Glaciers on a distant Australian subantarctic island are shrinking rapidly, losing approximately a quarter of their size in just 70 years, with researchers concerned that glaciers on a neighboring peninsula might have already vanished.
Feedback involving aerial photographs and maps dating back to 1947, merged with satellite data, was used to track melting on 29 glaciers on the uninhabited wilderness of Heard Island, situated 4,100km south-west of Perth and 1,500km north of Antarctica.
Experts indicate global heating as the most likely cause of the notable ice loss. Between 1947 and 2019, the island warmed by 0.7C, as the area covered by glacial ice dropped from 289 sq km to 225 sq km.
The most substantial changes were observed on the island’s east, with particular notice on the retreat of the Stephenson glacier, having receded almost 6km since 1947. In the past 20 years, this glacier retreated on average 178 meters annually, according to research published in The Cryosphere.
“Glaciers are extremely sensitive to small changes in temperature,” asserts Prof Andrew Mackintosh, one of the paper’s authors and chief investigator at Monash University’s Securing Antarctica’s Environmental Future (SAEF). As temperatures rise, the melt rate increases, and more snow falls as rain, notes Mackintosh.
“I have no doubt that the rise in temperature is mainly responsible for driving the glacier retreat. This demonstrates that nowhere is immune from the impact of climate change.”
Glacier loss was more dramatic on the neighboring Laurens peninsula, where 10 out of 11 glaciers have nearly disappeared. The 10.5 sq km of glacier ice in 1947 had dwindled to just 2.2 sq km by 2019.
“One or two of those glaciers might have already disappeared now,” suggests Dr Levan Tielidze, the paper’s lead author and a research fellow at SAEF.
“Despite their small size, it’s a signal of what could happen in the future to larger glaciers on Heard. This serves as an indicator of change for our global climate system.”
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SAEF is exploring the future of the island’s glaciers using climate models to understand the potential impact of greenhouse gas emissions.
Mackintosh stated: “Although this mapping highlights stark glacier retreat and further ice loss is inevitable, whether we retain glaciers or lose most of them is dependent on human actions and the greenhouse gas path we follow.”
He further noted: “It may also determine whether biodiversity is devastated or key aspects are preserved.”
Pristine yet endangered
Heard Island draws attention for its recent listing under a 10% trade tariff by Donald Trump, despite being uninhabited.
This heritage-listed island, featuring Australia’s only active volcano, Big Ben, attracts wildlife such as penguins, petrels, albatross, elephant seals, and unique, slow-growing plants.
Dr. Justine Shaw, an associate professor at SAEF and Queensland University of Technology, visited the island in 2003.
Shaw highlighted the devastating impact of glacial retreat on the unique flora of the island, creating a risk for invasive plants to establish themselves.
She expressed concern about the growing lagoon at the foot of the Stephenson glacier, which could lead to soil erosion and nesting issues for birds.
The Australian Antarctic Program has announced two scientific expeditions to Heard Island later this year, the first in over two decades.
Shaw is organizing a team of researchers for the expedition to study the island’s exceptional combination of insects and plants, an ecosystem found nowhere else on the planet.
Expressing no surprise at the glaciers’ retreat, she emphasized: “What’s astonishing is the speed of the melting – it is incredibly rapid.”
