Researchers are painstakingly piecing together thousands of photographs of New Zealand’s Southern Alps as part of the annual glacier snowline survey, which tells the story of our shrinking glaciers.
Survey founder Dr Trevor Chinn said the survey took place in March and showed the summer’s marine heatwave had resulted in one of the largest glacier melt seasons observed since flights began in 1977.
Since the first survey 40 years ago, scientists had detected a 30% loss of ice, he said.
But Dr Chinn said there was so much melt over the past summer that more than half the glaciers had lost all the snow they gained over the past winter, and some from the winter before.
"A glacier is the best climate change indicator you can use," he said.
Changes in the Fox and Franz Josef glaciers are still being calculated.
Niwa climate scientist Dr Andrew Lorrey said the South Island glaciers held a lot of water that was crucial for ecology, agriculture and power generation, so it was important to monitor them.
"You can say what you like about temperatures on the ground, but you can’t make a glacier lie."
The annual survey forms part of the Climate Present and Past project, which looks at recent and historical data to track past variability and changes in climate.
During the survey, conducted from a fixed wing aircraft, the scientists take thousands of photographs to build 3-D models of glaciers that can be compared year on year.
