Réf. EURAC 2011 - R: CLISP

Référence bibliographique complète

EURAC 2011. WP 4 Vulnerability Assessment. Synthesis Report. Alpine Space CLISP Project Report, 30 April 2011, 144 pp. (65 pp + Annexes). [Rapport en ligne]


Mots-clés

 

 

Organismes / Contact

Authors: EURAC – Institute for Applied Remote Sensing

The CLISP project wass co-funded by the European Territorial Cooperation "Alpine Space" Programme 2007–2013. The following Project Partners and their external expert teams have collaborated in the CLISP project:

Acronym 

Partner Institution – in native language

Partner Institution – in English language

 Country

Role

UBA / EAA

Umweltbundesamt GmbH      

Environment Agency Austria

AT

LP

BMLFUW

Bundesministerium für Land‐ und Forstwirtschaft, Umwelt und Wasserwirtschaft, Sektion Forst

Federal Ministry of Agriculture, Forestry, Environment and Water Management, Forest Department

AT

WP 6
Responsible

Salzburg

Amt der Salzburger Landesregierung, Abteilung Raumplanung

Regional Government of
Salzburg, Department of Spatial Planning

AT

 

Steiermark

Amt der Steiermärkischen Landesregierung, Abteilung 16 ‐ Landes‐ und Gemeindeentwicklung

Office of the State Government of Styria, Department 16 ‐ State Planning and Regional Development

AT

WP 7
Responsible

Oberösterreich

Amt der Oberösterreichischen Landesregierung, Abteilung Raumordnung

Office of the Government of Upper Austria; Department of  Spatial Planning

AT

 

STMWIVT

Bayerisches Staatsministerium für Wirtschaft, Infrastruktur, Verkehr und Technologie, Abtl. 5 Raumplanung und Fachplanung II

Bavarian Ministry of Economic Affairs, Infrastructure, Transport and Technology, Department for Regional Planning and Development

GE

 

MATT

Ministero dell'Ambiente e della Tutela del Territorio e del Mare

Italian Ministry for the Environment, the Land and the Sea

IT

WP 3
Responsible

EURAC

Accademia Europea di Bolzano

European Academy of Bolzano

IT

WP 4 Responsible

Alessandria

Provincia di Alessandria

Province of Alessandria

IT

 

UIRS

Urbanistični Inštitut Republike Slovenije

Urban Planning Institute of the Republic of Slovenia

SLO

 

UNEP

United Nations Environment Programme, Interim Secretariat of the Carpathian Convention

United Nations Environment Programme, Interim Secretariat of the Carpathian Convention

AT

 

ARE

Bundesamt für Raumentwicklung, Sektion Ländliche Räume und Landschaft

Swiss Federal Office for Spatial Development, Strategy Group Politics of Rural Areas

CH

 

Graubünden

Graubünden, Amt für Raumentwicklung

Grisons, Office for Spatial Development

CH

 

Liechtenstein

Fürstentum Liechtenstein, Ressort Umwelt, Raum, Land‐und Waldwirtschaft

Principality of Liechtenstein, Ministriy of Environmental Office, Land Use Planning, Agriculture and Forestry

FL

 

 

(1) - Paramètre(s) atmosphérique(s) modifié(s)

(2) - Elément(s) du milieu impacté(s)

(3) - Type(s) d'aléa impacté(s)

(3) - Sous-type(s) d'aléa

Temperature, Precipitation

Droughts, Forestry, Permafrost, Water...

Avalanches, Rockfalls, Debris flows, Floods, Forest fires

 

 

Pays / Zone

Massif / Secteur

Site(s) d'étude

Exposition

Altitude

Période(s) d'observation

Alpine Space 

 

 

 

 

 

 

(1) - Modifications des paramètres atmosphériques

Reconstitutions

 

Observations

 

Modélisations

Climate Scenarios

The results for temperature and precipitation are visualized in the Annex by maps and graphs for the four seasons winter, spring, summer and autumn (DJF, MAM, JJA, SON). The REMO UBA scenarios had to be excluded for the diagrams, since they do not cover the entire Alps.

Mean Temperature

Seasonal summary of absolute temperature changes: Temperature shows a clear warming trend in all seasons with a more pronounced warming after 2030. The strongest warming is expected for summer with increases between 1.3°C and 3°C until 2050 (1.3°C 2°C for ECHAM5 driven RCMs). In line with the temperature trend of the past, the central Alps are in most scenarios warming faster than the foothills of the Alps.

Temperature can be regarded as a rather robust parameter within climate models with a clear trend towards warning. Anyhow, projections show wide ranges of potential changes. While the ECHAM5 driven RCMs are quite consistent, other GCM (ARPEGE and, even more, HadCM3) show a stronger warming.

Minimum Temperature

Seasonal summary of absolute minimum temperature changes: Minimum temperatures show a trend very much in line with average temperatures. However, the trend of increasing minimum temperatures in winter is slightly stronger than the trend in average temperature. This might have implications for frost- and ice days and therefore also on snow cover and glaciers, which reacts sensitive to an increase in minimum temperature. As average temperature, minimum temperature can be regarded as a quite robust indicator.

Maximum Temperature

Seasonal summary of absolute maximum temperature changes: Maximum temperature shows almost the same trend like average temperature, indicating that temperature extremes will become more frequent in the future.

Precipitation

Seasonal summary of absolute precipitation changes: Precipitation shows a quite heterogeneous picture. The clearest trend can be observed for summer, where five out of six scenarios show a trend to a slight decrease of precipitation of up to –55mm (–5mm to –40mm for ECHAM5 driven RCMs). Winter tends to become wetter or at least stay stable in most scenarios. For autumn and spring no clear trend can be observed. The partly inhomogeneous trend from 1990 to 2030 and from 2031 to 2050 can be explained by long-term oscillations in the driving GCMs.

The geographic distribution of the trend is very heterogeneous. If taking into account only the ECHAM5 driven scenarios in the northern Alps there is a trend of an increase of precipitation in Winter, Spring and Autumn, while summer is getting drier. For the southern Alps all seasons besides Winter show a tendency to less precipitation with strong variances amongst the scenarios.

Precipitation is, compared to temperature, less robust and reliable. Different GCMs produce partly contrasting patterns of spatial distribution of precipitation. Regional projections should be handled with care.

Hypothèses

 

 

Informations complémentaires (données utilisées, méthode, scénarios, etc.)

Climate Scenarios

Here the results for climate change scenarios as part of EURAC’s contribution to Action 4.2 (determining vulnerability indicators & elaborating assessment methodology within WP4 ‘Vulnerability Assessment’) of the project CLISP are summarized.

The presented climate change scenarios were calculated on the basis of eight climate scenarios which are freely available from national sources (Umweltbundesamt Deutschland) or EU-projects (FP6 ENSEMBLES) (see Table 1). The single scenarios differ in:

• the underlying SRES emission scenario (B1 – low emission scenarios, A1B moderate/high emission scenario

• the driving General Circulation model (GCM) (ECHAM5, HadCm3, ARPEGE)

• the applied Regional Climate Model (RCM) (REMO, CLM, RegCM3, ALADIN)

These eight scenarios reflect a large range of possible future climate conditions. Accordingly, results can differ greatly depending on GCM, RCM and emission scenario. Since ECHAM5 is widely regarded as a kind of standard driving GCM for Europe most scenarios rely on this GCM (1-6). Results for RCMs driven by other GCMs (7,8) may deviate significantly. Where this applies, we interpret all scenarios as well as the ECHAM5 driven RCMs only.

All parameters were calculated in terms of an absolute change from the reference period (1961-1990) to the 20 year mean of two future periods (2011-2030; 2031-2050). Results are presented as maps (temperature and precipitation only) and as graphs with averaged values for the alpine region.

Climate projection represent future possible scenarios modelled for a large range of meteorological parameters. All modelled projections deal with a certain level of uncertainty, which is particularly true for complex climate models. Amongst the range of meteorological output parameters temperature is the most reliable one. Nevertheless also the parameter temperature exhibits a great variance at a coarse scale level that even increases when looking at the finer regional scale.

Precipitation projections are subject to much greater uncertainty. Climate models are, for instance, not very good in reproducing convective precipitation events, which could in the Alps make up a considerable part of summer precipitation.

While temperature or precipitation represents quite stable parameters, the variations and uncertainties of the values of other parameters such as wind speed, humidity or cloud cover are significantly greater with the strong potential to influence adversely the outcome of the CLISP indicators describing exposure or sensitivity.

We focused in this document only on relevant indicators with quite clear trends and interpretation potential. Other indicators were calculated and can be provided to the model regions on demand.

Additionally, long-term climate oscillations within the GCM climate scenarios overlay the short term trends with which we deal in CLISP. This may lead for instance to inconsistent trends for 2030 compared to 2050.

In CLISP we will focus on long term (20years) periods and calculate mean values for month, season and year in order to provide relatively robust results. In any case and depending on the parameter at stake, the results will contain uncertainty and represent a large range of possible intensities of impacts. Particularly those impacts relying on parameters with higher uncertainties should be interpreted with care.

Another aspect is the considered mean value for the whole region. It should always be kept in mind that the value represent an aggregate number and is not representative for valleys nor for altitudes over 1500, but covering the whole range of altitudes of the model region or the Alps.

For more information on how to read climate scenarios see ARL_Leseanleitung_Klimaszenarien_Deutschland.pdf (in German only).

 

(2) - Effets du changement climatique sur le milieu naturel

Reconstitutions

 

Observations

 

Modélisations

Synthesis of vulnerability assessment results by sectors

Agriculture (…)

Potential Impact

Growing season length (I1), Growing degree-days (I2): The Growing season (GS) is defined as the period of the year when the daily mean temperature is above 5°C. The beginning of the growing season (BGS), the end of the growing season (EGS) and the length of the GS can be derived for each cell in the grid. The growing degree days (GDD) are defined as the accumulated degree sum above a defined reference temperature (here set to 5°C). Finally the difference of those parameters between future and reference (present) conditions is an indicator of potential changes.

From the climate scenarios considered, it can be seen that an extension of the growing season for the Alps is expected, with respect to reference conditions of the period 1961-1990 (see Figure 12). This extension is closely related to an earlier start of the Growing season as well as an later end of it.

It must be clearly borne in mind that this assessment has strong limitations related to the reliability of absolute values of daily temperatures estimated by the climate models. Whenever such daily temperatures are compared to a threshold, as for the present indicator, the bias in model estimates may be reflected in the final result to a significant extent. Despite these limitations, the assessment indicates a potentially significant increase in the length of the growing season, which may result in positive impacts in terms of agricultural production in some areas. (…)

Potential evapotranspiration (I3) and Meteorological water balance (I4): The meteorological water balance is defined as the difference of precipitation sum and the sum of potential evapotranspiration. It can be used as indicator where reduced rainfall in combination with higher potential evapotranspiration will contribute to higher requirement for irrigation water. In turn, potential evapotranspiration can be seen as an indicator of water demand from crops under given climate conditions. The Alps show a trend in potential evapotranspiration that is up to about an additional 50 mm/y in the valley bottoms and on the southern side, i.e. about +10% compared with current conditions. This will on one side correspond to more crop opportunities, but on the other side to generally higher crop water requirements.

This is reflected in corresponding variations of the meteorological water balance. In higher and more central parts of the Alps, increased precipitation suggests positive changes in the meteorological water balance. On the Southern and less elevated sides of the Alps, however, increased potential evapotranspiration indicates possibility of conditions where water availability is limiting for crop growth.

Drought Index (de Martonne) (I5): This index suggests generally more arid conditions throughout the Alps, with the exception of some central and more elevated parts where the trend could be inverse. The index in itself has a comparative nature, as it is a conventional ratio of precipitation and temperature. The variation of the index provides the relative intensity and sign of aridity changes across the region. The spatial pattern is similar to the one of the meteorological water balance.

Forestry

Status quo / sensitivity

Forestry is a key economic sector in the Alps. Forests provide services ranging from raw materials to recreation, to climate and water cycle control. Climate trends suggest an increase of the elevation of the timberline and an expansion of crop variety. At the same time, more frequent and prolonged stress due to extreme weather events as well as ecological modifications (more pests, hoofed game etc.) may threaten forests in the future. Climate change may trigger to some extent also forest fire.

Potential Impact

Forest line (I15): Figure 21 shows the projected increase in timberline elevation, according to an analysis further described in Kass et al., 2011. This is based on thermal effects only, inconsiderate of morpho-edaphic limitations. The general indication is that areas suitable for forest may increase significantly over the Alps.

Nesterov index for fire danger (I16): While the eastern Alps are projected to experience minor increase of forest fire danger, the western (Maritime) Alps are predicted to be much more at risk under climate change due to combined aridity and higher temperature effects (see Figure 22). The southern foot of the Alps is also generally more at risk.

Adaptive capacity

Forestry in the Alps is a variedly managed sector, and adaptive capacity depends very much on the specific context. In the model regions examined within CLISP, adaptive capacity tends to be quite good as forests represent a considerable asset in the local economies. A different situation may be present in areas of the Alps where forest management is more dispersed and less associated to local economic activities.

Vulnerability summary

Whenever adaptive capacity, and in general the management of forest ecosystems does not compensate potential negative effects, prolonged stress of forests may result in their degradation. (…)


Upscaling of vulnerability assessment framework

Droughts

Droughts are expected to increase in severity and frequency following climate change. However, a sound quantification of the trend is far from being available. At present, a standard approach consists in using climate scenarios to modify precipitation and temperature inputs to hydrological models. This enables simulating streamflows and water availability under climate change scenarios, and is easily applied at each location where a hydrological model can be soundly calibrated. One such exercise has been developed in model regions Alessandria and Graubunden within CLISP. The results indicate that for Alessandria, which is already a relatively drought-prone area within the greater Alpine context, variations of climate input induce hydrological changes practically encompassing the natural variability of present conditions. On the contrary, in more water-rich areas such as Graubunden a shift of hydrological regimes from nival and glacial to pluvial will have significant impacts on water availability.

Hypothèses

 

 

Sensibilité du milieu à des paramètres climatiques

Informations complémentaires (données utilisées, méthode, scénarios, etc.)

 

 

 

(3) - Effets du changement climatique sur l'aléa

Reconstitutions

 

Observations

 

Modélisations

Built-up areas / land development

Status quo / sensitivity

Built-up areas were a sector of concern for all model regions except Alessandria, Graubunden and Liechtenstein. The main issues with built-up areas were identified in natural hazards and extreme weather events. The latter could not be analysed in quantitative terms. The former require on the one side a very local assessment of physical conditions and the exposure of settlements to risks. At the same time, our understanding of the effects of climate change on natural hazards is still very vague and weak. Another relevant issue with climate change in built-up areas is increased heat stress in cities. Although the Alps are a relatively non-urban context in Europe, settlements tend to concentrate in the valley bottoms, which are also the most sensitive areas for heat waves.

Potential Impact

Flood prone areas (I7): It is generally acknowledged that climate change may induce an increase in flood frequency and severity, especially in mountain regions such as the Alps. An increase of flood frequency and magnitude has been observed parallel to the warming of the last years in Switzerland and elsewhere. Several alpine areas have experienced floods, in the recent past, which used to be regarded as exceptional in the past. Allamano et al., 2009, have used a simple conceptual model to predict an increase in flood frequency in the Alps following climate warming. Castellarin and Pistocchi, 2011, by analysing long time series of annual maximum discharges in Switzerland, showed that the simple model of Allamano et al., 2009, is compatible with observations referred to the past. However, our understanding of the exact magnitude of flood frequency and magnitude changes is still rather poor. Within CLISP, we have used a practical, conventional method to estimate expected increases of flood intensity for a reference return period of 100 years. The method points at increments of the 100-year return period flow in the order of 30%. Such increment may be critical in all circumstances where flow is controlled by hydraulic structures such as bridges or levees, having a design conveyance beyond which levee or river bank overtopping is likely to occur. Whenever a floodplain is already interested by a 100-year return period discharge, however, it is likely that the extent of flooded areas does not change significantly. This has been observed in the model regions of Gorjenska and Bavaria, in each of which two sites have been investigated in order to assess the variations of flooded areas following an increase of discharge after climate change. In the four case studies analysed, it appeared that new flooded areas that are presently not affected by water flow are marginal and negligible. This suggests that, in order to cope with climate change, land planning considerate of present flood hazards is a first and essential step towards improved resistance. Pistocchi, 2011, further generalizes these considerations to discuss scenarios of flood risk and mitigation options in the Alpine area.

Avalanche prone areas (I8): Avalanches may be affected by climate change as both snowfall intensity and the parameters controlling snow transformation and the mechanical characteristics of the snow pack may change under future scenarios. However, at present we have no understanding of these changes and, therefore, any consideration on the topic is purely speculative. In general, it is expected that areas presently at risk of avalanches will remain such under climate change. In the same areas, the precautionary principle suggests that avalanches may become more frequent and more severe. In the model regions where avalanches were considered a concern, an analysis has been conducted about present avalanche hazards, with the implicit assumption that future scenarios will affect the same areas. In this perspective, it is extremely important to achieve a sound characterization of potential avalanche release areas (PARAs). Pistocchi and Notarnicola, 2011, characterize PARAs in South Tyrol using a bayesian approach. Lermer et al., 2011, extend the approach to the model regions that provided data on purpose, namely Gorjenska, Bavaria (Miesbach and Berchtesgadener Land) and Salzburg.

Rockfall prone areas (I9): Our understanding of climate change effects on rockfalls in general is extremely weak. However, in recent years a concern has been raised by the effects of permafrost melting on rockfalls. Within CLISP, an assessment has been conducted on the extent to which permafrost may melt down and originate additional rockfalls. An analysis of potential permafrost under current conditions has yielded a map showing the distribution of very likely (red) and likely (yellow) permafrost areas in the Alps (see Figure 17). All areas judged to likely or very likely host permafrost, and with slopes above 45°, were considered as potential sources of rockfall under climate change scenario. With this assumption, trajectories of rockfall were calculated for the whole Alpine region (e.g. Figure 18) indicating a rather extended impact. However, this impact generally concerns upper valleys and not the main settlements. A more extensive impact is projected to affect communication infrastructure, in which case some valleys may experience problems of connection with the main centres of the plains whenever rockfall contributes to temporarily closing roads or lifelines. Lermer et al., 2011 (see Annex), provide an example analysis of the impacts of permafrost degradation-triggered rockfall on the Alps.

Torrential process prone areas (I10): The same considerations made for avalanches hold for torrential processes as well.

Adaptive capacity

Natural hazards are considered in practically all land management processes. However, throughout the Alps the legal status of hazard maps and the degree of legal enforcement of land use constraints on hazardous areas varies considerably.

The capacity to predict and monitor natural hazards under present conditions is generally quite good. However, the capacity to predict climate change effects on natural hazards is generally poor.

If climate change will make natural hazards more frequent and more severe, but will substantially keep them on the same areas as at present, the adaptive capacity of the Alps can be regarded as satisfactory and, in fact, adaptation is already underway (e.g. through the Flood directive 2007/60/EC).

The capacity to adapt to heat waves and hot climate is highly variable. A point of strength is the tradition for good energy management in buildings within mountain areas. In the future, there will be more and more need for green urban areas, green roofs and similar devices, which may be conflicting with the intensive land uses at the valley bottoms, which represent the few usable areas in a mountainous context.

Vulnerability - summary

Vulnerability of builtup areas to climate change may show up whenever land use inconsiderate of natural hazards is made. Whenever consideration of natural processes is included in land planning, the effects of climate change may become relevant. An issue that has been slightly underconsidered so far is the one of heat waves, which tend to affect not just metropolitan areas in the plains but also valley bottoms. More careful planning and management of urban surfaces and land uses is a key element for adaptation, the lack of which may induce high vulnerability under climate change.

Forestry

Status quo / sensitivity

(…) Climate change may trigger to some extent also forest fire.

Potential Impact

(…) Nesterov index for fire danger (I16): While the eastern Alps are projected to experience minor increase of forest fire danger, the western (Maritime) Alps are predicted to be much more at risk under climate change due to combined aridity and higher temperature effects (see Figure 22). The southern foot of the Alps is also generally more at risk. (…)


Up-scaling of vulnerability assessment framework

Avalanches

The effects of climate change on avalanches are far from being even qualitatively understood: on the one side, more abundant winter precipitation may signal more snow accumulating on the hillslopes, hence more potential instability. On the other hand, climate change models predict winter precipitation to be more and more in the form of rain instead of snow, which indicates a shift of the snowline towards higher, and potentially less inhabited, land. Even less can be said about the influence of climate change on the mechanical parameters of avalanches, which depend on the interplay of temperature and other climatic factors in a way not fully understood even under present conditions. Martin et al., 2001, found that avalanche hazard may decrease and the proportion of wet avalanches over dry ones may increase in the French massifs. In more recent years, several studies have focused on the relationship of climate and avalanche activities (Jomelli et al., 2007; Eckert et al., 2009; Carles et al., 2009, 2010; Schweizer et al., 2009); attempts at reconstructing time series of avalanche activity aimed at analyzing trends were done (Szymczak et al., 2010; Casteller et al., 2011; Corona et al., 2010 ), but with little conclusive evidence on the impacts of climate change: at present, there seems to be no sound evidence that climate change will induce more severe or more frequent avalanches in a generalized sense.

Rockfalls

The one effect of climate change on rockfalls, which is broadly acknowledged to be relevant in mountain environments, is permafrost degradation, which may affect bedrock cohesion mechanisms (Menendez Duarte et al., 2002; Gruber and Haeberli, 2007; Harris et al., 2009). Other mechanisms, such as precipitation, show less clear trends and the impacts of climate change are on purpose rather difficult to identify. Rockfalls due to permafrost melting are expected to be triggered at high elevation and, most of the times, in low population density areas. The consequences are therefore likely to affect mainly mountain trails and infrastructures, and the road network. For some isolated valleys in the Alps, this impact is likely to be quite important.

Within CLISP, a pan-Alpine assessment of the potential impacts of permafrost melting in terms of reduction of road accessibility of the valleys has been conducted. The study consisted in identifying the permafrost areas that, under climate change, may generate rockfalls due to permafrost degradation (see example in Figure 28).

This analysis allows to evaluate which roads may be intercepted by the trajectories of potential rockfalls. It is consequently possible to evaluate how many people may be affected by the obliteration of a road, i.e. how many people may suffer from an extension of the time of travel from their residence to central places (either the nearest cities, or the Alpine area border) in the event of rockfalls.

Figure 32 shows the trajectories with highest traffic in the Alpine region, either due to movements towards the nearest city or to the region boundary. In the event of a road hit by a rockfall, it is possible to recalculate the time of travel to the nearest city and to the Alpine region border. The variation of time of travel, multiplied by the population affected by the variation, is an indicator of the magnitude of the potential impact due to rockfalls (Figure 30). From inspection of Figure 30, it is apparent that the phenomenon is quite widespread throughout the region, with several valleys potentially affected by rockfalls under permafrost degradation, hence at risk of suffering from slow communications and the associated economic consequences. Consequently, costs to protect or restore the road network may considerably increase in the future. This may be a relevant management issue in order to adapt to climate change in the Alpine region.

Debris flows

There is no conclusive evidence about a change in frequency and intensity of debris flow. Stoffel et al., 2008, suggest that climate change may imply a reduction in frequency of debris flow in the Swiss Alps. This contrasts with other evidence (e.g. Pelfini and Santilli, 2008, who highlight an increasing trend in the frequency of debris flow in the Central Italian Alps). Debris flow is clearly sensitive to precipitation of high intensity and duration depending on the catchment characteristics. Anyway the linkages between precipitation variation and debris flows are far from being well understood. At present, no widely agreedupon conceptual model of climate change impacts on debris flow seems to exist.

Floods

The assessment of climate change on floods is a prominent topic of interest in land planning. However, so far little evidence has been collected about relationships between climate change and flood frequency and intensity variations. An established reasoning line consists in assuming that, as weather extremes are projected to increase in frequency and severity, floods will follow the same trends in rainfall-dominated flood regimes. A conceptual model has been developed recently by Allamano et al., 2009a,b, that enables linking the change in flood return periods with the extent of the contributing area of a stream above the freezing line. Based on this model, Alpine catchments are expected to exhibit return period (RP) changes of floods such that a 100-years RP today may become a 20-years following climate change. Castellarin and Pistocchi, 2011, observe that empirical evidence from the Swiss Alps is compatible with this model and suggest a practical method to assess design discharges (e.g. 100-years RP discharges) under climate change starting from the assumption of a given (e.g. 100-to-20 years) RP shift.

A map of 100-year-RP discharge variations in the Alps following the conceptual model of Allamano et al., 2009a,b , and the approach proposed by Castellarin and Pistocchi, 2011, is shown in Figure 31. According to this model, discharges are projected to increase more in catchments at higher elevation, and in the western Alps compared to the East. The most affected catchments seem to be in the Swiss and Italian Alps, where more catchments tend to turn from nival to pluvial regimes.

Forest fires

Dryer and hotter summer climate implies apparently higher forest fire danger. This aspect seems to be adequately predictable in climate change impact studies. The map of forest fire hazard (Nesterov’s index) change that has been produced for the Alps within CLISP is an example of an assessment of this type.

Hypothèses

 

 

Paramètre de l'aléa

Sensibilité des paramètres de l'aléa à des paramètres climatiques

Informations complémentaires (données utilisées, méthode, scénarios, etc.)

 

 

Upscaling of vulnerability assessment framework

Testing the applicability of the assessment methodology to coarser scales

The methodology proposed within project CLISP relies substantially on the joint interpretation of some quantitative and many qualitative elements of knowledge.

One general issue with climate change impact studies is the lack of hard figures based on which to evaluate scenarios. This is due to the high uncertainties, and even contradictions, associated with different climate change scenarios, the lack of capability to predict certain climate variables to a sufficient accuracy (only temperature predictions appear to be robust enough), and the uncertainty associated with the prediction of consequences of climate change on individual aspects. For instance, while a general intensification of the water cycle is forecasted, the prediction of river discharges as a consequence of this intensification is questionable, and a quantitative prediction of extreme events is beyond our current modelling capacity.

In particular, potential impact indicators computed on the basis of climate scenarios within CLISP may only provide hints for certain trends and cannot be used as a hard quantitative statement on the evolution of different aspects of the Alpine climate. Nevertheless, general trends that emerge from an overall reading of these indicators are reasonably consistent with evidence of climate variations and currently observed trends.

Some potential impact indicators were designed for assessment at a sitespecific level (snow reliability natural hazards). For these indicators, the project has highlighted the difficulty to bring together data which are available, but sparse and heterogeneous, into a single consistent frame. This suggests that the main limitation in the application of such indicators at coarser scales is the construction of adequate databases of weather variables, morphology, and other physical variables.

All other potential impact indicators were designed to be computed at the pan-Alpine level, which suggests that they could be used for coarser scale assessment without particular limitations. What should be questioned, however, is their actual usefulness in capturing actual issues. In particular, drought/aridity indicators used in CLISP are rather preliminary and should be replaced by more refined indicators based on an adequate, albeit simplified, representation of the water cycle. This was beyond the scope of the CLISP project, and could be only achieved in certain model regions (Alessandria, Graubünden) where substantial investment has been done for the characterization of the water sector.

Growing season, wine credibility, timberline elevation, forest fire hazard, heating/cooling energy demand, tourism and health related climate indicators retain a meaning for the whole Alpine region, as they highlight trends both in time and space that help supporting an assessment also at coarser scale.

However, an interpretation of indicators of potential impact can only be done on the basis of other evidence from a qualitative inspection of the different contexts, as was done for each model region; the mere use of computed indicators is still too imprecise and unreliable to achieve an assessment at pan-Alpine level. Therefore, the frame for the assessment of potential impacts proposed within CLISP can be considered suitable for the whole Apine region, provided that an appropriate qualitative assessment is also conducted, which cannot be automated starting from presently available data.

The adaptive capacity assessment relies heavily on region-specific information. An aggregation of adaptive capacity indicators beyond national borders is not useful. From an institutional point of view the adaptive capacity of the overall GAR should look at strengths and weaknesses of the Alpine Convention and should scrutinise relevant policies and programs of the European commission such as the Alpine Space European Territorial Cooperation.

Test results

In this synthesis report maps or graphs of potential impact indicators are shown for the whole Alpine region, for those indicators (heating/cooling energy demand, growing season, timberline elevation, forest fire hazard, wine credibility, tourism/health related climate indicators) for which a calculation based on the present level of knowledge is possible. Evidence of situations from the qualitative assessment of individual model regions were used to draw interpretations of both adaptive capacity and vulnerability. A more indepth assessment is beyond the scope of the project. Attempts at generalizing the indicators of natural hazards have been done for floods (Pistocchi, 2011) and for the impacts of rockfalls related to permafrost degradation (Lermer et al., 2011). However, from these applications it has appeared that indicators at panAlpine level only reveal general trends and need to be checked locally for effective decision support.

The authors provide some important considerations of relevance for the Alpine region related to the potential impact of climate change on natural hazards as a crucial point in regional planning. We also present some more detailed results about the potential impact of rockfall from permafrost degradation.

The investigation of potential impacts of climate change on natural hazards

Within the Interreg IVb Project CLISP, land planners and researchers from 6 Alpine countries have tried to understand the complex issue of how alpine societies may adapt to the potential impacts of climate change through land planning. Among the several difficult questions to answer towards this goal, one concerns the understanding of how natural hazards may be actually modified by climate change.

Although there is relatively broad literature on possible alteration of natural hazards after climate change, the scientific community is far from being able to provide sound and uncontroversial quantitative evidence of the mechanisms by which avalanches, slope instabilities and floods would be altered under presently considered climate scenarios. Yet, the European Flood Directive and other European legislation on natural hazards stimulates, or even requires, that climate change effects be taken into proper consideration.

Here is briefly reviewed the knowledge presently available to assess the potential impact of climate change on natural hazards, and the practical use of such knowledge that is made, or can be made, in land planning. The contexts of avalanches, rockfall, debris flows, floods, forest fires, and droughts are briefly discussed. For each of these contexts, we point out the level of understanding available and we express considerations on possible coping strategies in land planning.

 

(4) - Remarques générales

Summary of results for model regions

Please find the executive summaries of the vulnerability assessment results of all CLISP model regions in the respective attached documents (www.clisp.eu).

 

(5) - Syntèses et préconisations

Upscaling of vulnerability assessment framework

Concluding remarks

Although the Alps are among the European regions experiencing the most marked changes in climate over the last decades, there is still little knowledge available to quantify in a well defined way changes in natural hazards that may be triggered by climate change. Uncertainties owe to a large extent to the lack of resolution (in space and time) and clarity in the trends of climate scenarios (e.g. in precipitation). To an equally large extent, however, they also owe to the lack of capacity to model phenomena such as avalanches, debris flows, and rockfalls in a deterministic way. A clearer understanding appears at the level of forest fires and droughts, for which the trends in temperature and aridity suggested by climate scenarios are relatively agreedupon. Concerning floods, although a general understanding of climate change controls is still far from being reached, a conceptual model has been proposed that provides a reasonable working hypothesis for screeninglevel assessment of flood hazard changes in the Alps.

Under such large uncertainties, it is recommendable that natural hazards be coped with considering present conditions, by identifying good practices and undertaking noregret actions to adapt in a robust and socio-economically acceptable way, as pointed out e.g. by Wilby and Dessai, 2010.


Conclusions

The assessment of vulnerability to climate change is not an easy exercise. In the first place, it requires to have a critical look at current, and mostly well established, planning practices. Within WP4, a first checkup has been prepared for each model region that helps triggering the discussion on how spatial planning should adapt to climate change: what are the main issues related to a changing climate, which economic sectors are expected to suffer more than others, how well, and how deep, can change impacts be predicted, which practices are good and should be empowered and pursued, and which should be revised as not sustainable in the event of change.

Within the project CLISP, it has been experienced how the assessment of Adaptive Capacity requires specific analysis of the regional context from a highly integrated assessment in the form of specific strength, weakness, opportunity and threat (SWOT) analyses as is common practice already in other contexts (such as strategic environmental assessment (SEA) of plans and programmes). Potential impacts of climate change, on the other hand, may be assessed in some cases on the basis of quantitative indicators derived from the modelling of climate scenarios and their effects. Nevertheless, uncertainty remains high and often no clear trend and, consequently, indication for decision support may be extracted from such assessment exercises. “Pure” climate indicators (i.e. indicators related to temperature, precipitation and similar variables) are relatively easy to derive from climate scenario models. Effects in terms of natural hazards, on the other hand, are ways more complex and uncertain to predict.

In the following a list of strategic recommendations has been compiled that is intended to support practitioners in planning and implementing regional climate change vulnerability studies.

When assessing your vulnerability, use climate change scenarios with care and don’t count too much on quantitative approaches

• Climate change scenarios are a useful and necessary input for a vulnerability assessment but regional climate scenarios show a large range of results and a high uncertainty (particular for precipitation)

• Information on changes in extreme events are not reliable (besides temperature extremes)

• Quantitative assessment of impacts (models) are only available for a small number of potential impacts and subject to uncertainty

• Time horizon for most stakeholders: << 20 years but weak Climate Change signal within this time frame

Take a close look on the status quo of your system and learn from history

• A large part of the vulnerability to climate change can already be understood by analysing the status quo of the system with respect to the sensitivity of the system to climate and weather extremes now and in the past (like the heatwave 2003)

• Regions, which are already sensitive to the climate extremes which are expected to increase are the most vulnerable regions

Don’t be afraid of being qualitative and narrative, respect stakeholder as experts

• Involve the stakeholders on all levels (farmers, water managers, decision makers, …) in a vulnerability assessment, and respect them as experts. They are the one who know their system best and the one who have to adapt to climate change in the end.

• Qualitative and narrative information (for instance on the sensitivity of the system) can often better reveal the relevant details for a vulnerability assessment than a purely quantitative approach.

For future vulnerability consider also the development of your system and other pressures on your system

• Climate change is in most cases just an additional pressure, consider also the other ones like landuse change, demographic change, increase in traffic, …

• Often, vulnerability arises more from a combination of expected change in the system and climate change. E.g. the risk of damage on buildings or infrastructure by natural hazards might increase in future due to an expansion of settlements into hazards zones combined with an increase of the frequency and intensity of natural hazards.

Plan and implement appropriate adaptation measures in time and be ready to act under uncertainty

• Often technical measures (torrent protection, dikes, …) are already well implemented. What is missing are more soft adaptation strategies like a proper climateproof spatial planning, a better coordination of actions within institutions, or better riskcommunication

• Adopt “no regret” or “low regret” adaptation measures whenever possible; for instance, energy efficient buildings are good even today, imagine under hotter summers!

• Natural hazards and related impacts will occur more frequently and more severely, but firstly in the same areas where they occur today: good planning of adaptation to current natural hazards is also a good option for adaptation to climate change.

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