A timelapse camera, installed in 2012, records the retreat of Franz Josef Glacier/Kā Roimata o Hine Hukatere. Until 2019 the glacier retreated about 900 m. Video / Victoria University
New Zealand’s extreme summer has bitten another chunk out of our postcard glaciers – some of which have now largely vanished.
Scientists had been expecting to find devastation when they recently took to the skies to run their 46th annual health-check of our mountain wonders following a scorching West Coast summer: and that’s just what they found.
“I was shocked by the state of the small low elevation glaciers, which have largely disappeared,” said Monash University’s Professor Andrew Mackintosh, who joined the latest fly-over.
Even much larger, iconic glaciers like the tourist-pulling Fox and Franz Josef had retreated markedly.
“The scale of retreat is confronting, even to a glaciologist,” Mackintosh said.
“It emphasises the urgency of slowing climate change because the impacts are going to become increasingly costly and hard to avoid.”
A comparison of dramatic changes at the Brewster Glacier in Mt Aspiring National Park over the last two decades. Photo / Rebekah Parsons-King / Niwa
The end-of-summer survey, started by the late glaciologist Trevor Chinn, has been capturing an aerial portrait of more than 50 “index” glaciers in the Southern Alps since the late 1970s.
Over that time, they’re estimated to have lost a whopping third of their total ice volume, with much of the destruction coming in just the last decade.
Our dramatic La Niña summer – which brought record-warm sea surface temperatures to the West Coast and historic deluges to the north – looks to have put another sizeable dent in the icy wonders.
In January, swathes of water off the West Coast were shown to be running even warmer than balmy eastern shores of the Far North, in an extreme marine heatwave that broke local records.
Typically, sea surface temperatures (SSTs) in the region would be sitting somewhere in the mid-teens at this time of year – but observations over summer showed some coastal waters were as warm as 21C to 22C.
The wider southwest coast region, stretching down to Fiordland, had shown an average anomaly of 3.7C over the week to January 17, with some pockets registering whopping anomalies of more than 5C.
The Brewster Glacier, pictured last month. 2022′s survey showed the Brewster and several other glaciers had snowlines at least as high as in 2016, one of the top five high snowline years. Photo / Rebekah Parsons-King
For glacier health, warm waters in the Tasman Sea mattered much.
That warmth translated to warmer local air temperatures, which, when carried up to altitude, meant more heat – and more melt – for alpine glaciers.
The melt not only diminished the amount of material built up from the last season’s snow, but also ate into what had fallen over the years prior.
This summer had also coincided with a third consecutive La Niña - a climate pattern that came with regular hot spells along the West Coast, including a record-high reading of 30.9C in Greymouth on January 8.
Another driver called the Southern Annular Mode had also been predominantly positive – a phase that’s ripened conditions for glacier loss over time – while background climate change continued to steer a warming trend.
Niwa climate scientist Dr Drew Lorrey takes pictures from March's end-of-summer flight over the South Island's shrinking glaciers. Photo / Rebekah Parsons-King / Niwa
“With the South Island’s incredibly hot summer, we were expecting snowlines to be very high,” said climate scientist Dr Drew Lorrey of Niwa, which runs the surveys with Victoria University and the Department of Conservation.
“The picture from this survey was a mixed bag. Snowlines were clearly visible across some glaciers while others had exposed ice from prior years laid bare up to the mountain top.”
Melting glaciers are seen as global warming’s coalmine canaries, as they form the sum of a range of climate components, from temperature to precipitation and sunshine.
Even much larger, iconic glaciers like the tourist-pulling Fox - pictured last month - have retreated markedly. Photo / Rebekah Parsons-King / Niwa
That signal is becoming ever clearer: one recent study estimated how, over the record-warm summer of 2017-18, climate change made the extreme ice loss at least 10 times more likely.
Eleven of the original 50 glaciers selected by Chinn as a baseline for monitoring were expected to disappear by the middle of next decade, with another 10 swiftly approaching a similar fate.
2022′s survey showed how several glaciers – including the Brewster, a jewel of Mt Aspiring National Park – had snowlines at least as high as in 2016, one of the top five high snowline years.
Carrington Glacier, in Arthur's Pass National Park, pictured in March. Photo / Rebekah Parsons-King / Niwa
The nearby Volta Glacier had also been eaten away to the point that layers of ice and snow accumulated from previous years were sitting exposed.
In this year’s survey, the team spent nearly eight hours travelling back and forth across the Southern Alps.
They took thousands of aerial photographs of glaciers of differing sizes and orientations to use in various national and international research projects, including one that builds 3D models that are used to compare snow and ice year-to-year.
“Since the snowline survey began, the global climate has warmed significantly,” Lorrey said.
“This year’s observations do not suggest a reprieve or a reversal of the ongoing ice loss trend.”
Franz Josef Glacier, as it appeared last month. Photo / Rebekah Parsons-King / Niwa
“We’ve already had to abandon some of the index glaciers that we used to monitor because their snowlines and meaningful ice volume have completely disappeared.
“If current trends continue, we will see further contraction of snow and ice to only the highest places, leaving very little across the Southern Alps.”
Last year, Lorrey and colleagues published a study finding that, if contemporary decadal patterns continued, the Southern Alps’ average snowline elevation would be displaced at least 200m higher than normal, as early as 2025 to 2034.
They help regulate streams and rivers, support alpine ecosystems, contribute tens of millions of dollars to our tourist economy and were cherished by mountaineers and mana whenua alike.
“Not only do we risk losing the glaciers and our intimate relationship with them completely,” Lorrey said, “but it will also affect the livelihoods of people who rely on these natural wonders for tourism, as well as flow on effects from decreased meltwater during periods of drought.”
The scientific results from this year’s glacier and snowline survey will be known later this year.
