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Climate change is endangering the Alpine region more than the rest of Europe.

The Slovenian Alps tomorrow – extreme weather events and disappearing glaciers

The interaction of three major climate systems (Continental, Alpine and sub-Mediterranean) influences the precipitation regime in the territory of the Slovenian Alps.

Geography and climate

The interaction of three major climate systems (Continental, Alpine and sub-Mediterranean) influences the precipitation regime in the territory of the Slovenian Alps. The spatial variability of precipitation is high – annual precipitation varies from 1100 mm in the coastal parts of river basins to more than 3500 mm in the Julian Alps, where maximum Alpine precipitation has been detected. The spatial distribution of precipitation is highly influenced by the complex terrain. Due to an orographic effect, the Julian Alps and the Dinaric barrier receive the most precipitation. This distribution is a consequence of the fact that the largest amount of precipitation falls during conditions of wet southwesterly winds blowing perpendicularly to the high Dinaric-Alpine orographical barrier.

In the Alpine region the most pronounced precipitation maximum occurs in autumn. Precipitation measurements are generally underestimated, especially in high and exposed mountainous regions. Apart from averages, another important aspect involves extreme weather events, as they constitute an integral part of the natural climate. Due to pronounced variability and, by definition, the rare occurrence of weather and climate extremes, it is difficult to assess trends and long-term variations. The time between two occurrences of a particular extreme event in a certain area may extend over a period of several years. The greatest daily quantities of precipitation, even above 400 mm, have been recorded in the region of Posočje (Upper Soča river basin). During the warm part of the year, there are also frequent strong showers, and the estimation is that precipitation exceeding 100 mm in one hour is possible. All extreme events observed to date will continue to occur in the future. Along with the expected impact of climate change on extreme weather we will most likely experience an increase in both intensity and frequency.

We also need to take into account the possible synergistic effects of various components of the climate system and the environment. Extremes have always represented a threat to society and the environment. In such a varied climate as ours, extremes have various impacts and their consequences involve different aspects. Torrents and floods are a direct result of heavy precipitation, which may cause a series of other harmful events such as soil erosion, landslides and material deposits onto fields and pastures.

Although on average there is enough annual precipitation, we have experienced severe summer droughts in Slovenia four times during the last 15 years – till now never in the Upper Soča river basin, but the Upper Sava Valley was affected during the summer of 2003. Even if mountains are not threathened by drought, summer droughts may be experienced in the lower part of river basins.

One of the important features to be considered in planning for adaptation is the fact that a significant part of the Alps belongs to the national nature protected area, and therefore land use changes and interventions that would corrupt the natural environment are heavily restricted. Additional territory belongs to Natura 2000 and is also subject to certain constraints regarding land use and human-induced changes in the environment.

Climate change and scenarios

Changing climate conditions such as rising temperatures will influence the availability and consumption of water, evaporation is expected to increase and the precipitation regime is expected to change. Snow cover in the mountains could melt sooner in the season, and lower altitudes could get less snow due to a change in the ratio between solid and liquid precipitation. Therefore, the river regime might also change from a snow-rain to a rain-snow regime. But climate change will also induce other environmental changes (e.g. erosion, vegetation, soil and water pollution).

Extreme events represent a major burden on the environment, and so climatic analyses of such events are necessary for assessing the damage and for all spatial interventions (threat risk, planning etc.). Regular monitoring and analysis of extreme events is important for establishing climatic changes, since with such monitoring we also monitor the frequency and intensity of these events. At the same time, data on the intensity of extreme events provide the necessary basis for assessing the damage that such events can cause.

Normally, extreme events that cause damage receive greater attention, but it is not necessary for any meteorological variable to achieve an extreme value. How a specific extreme weather event affects the environment therefore depends on a range of factors: the adaptability of the environment, the time in which the event occurs, the weather in the previous period, etc. An increase in the intensity and frequency of extreme events is considered to be closely related to climate change.

Finally, it might seem that the region under consideration is particularly endangered by extreme weather events, but fortunately they are quite rare and reach a destructive force only in a very limited area. Nevertheless, this might change in the not too distant future.

At present, precipitation trends in the Julian Alps in the Soča river basin do not show a decrease everywhere in the Alps as predicted by climate change scenarios. In the Upper Sava Valley there is a decreasing precipitation trend. Also in the lower part of river basins, a decreasing precipitation trend has already been detected, and water consumption may increase in the future, not only due to increasing mean temperature and increasing sunshine duration, but also due to human activities and changes in water use. More important than annual trends are seasonal trends. In the Alpine area, like everywhere in Slovenia, precipitation shows an increasing trend in autumn.

Figure 1: Different precipitation trends in the Alpine region
Different precipitation trends in the Alpine region
Source: Monthly bulletin Naše okolje

Glaciers are indirect indicators of climate change, as they respond quickly and noticeably to temperature changes.

Glaciers and snow cover as indicators of climate change

There are only two small glaciers in Slovenia, the best known being the Triglav glacier and the second situated on the slopes of Mount Skuta. Both lie at a relatively low altitude and are subject to the detectable impact of climatic changes. The existence of the Triglav glacier can no longer be taken for granted. In the 19th century, it covered 45 ha but significantly contracted in 2003, when it encompassed only 0.7 ha, and in September 2008 extended over 1.1 ha.

The accumulation of fresh snow increases with altitude and precipitation, and thus the areas of maximum fresh snow accumulation are found in the Julian Alps. Nevertheless, huge amounts of fresh snow are rare in the Upper Soča Valley despite significant precipitation there in winter. Due to the influence of the Mediterranean climate, very little snow falls in the lower parts of that region. The seasonal maximum depth of total snow cover is another important climatic variable. The relative variability is greater in areas with lower values because the snowfall in these areas is less regular than at higher altitudes.

The depth increases with altitude, reaching about 2 metres at 1000 m and more than 5 metres in the highest parts of the country. At our highest station, Kredarica, at 2514 m a.s.l., a maximum depth of exactly 7 metres was measured in April 2001. Yet the conditions in the lowlands west of the main Dinaric ridge are completely different. Snowfall there is of short duration and frequency, because that area is under a strong Mediterranean influence.

Figure 2: Triglav glacier extent in ha
Triglav glacier extent in ha
Source: Anton Melik Geographical Institute at the Science and Research Centre of the Slovenian Academy of Sciences and Arts (Ref: Environmental Indicators in Slovenia, PS05)

A pronounced temperature rise is expected in the warm half of the year, with a decrease in precipitation during summer and increase during the cold half of the year.

Climate projections based on historical data and numerical models

Compared to the period 1961–1990, summers towards the end of the century will get warmer by 3.5 °C to 8 °C, and winter warming is expected in a range from 3.5 °C to 7 °C, spring from 2.5 °C to 6 °C, and autumn from 2.5 °C to 5 °C. In spring and autumn months, no significant change in precipitation is expected. In winter, an increase is expected up to 30 %, while during summer, precipitation will decrease by 20 % (Bergant, 2007). Less precipitation and higher temperatures will result in drought conditions in Alpine valleys, which was not the case in the past. We are still more concerned about heavy precipitation rather than drought in the Alpine region.

Source: Bergant, K. 2007. Projekcije podnebnih sprememb za Slovenijo [V: Jurc, M. (ur.). Podnebne spremembe: vpliv na gozd in gozdarstvo], Studia forestalia Slovenica, 130, 67-86.

Protected natural areas

Triglav National Park (TNP) is the only Slovenian national park. It extends along the Italian border and close to the Austrian border in northwestern Slovenia, that is, in the southeastern section of the Alps. Its territory is nearly identical with that occupied by the Eastern Julian Alps. The park covers 880 square kilometres, or 3 % of the territory of Slovenia. Triglav National Park is among the earliest European parks. The first protection of this park dates back to 1924 when the Alpine Conservation Park was founded. The principal task of the Triglav National Park Public Institution is protection of the park, but it also carries out specialist and research tasks.

The park's landscape features are characterised by young folded ranges of the Eastern Julian Alps, diverse relief forms with pointed summits, steep rock faces and deeply-carved glacier valleys. Average temperatures in the warmest month range from 20 °C in the valleys to 5.6 °C in the mountains, and in the coldest month between 0.7 °C and -8.8 °C. Average annual precipitation exceeds 1500 mm, reaching up to 3500 mm.

Forest covers two-thirds of the park's territory; the predominant tree species on the south side of the park is beech, whereas spruces and larches are characteristic of the northern side of the park.

Subterranean waters, karst springs, water sources and glacier lakes are invaluable TNP assets. The mountain ridges between the Sava and the Soča rivers mark the watershed between the Mediterranean and the Black Sea.

There are 25 settlements in the park, accounting for 2352 inhabitants. Among the prevailing activities in the park are: agriculture with a pastoral economy, craft (wood and wool products), ecofarming and tourism. Tourism seems to be the most prosperous activity in this region.

The Alpine region and tourism

The tourism industry's heavy reliance on the local environment to sell holidays means that it could face serious challenges as a result of climate change. The mountains exhibit a great range of climatic conditions, with virtually every Alpine valley having a unique local climate. Tourism in the Upper Soča and Upper Sava valleys represents the most important economic activity. On average, there are 1.6 million visitors per year to Triglav National Park alone. Tourism is therefore important to the economy in the Alps, but in recent decades, winter tourism has endured several consecutive years of losses.

During winter, skiing is the dominant sport activity in the region. Expecting a temperature rise, there will be a considerable shortening of the snow season as well as reduced snowfall. Lower-lying resorts have already had to diversify into other holiday activities. Mount Kanin is one of the highest ski resorts in Slovenia and, with a connection to the ski resorts on the Italian part, represents one of the Slovenian ski resorts which are expected to suffer less because of climate change. In the Upper Sava Valley there are famous ski resorts where some of the most well-known world cups in ski jumping and downhill skiing take place. These ski resorts are situated at a relatively low altitude and could be compromised by changing climate in the not too distant future. Of course, artificial snowmaking could help, but it implies higher operating costs.

The Alps are not only one of the primary winter holiday destinations for skiers, they are also a popular destination for summer walking holidays. Rafting and other activities on the Soča River are dominant. Hiking and alpine climbing are also very popular and attract many tourists in this region. Climate change is expected to extend the season for such activities more towards the shoulder season, and in this respect climate change is expected to have positive effects on summer tourism not only due to the longer season but also due to the fact that more people will come in search of a more temperate summer climate in this mountain region instead of going to the seashore or other tourist resorts in the lowlands where temperature conditions during summer are often oppressive. More tourists and a longer tourist season could increase water consumption and other pressures on the environment in this region.

Hydropower plants

There are already two accumulation basins on the Soča River built as part of two hydropower plants and a third is under construction, which could potentially be used for tourism. It would have to be investigated if they could also serve as water reservoirs for a more sustainable water supply in the downstream parts of the river basin. Of course, there is a potential conflict of interest between nature protection and new water reservoirs.

Lakes, small rivers and streams

There are several Alpine lakes, many of which are quite small and therefore very susceptible to any change in climate. They also immediately react to any form of pollution. The resulting changes in water level could have an adverse impact on the local tourist industry. A decrease in water level coupled with higher temperatures may result in greater concentrations of pollution, including algal blooms, which could discourage water sports. Small rivers and streams are also vulnerable and this could have an impact on sports fishing.

Adaptation strategies

The mountain environment is sensitive to climate change. As for many alpine areas, winter tourism is the most important income source, the financial viability of winter tourism thus depends on sufficient snow conditions. The lack of snow at the end of the 1980s and early 1990s left a lasting imprint on the tourism industry. Snow-deficient winters and shortened skiing seasons result in less earnings in ski tourism. Despite global warming, it is impossible to exclude the possibility of winters with heavy snowfall in the future. Climate change must be viewed as a catalyst that potentially reinforces and accelerates structural changes in tourism. Today, adaptation strategies are predominant in tourism (e.g. artificial snow production, although it is considered to be unsustainable). Such strategies include maintenance of ski tourism (artificial snowmaking, extending skiing paths towards higher altitudes, ski slope design, cooperation), and alternatives to ski tourism, such as non-snow-related activities in winter and all-year tourism. No national adaptation strategy has yet been adopted.

Generally, milder conditions, especially in the winter and shoulder months, could attract more people to the uplands for hill-walking, creating opportunities and threats for agriculture and nature conservation. Mountaineering may provide partial compensation for reduced skiing opportunities, but there will be a greater risk of snow avalanches in the warmer conditions. Mountain areas are vulnerable to landslides, infrastructure becomes unstable, and hiking and climbing are more dangerous due to increasing rockfall. In the future, the climate will change its pattern. More frequent precipitation or a higher fog level could lead to new conditions in summer tourism in mountain areas (hiking, trekking, biking), and more frequent and more intensive extreme events could threaten tourism activities and infrastructure. Climate change also jeopardises mountain agriculture, and consequently farm tourism. Initiatives to develop organic farming and open such farms to tourists seem to be the way forward.

Increased risks for the tourism industry, individual travellers and the environment are expected at tourist destinations, but even now various trends are forcing the tourist industry to develop and adapt constantly. If tourism is not responsibly planned, managed and monitored, it can lead to negative cultural and social impacts. Mass tourism potentially constitutes an enormous burden on the environment.

Figure 3: Triglav glacier in 1957 and 2003
Triglav glacier in 1957 and 2003
Photo: Archive GIAM ZRC SAZU and Matej Gabrovec


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