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THE ROLE OF SCENARIOS IN GLOBAL CHANGE STUDIES

  1. Top of page
  2. THE ROLE OF SCENARIOS IN GLOBAL CHANGE STUDIES
  3. SCENARIOS FOR ADDRESSING FUTURE RISKS TO BIODIVERSITY
  4. APPLICATION OF THE ALARM SCENARIOS
  5. ACKNOWLEDGEMENTS
  6. REFERENCES

Scenarios can play a valuable role in providing coherence to studies of future global change, especially when such studies address multiple objectives and draw upon diverse disciplines and research traditions. The advantages of a scenario-based approach can include (Alcamo, 2001; Rounsevell & Metzger, 2010):

  • 1
    Offering a framework for representing uncertainties in future socio-economic and technological developments that are the driving forces of environmental change.
  • 2
    Providing an opportunity to integrate the key drivers of environmental change and their impacts and interactions within a common logic.
  • 3
    Raising awareness of future changes, all plausible, many contingent on human decisions, some seemingly unavoidable, others merely conceivable, but none predictable in a probabilistic sense.
  • 4
    Combining qualitative and quantitative information about the evolution of future environmental conditions.
  • 5
    Imposing consistency in characterizing future conditions across diverse studies spanning different sectors, regions, societies and scales of analysis, thus facilitating the direct inter-comparison of results.
  • 6
    Allowing analysts to explore plausible future developments that may have important implications for current and future decision making.

There can also be disadvantages in adopting a scenario approach. For instance, selection of a few scenarios that are subsequently applied in all aspects of a study may impose constraints on the analysis that could result in too narrow or unrepresentative visions of the future. Furthermore, the credibility of results that rely upon scenarios will normally rest on the perceived legitimacy of the scenarios among those groups analysing and using them. To encourage ‘buy in’, extensive stakeholder involvement is usually required in the design and development of scenarios and storylines, a process that can be time-consuming and resource intensive (Alcamo, 2001).

SCENARIOS FOR ADDRESSING FUTURE RISKS TO BIODIVERSITY

  1. Top of page
  2. THE ROLE OF SCENARIOS IN GLOBAL CHANGE STUDIES
  3. SCENARIOS FOR ADDRESSING FUTURE RISKS TO BIODIVERSITY
  4. APPLICATION OF THE ALARM SCENARIOS
  5. ACKNOWLEDGEMENTS
  6. REFERENCES

Whilst acknowledging its potential difficulties, a scenarios approach appeared to offer the most promising basis in the ALARM (Assessing LArge-scale environmental Risks for biodiversity with tested Methods) project for exploring possible future risks to biodiversity and for integrating across diverse disciplines. ALARM involved more than 250 scientists from 68 institutions and 35 countries (see Settele et al., 2005; Spangenberg et al., 2012). Its central goal was to undertake an integrated large-scale assessment of risks to biodiversity in terrestrial and freshwater ecosystems, with a focus on the following four risk areas: climate change, environmental chemicals, pollinator loss and biological invasions. The project developed a set of risk indicators that can be related to various socio-economic drivers of biodiversity pressure, which are intended to support long-term policy-making on biodiversity conservation as well as offering a guide for monitoring the effectiveness of policy implementation.

A key scientific challenge of the project was to integrate the multiple disciplines, perspectives and scales represented by the consortium within a common research framework that could draw upon diverse disciplinary traditions, methods and tools, while adequately addressing issues of uncertainty. In this context scenarios were regarded as a potentially valuable tool, both as a method of integrating different strands of the project and as a means for addressing alternative future pathways that might have an important effect on biodiversity. Thus, the use of scenarios is aimed at:

  • 1
    Making the results more consistent across the project, and hence potentially more useful to the policy process than multiple independent analyses of future risks.
  • 2
    Stimulating multidisciplinary exchange and interdisciplinary learning.
  • 3
    Gaining the attention of key stakeholders with a set of coherent messages that contribute towards enhanced awareness of threats to biodiversity in Europe and beyond.

Scenarios are not predictions but rather a means to generate information by illustrating possible future developments under conditions of uncertainty (Alcamo, 2001; Spangenberg et al., 2012). They deal with multivariable state changes, which cannot be analysed empirically in a laboratory or greenhouse setting while – as often also in economic theory – assuming that everything else remains constant. Unlike forecasts or predictions, to which probabilities can be attached, scenarios characterize future developments that are largely driven by human actions and are generally regarded, to all intents and purposes, as being impossible to predict or foresee (van der Sluijs, 2002). Thus, assumptions have to be made, constituting scenario narratives which are supported whenever possible by model simulations (Alcamo, 2001).

Scenarios can provide a comprehensive view of plausible (not necessarily probable) future developments, and they can deal with complexity. This way they serve as a means to explore the possible future outcomes of decisions taken (or not taken) now. Within ALARM, scenarios developed are broad pictures of archetypical possible futures aiming to derive information on risks to biodiversity from a diverse range of factors during the 21st century. The three core scenarios are BAMBU (‘Business As Might Be Usual’), an extrapolation of current policy trends, and two alternative policy options, GRAS (‘GRowth Applied Strategy’) simulating a policy of deregulation and globalization, and SEDG (‘Sustainable European Development Goal’), a sustainable development policy scenario. To test the robustness of the scenarios, and as the future can be expected to diverge from simple trend extrapolation, three ‘shock scenarios’ (assuming unexpected events) were also developed. Further details on the development of these scenarios are provided in the opening paper in this collection (Spangenberg et al., 2012). More information on the quantification of specific elements of the scenarios is given in Fronzek et al. (2012), Stocker et al. (2012) and Reginster et al. (2010). Figure 1 illustrates the linkages between these papers and with other papers in the Special Issue that describe applications of the scenarios.

image

Figure 1. Relationships between the ALARM (Assessing LArge-scale environmental Risks for biodiversity with tested Methods) storylines and scenarios, and to their application in impact studies (arrows). Citations in italics are to papers in this Special Issue (undated) and to a published source (dated). BAMBU, ‘Business As Might Be Usual’; GRAS, ‘GRowth Applied Strategy’; SEDG, ‘Sustainable European Development Goal’.

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APPLICATION OF THE ALARM SCENARIOS

  1. Top of page
  2. THE ROLE OF SCENARIOS IN GLOBAL CHANGE STUDIES
  3. SCENARIOS FOR ADDRESSING FUTURE RISKS TO BIODIVERSITY
  4. APPLICATION OF THE ALARM SCENARIOS
  5. ACKNOWLEDGEMENTS
  6. REFERENCES

So how can we judge the usefulness of the ALARM scenarios? Of course, they have served a purpose within the project itself, as evidenced from the papers in this issue and elsewhere (or yet to appear) that made use of them (cf. Fig. 1). Economic (GINFORS; see Stocker et al., 2012) and land-use scenarios (MOLLUSC; Reginster et al., 2010; see Spangenberg et al., 2012) were harmonized and related to different IPCC Special Report on Emissions Scenarios (SRES) climate scenarios (A1FI, A2, B1; see Fronzek et al., 2012), providing a reference base for the vegetation, plant invasion and chemical deposition scenarios (Chytrýet al., 2012; Hickler et al., 2012; Paul et al., 2012) as well as species distribution models for the projection of species ranges and species richness under scenario conditions (e.g. Araújo et al., 2006; Pompe et al., 2010; Schweiger et al., 2012).

However, a more lasting measure of their utility would be their continued adoption within the wider research community. They have already been adopted in other European Commission (EC)-funded projects like COCONUT1, ECOCHANGE2, MACIS3, SCALES4, and STEP5, national research programmes like Mistra-SWECIA6, and ISTO7, as well as other research projects like LEGATO8, CLIMIT9, and PRONAS10. Further success here can only be evaluated at some future time, but would provide a judgement on whether the scenarios: (1) are comprehensible and readily accessible to the research community; (2) are regarded as credible, salient and legitimate (Cash et al., 2003) by potential users; and (3) offer advantages over other comparable scenarios available from elsewhere.

This was not the first EC-funded integrated project to develop and apply scenarios, so it would be instructive to point to earlier cases where scenarios developed for a specific application have been embraced more widely. Examples include the Fifth Framework Programme (FP5) ATEAM (Advanced Terrestrial Ecosystem Assessment and Modelling) scenarios, elements of which were developed in the parallel FP5 ACCELERATES (Assessing Climate Change Effects on Land use and Ecosystems: from Regional Analysis to the European Scale) project on European land use and subsequently adopted in ALARM, the FP5 PRUDENCE (Prediction of Regional scenarios and Uncertainties for Defining European Climate change risks and Effects) climate projections, which were used to frame the PESETA (Projection of Economic Impacts of Climate Change in Sectors of the European Union Based on Bottom-up Analysis) study of economic impacts of climate change in Europe, and the FP6 SCENES (Water Scenarios for Europe and for Neighbouring States) scenarios for the water sector in Europe (Kämäri et al., 2008), aspects of which have been adopted in the ongoing FP7 CLIMSAVE (Climate Change Integrated Assessment Methodology for Cross-Sectoral Adaptation and Vulnerability in Europe)11 and MEDIATION (Methodology for Effective Decision-making on Impacts and Adaptation)12 projects.

Other measures of the usefulness of scenarios are the citation rate of publications in which they are described, the breadth of disciplines represented by the citing articles and the frequency of downloads of the scenario data. For example, the heavy citation of the European climate dataset prepared for the ATEAM project (Mitchell et al., 2004) and subsequently adopted by ALARM (Fronzek et al., 2012), especially in ecological, agricultural and forest modelling articles, appears to be explained by a conjunction of factors, including:

  • 1
    The utility of combining historical climate data with future projections in a single, easily accessible, gridded dataset.
  • 2
    The salience of the scenarios, which are largely consistent with the core set described in the IPCC SRES (Nakićenovićet al., 2000).
  • 3
    The variables represented in the dataset, which comprise those most frequently requested as input to models simulating plant growth and evapotranspiration.
  • 4
    The format of the data, which is ideally suited for application in ecological models, either as a whole (for running time-dependent, dynamic vegetation models), or as time slices in the past for which ecological data are available and can hence be matched statistically to the climate.

Moreover, a progressive annual growth in citations has been recorded, many of which are common between this dataset and the similarly well-cited land-use change scenarios prepared for the same ATEAM project (Rounsevell et al., 2005), especially concerning studies of multiple stresses on biodiversity in Europe.

Only time will tell whether the ALARM scenarios will succeed in offering useful insights to a wider constituency of users. The SRES scenarios are due to be superseded by a new set of global socio-economic, technological, land-use, emissions and climate scenarios developed by the international research community (Moss et al., 2010) ahead of the IPCC Fifth Assessment Report (AR5). However, this should not imply that the ALARM scenarios will become invalid; rather the new scenarios can be regarded as complementary, providing richer and more regionally specific socio-economic characterizations than the SRES, some of which are still perfectly consistent with the ALARM biodiversity-orientated information. An important task of the IPCC AR5 will be to assess how the new scenarios relate to SRES and to some other global scenario exercises. From this analysis it should then be possible to gauge the lasting value of the ALARM scenarios for continued application in the future.

ACKNOWLEDGEMENTS

  1. Top of page
  2. THE ROLE OF SCENARIOS IN GLOBAL CHANGE STUDIES
  3. SCENARIOS FOR ADDRESSING FUTURE RISKS TO BIODIVERSITY
  4. APPLICATION OF THE ALARM SCENARIOS
  5. ACKNOWLEDGEMENTS
  6. REFERENCES

The authors are indebted to the entire project consortium, including all members of the different advisory boards and the external referees; and to the EC for granting support for this FP6 Integrated Project ALARM under grant number GOCE-CT-2003-506675.

REFERENCES

  1. Top of page
  2. THE ROLE OF SCENARIOS IN GLOBAL CHANGE STUDIES
  3. SCENARIOS FOR ADDRESSING FUTURE RISKS TO BIODIVERSITY
  4. APPLICATION OF THE ALARM SCENARIOS
  5. ACKNOWLEDGEMENTS
  6. REFERENCES
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