Tiel et al. (2026) Swiss glacier mass loss during the 2022 drought: persistent streamflow contributions amid declining melt water volumes

Identification

• Journal: Hydrology and earth system sciences
• Year: 2026
• Date: 2026-01-06
• Authors: Marit Van Tiel, M. Huss, Massimiliano Zappa, Tobias Jonas, Daniel Farinotti
• DOI: 10.5194/hess-30-23-2026

Research Groups

• Laboratory of Hydraulics, Hydrology and Glaciology (VAW), ETH Zurich, Zurich, Switzerland
• Swiss Federal Institute for Forest, Snow and Landscape Research (WSL), Sion, Switzerland
• Department of Geosciences, University of Fribourg, Fribourg, Switzerland
• Swiss Federal Institute for Forest, Snow and Landscape Research (WSL), Birmensdorf, Switzerland
• WSL Institute for Snow and Avalanche research (SLF), Davos, Switzerland

Short Summary

This study analyzed the role of glaciers in mitigating the severe hydrological drought in Switzerland during the extremely warm and dry year of 2022. It found that while glaciers significantly buffered water deficits, total meltwater volumes have declined compared to past extreme years due to ongoing glacier area loss, despite higher melt rates per unit area.

Objective

• To analyze the role of glaciers in sustaining downstream water supply during the 2022 drought in 88 glacierized catchments across Switzerland.
• To assess if ongoing glacier retreat has led to a declining meltwater supply during extreme conditions by comparing 2022 with previous extreme years (1921, 1928, 1947, 1998, 2003, 2018).
• To quantify the compensation effect of glacier meltwater for deficits in rainfall and snowmelt, and how this varies spatially and with distance from glaciers.
• To identify the hydro-meteorological drivers behind the extreme glacier melt and downstream flow deficits.

Study Configuration

• Spatial Scale: 88 gauged glacierized catchments in Switzerland, covering 97% of the 1400 Swiss glaciers. Catchment sizes range from 9 km² to 35 877 km². The study focuses on four main river basins: Rhine, Rhone, Po, and Danube.
• Temporal Scale: Primary focus on the year 2022. Comparisons are made with seven past extreme years (1921, 1928, 1947, 1998, 2003, 2018). Daily resolution data is used, with glacier storage changes estimated from 1916–2022 and some meteorological data from 1900–2022. Reference period for anomalies is generally 1991–2020.

Methodology and Data

• Models used:
  • Distributed hydrological model PREVAH (for actual evapotranspiration, using Penman-Monteith scheme).
  • Snow model OSHD_TICL (for snow water equivalent, SWE).
  • Distributed accumulation and temperature-index model (for daily glacier mass balance).
  • Volume-area scaling (Bahr et al., 1997) for glacier area evolution.
• Data sources:
  • Streamflow: Gauging stations from the Federal Office for the Environment Switzerland (FOEN), Cantonal stations (Bern, Valais, Glarus, Vaud), and hydropower companies.
  • Meteorology (Precipitation, Temperature): Gridded products (RhiresD and TabsD) and station data from MeteoSwiss.
  • Snow Water Equivalent (SWE): Swiss operational snow product (SLF).
  • Glacier Mass Balance: In-situ annual and seasonal mass balance data (GLAMOS), geodetic mass balances (Fischer et al., 2015).
  • Glacier Outlines: Swiss Glacier Inventory 2016 (Linsbauer et al., 2021) and 1973 inventory (Müller et al., 1976).
  • Glacier Volume: Grab et al. (2021) for 2016.
  • Glacier storage change: Daily time series derived in this study (Van Tiel and Huss, 2025).

Main Results

• In 2022, summer temperature anomalies ranged from +1.8 °C to +2.7 °C, and annual precipitation was 17% to 40% lower than the 1991–2020 reference period.
• Swiss glaciers lost an estimated 3 km³ of ice volume (equivalent to 2.6 km³ of meltwater) in 2022, which is more than three times the mean loss over 1991–2020. Total meltwater generated was 3.6 km³.
• 60%–80% of the total glacier melt in 2022 resulted from net mass loss (imbalanced melt).
• The anomalous annual mass balance of 2022 was primarily driven by the summer mass balance anomaly (55%–75% contribution).
• The anomalous summer melt was attributed 15%–20% to an earlier onset of the ablation period and 75%–85% to more intense melt.
• Glacier melt fully compensated precipitation and snowmelt deficits in catchments with approximately 25% glacierization annually, and 15%–20% glacierization during summer. Even in catchments with 1%–5% glacier cover, melt alleviated deficits by about 10%.
• Relative glacier melt contributions to streamflow in 2022 were among the highest compared to other extreme years, reaching up to almost 100% of summer streamflow in some highly glacierized catchments.
• While 2022 recorded the most negative specific glacier mass balance (annual and summer), total glacier meltwater volume (Swiss-wide) was smaller than in 2003 due to a 21% reduction in glacier area since 2003.
• In July 2022, 48 out of 76 catchments experienced higher glacier meltwater volumes than in July 2003, but only 13 of these also showed higher streamflow due to larger precipitation and snowmelt deficits.
• Over the entire summer (May–August), only 20 out of 76 catchments had higher glacier meltwater volumes in 2022 than in 2003, indicating a declining meltwater supply in 68% of catchments despite higher melt rates.
• Glacier melt sensitivity (meltwater volume per unit temperature in Kelvin) declined for most glaciers smaller than 0.1 km² after 2003, but larger glaciers (>10 km²) still showed high sensitivity in 2022.

Contributions

• Provides the first regional-scale, observation-based quantification of the glacier compensation role during drought in Switzerland.
• Introduces a novel approach for estimating daily glacier mass change for all 1400 individual Swiss glaciers from 1916 to 2022.
• Offers a comprehensive analysis of the hydro-meteorological drivers of extreme glacier melt and downstream flow deficits during the 2022 drought.
• Delivers a long-term perspective by comparing 2022 with past extreme years, demonstrating a critical shift where glacier area loss now often outweighs increased melt rates, leading to declining total meltwater volumes.
• Highlights the importance of distinguishing between net annual meltwater volumes (mass losses) and total meltwater volumes when assessing the "decreasing glacier meltwater supply."

Funding

• Deutsche Forschungsgemeinschaft (grant no. 510684314)
• Swiss National Science Foundation (grant no. 184634)

Citation

@article{Tiel2026Swiss,
  author = {Tiel, Marit Van and Huss, M. and Zappa, Massimiliano and Jonas, Tobias and Farinotti, Daniel},
  title = {Swiss glacier mass loss during the 2022 drought: persistent streamflow contributions amid declining melt water volumes},
  journal = {Hydrology and earth system sciences},
  year = {2026},
  doi = {10.5194/hess-30-23-2026},
  url = {https://doi.org/10.5194/hess-30-23-2026}
}