Scientists and glaciologists are now taking to the skies to find out how New Zealand’s glaciers are faring following this summer’s record-breaking warmth.
NIWA’s annual long-term aerial snowline survey marks its 40th anniversary of recording the snowline altitude of up to 50 glaciers across the South Island. The survey is undertaken every March at the end of summer and carried out using specialised cameras from a light aircraft.
NIWA said the survey reveals how much of the previous winter’s snow remains to contribute to long-term glacial ice accumulation.
NIWA climate scientist Dr Andrew Lorrey, who leads the project, said information gathered over the past four decades has produced a unique and incredibly valuable dataset that provides an independent measure of how climate change and variability are affecting NZ water resources.
“We look at the surface of each glacier and the line of demarcation where there is snow from the previous winter above, and exposed bare ice below. That line can tell you about the amount of snow gained versus the amount lost since the start of the glacier year in April.”
Dr Lorrey expects this year’s survey to reveal some “pretty pathetic” glaciers, following the claimed hottest summer on record.
“At this time of year we can see the effects of the summer melt but following such an extreme summer the layers really start to peel back and you can see how harsh the effect has been on the glaciers. Where it becomes a concern is if there is a succession of seasons like this within a decade or two – that’s when it can cause the overall volume of the glacier to decline.”
Victoria University glaciologist Professor Andrew Mackintosh also said he was also expecting one of the largest melt years ever recorded.
“Our team has previously investigated the relationship between the South Island glaciers and sea surface temperatures. We have seen that when the Tasman Sea is warmer than normal, you tend to lose a great deal of snow and ice in the Southern Alps.
“The marine heatwave this summer, where temperatures have been up to 6°C higher in some parts of the Tasman Sea, means we are expecting to see a much higher snow line.”
The five scientists on board the snowline flight are Andrew Lorrey and Trevor Chinn, together with Dr Huw Horgan, Dr Brian Anderson and PhD student Lauren Vargo from Victoria University.
They will take thousands of photos from different angles that will then be used to build 3D models of glaciers that can be compared year on year to give an accurate depiction of the volume of ice that has changed.