Glacial Ice Loss Escalates Freshwater Depletion and Sea Level Rise
by Erica Marchand
Paris, France (SPX) Feb 20, 2025
A recent study underscores the accelerating loss of glacial ice worldwide, depleting regional freshwater reserves and significantly contributing to rising global sea levels. Conducted as part of the Glacier Mass Balance Intercomparison Exercise (GlaMBIE), the research, published in *Nature* on February 19, 2025, involves contributions from 35 international teams, including the German Aerospace Center (DLR).

Global Glacial Ice Loss Intensifies

At the start of the 21st century, glaciers spanned over 705,221 square kilometers, containing an estimated 121,728 billion tonnes of ice. Since then, they have been losing an average of 273 billion tonnes of ice annually. This loss rate, however, has escalated in the last decade, as highlighted in the GlaMBIE study, which focused on predefined glacier regions that are particularly vulnerable due to their size and location. Notably, the study excluded the Greenland and Antarctic ice sheets.

Over the past two decades, glaciers within the study have lost roughly five percent of their total volume, with regional losses varying significantly. The Antarctic and sub-Antarctic islands experienced a two percent reduction, while Central European glaciers saw a staggering 39 percent decline. The study further reveals that smaller glacier regions, particularly those under 15,000 square kilometers, are more susceptible to rising global temperatures. The rate of ice loss surged by 36 percent in the latter half of the study period (2012-2023) compared to the earlier period (2000-2011), with annual losses climbing from 231 billion tonnes to 314 billion tonnes after 2012.

Satellite Data Sheds Light on Ice Decline

"At the DLR Earth Observation Center, we analyzed over 5,000 TanDEM-X datasets to estimate ice loss from Greenland's peripheral glaciers. Additionally, we extended our assessment of Patagonian Ice Fields up to 2016 and further across the Southern Andes," explained Dana Floricioiu, co-author from DLR's Earth Observation Center (EOC).

Using the high-resolution radar capabilities of the TerraSAR-X and TanDEM-X satellite duo, researchers can continuously monitor changes in ice sheets and glaciers, independent of weather conditions or daylight. These satellites provide critical data, offering the most precise mapping of Greenland and Antarctica while also supporting numerous scientific, commercial, and security applications.

Integrating Multi-Source Data for Global Glacier Mass Assessment

The GlaMBIE initiative coordinated the collection, standardization, and evaluation of diverse data sources, incorporating field measurements and various satellite-based observations, including optical, radar, laser, and gravimetric methods. Contributions came from missions such as the US Terra/ASTER and ICESat-2, the US-German GRACE project, Germany's TanDEM-X mission, and ESA's CryoSat mission. This approach enabled the creation of a comprehensive annual time series of glacier mass changes spanning 2000 to 2023.

"We compiled 233 regional glacier mass change estimates from about 450 data providers across 35 research teams," said Michael Zemp from the University of Zurich, co-leader of the study. "By combining various observation techniques, GlaMBIE offers fresh insights into regional trends and year-to-year variations while also improving comparisons across different measurement methods. This work provides a new benchmark for future studies assessing glacier melt impacts on regional water resources and global sea-level rise."

Co-author Sahra Abdullahi elaborated on the findings for Greenland's peripheral glaciers: "With an annual loss of 35 billion tonnes of ice since 2000, these glaciers rank as the third-largest contributors to global glacier mass loss, following Alaska and the Canadian Arctic. This is largely due to the Arctic's rapid climate changes, where warming rates are among the highest in the world."

EOC colleague Lukas Krieger added: "The Southern Andes are losing 26.5 billion tonnes of ice each year-accounting for ten percent of global glacier ice loss and ranking as the fourth-highest contributor worldwide."

Consequences for Freshwater Availability and Sea Level Rise

The study examined 19 glacier regions, revealing a total ice loss of 6,542 billion tonnes from 2000 to 2023, contributing 18 millimeters to global sea level rise. Glaciers are now the second-largest driver of sea-level increase, surpassed only by ocean warming-induced thermal expansion. Alarmingly, glacier loss has a more significant impact on sea levels than the melting of the Greenland and Antarctic Ice Sheets.

In addition to rising sea levels, the decline of glacial ice significantly threatens regional freshwater supplies. "To put this in perspective," said Zemp, "the 273 billion tonnes of ice lost annually is equivalent to the freshwater consumption of the entire global population over a 30-year period, assuming a daily intake of three liters per person."

Research Report:Community estimate of global glacier mass changes from 2000 to 2023

Related Links
CryoSat at ESA
Beyond the Ice Age