The Hintereisferner, a sentinel glacier nestled at the rear of the Tyrolean Ötztal in the Alps, has been monitored for more than 100 years.
There are continuous records of the glacier’s mass balance dating back to 1952, and these records have been the focus of decades of climate research at the University of Innsbruck.
What sets apart the research at Hintereisferner from other glacier studies is the technology used by scientists.
Since 2016, a unique system – a terrestrial laser scanner – has been scanning the glacier’s surface daily, registering real-time elevation changes. This provides experts with a precise record of its volume fluctuations.
Annelies Voordendag, the lead glaciologist from Innsbruck, introduced a term that represents the balance of the glacier: “Glacier Loss Day” or GLD. This term symbolizes the day when the ice accumulated during winter begins to melt.
“Tracking the volume and mass changes of a glacier in daily time steps allows a nearly instant evaluation of the state of a glacier in a particular year,” wrote the study authors.
“We introduce the Glacier Loss Day (GLD) as being the day in the hydrological year on which the mass accumulated during winter is lost, and the glacier loses mass irrecoverably for the rest of the mass balance year.”
The researchers said it became clear early in the summer of 2022 that Glacier Loss Day would be reached very soon. They compared GLD to the Earth Overshoot Day, which marks the date when we use up more natural resources than the Earth can renew in a year.
According to the experts, monitoring this Glacier Loss Day provides a snapshot of the Hintereisferner’s health each year.
“The earlier the GLD is reached, the higher the probability of massive mass loss. The key to interpreting and using the GLD as a near-real-time gross but expressive indicator for a glacier’s state of ‘illness’ is to record its progressing volume and mass loss during an ablation season at a daily resolution,” explained the researchers.
In 2022, the GLD for the Hintereisferner was recorded as early as June 23rd. By contrast, the Glacier Loss Day in the preceding two years was not reached until mid-August.
Even during years with extreme negative balances, like 2003 and 2018, this date was not recorded until July’s end.
The premature Glacier Loss Day indicates that the Hintereisferner spends a larger portion of the year losing mass rather than staying balanced or gaining.
“These are clear signals of anthropogenic climate change. The consequences of our greenhouse gas emissions are already hitting us hard today,” said glaciologist Rainer Prinz.
The repercussions of human-induced greenhouse gas emissions are manifesting now, and the trend only seems to escalate. The team’s study paints a grim future – projecting that in a span of 10 to 20 years, only half of the Hintereisferner will remain.
“These are clear climate change signals that are due to anthropogenic global warming and the consequences of our greenhouse gas emissions, which are already fully affecting us today,” wrote the study authors.
The research is published in the journal The Cryosphere.
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