Drew Lorrey is staring out the window of a Cessna airplane as it swoops low alongside Mt Caria in the Southern Alps.
“Bye, and thanks,” he says, as the tiny plane zooms away from the mountain. He’s speaking, not to the other climate scientists on board, but to a glacier, one which has been photographed every year since the 1970s. The glacier has had its day now, though.
When Mt Caria’s glacier was chosen to be part of the survey in 1977, there was plenty of it to study. Now, says Lorrey, it’s “shot”, or as another scientist on board describes it, “cooked”. All that remains is a small clump of ice and snow clinging precariously to the side of a mountain.
Although the annual flights have become a powerful indicator of a heating planet, glacier scientist Trevor Chinn wasn’t thinking of climate change when he came up with the idea of flying over about 50 glaciers and taking their photos.
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Chinn wanted to understand the ice that gives the South Island its precious freshwater reservoirs. By the time he died, in 2018, his survey showed the glaciers had collectively lost a third of their mass in four decades.
The record-hot 2018 and 2019 were probably the worst years, says Lorrey, who, along with climate scientists from Victoria University and elsewhere, has continued Chinn’s flying tradition for Niwa. The years 2011 and 2014 were the next-worst. This year, there’s been a slight reprieve. While it’s too late to save Mt Caria, bigger glaciers like Mt Rolleston and Brewster have a lower snowline than last year, indicating they’re in better shape.
“It’s better, but it’s the new better,” says Lorrey, pointing to photos from the same flight taken in the1980s, when the glaciers look much bigger and healthier. “If we got 20 years like this in a row, they might start to come back. They took such a hit over the last two years that this has only brought them back to a remnant of what they once were.”
The problem, he says, is that the bad years aren’t being balanced out by equally good years. “Since I’ve been doing this survey, there have been four really bad years and the rest were only OK,” he says.
The survey confirms what you might suspect if you walked up to the well-known Fox or Franz Josef Glaciers in the1980s or 90s. People who touched the famous glaciers as children now take horrified photos of themselves for social media, standing in the same spot, during the same month of the year – with the glacier retreated far up a rocky ravine. Tourist magnets such as Franz Josef and Fox can now only be reached by helicopter – a CO2-packed enterprise that, the Parliamentary Commissioner for the Environment has noted, itself worsens global heating.
This year, there’s a new complication to the survey. Many of the glaciers are coated with ash from the Australian bushfires – themselves intensified, climate scientists say, by the dryer, hotter trends of global heating. The ash flew across the Tasman sea and settled on the Southern Alps. Viewed from the Cessna’s windows, it’s everywhere.
While the ash is a reminder of the dry conditions that will get worse with climate change, ironically, having pink on the glaciers makes the surveying easier. Lorrey and the other researchers, such as Victoria University’s Lauren Vargo, are here to look for the snowline. A lower snowline means there’s more compressed snow left at the end of summer to rebuild the glaciers.
Since the snowline has retreated up the mountain since the bushfires, there’s pink dust on the remnant snow, but not the lower, icy layer below it. The line between white and pink makes it easier to see where the old snow ends. “This would be a great year to teach someone how to find the snowline,” says Lorrey.
What happens to the glaciers now largely depends on governments. Glaciers are sensitive indicators of a heating planet. Without strong, co-ordinated emissions cuts, those that are left maybe be almost unrecognisable by 2100. The reason is that glaciers are smaller and more vulnerable than the enormous ice sheets at the North and South poles, which contain more ice than glaciers, but take longer to start melting in earnest.
So far, melted glaciers have contributed more to sea level rise than Antarctica and Greenland, but that may be changing. According to the IPCC, as the world’s glaciers shrink and the heftier polar ice sheets melt faster, polar ice will become the main driver. Already, most of the acceleration of sea level rise in recent years was caused by melt-water from Greenland and Antarctica, said last year’s IPCC report on Oceans and the Cryosphere.
Lorrey hopes the bigger glaciers he monitors will stick around. “Some of them are toast, some have got a bit longer. We hope they will be around in years to come.”
In the meantime, though, he and the other climate scientists on board the plane will need to find another glacier to measure to replace Mt Caria. They’re looking for one at higher altitude, with a better survival chance. Two or three other glaciers in the 50-strong survey have also been reduced to clumps, and have had to be removed from the survey. “They don’t tell us much any more, so there’s no need to burn fuel to get to them,” says Lorrey.