A visiting team of scientists have found many of New Zealand's climate-sensitive glaciers still haven't recovered from the biggest snow melt ever recorded in the Southern Alps.

The group, from Switzerland's Swiss Federal Institute of Technology Lausanne, have begun in the South Island a three-year expedition visiting glaciers in 15 countries.

Their mission is to make a crucial, first-of-its-kind stocktake of hardy bugs that live in streams and rivers fed from the world's mountain glaciers, before they're lost forever.

By collecting samples of this microbial life and analysing their genomes, they hope to understand how they'd managed to adapt to such extreme conditions, and how they were faring in the face of climate change.

Advertisement

Here in New Zealand, expedition leader Mike Styllas and his team are part-way through a trip taking them from Arthur's Pass, through the Fox, Franz Josef and Victoria glaciers, and down to Milford Sound.

Our glaciers have shrunk in area by one third over the past four decades - an astonishing loss that scientists have partly attributed to climate change.

"What has been impressive is that the smaller glaciers are decaying much faster and in some cases, they really tend to vanish," Styllas said.

The Brewster glacier, near the Haast Pass, has receded so much that a new stream had formed off it, the scientists found. Photo / Supplied
The Brewster glacier, near the Haast Pass, has receded so much that a new stream had formed off it, the scientists found. Photo / Supplied

"But larger glaciers respond differently to the climate forcing the last warm decades."

The impact of New Zealand's hottest summer of 2017-18, which stripped around nine per cent of the alps' total ice volume within just a few months, was strikingly evident.

"In some cases, we had photos of the glaciers' terminus dating from 2013 and we found a much different situation," he said.

"For example, Brewster Glacier has receded so much that a new stream has formed.

"For our study, this is an asset as we get to study the microorganisms in such a newly formed glacier-fed stream, but in the long-run this emphasises the vulnerability of these ecosystems to future climate change."

Advertisement

This was the reason the project focused on these sensitive havens for life.

Collapsed ice at the Brewster glacier. Photo / Supplied
Collapsed ice at the Brewster glacier. Photo / Supplied

"We want to study them before they will entirely disappear, along with all the genetic information that exists in their cells."

Their New Zealand leg would wrap up at the postcard Ice Lake fed from the Whataroa, Shackleton and Mawson glaciers, before the team move on to Greenland and Russia's Caucasus Range.

Figures reported to the American Geophysical Union in 2017 revealed how New Zealand's total glacier area had shrunk from 1240 sq km to 857 sq km - a decrease of 31 per cent since the late 1970s, or just under one per cent of loss each year.

The number of glaciers also fell slightly from 3283 to 3180, while mean altitude climbed from 1859m to 1939m above sea level.

The team's sampling site, downstream from the Brewster glacier. Photo / Supplied
The team's sampling site, downstream from the Brewster glacier. Photo / Supplied

Those figures followed a 2014 analysis which showed ice volume in the Southern Alps had shrunk by 18.4cu km or 34 per cent since the 1970s, and ice losses had been accelerating rapidly since the turn of the new century.

Whether the overall trend of ongoing loss continued was dependent on how the world acted on climate change.

The Age glacier near Milford Sound. New Zealand's glaciers have shrunk in area by one third since over the past four decades. Photo / Supplied
The Age glacier near Milford Sound. New Zealand's glaciers have shrunk in area by one third since over the past four decades. Photo / Supplied

One scenario that assumed future warming could be limited only to another 2C - the ultimate goal of the Paris Agreement on climate change - would see glaciers keep retreating but stabilising by the middle of the century.

But if emissions continued to ramp up without any efforts to curb them, glaciers could become virtually unrecognisable by 2100.

Around the world, glaciers were already melting at an unprecedented rate, losing on average between half a metre and metre of ice thickness every year.