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Glacier Melting Accelerates Global Sea-Level Rise and Regional Freshwater Depletion

Global glacier melt is increasingly jeopardizing freshwater resources and exacerbating the rise in sea levels, according to recent research findings. An international collaboration of 35 research teams has revealed that glaciers are shedding an average of 273 billion tonnes of ice each year since 2000, with a concerning acceleration observed over the last decade.

In the year 2000, glaciers worldwide, excluding the massive ice sheets of Greenland and Antarctica, covered an area of 705,221 square kilometers and contained approximately 121,728 billion tonnes of ice. Over the last 20 years, these glaciers have experienced a roughly 5% reduction in overall volume, with losses ranging from 2% in the Antarctic and Subantarctic Islands to a staggering 39% in Central Europe. This trend corresponds to an average loss of 273 billion tonnes annually, with a 36% increase in loss rates during the latter half of the study period (2012–2023) compared to the earlier years (2000–2011).

The Glacier Mass Balance Intercomparison Exercise

The recent findings were published in the journal Nature as part of the Glacier Mass Balance Intercomparison Exercise, known as Glambie. This substantial initiative, coordinated by the World Glacier Monitoring Service (WGMS) in Zurich, along with the University of Edinburgh and Earthwave Ltd., aimed to create a comprehensive assessment of global glacier mass loss.

Researchers utilized a variety of satellite technologies, including data from the US Terra/ASTER and ICESat-2 missions, alongside the US-German GRACE mission, among others. By integrating diverse data sources, Glambie produced a detailed annual timeline of glacier mass changes across all global glacier regions from 2000 to 2023.

Michael Zemp, co-lead of the study, highlighted the collaborative nature of the project: “We compiled 233 estimates of regional glacier mass change from around 450 contributors organized in 35 teams. This multifaceted approach not only sheds light on regional trends and annual variability but also establishes a new observational foundation for future research into the implications of glacier melting on water availability and sea-level rise.”

Impacts on Freshwater Resources and Sea-Level Rise

The study revealed that between 2000 and 2023, glaciers collectively lost 6542 billion tonnes of ice, contributing approximately 18 millimeters to global sea-level rise. The annual average loss of 273 billion tonnes equates to a sea-level increase of 0.75 millimeters. Importantly, the rate of ice loss has risen significantly, from 231 billion tonnes annually in the initial phase to 314 billion tonnes in the later years.

Glaciers are now identified as the second-largest contributors to global sea-level rise, following thermal expansion associated with ocean warming. Their contributions exceed those from the Greenland Ice Sheet, the Antarctic Ice Sheet, and changes in land water storage.

Beyond the implications for sea-level rise, the melting of glaciers represents a substantial reduction in regional freshwater supplies. To contextualize this loss, Zemp noted, “The annual loss of 273 billion tonnes of ice corresponds to the water consumption of the entire global population over a span of 30 years, assuming an average of three liters per person per day.”

Inés Dussaillant, a glaciologist involved in the Glambie project, emphasized the critical role of glaciers for freshwater supply. “These ice masses are essential for local populations, particularly in regions like Central Asia and the Central Andes, where they significantly contribute to water runoff during warmer seasons.” She further indicated that while Arctic and Antarctic regions dominate glacier extent, about 25% of the glacier contribution to sea-level rise stems from Alaska.

Noel Gourmelen, another co-leader of the study, acknowledged the collective efforts of the community and space agencies over several years to maximize satellite data usage for glacier monitoring. He alluded to ongoing advancements in satellite technology aimed at enabling effective operational monitoring of glacier dynamics, exemplified by Europe’s Copernicus CRISTAL mission.

This research received funding from the Science for Society element of ESA’s FutureEO programme, alongside contributions from the International Association for Cryospheric Sciences and various institutional collaborators.

As highlighted by ESA Earth Observation Applications Scientist Stephen Plummer, the collaborative nature of Glambie underscores its significance: “These findings are crucial for enhancing our comprehension of glacier transitions and developing strategies to tackle the challenges posed by diminishing freshwater resources and increasing sea levels.” This study also serves as a timely contribution to the upcoming United Nations’ International Year of Glaciers’ Preservation and the inaugural Decade of Action for Cryospheric Sciences (2025–2034).

Source
www.esa.int