Climate and environmental applications principal scientist and survey leader Dr Drew Lorrey said New Zealand had just experienced its hottest year (2022) on record, and many of the South Island’s glaciers would have been decimated.
Niwa’s annual climate summary showed the nationwide average temperature was 13.76degC, 1.15degC above the 1981-2010 annual average and surpassing 2021 by 0.20degC.
The top-four warmest years on record have all occurred since 2016.
At the end of every summer, the snowline altitude of up to 50 glaciers across the South Island is recorded using specialised cameras from a light aircraft.
Thousands of photos are taken from different angles to build 3-D models of glaciers that can be compared year on year, to give an accurate depiction of how much of the previous winter’s snow remained to contribute to long-term glacial ice accumulation.
"This year, I’m expecting to see utter devastation, to be honest.
"We formerly had about 3200 glaciers in the late 1970s, and now, after our last inventory, we’ve got about 2900.
"Some of the smaller ones have disappeared. And probably the most important thing to note is the ice coverage has retracted significantly since we started the survey.
"There’s an acceleration of the retreat — there’s an acceleration of the snowline that is going up the side of the mountain and that is what is helping to drive that."
He said he was "resigned to the fact" that an increasing number of the South’s glaciers would disappear in the coming years.
"I know it’s going to happen on my watch.
"We will see a significant proportion of the glaciers that we survey every summer, gone by the next decade.
"For some of them, it’s too late, but our actions now are going to dictate how many more we are going to lose in the middle and late 21st century.
"We are fighting for the future here."
He said once they were gone, it was possible some of them could regrow.
"If you change the climate back to a state where the snowlines are lower during the summer than they are now, you can get snowfall up in the mountains accumulating from one season to the next, and rebuilding the glacier.
"But under the current conditions, that’s not possible."
The survey would take place next month.
The 2023 results were expected to be released mid-year, Dr Lorrey said.
