cascading ice coming straight down off a mountain. They are beautiful things to climb in. They are ever-changing and impermanent, only lasting a few months to climb, this makes them special,'' he said.

Warner has seen his fair share of dead bodies that litter the route to the top of Everest, but on K2 the mountain is too steep and according to Warner, it sheds the bodies.

''It's cold, constantly trying to keep your hands and feet warm. It's unstable with ice breaking often and wet in places were the water is still flowing. Long days with plenty of suffering and moments of terror and joy.''

Warner said you are more likely to be injured climbing waterfall ice, but less likely to die.

''It's as dangerous as you want it to be. Ice can move and break,'' he said. ''You often get hit with ice debris knocked off from your partner above. Protection can be very poor at times.

''The last route we did was this free standing pillar of ice, at the top it was only about 10cm thick, I could see the water flowing behind the ice so the ice was detached from the rock, a beautiful thing to watch through the clear blue ice.

''I'm swinging my axes in and kicking my crampons into the thin ice and near the lip the whole pillar cracked loudly as a seam above my tools cut through all the ice.

''The whole thing had dropped down only a few millimetres but enough to frighten me as I quickly climbed above it to safety.''