New Zealand's melting glaciers show the human fingerprints of climate change
New research has found extreme melting of the country’s glaciers in 2018 was at least ten times more likely due to human-caused global heating.
Twice a year, glaciologist Dr Lauren Vargo and her colleagues set up camp beside two small lakes close to New Zealand’s Brewster glacier. Each time the trek to carry the measuring stakes takes a little bit longer as the glacier’s terminus gets further away.
Lauren, a native of Ohio now working at the Antarctic Research Centre at the Victoria University of Wellington, is studying New Zealand’s glaciers from the air and on the ice.
New research just published in the journal Nature Climate Change has found that extreme melting of the country’s glaciers in 2018 was at least ten times more likely to have happened because of human-caused global heating.
Loss of ice across New Zealand’s glaciers in 2011, which was another extreme melt year, was six times more likely because of the planet’s warming, the study found, caused by an accumulation of greenhouse gases in the atmosphere mostly from burning fossil fuels.
Lauren, the lead author of the study, told the Guardian: “As scientists we know that theoretically warm temperatures should melt ice, but the goal of the research was to formally show that link between melting and climate change.”
The study looked at changes to 10 of New Zealand’s glaciers and was sparked by what Lauren and colleagues witnessed on monitoring flights in 2018.
“In previous years there was always snow on the glaciers but, in 2018, about half of them had no snow on them at all,” Lauren said.
The annual monitoring flights over 50 glaciers have been taking place in New Zealand since 1977 and record the position of the snowline and the thickness and flow of the ice.
There was less snow on the glaciers in 2018 than had ever been seen on the flights before.
Brewster is one of New Zealand’s smaller glaciers, but between 2016 and 2019 the glacier on New Zealand’s south island had lost 13m cubic metres of ice.
Lauren's calculations suggest that in 2018 alone, the glacier lost 8m cubic meters of ice. That year was New Zealand’s second hottest on record, behind 2016.
The melting seen on the Rolleston glacier in 2011 may have happened once every 100 years under climate conditions that had not been altered by humans, the study found, but human influence now meant an extreme melt year like 2011 would come around once every eight years.
Lauren said the country’s glaciers were important for tourism and water resources and she hoped the study “will encourage and convince people around the world, but especially Kiwis, that we need to take stronger actions to stop climate change.”