A culmination of over 45 years of research is painting a grave picture for the state of our iconic glaciers.
NIWA’s Dr Andrew Lorrey says that hotter temperatures are to blame.
“We’ve had a flurry of harsh summers and repeated marine heatwaves that have caused warm air to cook our glaciers. As part of our annual snowline survey, we’ve documented ice cover for the Southern Alps since the late 1970s by taking aerial photographs of the snowline position at the end of summer.
“These photos are then put into a 3D model pioneered by Dr Lauren Vargo and Associate Professor Brian Anderson from Te Herenga Waka—Victoria University of Wellington, which shows how glacier volume has changed. This collaboration has provided us with a long, nearly unbroken record of ice loss,” said Dr Lorrey.
NIWA estimates that at least 13 trillion litres of water have been lost from our iconic New Zealand glaciers since the late 1970s. This is the equivalent of nearly five decades of basic household water use for the whole country.
In addition, NIWA has recently worked with a landscape art historian Dr George Hook to study 19th Century paintings by artist John Gully, which captured ice retreat already underway in the mid-1800s. “The paintings were intended to convey the dramatic scale of a mysterious land far away from industrialised British society. They show vast and vivid snow cover across New Zealand’s mountains and documents the beginning of their retreat.
“Serendipitously, for contemporary scientists, comparing these artworks with current photos vividly shows the magnitude of ice loss that has occurred since the mid-1800s,” said Dr Lorrey.
Simultaneously, researchers based at University of Otago and Victoria University of Wellington have conducted a programme measuring glacier change at Brewster Glacier, located in Mount Aspiring National Park, since the early 2000s.
Professor Nicolas Cullen from the University of Otago is part of the team. His work involves snow probing and installing ablation stakes into the ice with a steam drill to measure how much snow and ice is gained and lost over each season.
"Our unique long-term observations on Brewster Glacier have led to it becoming a global benchmark for understanding how glaciers in the Southern Hemisphere are responding to climate change," says Professor Cullen.
Dr Shaun Eaves from Victoria University of Wellington has been doing similar work around the summit of Mt Ruapehu. He says the findings tell a similar story.
"We;ve done mapping around the summit region of Mt Ruapehu and its showing the same pattern as the Southern Alps, with small glaciers there disappearing fast.
"Many are reduced to slivers of ice covered with a thin veneer of debris. All suggestions point to some going extinct in the years ahead," says Dr Eaves.
While the overall findings are bleak, Dr Lorrey says there is still time to make a difference.
“These fantastic collaborative efforts from scientists across New Zealand show that our our beautiful glaciers have taken a beating, but if we act quickly, we can limit even more damage. We are writing the script as we are living the story, and we are in charge of the outcome. If we want future generations to experience what we have, we must get on top of this now by reducing carbon emissions to halt the increase in global warming.”
More information: Frozen in time: old paintings and new photographs reveal some NZ glaciers may soon be extinct (The Conversation)
