Across the world, as the climate warms, mountain glaciers are disappearing. Not only are they rapidly losing mass, with recent assessments indicating that globally, glaciers lost 273 gigatonnes of ice from 2000-2023, which is 5% of their year 2000 total ice mass1.
This global scale ice loss is causing glaciologists to start to record the concept of ‘glacier extinction’ 2. Many glaciers have already been lost, though there is nuance in exactly when a glacier becomes ‘extinct’3. You can now search for reported ‘extinct glaciers’ in the GLIMS database, though this is likely to be an underestimate due to a lack of systematic reporting to date.
But what about the future? How will our future climate impact glacier extinction? Which valleys will no longer contain ice and where is most vulnerable? How will glacier extinction impact those places where glaciers perform important touristic functions, or where glaciers hold deep cultural, historic or symbolic importance?
Van Tricht and colleagues tackle this in their recent research4, tracking glacier extinctions under different climate scenarios. They use a glacier model to predict glacier extinctions under global warming levels of +1.5°C, +2°C, +2.7°C (the current policy pledges), and +4°C.
Glaciers are classified as disappeared, or extinct, when the projected area falls below 0.01 km2, or its remaining volume is less than 1% of its initial value in the RGI v.6.0.
Van Tricht and colleagues show that glacier extinction will peak in the mid-century, with ~2000 glaciers per year going extinct by 2040 CE under +1.5°C. Under 4°C, this peak shifts to the mid-2050s, and is ~4000 glaciers per year.
Unsurprisingly, it is the smallest ice masses that are most vulnerable4. Places with small and rapidly responding glaciers, such as the Caucasus, Subtropical Andes and European Alps, over 50% of glaciers are projected to disappear over the next two decades. These glaciers are mostly small and contribute little to total ice volume; the largest glaciers will remain for a while yet.
Places with larger glaciers, such as the ice sheet peripheries or Svalbard, have a later peak extinction that occurs later in the 21st century or beyond.
The loss of glaciers is sensitive to the global warming level. Under a +1.5°C scenario, the projected number of glaciers lost over the next 20-30 years is half that expected under a 4°C scenario.
This shows that every fraction of a degree is worth fighting for – and that the longer time we spend in an overshoot of above 1.5°C, the more glaciers we will lose.
You can explore the projected glacier extinctions yourself under the team’s fabulous Glacier Explorer. Is your favourite glacier extinct?
This tool allows you to visualise the landscape in 3D, and to switch between different global warming levels. It gives you an estimate of the year when glaciers will be extinct and you can see how extinction evolves across mountain ranges.
