Summer 2022-23 was the warmest on the West Coast and set new records.
One West Coast tramper says Mount Aspiring can now be climbed in summertime in running shoes, without touching snow or ice, and no need for crampons or ice axe.
With the retreat of snow and ice — which held the ground together — some alpine walks and climbing routes are starting to disappear.
West Coast Alpine Club captain Jason Blair said it was hard to objectively state how bad the retreat was, which was why they relied on the upcoming Niwa snowline aerial survey.
However, in his experience things had fundamentally changed in the Southern Alps.
His playground is Arthur's Pass National Park and the glaciers, where he found himself on Christmas Day. He said he could see Franz Josef Glacier melting before his eyes, with water streaming off the ice face.
Mr Blair said while that may be a pattern in summer months, the melt felt "very visible".
"Stable moraines are falling apart now they are not held together by ice."
Federated Mountain Clubs president Robin McNeill said people had been able to climb Mt Aspiring without touching snow for a few years.
"I've been climbing mountains for years, and it seems somehow immoral, the recent changes to Mt Aspiring. I'm personally appalled. It's one of the worst things that could happen."
He was despondent, having witnessed glaciers retreat and even disappear, replaced by lakes.
At Mt Blanc in Europe, they were starting to see more rockfalls as the ice thawed; this was happening at -2degC — not 0degC.
In New Zealand, as glaciers retreated the moraine rock left behind became unstable.
A number of climbing routes were no longer possible because the glacier had receded and they were too difficult to reach.
"It's dismal," Mr McNeill said.
It was hard to know how much of that was due to three La Nina summers, and how much was climate change.
Tom Hoyle from the New Zealand Alpine Club agreed it had been increasingly common in the past few years to climb Mt Aspiring in shoes.
"I recently did the popular Macpherson-Talbot Traverse in the Darran Mountains of Fiordland and the permanent snowfield between these two peaks is becoming very thin and looks to have only a few years left. It used to be mandatory to take crampons and ice axe on this route, no matter the time of year, but soon it will be on rock the whole way."
Mr Hoyle said the retreat of the West Coast glaciers was well-documented. As they retreated, they left behind unstable moraine walls, which inevitably collapsed when the ice was no longer there to support them. This made it increasingly difficult to find safe routes through these areas.
"Our NZAC huts in the high alpine areas are becoming increasingly hard to get to on foot. In the case of Murchison Hut in Aoraki-Mt Cook National Park, the once stable mountainside it is sited on has developed large fissures, and geological surveys have suggested it is no longer safe to use because of the imminent threat of the slope collapsing."
Niwa glaciologists said last month they were preparing to find "utter devastation" when they do their annual snowline survey this month.
Niwa's annual climate summary showed the nationwide average temperature was 13.76degC — which is 1.15degC above the 1981 to 2010 annual average and surpassing the 2021 temperature by 0.20degC.
The top-four warmest years on record have all occurred since 2016.
In the late 1970s New Zealand had about 3200 glaciers; by last year there were 2900.
