2019 Annual Snowline Survey shows increased glacial melt

Results from the 2019 Annual End of Summer Snowline Survey once again show a dramatic reduction in glacier mass in South Island glaciers, Victoria University of Wellington scientists say.

Brewster Glacier
Capture of the digital model made by Lauren Vargo of Brewster Glacier

The survey documents changes in South Island glaciers over the preceeding 12 months, as well as measuring new snowfall that will contribute to future glacier growth. The last few years have shown a dramatic loss in mass across these glaciers, and initial analysis of this year’s data suggests this trend has continued.

“So far, our analysis shows that 2019 was one of the highest mass loss years for Brewster Glacier since the survey began in the 1970s,” says PhD student Lauren Vargo from the University’s Antarctic Research Centre. “The loss wasn’t as dramatic as the previous year, but this does suggest that these high mass loss years are becoming the norm.”

Lauren will use the data collected from the survey to create 3D models of the South Island glaciers to see if this high mass loss trend has continued across all of them. She will also use the data to provide insight to what exactly is causing this mass loss, and how much humans have contributed to it.

Postdoctoral Fellow Dr Oliver Wigmore is also using data from the survey to study the melting of the Tasman glacier, focusing particularly on the lower areas of the glacier that are covered in thick debris.

“I’m looking at changes in glacier debris cover, extent, and thickness, and the effect that debris has on glacier melt processes,” Dr Wigmore says. “We know that variable debris cover impacts melt rates, but the processes behind this are poorly understood.”

Dr Wigmore is using thermal data to estimate the thickness of the debris on the Tasman glacier, and investigating how this increases or decreases melting. The snowline survey is just one part of Dr Wigmore’s study, which will also involve collecting data from drones, satellites, and field measurements.

The Annual End of Summer Snowline Survey is a joint project between Victoria University of Wellington and NIWA. Glacier expert Dr Brian Anderson from the Antarctic Research Centre also took part in the survey this year, as did Dr Andrew Lorrey and other researchers from NIWA. This year, Dr Lorrey spearheaded a new section of the survey, using a thermal imaging camera to show temperature differences in different glaciers and how those temperatures are linked to debris cover. He says this data will help the survey produce even more accurate models in the future.