This picture, taken on Friday, shows the upper reaches of the Tasman Glacier neve and a rock avalanche runout. Scientists say our glaciers fared better this summer. Photo / Drew Lorrey, Niwa
This picture, taken on Friday, shows the upper reaches of the Tasman Glacier neve and a rock avalanche runout. Scientists say our glaciers fared better this summer. Photo / Drew Lorrey, Niwa
An aerial stocktake has found New Zealand's glaciers fared better than expected over summer - but the long-term prognosis for the icy wonders remains dire.
Glaciologists last week made their 43rd annual flight over about 50 glaciers across the Southern Alps, some of which have lost millions of cubic metres of ice in the past five years alone.
Over the last four decades, the alps have shed nearly a third of their ice volume - equivalent to the basic daily water use requirements of our current population for that whole period.
Niwa climate scientist Drew Lorrey, who joined other scientists for the Friday fly-over, described current snowlines as being close to "normal" in terms of their altitude.
"But they looked really variable across the range of glaciers we survey," he added.
"In some cases, the snowline was clear, and in others it was not."
Brewster Glacier in Mt Aspiring National Park, as pictured on Friday. Photo / Drew Lorrey, Niwa
Ahead of last summer, Lorrey and other scientists aired worries over the potential impact of La Nina, given the system usually brought hotter, drier conditions to the West Coast.
But the climate driver, which peaked in January, didn't bring its traditional patterns and appeared to have spared the glaciers its usual melting effects.
"The glaciers looked quite different from 2014, and other recent La Nina years we've experienced, where dirty glaciers and a higher-than-normal snowline are typically observed."
Lorrey said he'd been initially doubtful about seeing any remnant snow cover up in the alpine reaches, until stations in the central alps indicated summer temperatures had actually kept close to average.
Park Pass glacier - one of many we monitor during the @niwa_nz end of summer snowline and glacier survey. Snowlines this year appear quite variable across different sites and aspects, and it’s a world of difference from last year... #EOSS2021pic.twitter.com/viTfnM3dgV
"Temperatures leading into the survey this year were not nearly as warm as the lead-in to March 2018 and March 2019, when we had scorching summers ahead of the survey flight," he said.
"Relative to those recent surveys, I'd say the 2020-21 summer was an okay one for many of our glaciers - even offering a bit of respite from more harsh conditions and a string of poor years experienced since 2017."
The glacier atop Mt Butler, pictured on Friday. The snowline seen across this glacier marks the altitude where a balance between retention or melt of snow and ice are equal. Photo / Drew Lorrey, Niwa
But many had taken a "severe beating" over the past decade, he said - especially smaller ones.
When the renowned glaciologist Dr Trevor Chinn set up the survey in the late 1970s, he travelled as far north as the Kaikoura Ranges, capturing photographic evidence of several glaciers in north Canterbury along the way.
In 2018, the team visited some of those sites and decided it was virtually pointless to return to several.
"Some are either in their death throes and past the point of no return or gone altogether." One tragic case was the Faerie Queene glacier, in the Spenser Mountains at the southern end of the Nelson Lakes National Park.
The Faerie Queene glacier in north Canterbury - pictured in December - is flanked by moraine ridges that show it has undergone retreat. Photo / Rebekah Parsons-King, Niwa
"It's a great example of recent catastrophic ice loss for a small glacier," he said.
"The combined elements of rising snowlines, warmer temperatures, and expansion of a proglacial lake helped to drive that particular glacier to collapse."
Regardless of last season's bump, Lorrey pointed out that glaciers took many years to accumulate enough mass of snow and ice to survive over the long-term.
"Normal years, where the balance between snow gain and loss occurs from one season to the next ... aren't going to counteract the significant impacts negative mass balance years and ice reduction we've experienced recently," he said.
"The current trajectory of rising temperatures also means we're going to continue to see our glaciers shrink this century.
Haupapa / Tasman Glacier is Aotearoa’s longest glacier. It captivates us with raw beauty - and it makes contributions to tourism, recreation, and water resources of the Waitaki River. A rock avalanche above the 2021 snowline reminds us of the dynamic scene it constantly provides. pic.twitter.com/xVMon4jk1A
The microscopic animals, reported in a just-published study, were found within ice samples, gathered from the Fox, Franz Josef and Whataroa glaciers last summer.
"They were discovered by taking a small lump of ice from the top of these glaciers, melting it and then filtering it," said study co-author Professor Peter Dearden, of Otago University.
"I think no one has tried this before because we assume that animals couldn't live in such extreme environments."
Dearden said the study team, led by Dr Daniel Shain of Rutgers University in the US, were now trying to learn as much as they could about them.
"We can say that we have found a type of copepod - a kind of shrimp-like thing found in both fresh and salt water - and a number of rotifers, which are microscopic animals with a specialised wheel-like feeding organ."
Also among the samples was a tardigrade - a segmented, eight-legged animal often called a water bear, and which has found fame on popular science websites - and nematodes, or roundworms.
This copepod was among new species discovered in New Zealand glacier ice. Photo / Peter Dearden
"We have no idea how they are living but suspect they might graze on the algae found in glacial ice - we are hoping to find this out as the project goes on," he said.
"Remarkably, in a couple of litres of melted ice, we found more than 5000 of these tiny animals.
"We really need to find out how they came to live on glacier ice, how they cope with the cold, and how they find food."
A genetic analysis had suggested that each animal from each glacier appeared to have a common ancestor that lived when all of the glaciers were a single ice sheet - possibly one to two million years ago.
"This is the only place in the world where such a diversity of animals is found on a glacier," he said.
"In North America and Tibet, Annelid worms - a group we didn't find - live in glaciers, and in Iceland Rotifers have been found.
"There is something surprising and unique going on in our glaciers that is allowing this diversity of animals to live there - and we really need to find out what."
But he said time was running out, as glaciers retreated with climate change.
"This ecosystem and environment will be gone in 100 years, if not much sooner, if we do not control our carbon dioxide emissions," he said.
"It is urgent that we learn all we can from these animals while they are still here, but I hope we can also change the way we live, so that these guys can survive for at least a few more million years."
