Scientists now have a more detailed map of how much ice the world's glaciers actually hold, and where it is located.
A new study led by Ca' Foscari University of Venice, in collaboration with the Institute of Polar Sciences of the National Research Council of Italy, introduces IceBoost v2.0, a machine-learning model that calculates the ice thickness and total volume of glaciers worldwide. The study was published in Scientific Data.
The model was developed by Niccolò Maffezzoli, a physicist and researcher at Ca' Foscari University who is also affiliated with the CNR-ISP. IceBoost v2.0 was trained on more than 7 million ice-thickness measurements collected from glaciers across the globe. It then combined those observations with 26 physical and geometrical variables, including topographic slope, ice velocity, and temperature, to reconstruct ice thickness on a point-by-point basis for every glacier in the Randolph Glacier Inventory, the world's most current global glacier database. The polar ice sheets of Antarctica and Greenland were excluded.
According to the new estimates, the world's glaciers contain approximately 150,000 cubic kilometers of ice. If those glaciers were to melt entirely, sea levels would rise by about 32.3 centimeters, or roughly 12.7 inches, on a global average. While that figure is broadly consistent with earlier estimates, what makes IceBoost v2.0 significant is its precision. The model matches field observations up to 40% more accurately than previous approaches.
One example that stands out is the Geikie Plateau in eastern Greenland. The glacier there reaches up to 2 kilometers thick. In that area, IceBoost v2.0 estimates nearly twice as much ice as was previously reported, a substantial revision with implications for sea-level projections tied to that region.
Maffezzoli explained the stakes of getting glacier measurements right. "The distribution of glacier ice thickness is a fundamental variable for glaciological and climate models. To predict how glaciers will evolve by 2100 and quantify their contribution to sea-level rise, we first need the most detailed possible picture of their current state. Researchers involved in the Glacier Model Intercomparison Project (GlacierMIP4), who are producing the next generation of glacier simulations to inform the IPCC's assessments of glacier evolution through 2100, will use IceBoost v2.0 as their sole representation of the present-day situation."
The model also flags where it is most reliable and where data gaps remain largest. The Himalaya and Karakoram mountain ranges and the major Patagonian ice fields are among the areas where additional field measurements are most urgently needed.
Beyond climate projections, the research has implications for freshwater supply. Glaciers feed rivers and sustain agriculture and ecosystems in many regions of the world. Knowing more precisely how much ice exists, and where it is thickest, helps water resource managers and governments plan for long-term changes in supply.
An interactive web application has been made publicly available, allowing anyone to explore the model's data for any glacier worldwide.
