Glacier mass loss affects sea level rise, water resources, and natural hazards.
A recent study suggests that the glaciers are melting more quickly than scientists had anticipated. And if the current climate trends continue, it is estimated that two-thirds of the glaciers now found on Earth will vanish by the end of this century.
The study, published Thursday in the journal Science, projects that glaciers will be affected under global temperature increases of 1.5 degrees Celsius to 4 degrees Celsius, with losses of one quarter to nearly one half of their mass by 2100.
"Mountain glaciers, perennial ice masses excluding the Greenland and Antarctic ice sheets, are a critical water resource for nearly two billion people and are threatened by global warming," the study mentioned.
In an also unlikely worst-case scenario of several degrees of warming, 83% of the world's glaciers would likely disappear by the year 2100, Time magazine reported citing the study authors.
In comparison to other studies, the study evaluated all 215,000 land-based glaciers on the planet.
According to Time Magazine, the study's lead author, David Rounce, said that "the world is now on track for a 2.7-degree Celsius (4.9-degree Fahrenheit) temperature rise since pre-industrial times, which by the year 2100 means losing 32% of the world's glacier mass, or 48.5 trillion metric tonnes of ice, as well as 68% of the glaciers disappearing. That would increase sea level rise by 4.5 inches (115 millimeters) in addition to seas already getting larger from melting ice sheets and warmer water."
Even in a best-case, low-emissions scenario, where the increase in global mean temperature is limited to +1.5 degrees Celsius relative to pre-industrial levels, over 25 percent of glacial mass will be gone and nearly 50 percent of glaciers by number are projected to disappear, the study said.
A majority of these lost glaciers are small (less than one sq km) by glacial standards, but their loss can negatively impact local hydrology, tourism, glacier hazards, and cultural values, the study said.
Rounce's work provided better context for regional glacier modelling, and he hoped it would spur climate policymakers to lower temperature change goals beyond the 2.7 degree Celsius mark that pledges from COP-26, held in Glasgow, UK, are projected to hit.
Smaller glacial regions like Central Europe, Western Canada, and the US will be disproportionately affected by temperatures rising more than 2 degrees Celsius C. According to the study, the glaciers in these regions will almost completely disappear if temperatures rise by 3 degrees Celsius.
Rounce noted that the way in which glaciers respond to changes in climate takes a long time.
He described the glaciers as extremely slow-moving rivers.
Cutting emissions today will not remove previously emitted greenhouse gasses, nor can it instantly halt the inertia they contribute to climate change, meaning even a complete halt to emissions would still take between 30 and 100 years to be reflected in glacier mass loss rates, the study said.
Many processes govern how glaciers lose mass and Rounce's study advances how models account for different types of glaciers, including tidewater and debris-covered glaciers, the study said.