ARC scientists measure glaciers after record-beating summer

Scientists measure glaciers after record-beating summer

NIWA’s annual long-term aerial snowline survey marks its 40th anniversary this year of recording the snowline altitude of up to 50 glaciers across the South Island. Every March, NIWA undertakes a photographic survey using light aircraft to study how much of the previous winter’s snow remains to contribute to long-term glacial ice accumulation.

Dr Huw Horgan, Dr Brian Anderson, and PhD student Lauren Vargo will join Andrew Lorrey and Trevor Chinn from NIWA on the expedition. Together they will use specialized cameras to take thousands of photos that will used to build 3D models of glaciers to measure any changes in their size.

Professor Andrew Mackintosh, glaciologist and head of Victoria’s Antarctic Research Centre, says the photos will produce “precise measurement of snowlines and the glacier surfaces”. The processing of these photographs using powerful computer methods, Professor Mackintosh says, takes the guesswork out of expert judgement.

“The survey is a tremendous resource that gives us quantitative digital information on how glaciers have changed. It also allows us to reconstruct length changes for glaciers that have never been measured on the ground.”

Andrew Lorrey, leader of the NIWA snowline project, says information gathered over the past four decades has produced a unique and incredibly valuable dataset that provides an independent measure of how climate change is effecting our water resources.

This year the expedition team expects to see a huge decrease in snow cover on the glaciers.

“Computer modelling as part of a NIWA-Victoria collaboration, published last year in the prestigious journal Nature Communications, showed that increased ocean temperatures in the Tasman Sea result in significant loss of snow and ice in the Southern Alps. This summer has seen temperatures up to six degrees higher than normal, so we are expecting to see a much higher snow line.” says Professor Mackintosh.

Glacier fluctuations are among the clearest signals of climate change, because they are highly sensitive indicators of atmospheric temperature and precipitation levels.

“If there is a succession of seasons like this within a decade or two it can cause the overall volume of the glacier to decline.” says Andrew Lorrey.

The scientists begin this year’s aerial snowline survey on Saturday 9 March.

Read more on their survey here.