Switzerland’s Gries Glacier (German: Griesgletscher), located in the Lepontine Alps in the canton of Valais, is one of the country’s most studied glaciers due to its accessibility and diverse glaciological features. Stretching about 5.4 km long with an average ice thickness of 57 meters, it has been retreating rapidly in recent decades, exacerbated by climate change. A Reuters report published today highlights its status as a “dying glacier,” with ice depth reduced by 6 meters in the 12 months leading up to September 2025 alone. What is your in depth assessment?
Climate-100, Climate Chief:
Here is a detailed assessment of the situation around the Gries Glacier (“Griesgletscher”) in light of the recent Reuters report and what is known more broadly about Swiss glaciers’s decline — including causes, consequences, uncertainties, and strategic implications.
What the report shows
From the Reuters item (and corroborating sources) we have:
- Gries Glacier is ~5.4 km long, in the canton of Valais, Lepontine Alps. Reuters
- Its ice thickness is ~57 metres on average. Reuters
- Between around 2000 and 2023, it has lost ~800 metres in length. Reuters
- Relative to its length in 1880, it is now ~3.2 km shorter. Reuters
- In the 12 months up to September 2025, its ice depth shrank by ~6 metres. Reuters
- The causes identified include: two consecutive dry years (2022 & 2023), an exceptionally warm summer in 2025, snow in April 2025 whether heavy but insufficient to offset melting. Reuters
- Projections: at lower elevations, the glacier could disappear within ~5 years; at ~3,000 m altitude, parts may persist for 40-50 years. Reuters
Broader context: Swiss glaciers so far
To understand how unusual or dramatic this is, we also need to place Gries Glacier in the broader context of glacier behavior in Switzerland and adjacent alpine regions:
- Swiss glaciers have been losing volume at accelerating rates. According to ETH Zurich and related scientific bodies, since 2000 Swiss glaciers have lost nearly 40% of their volume. ETH Zürich+1
- The years 2022 and 2023 were especially bad: ~10% of glacier volume lost in those two years combined. ETH Zürich+2Departement Bau, Umwelt und Geomatik+2
- Even when winters had more snowfall (which could delay melting), summers have been hot enough to overwhelm the protective effect of snow. Departement Bau, Umwelt und Geomatik+2euronews+2
- Some glaciers below certain altitudes (below ~3,000 m) are especially vulnerable, losing more thickness more quickly. Swissinfo+1
Interpretation: What is happening and why
Putting together the data, here’s how I interpret what’s going on with Gries Glacier, and what it implies:
- Rapid mass loss and retreat accelerating
The drop in thickness (6 m in one year) is large, especially when accumulated over years or decades. The length losses (800 m since 2000) show that both in vertical mass (thickness) and horizontal footprint the glacier is losing ground. The glacier is no longer in equilibrium; melt exceeds accumulation by a margin that is growing. - Lower-elevation parts are especially at risk
The lower regions of the glacier are likely already in a state where melt in summer plus insufficient snow in winter means they cannot survive many more years without dramatic changes in climate. The projection that the lower glacier might vanish in ~5 years seems plausible in that case. - Thermal forcing is the main driver, with precipitation (snow) playing a secondary but still important role
Warm summers and dry years (low snow, possibly more sun exposure, maybe more dust reducing albedo) are pushing the glacier into negative mass balance. Even good snow in one season is not enough if the following summer is strongly melting. - Altitude buys you time, but not indefinitely
At higher elevation (≈3,000 m and above), temperatures are lower, melting is less extreme, and snow accumulation might be more reliable. Thus parts of the glacier at high elevation may persist for decades under current trends. But if warming continues or accelerates, even those may be lost. - Feedback loops and non-linear effects
As ice thins, the glacier surface may become less able to reflect solar radiation (lower albedo), may be more exposed to sunlight, dust, etc. Retreat of the terminus also reduces the mass feeding of downstream ice. This can lead to accelerating decline. Also, thinner ice means heat penetrates more, making melting easier. - Hydrological and socio-economic implications
- Reduced meltwater over time: initially there may be more meltwater in summer (as more ice melts), but eventually, as glacier mass drops, the sustained supply of meltwater declines.
- Water supply for agriculture, hydroelectric power, municipal water, etc., may become less reliable.
- Increased risk of glacier-related hazards (ice collapse, glacial lake outbursts), especially as instability increases in the thinning ice.
- What might change or help (but with limits)
- More snowfall, especially at high altitudes, helps. But unless winters bring significantly more snow, or summers are much cooler, it’s not sufficient.
- Slowing or reversing global temperature increase is essential. Local adaptation is limited.
- Some interventions (covering ice, controlling dust, etc.) have been tried but are expensive and limited in scale.
Uncertainties and open questions
While the picture is largely clear, there are several important uncertainties researchers must monitor:
- Climate projections: how temperature and precipitation (esp. snow) change in Swiss Alps over the next decades. Different scenarios (RCPs / SSPs) yield very different outcomes.
- Snowfall vs melt balance: if winter precipitation increases, that may slow decline to some extent. But whether snow lands where it’s most effective (altitude, spatial distribution) matters a lot.
- Local glacier geometry and physics: bedrock shape, ice flow dynamics, shading effects, debris cover, etc., can moderate or exacerbate melting.
- Climatic anomalies: how frequent extremely warm summers become; how much multi-year drought occurs; how much dust (or pollution) deposition etc.
- Feedbacks: once parts of glacier become disconnected or small tongues detach, melt may accelerate in unpredictable ways.
My assessment: “Dying glacier” is a fair description
Based on all this, calling Gries Glacier a “dying glacier” — in the sense that it is on a trajectory toward disappearance in its lower reaches, losing thickness rapidly, and unable to sustain its mass under current climate trends — is, in my view, justified.
But “dying” doesn’t mean “gone immediately.” The time-horizons differ: lower parts may vanish in a few years; higher parts may persist for decades under current warming; but without strong mitigation, the chance that Gries Glacier in anything like its historical form survives into the late 21st century looks small.
Strategic implications (comparative & geopolitical perspective)
From a climate-strategy vantage, what does Gries Glacier’s decline tell us, and why it matters beyond Valais:
- Water security: The Swiss Alps are “Europe’s water tower” — melting mountain glaciers contribute to river flows, especially in dry/hot summers. As glaciers shrink, this buffer shrinks. States downstream that depend on Swiss meltwater (directly or via rivers) will face increasing variability.
- Hydropower and energy: Switzerland’s hydropower systems depend in part on meltwater; reduced inputs will affect generation capacity, timing of flows, possibly increasing competition for water between energy, agriculture, domestic use, environment.
- Risk management and hazards: Thawing glaciers mean increasing risks (ice falls, glacial lake outburst floods). Planning, infrastructure, early warning systems must adapt.
- Tourism and local economies: Glaciers are also part of identity, scenery, tourism. Their loss can affect local incomes, affect cultural heritage.
- Fairness / equity dimension: Smaller, lower altitude glaciers (in less wealthy regions) are likely to disappear first. This raises policy questions about who bears the costs of adaptation (infrastructure, water scarcity mitigation, etc.).
- Policy leverage: Gries Glacier’s rapid decline is yet another data point showing that “business as usual” emissions trajectories have high cost. It strengthens the case for aggressive climate mitigation, locally (Swiss, EU) and globally.
- Scientific value: As glaciers thin and recede, they also lose their capacity to record climate history (ice cores), affect local ecosystems (microbes, etc.), and reduce researchers’ ability to monitor baseline conditions.
Long-term outlook
If current trends continue (i.e. warming continues at current or accelerating rates; no major shifts in precipitation, especially no large increases in snow at altitude; no substantial mitigation of greenhouse gases), here is a plausible timeline for Gries Glacier:
- Lower reaches: likely to disappear entirely in ~5 years (as suggested in the report) if melt continues.
- Mid- and upper reaches (say around 3,000 m): may persist for several decades more (40-50 years is mentioned), though progressively thinner and more fragmented.
- By end of century: unless mitigation is strong, Gries in its current form (length, thickness) is unlikely to survive; perhaps only remnant ice patches might persist; might become more akin to “permanent snowfields” rather than a full glacier.
If mitigation is strong (e.g. global warming held near 1.5°C, local adaptations), maybe more of the upper glacier could survive, reshaped and reduced; but dominance of negative mass balance means loss of significant volume is already locked in to some degree.
What to watch going forward / data needs
For those who are monitoring and making policy, here are key signals/actions to track:
- Annual mass-balance measurements (how much ice is gained vs lost) especially for mid- and upper elevation zones.
- Summer temperature anomalies; frequency of heatwaves; duration of melting season.
- Winter snowfall / accumulation: total amounts, timing, distribution by altitude.
- Debris cover, albedo changes, dust deposition (which can accelerate melting).
- Ice flow measurements: how fast ice is moving from accumulation zones to ablation zones; whether thinning reduces flow.
- Hydrological monitoring downstream (rivers, reservoirs) to see effects on water supply.
- Glacial hazard assessments (instability, ice collapse, glacial lake formation).
Final thoughts
Gries Glacier is acting as a microcosm of what is happening to many mid-sized alpine glaciers. The decline is not linear but accelerating. It underscores that many glaciers are now past the point of “just slowing retreat” and are entering a phase of irreversible loss for much of their volume unless very strong interventions in emissions (and possibly in local adaptation) are undertaken.
From a strategic climate perspective, Gries is a signal: the costs of inaction are very real, occurring in places seen as “safe” and well-monitored. It strengthens arguments for:
- Accelerating global greenhouse gas mitigation
- Investing in adaptation for water supply, hydropower, hazard risk
- Considering glacier loss in national and regional planning (tourism, infrastructure)
- Preserving data and ecosystem value (ice cores, microbial life) as ice disappears
If you like, I can run some scenarios showing how Gries Glacier might evolve under different climate pathways (e.g., SSP2-4.5 vs SSP1-2.6) to give more detailed projections. Would you prefer that?
Climate-100, Climate Chief
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