Alpine areas are facing extreme climate change impacts, including warming temperatures and extreme rainfall intensity.
These mechanisms represent the main rockfall triggering factors. Recently, several researchers have found direct evidence linking climate change and the increasing size and frequency of rockfalls. One such example is Cinque Torri, also known as the Five Towers, which is a small, iconic mountain range in the Dolomites located in Northeastern Italy. Over the last two decades many significant collapses have been recorded in the Dolomites, including the complete collapse of the Trephor Tower, one of the Five Towers. The Dolomites are a popular tourism spot due to their stunning mountain scenery, being a UNESCO World Heritage site, with year-round outdoor activities such as hiking and skiing. This increase in hazard is causing greater risk to people and infrastructure in such mountainous regions.
Climate change in Alpine Areas
Climate change is significantly impacting alpine areas. Alpine areas worldwide are experiencing warmer temperatures and less rainfall. In NSW, ‘winter temperatures are projected to rise by more than 2°C in the far future’, and ‘spring rainfall is projected to decrease by 20% in the far future’ according to AdaptNSW (AdaptNSW 2025). The Alps in Europe are experiencing warming that is twice the global average, and studies have found a 2°C warming can double the frequency of extreme summer downpours (Peleg 2025). These changes are resulting in reduced snow depth and duration, earlier snowmelt, and warmer, drier conditions. Recent research has confirmed the theory that these conditions are causing increased rockfall in alpine areas.
Climate-induced Rockfall Mechanisms
The Freeze-thaw cycle is the primary process which results in rockfall. It occurs when temperatures repeatedly cross the freezing point of water. Initially water seeps into cracks and pores. As temperatures drop below zero the water then freezes and expands by about 9%. This exerts pressure on the surrounding material, leading to cracks and damage. As temperatures then warm the ice thaws, allowing the process to start again, where even more water can seep into the cracks. Over time, this repeated Freeze-thaw cycle can cause chips, flakes, and breaking of rocks into smaller pieces resulting in rockfall in mountainous areas.
Another mechanism is the melting of permafrost. On mountain slopes, permafrost, which is permanently frozen ground, contains ice that helps hold rocks in place. As global temperatures rise the ice melts, weakening the permafrost and causing it to break apart and fall.
In a similar process, glacier retreat, the shrinking of glaciers as global temperatures rise, increases rockfall risk because the ice, which once stabilized slopes, is melting away, leading to rock instability.
Activity in the Dolomites
Cinque Torri is an iconic rock formation in the Dolomites, consisting of five monolith towers. Its formation is the result of tectonic activity hundreds of millions of years ago creating vertical faults in the well-stratified Main Dolomite rock, which sits on softer clay-like layers.
In June 2004, one of the five towers, the Trephor Tower, came down. The English Tower is likely the next to fall, already displaying an evident diagonal crack where it is likely to break and slide down.
Since it fell there have been many significant collapses in the Dolomites. Some of the notable collapses include Grand Vernel (2015), Piccola Croda Rossa (2015, 2016), Cima Lastei (2016), Carè Alto (2018), Croda Marcora (2021, 2025), Sassolungo (2023), and Cima Tosa (2023).
These rockfalls pose significant risk to locals and tourists, as well as buildings and infrastructure. There are several notable towns and villages in the Dolomites such as Cortina d’Ampezzo and Ortisei which have high rockfall risk. The area is also popular for sightseeing, skiing, hiking, rock climbing and mountaineering. The main roads which provide access to remote towns in the region pass through the Dolomites, and Cortina d’Ampezzo in the dolomites is also a main venue for the upcoming 2026 Winter Olympics.
Evidence from the European Alps
Jacquemart et. al. (2024) published a joint study ‘Detecting the impact of climate change on alpine mass movements in observational records from the European Alps’. The international team evaluated 335 scientific papers from ~1995 to early 2024 on the most common natural hazards in the Alps, namely rockfall, rock avalanches, debris flows, ice avalanches, and snow avalanches. They determined the climate change signal is detectable in observations of all processes but large rock avalanches, and for rockfall they found an increased frequency in high-alpine areas due to higher temperatures.
For rockfall and rock avalanches 45 studies were identified that address the climate-related dynamics of rockfall and rock avalanches in the European Alps. Of these 45 studies, 12 had detected climate change impacts on rockfall activity and rock avalanches, and 21 maybe/partly had an observed climate change impact. The impact of climate change on rockfall and rock avalanches was also more pronounced in high elevation alpine areas.
Evidence from tree records
Stoffel et. al. (2024) sought to find direct evidence that rockfall in high-mountain regions is changing due to accelerating climate warming and permafrost degradation. They used growth-ring records from 375 trees damaged by past rockfall at Täschgufer in the Swiss Alps to compile a continuous time series of periglacial rockfall activity from 1920 to 2020. Trees in the area are hit by medium to larger rocks as smaller rock fragments are typically deposited upslope. The rockfall damages trees, causing injuries that the trees attempt to heal with chaotic callus tissue and the formation of tangential rows of traumatic resin ducts (TRDs). The group use these injuries and TRDs as indicators for dating past rockfall. They can even determine seasonality if the wounding occurred during the growing season.
The growth-ring tree records show a sharp increase in rockfall from 4.76 (1920–1940) to 31.23 (1990–2011) over time. However, this large increase is likely influenced by biases related to changing sample depth and target size. After removing such biases, substantial increases in rockfall frequency from the late 1940s to the early 1950s and especially since the mid-1980s were found. The rockfall frequency was also found to have significant correlation with air temperatures.
The group also found a shift in the seasonal occurrence of rockfall. Between 1920 and 1969, almost all tree injuries and a majority of growth disturbances occurred during dormancy (1 October to 15 May). However, after 1970, the relative frequency of winter-spring rockfall decreased, whilst there was a noticeable increase in ‘warm-season’ rockfall (16 May to 30 September). The ‘warm-season’ activity has risen sharply after 1970 and even more so since 2010.
Evidence in the Dolomites
Bonometti et. al. (2025) studied rockfall triggering and meteorological variables in the Dolomites (Italian Eastern Alps). They developed a new approach using meteorological variable frequencies to understand climatic scenarios from 1970 to 2019 with implication on triggering historical rockfall events in the Dolomites. They considered key climate variables such as mean air temperature, precipitation, thermal amplitude, freeze/thaw cycles and icing. They determined rockfalls to be correlated with high intensity rainfall events exceeding 31.5 mm in autumn, and rockfall to be correlated with mean temperature ranging from 5.8°C to 15.4°C at different altitudes in summer and autumn. They also observed a correlation between rockfalls and frequent temperature fluctuations, supporting the belief that changes in freeze-thaw cycles are correlated with the increase in rockfall occurrence.
Alpine hazards in Australia
Fortunately, the Australian alps have no permafrost and are not often affected by rockfall, rock avalanches, debris flows, ice avalanches, and snow avalanches. Australia’s mountains are typically not very steep, and are characterized by old weathered rocks and well developed soil profiles, which are not prone to rockfall, at least not in the areas where people and assets are located.
However, it does not mean Australia is devoid of such hazards. In 1997 Thredbo was impacted by a landslide. It destroyed two ski lodges and 18 people died The landslide was caused by water from heavy rain, melting snow and a leaking water main. The Coroner noted that there had been landslides prior to July 1997 and that these prior landslides should have warranted action from the relevant authorities (Hand 2000). In the aftermath, three terraces with gabions and reinforced fill were constructed on the site, the Alpine Way was rebuilt with upslope retaining walls, and the site is now monitored with 25 inclinometers to detect any slope movement and 12 piezometers to keep track of water flow in the soil.
The Australian Government is evidently wary of increasing rockfall hazard with climate change, having awarded a grant to The University of Newcastle (grant DP240100341) with the aim of transforming decision making for rockfall hazard assessment. The National Interest Test Statement stated ‘with the impact of climate change, the rate and severity of extreme events is predicted to significantly increase and further intensify the vulnerability of rock slopes’ (Australian Research Council 2024).