Almost a quarter of the glaciers in one of the world's last pristine ecosystems have melted from climate change, according to new research from Monash University.
The finding has scientists reiterating calls for decisive climate action as they brace for devastating consequences to biodiversity on Heard Island, a sub-Antarctic island and Australian external territory about 4,100 kilometres south west of Perth.
The research, undertaken by Monash University-led Australian Research Council (ARC) research centre Securing Antarctica's Environmental Future (SAEF), and published in academic journal The Cryosphere, found around 64 square kilometres, or 23.1 per cent, of the icy landscape has been lost since 1947.
Dr Levan Tielidze, a SAEF Research Fellow in the Monash School of Earth, Atmosphere and Environment, said despite its location, studying this remote environment can tell us a lot about how the rest of our planet is faring under climate change.
"These findings are a bellwether of change for our global climate system," Dr Tielidze said.
"While Heard Island is just about as remote as it's possible to be on Earth, it has still suffered profound consequences from climate warming, which is almost certainly due to rising greenhouse gas emissions in the 20th and 21st centuries.
"The island's location in the Southern Ocean makes it a key part of the global climate system and an important indicator of the planet's health, so the changes we are observing paint a really clear and concerning picture."
With much of Heard Island understudied due to the challenges of reaching and traversing the remote terrain, the Monash researchers used topographical maps from 1947 and satellite imagery from historical and current Earth observation platforms to study the island.
The resulting glacier inventory catalogues 29 glaciers, tracing their outlines in 1947, 1988 and 2019.
It also documents key morphological features, including area, slope, aspect and elevation, providing data for estimating mass balance, glacier volume, surface velocity and the impact of volcanic and other surface debris.
Researchers hope to build on this work during a planned visit to Heard Island with the Australian Antarctic Program later this year to study how glacier retreat threatens mountain biodiversity.
Professor Andrew Mackintosh, Head of Monash School of Earth, Atmosphere and Environment and SAEF Chief Investigator, said the team will use computer models to predict how the island's glaciers will respond to global warming.
"We'll explore two possible futures; one where strong action is taken to reduce greenhouse gas emissions, and another where little is done and emissions continue as usual," Professor Mackintosh said.
"Although this mapping shows stark glacier retreat and further ice loss is unavoidable, whether we retain glaciers or lose most of them entirely is up to humans and the greenhouse gas emission pathway we follow.
"It might also mean the difference between a future where biodiversity is devastated, or one where key parts are secured."
Heard Island is a UNESCO World Heritage-listed site located about 1,700 kilometres north of Antarctica.
It is 61 per cent covered in ice and dominated by an active volcano, Big Ben, with an official height of 2,745 metres, although recent studies suggest it has grown to more than 2,800 metres.
The island recently made headlines when US President Donald Trump imposed a 10 per cent tariff on it and nearby McDonald Island, despite no trade occurring there and no human visits since 2016.
To view the research paper, please visit: https://tc.copernicus.org/articles/19/2677/2025/
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Dr Levan Tielidze, Research Fellow at Monash School of Earth, Atmosphere and Environment and Monash-led Australian Research Council Securing Antarctica's Environmental Future Professor Andrew Mackintosh, Head of Monash School of Earth, Atmosphere and Environment and Chief Investigator at Monash-led Australian Research Council's Securing Antarctica's Environmental Future
