Researchers are painstakingly piecing together thousands of photographs of New Zealand's Southern Alps to tell a story about our shrinking glaciers.

The annual glacier snowline survey, a collaboration between NIWA and Victoria University, took place in March, and showed the summer's marine heatwave has resulted in one of the largest glacier melt seasons observed since flights began in 1977.

Since the first survey 40 years ago scientists have detected a 30 per cent loss of ice.

During the survey, conducted from a fixed wing aircraft, the scientists on board take photographs to determine how much snow remains after summer.
They will compare the photos to ones taken in previous years and make digital models of the glaciers to measure the changes.

Survey founder Dr Trevor Chinn says there was so much melt over summer than more than half the glaciers lost all the snow they gained over last winter, and some from the winter before.

“A glacier is the best climate change indicator you can use,” he said.

NIWA climate scientist Dr Andrew Lorrey says the South Island glaciers hold a lot of water that is 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 climate data to track past variability and changes in climate.

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