Mt Cook climbing risk extreme

Climbing New Zealand's highest peak is becoming increasingly dangerous, but authorities say they cannot stop people who are determined to tackle Aoraki-Mt Cook.

A winter of little snow and a warm summer have opened up large crevasses and made glaciers leading to the mountain hazardous.

Mountain guides are having to weigh up whether they can safely take people up the 3754m peak.

Experienced guide Gottlieb Braun-Elwert has suspended all of his Mt Cook climbs and will not reconsider the stance until next winter.

"I know some people will try. The question is how far you want to push the risk," he said. "We have to get our heads around the fact that we can't always do what we want."

The Department of Conservation will offer strong advice to climbers coming to tackle Mt Cook, but said it could not stop people going into a national park.

"People want the challenge of climbing the biggest mountain ... Most people I talk to are questioning whether they should be going," said DoC mountain rescue team leader Aaron Halstead.

The New Zealand Alpine Club said its members were still climbing the mountain.

"It's just a bit more effort and work to get up the thing. Guides are questioning the odds every day and they have other considerations," said executive officer, Richard Wesley.

"Like any mountaineering, there are risks involved. The mountain, in the end, decides who climbs it."

The National Institute of Water and Atmospheric Research says a quarter of all glacier ice in the Southern Alps has been lost in the last century as average temperatures have risen 1C.

That trend was likely to continue and further erode Mt Cook's glaciers, said Niwa scientist Dr Jim Salinger.

Mr Halstead said snowfall had alleviated the situation at Mt Cook, but another warm period could quickly set things back and raise avalanche risks.

"People from overseas tend to get focused on the main goals here, without having too much regard for the weather. There is so much climbing to be done in the park and 90 per cent of it is still relatively accessible and safe."

Climbing guide Guy Cotter said there came a point just about every year where conditions prevented climbing on Mt Cook.

He believed guided climbs would be back on soon after recent snowfalls settled.

"All you need is a reasonable snowfall and good conditions following, ie, freezing, and you're back in business," Mr Cotter said.

He did not believe any guiding companies relied solely on Mt Cook climbs. For most guides it was only one climbing option of many in the Southern Alps.

"We might guide maybe 20 people on Mt Cook in a season, out of about 250 climbs," Mr Cotter said.

Businesses in the Mt Cook village say there are plenty of other attractions to draw people even if the main peak cannot be climbed.

Mt Cook Alpine Lodge manager Tony Delaney said a lot of tourist climbers came to stay "particularly at the end of their trip for a little bit of luxury". But only a small percentage tackled Mt Cook. Most took on less demanding climbs on smaller peaks like Mt Aspiring and Mt Tasman.

"There are always going to be glaciers and crevasses and mountains."

A helicopter pilot for the last 20 years, Mr Delaney said it was noticeable how things were changing.

"The snow-line is rising. It makes it tougher in the winter-time for the heli-skiing and things like that."