Lessons Learned for Scenario Analysis · Lessons Learned for Scenario Analysis 451 •...

Chapter 13

Lessons Learned for Scenario Analysis

Coordinating Lead Authors: Nebojsa Nakicenovic, Jacqueline McGlade, Shiming MaLead Authors: Joe Alcamo, Elena Bennett, Wolfgang Cramer, John Robinson, Ferenc L. Toth, Monika ZurekReview Editors: Rusong Wang, Antonio La Vina, Mohan Munasinghe

Main Messages . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 450

13.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 451

13.2 New Contributions of the MA Scenarios . . . . . . . . . . . . . . . . . . . . . . 45213.2.1 An Analytical Typology of the MA Scenarios13.2.2 Contributions to the Process of Scenario Development13.2.3 Ecosystem Services and Human Well-being Development Paths across

Scenarios

13.3 Robust Findings of the MA Scenarios . . . . . . . . . . . . . . . . . . . . . . . . 457

13.4 Lessons Learned about Policy, Planning, and DevelopmentFrameworks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45913.4.1 Global Policies in Context of Other Scale Policies13.4.2 The Usefulness of the MA Scenarios for Stakeholders13.4.3 Path-dependencies, Irreversibilities, and Their Implications

13.5 Information Gaps and Research Needs . . . . . . . . . . . . . . . . . . . . . . . 46413.5.1 Global Storyline Development13.5.2 Modeling Complex Systems13.5.3 Harmonizing Models and Storylines for Understanding Complex Systems13.5.4 Research on Vulnerability

13.6 Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 466

REFERENCES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 467

FIGURES

13.1 Analytical Typology of Scenarios Analysis

13.2 Placing of MA Scenarios Analysis in Analytical Typology

13.3 Integrated Assessment Framework of IntergovernmentalPanel on Climate Change

13.4 Approach and Contributions of MA to Focus of ScenariosDevelopment

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450 Ecosystems and Human Well-being: Scenarios

Main Messages

The Millennium Ecosystem Assessment scenarios build on earlier sce-narios and modeling efforts and also extend scenario analysis to includeecosystem services and their consequences for human well-being, whichhas not been done before. The main objectives of the MA scenarios are toassess future changes in world ecosystems and resulting ecosystem servicesover the next 50 years and beyond, to assess the consequences of thesechanges for human well-being, and to inform decisions-makers at variousscales about these potential developments and possible response strategiesand policies to adapt to or mitigate these changes. These objectives are re-flected in the overall approach and are an integral part of the four narrativeand quantitative scenarios about alternative futures.

MA scenarios further refine and extend a number of recent methodologi-cal improvements in the scenario formulation process. These include inte-gration across social, economic, environmental, and ecosystems dimensions;disaggregation across multiple scales of global patterns down to regional andin some cases also place-specific developments; multiple futures across fouralternative scenarios to reflect deep uncertainties of long-range outcomes; andquantification of key variables linked to ecosystem conditions and ecosystemservices along alternative narrative storylines. In addition, the MA scenariosmake four important new contributions: They extend the integrated assessmentapproaches to include ecosystem services and their consequences on humanwell-being. They model explicitly changes in biodiversity as an integral part ofscenario development. They assess interactions and trade-offs among ecosys-tem services. And they assess possible replacement of some ecosystem ser-vices by other services and the emergence of new ways of providing theseservices, such as through technological change.

MA scenarios establish another important precedent in adopting the longtime horizon of 50 years, and for some variables, a century. Many salientbut slow trends in ecosystems will only become visible over this long timeperiod, but decisions influencing these trends have already been taken or willbe taken in the immediate future. Integrated scenarios, which portray humanactivities together with ecosystem dynamics, are the main tool available for theassessment of alternative futures and possible response strategies. Increas-ingly, long time horizons and global perspectives are required to understandcomplex interactions between human and ecological systems.

The MA scenarios provide rich and useful images of broad patterns ofpossible futures at the global scale and at the level of major world re-gions. However, the models are not able to perform detailed analyses oflocal processes and impacts. One possible remedy and a crucial improve-ment for similar future assessments in terms of usability for several stakehold-ers would be to ‘‘soft-link’’ sector- and region-specific models by using theglobal scenario framework and outputs of global models to drive them. A par-ticularly useful feature of the present effort is that scenarios provide the infor-mation about the socioeconomic and technological development patterns thatis necessary for the assessment of the viability and effectiveness of variousinstruments and response strategies currently available or that might becomeavailable in the future to different stakeholder groups.

A key goal of the MA scenarios is to help decision-makers gain a betterunderstanding of the intended and unintended effects of various policymeasures for maintaining ecosystem services and human well-being si-multaneously. Human activities have become an important co-determinant ofEarth systems, and decisions made now and in the immediate future will haveconsequences across both temporal and spatial scales. Alternative futures de-scribed in the MA scenarios are subject to human choices, both those alreadymade and those to be made in the future. Multiple dynamics of change charac-

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terize human activities and ecological systems. Bringing these interactions tothe foreground is one of the main goals of the MA scenarios.

While basic human conditions generally improve across three scenariosand decline for some people in one scenario, they all portray, to a varyingextent, perilous paths of ecosystems change. This illustrates complex link-ages and feedbacks of ecosystem service changes on human well-being.While material elements of human well-being generally increase, loss of eco-system services leads to higher inequalities in some of the scenarios and evendegradation of some aspects of human well-being in others. Degradation andloss of some ecosystem services also affects the trade-offs and relations be-tween provisioning and regulating functions of ecosystems. This is one centraland important development pattern shared by all four scenarios.

The paths of the four scenarios are fundamentally different. Each sce-nario includes inherent path-dependencies and irreversibilities that arethe results of the long response times and cumulative nature of manychanges that affect ecosystem services and human well-being. The sce-narios do not converge, though the possibility exists that decisions could bemade in one scenario to make it evolve (or branch out) into an alternativefuture resembling one of the other MA scenarios. They differ with respect tomany of the drivers of global change identified by the MA. In particular, thescenarios differ with respect to whether the world becomes more or less inter-connected and whether environmental management is reactive or proactive.

Land use changes are perhaps the most critical aspect of anthropogenicglobal change in influencing the future of ecosystems and their services.Nevertheless, indirect effects on future ecosystem services, which can poten-tially result from other global changes (climate change, biodiversity loss), willalso be of importance and superimposed on effects of land use changes. Inthe four MA scenarios, land use changes will directly determine many of theprovisioning and regulating functions of ecosystems. These will depend on thefuture changes in biodiversity, desertification, or wetlands—all a function ofland use changes. Land use patterns are in turn directly dependent on someof the main scenario driving forces, such as demographic, economic, and tech-nological changes.

The models used to quantify the MA scenarios were unable to explore orelaborate on the evolutionary path-dependencies among anthropogenicsystem and ecosystem development, possible emergence of thresholds,and the specific dynamics caused by bifurcations. The current quantitativemethodological approaches are not well suited for assessment of cross-scalephenomena such as place-specific developments in relation to regional andglobal ones. Extending the scenario development to more than one set ofintegrated models might better encompass some of the deep uncertaintiesassociated with alternative futures and the resulting ecosystem services. Sincethe qualitative development of the MA scenarios was able to address path-dependencies, thresholds, and bifurcation dynamics, the storylines should beconsulted for additional depth and richness about path-dependencies, thresh-olds, and cross-scale feedback.

Important lessons learned in the development of the MA scenarios couldhelp improve the development of global storylines in any future assess-ments:

• Development of regional and more place-specific scenarios would helpinform and create better global scenarios. Regional scenarios can usemore accurate local information to develop scenarios and might representsystem dynamics more accurately. They can also pinpoint specific vari-ables of interest.

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451Lessons Learned for Scenario Analysis

• Better communication and interaction with policy-makers would help informthe development of the storylines by indicating the key variables that areof interest to decision-makers. This would be useful both for understandingwhich are the most pressing questions of policy-makers as well as forcommunicating results to policy-makers at the end of the process. Havingmore policy-makers and decision-makers within the working group may beone way to improve this communication.

• Improved communication and interaction across scientific disciplines wouldimprove future scenarios. Differences among disciplines’ core beliefs abouthow the world functions were also often the critical issues that policy-makerswanted to have addressed in the scenarios. Better interdisciplinary com-munication prior to initiation of future assessments might make an exceed-ingly complex process a bit easier.

13.1 IntroductionThe main objectives of the MA scenarios are to assesschanges in ecosystems and their services over the next 50years and beyond, to assess the consequences of thesechanges for human well-being, and to inform diversedecisions-makers about these potential developments andhow they can affect them through response strategies andpolicies. These objectives, as stated in Chapter 5, are re-flected in the overall approach used to develop the new MAscenarios. The objectives are an integral part of the basicassumptions about the future of the main driving forces ofthe four scenarios.

The scenarios do not attempt to describe all possible fu-tures that can be imagined. The MA scenario paths weredeveloped to provide plausible answers to the major uncer-tainties and focal questions about the future of socioecologi-cal systems. (See Chapter 5.) In addition, the scenariossystematically follow through a number of assumptions andmanagement approaches currently discussed by decision-makers around the world. The quantification of changes inecosystem services across the four scenarios are based on anintegrated modeling framework, which uses an existing setof models, but with new linkages designed explicitly to re-flect the main objectives of the MA scenarios. A brief sum-mary of the four scenarios and their main characteristics isgiven in the SDM. Chapters 8, 9, 10, and 11 synthesize awide range of social, economic, environmental, and policyimplications of changes in ecosystem services on humanwell-being, and include an assessment of possible policy re-sponses to these changes.

The MA scenarios have been conceived and developedto provide insights into a broad range of potential futureecosystem changes. The objective was to portray plausibledevelopments that are internally consistent rather than thosethat may be considered to be desirable or undesirable. Theidea of what is ‘‘negative’’ or ‘‘positive’’ in any given sce-nario is inherently dependent on the eye of the beholderand thus highly subjective. Therefore, great attention wasgiven in previous chapters to presenting both positive andnegative aspects in the scenarios. Uniting only ‘‘positive’’or ‘‘negative’’ features in a scenario would result in homo-geneous and ‘‘unidimensional’’ futures that may not beplausible and consistent.

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The overall objectives, scenario formulations, and devel-opment of the MA scenarios are new. However, our ap-proach builds on previous scenarios and modeling efforts inthe literature. The new and innovative element is the focuson ecosystem services and human well-being. The MA sce-narios distinguish between provisioning, regulating, sup-porting, and cultural ecosystem services (MA 2003). Accessto ecosystem services is one of several factors affectinghuman well-being, which is considered along a multidi-mensional continuum—from extreme deprivation or pov-erty to a high attainment of experience of well-being—andhas five major components: material well-being, health,good social relations, security, and freedom and choice (MA2003, Chapter 3). Human well-being is context-dependent,reflecting factors such as age, culture, geography, andecology.

Many insights were gained in the process of developingscenarios that focus on ecosystem services and human well-being. In the models used to quantify the MA scenarios,land use changes were perhaps the most critical aspect ofanthropogenic global change in influencing the future ofecosystems and their services. As a first approximation, theresults of MA scenarios modeling exercises suggest that landuse changes directly determine many of the provisioningand regulating functions of ecosystems. These will dependon future changes in biodiversity, desertification, or wet-lands, all a function of land use changes. Land use patternsare in turn directly dependent on some of the main scenariodriving forces such as demographic, economic, and techno-logical change. Another important finding across all scenar-ios is that indirect effects on future ecosystem services thatmight result from other global changes, such as those ofclimate, will be of secondary importance compared withland use changes. In the scenarios, the global changes gener-ally tend to amplify effects, especially the adverse conse-quences of changes in ecosystem services.

The MA scenarios also have important weaknesses thatpoint to potential areas for future improvements. Manyneeded improvements relate to our ability to quantify thefuture of ecosystem services. These include improvingcapabilities for modeling ecosystem services and humanwell-being, especially for supporting and cultural ecosystemservices; consideration of the consequences of a larger rangeof driving forces; and more-explicit treatment of the deepuncertainties associated with alternative futures, especiallythose related to quantifying ecosystem services.

Perhaps the most important deficiency in the new sce-narios is that the current models are not well suited for theassessment of cross-scale phenomena such as place-specificdevelopments in relation to regional and global ones. Thismeans that the models are not able to sufficiently explorethe evolutionary path-dependencies among anthropogenicsystems and ecosystem developments or the possible emer-gence of resilience or irreversibilities. However, many ofthe cross-scale feedbacks and many other scenario charac-teristics that could not be captured by models were treatedin greater detail in the narrative storylines. Extending sce-nario development to more than one set of integrated mod-els might be another way to better encompass some of the

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deep uncertainties associated with alternative futures andthe resulting ecosystem services.

13.2 New Contributions of the MA ScenariosThe MA scenarios make a number of new contributions tothe method of scenario analysis for exploring (inherentlyunknown) alternative futures, to the process of how scenar-ios are developed, and to the inclusion of an integrated as-sessment of ecosystem services and human well-being.

13.2.1 An Analytical Typology of the MA Scenarios

The MA was developed in the context of major advancesin the methodology of scenario analysis. Figure 13.1 showsa typology for assessment based on the distinction made byRayner and Malone between descriptive social science re-search, based on an analysis of mostly quantitative energyand material flows, and interpretive social science, focusedon the values, meaning, and motivations of human agents(Rayner and Malone 1988; see also Robinson and Timmer-man 1993). The figure further distinguishes between moreglobal and more local analysis and attempts to indicate typi-cal forms of analysis that correspond to the four quadrantsidentified. The distinctions among the quadrants shown inFigure 13.1 underlie many of the problems of interdisci-plinary communication and analysis in the sciences. It iswell known that it is difficult to combine, for example, in-terpretive place-based analysis of human motivations with,say, a quantitative analysis of energy systems and emissions.Much of the early work in the climate field, whether globalor local, was located on the descriptive side of the typology.

It is particularly noteworthy therefore, that recent devel-opments in scenario analysis are beginning to bridge thisdifficult gap (Morita and Robinson 2001; Swart et al. 2004;see also Chapter 2). Over the past decade, the global sce-nario analysis community has begun to combine the pri-marily qualitative and narrative-based scenario analysesundertaken by Royal Dutch/Shell and other companies(Wack 1985a, 1985b; Schwartz 1992) with global modelingwork in the form of analyses that bring together the devel-opment of detailed narrative storylines with their ‘‘quanti-fication’’ in various global models (Raskin et al. 1998;Nakicenovic et al. 2000). For example, the Special Report

Figure 13.1. Analytical Typology of Scenarios Analysis. Thisfigure illustrates local and global scenarios exercises and exercisesthat are more based on interpretive, qualitative, or descriptive modeling-based approaches.

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on Emissions Scenarios work (Nakicenovic et al. 2000), un-dertaken for the Intergovernmental Panel on ClimateChange, cut across the interpretive/descriptive divide,though it still focused mainly on the global and regionallevel.

As shown in Figure 13.2, the MA scenarios work alsocuts across the divide between interpretive and descriptiveresearch by combining narrative storylines and quantitativemodeling. However, it also begins to reach across theglobal/local gap, with a stronger focus on local analysis ofecosystem effects. This was mainly accomplished by incor-porating information from a few of the sub-global assess-ments in the global scenario effort and vice versa. Also, afew methodological steps were explored to link or nest thedevelopment of the local, regional, and global scenarios.Linking and nesting different scale scenario exercises is afield that needs further exploration in the future. In thisway, the MA work contributes to the trend toward moreintegrated and more interdisciplinary work on the relation-ships among human and natural systems.

Figure 13.2 demonstrates the place of the MA analysisalong two axes describing the geographical scale of workand the degree to which the scenarios are based on interpre-tive, qualitative storylines or grounded in model-baseddescriptions. The MA scenarios combine the storyline ap-proach with a modeling exercise. (See Chapter 6.) The fourscenarios presented in this volume are primarily global sce-narios, but the MA did go one step in the direction of de-veloping multiscale scenarios (MA Multiscale Assessments,Chapter 10).

13.2.2 Contributions to the Process of ScenarioDevelopment

The MA further refined and extended a number of recentmethodological improvements in the scenario formulationprocess. They include integration across social, economic,environmental, and ecosystems dimensions; disaggregationacross multiple scales of global patterns down to regionaland in some cases also place-specific developments; multi-ple futures across four alternative scenarios to reflect deepuncertainties of long-range outcomes; and quantification ofkey variables linked to ecosystem conditions and ecosystemservices along alternative narrative storylines (See Chapter2).

Figure 13.2. Placing of MA Scenarios Analysis in AnalyticalTypology. For a description of the typology see Figure 13.1.

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Integration across dimensions is needed because multipleanthropogenic stresses have an impact on the environmentvia direct driving forces such as pollution, climate and hy-drological change, resource extraction, and land usechanges, and they play an important role in co-determiningfuture evolution of ecosystems. These changes in directdrivers result from long causal chains of indirect drivers suchas population, economic, and technological patterns, thatare, in turn, conditioned by such ultimate drivers as humanvalues, culture, interest, power, and institutions. To capturethis nexus of interactions and emergent systems properties,a systemic framework is required that includes the key driv-ing forces, possible consequences of their unfolding or col-lapse, and feedbacks. (See Chapter 1.) MA scenarios achievethis by introducing these integrative elements:• formulation of extensive narrative stories, or storylines,

of four alternative sets of main driving forces to 2050and beyond to provide a context for unfolding ultimatedrivers and impacts on ecosystem services and humanwell-being;

• quantification of the narrative storylines by extended in-tegrated assessment models that include quantitative as-sessment of biodiversity, water, and fisheries; and

• qualitative assessment of possible trade-offs among eco-system services and substitutions by other services, theimplications for human well-being, and possible policyresponses.Many of these integrative elements are present in other

scenarios in the literature, but the emphasis on and integra-tion of ecosystem services and human well-being is new.

Disaggregation across multiple scales is essential becausemultiple interactions between anthropogenic and ecologicalsystems occur within and across scales from global and re-gional to local and place-specific levels. These differentspatial scales are often associated with characteristically dif-ferent temporal scales and provide mutually enhancing per-spectives into possible futures. Many of the relevant globalprocesses operate over very long time periods ranging fromdecades to centuries, and their impacts on human well-being are usually indirect and complex but fundamental,in some cases even threatening human existence itself. Incontrast, place-specific and local processes are usually muchmore direct in the ways that they affect human well-being,such as health, air and water quality, or nutrition.

Scientific capabilities to model links across temporal andspatial scales are very modest. Often such attempts are re-duced to disaggregating global development into a (small)number of global regions. Narrative storylines are richer inthe sense that they can provide apparently seamless connec-tions across multitudes of scales, but compared with numer-ical and analytical models they are not quantitative and donot provide reproducibility under varying assumptionsabout main driving forces. In Chapter 2, the hope was ex-pressed that perhaps future scenario-building techniquesand models would evolve to allow seamless views acrossscales and levels of analysis, representing each spatial unit asan interacting component of an integrated global system.The MA scenarios provide a first step in this direction byproviding, for example, quantitative links between different

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scales of land use patterns, climate change, and biodiversity.Another method of bridging across scales is more anecdotaland is provided in Chapter 10, where some place-specific,scenario-dependent developments of marine biodiversityare briefly described for places such as the Gulf of Thailandand the North Pacific.

Multiple futures are fundamental to any scenario enter-prise, because prediction of complex and evolving systemsis not possible. They are required for indicating the rangeof plausible futures and for encompassing some of the deepuncertainties associated with the evolution of complex sys-tems. Examples of deep uncertainties are nonlinear re-sponses of complex systems, emerging properties and path-dependencies, and generally unpredictable behavior thatemerges due to branching points, bifurcations, and complextemporal and spatial dynamics. Complex systems are inher-ently unpredictable, especially when human response strate-gies that have yet to be defined are involved.

The overall time horizon of the four MA scenarios is to2050 and beyond. Such long time horizons are requiredto encompass fundamental changes in anthropogenic andecological systems and their interactions. It is likely thatthey will unfold in unexpected ways and will embody im-portant surprises. Such surprises could include unexpectedemergent properties, path-dependencies, and the crossingof critical thresholds, leading to irreversibilities. Given themodest modeling techniques available today, developmentof a rich set of alternative scenarios is the main method usedto encompass these different possibilities and the associateduncertainties. This approach is also followed in the four MAscenarios. In addition to the quantitative formulation ofmany of the alternative scenario characteristics with an ex-tended integrated assessment modeling framework, the MAscenarios also have elaborate narratives that extend across amultitude of levels and scales. They provide the backgroundinformation about the main driving forces, the associatedfundamental drivers, and their consequences. In this way,they link various analytical and numerical methods that arenot (yet) an integral part of the IAM used to quantify thefour scenarios.

The long time horizon for the scenarios of 2050 andbeyond extend the state-of-the-art in scenario building.Such long time horizons were used first in the scenariosfor assessing anthropogenic climate change, its impacts, andpossible response strategies. The time horizon of a centuryor more was imposed by long-time constants in the climatesystem response to anthropogenic forcing, such as the emis-sions of greenhouse gases, aerosols, and particulate matter.In contrast, most of the economic scenarios, whetherglobal, regional, or national, are associated with relativelyshort time horizons of a decade or two at most; this doesnot allow for fundamental changes in economic system, butit does capture the accumulation of more gradual and incre-mental changes based on current trends and tendencies. De-mographic scenarios are usually somewhere in between dueto the large inertia associated with population momentumand slow cumulative changes arising from migration pat-terns or the emergence of pandemics. Fundamental techno-logical, institutional, and infrastructure changes can also

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take many decades or centuries, so that scenarios of the pos-sible emergence and diffusion of new technologies usuallyhave time horizons of 50 years or more. Integrated climatescenarios that included possible human response strategieswere the first applications of integrated scenarios with timehorizons of century or more.

The MA scenarios establish another important precedentin adopting a similarly long time horizon so as to encompassalternative future developments of ecosystem services andhuman well-being. This is important not merely becausesome of the ecosystem services such as biodiversity may sig-nificantly decrease over these longer time horizons, threat-ening at least some aspects of human well-being, but alsobecause these futures are subject to human choices that havenot yet been made. It is difficult to separate all complexinteractions that co-determine changes in human well-being components related to biodiversity.

So far it is not possible to quantify all these interactions,but an innovative part of the MA is a first attempt in thisdirection. Decision-makers and various stakeholders needto understand how policies and other measures can influ-ence and affect future provision of ecosystem services andhuman well-being. Human activities have become an im-portant co-determinant of Earth systems, and decisionsmade now and in the immediate future will have conse-quences across both temporal and spatial scales. Integratedscenarios are the main tool available for the assessment ofalternative future developments and possible response strat-egies. Increasingly, long time horizons and global perspec-tives are required to understand complex interactionsbetween human and natural systems.

The combination of narrative storylines and their quan-tification in integrated scenarios of alternative futures is themain method for capturing complexity and uncertainty andtranscending limits of conventional deterministic models ofchange. (See Chapter 2.) MA scenarios address a highlycomplex set of interactions between human and natural sys-tems, a scientific challenge that is compounded by the cu-mulative and long-term character of the phenomena. Whilethe world of many decades from now is indeterminate, sce-narios offer a structured means of organizing informationand gleaning insight into the possibilities. Scenarios candraw on both science and imagination to articulate a spec-trum of plausible visions of the future and pathways of de-velopment. Some characteristics of the MA scenarios areassumed to evolve gradually and continuously from currentsocial, economic, and environmental patterns and trends;others deviate in fundamental ways. A long-term view of amultiplicity of future possibilities is required in order to beable to consider the ultimate risks of maintaining adequateecosystem services, assess critical interactions with other as-pects of human and environmental systems, and guide pol-icy responses.

The development of methods to effectively blend quan-titative and qualitative insights is at the frontier of scenariosresearch today. The narrative storylines give voice to im-portant qualitative factors shaping development such asvalues, behavior, and institutions, providing a broader per-spective than is possible by analytical and numerical model-

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ing alone. (See Chapter 2.) Storylines are rich in detail,texture, metaphors, and possible insights, while quantitativeanalysis offers structure, discipline, rigor, and reproducibil-ity. The most relevant recent efforts are those that havesought to balance these attributes. They provide importantinsights into how current tendencies and trends might be-come amplified in different future worlds across the fourstorylines and provide a multitude of different details acrossscales and systems. They are embedded in extensive assess-ment of the main driving forces and their future develop-ments across scenarios in the literature. (See Chapter 7.)

13.2.3 Ecosystem Services and Human Well-beingDevelopment Paths across Scenarios

The MA scenarios make four important new contributionsto the contents of global environmental scenarios exercisescompared with the literature:• extending the integrated assessment approaches to in-

clude ecosystem services and their consequences onhuman well-being;

• modeling changes in biodiversity as an integral part ofscenario development;

• assessing the interactions and trade-offs among ecosys-tem services; and

• assessing the possible replacement of some ecosystemservices by others and the emergence of new ways ofprovisioning of these services, such as through techno-logical change.Perhaps the most important new contribution of MA

scenarios to global scenario analysis is the extension of inte-grated assessment and modeling of alternative futures to ex-plicitly include ecosystems and their services and humanwell-being. The vast body of environmental scenarios liter-ature deals primarily with climate-related issues. The firstintegrated assessment models and frameworks were devel-oped to link driving forces to possible climate change con-sequences, including impacts of climate changes, andvarious response strategies, including mitigation and adapta-tion.

Figures 13.3 and 13.4 compare the MA modeling systemto that of the IPCC, which is an integrated assessment of

Figure 13.3. Integrated Assessment Framework ofIntergovernmental Panel on Climate Change (IPCC 2001)

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I

Figure 13.4. Approach and Contributions of MA to Focus of Scenarios Development

climate change that takes account of the human drivers of,and responses to, changes in the physical climate system.The MA scenarios add a new element by exploring feed-backs from the responses to environmental change to thedrivers that affect this change. Prior to the MA, the majorityof scenario exercises explored changes in socioeconomicsystems and their impacts on the variable of interest (such asclimate change or water supply and quality). This approachwas enhanced in the MA scenarios by focusing on parallelchanges in ecosystem services and human systems and theirimpacts on one another. Figure 13.4 demonstrates this newapproach to integrating across the various driving forces andsimultaneously describing the feedback loops within thesocioecological system.

In some sense, there is a symmetry between integratedapproaches to assess future climate change and the MA ap-proach to assessing future ecosystem changes. MA scenariosextend the state-of-the-art by including both an integratedtreatment of climate and ecosystems change as well as theresulting changes in ecosystem services and human well-being. However, they do not explicitly deal with the ethicaldimension of the social developments suggested by someof the scenario features. For example, the scenarios do notprovide details on possible implications for equity or life-style changes, but they directly address changes in humanwell-being that result from changes in ecosystem services.While the perspective of services is not new in itself, theexplicit inclusion of a multitude of ecosystem services inMA scenarios is unique in scenario analysis. Assessing multi-ple ecosystem services is a formidable task because ecosys-tem services do not act in isolation; they interact with oneanother and with anthropogenic systems in complex andusually unpredictable ways.

Technology and institutions also play a role in the provi-sion of ecosystem services; the nature of the interaction be-tween ecosystems, technology, and institutions is not alwaysentirely clear, however. The MA scenarios also address theissue of the extent to which alternative services, derivedfrom new technologies, institutions, and other human ac-tivities, offer new solutions to improve the efficiency, acces-sibility, affordability, and quality of the provision ofecosystem services.

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It may be easy to replace some services with others or toimprove their provision through technological or institu-tional advances. More often, however, ecosystem servicesmay not be easily substitutable by other services. Thus thedegree to which the provision of ecosystem services can beimproved and pressure on ecosystems reduced by techno-logically generated alternatives is highly uncertain. It willdepend on what services are demanded in the future, whatnew technologies are available, and what other ecosystemservices are (purposefully or accidentally) traded off by thesubstitution processes. (See Chapter 12.)

It is true that future technologies may offer feats that areimpossible or prohibitively expensive today. The costs ofmany technologies are likely to decrease, making theirwidespread diffusion possible and affordable. However,some technologies may have unpleasant and unexpectednegative effects and cause unanticipated interactions amongecosystem services. Similarly, currently unknown ecosystemservices, or those considered to be less important, may befound to be fundamental to people or the future mainte-nance of ecosystems. These are some of the dimensions ofecosystem change that are addressed across the four MAscenarios.

While an important step forward, the MA scenarioswork is incomplete. Particularly the quantitative analyses ofecosystem services and human well-being were driven bythe underlying scenario analysis, with no explicit modelingfeedbacks from those analyses back to the underlying an-thropogenic driving forces. In other words, while in thequantitative models changes in ecosystems affect ecosystemservices and human well-being, changes in ecosystem ser-vices and human well-being do not lead to further changesin the anthropogenic drivers of change. These feedbackswere, however, included in the narrative analysis of the in-teraction between human well-being and ecosystem ser-vices outcomes.

While incomplete, the inclusion of ecosystem effects inthe MA represents a major step forward. It points the waytoward a truly integrated assessment of possible future rela-tionships among human and natural systems.

The MA scenarios develop four different futures, eachplausible in its own right, and detail the resulting changes in

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ecosystem services and their consequences for human well-being. While basic human conditions generally improveacross all four scenarios, the scenarios nevertheless all resultin perilous paths of ecosystem changes. Global populationincreases in all four scenarios, as does the affluence of anaverage person, but this generally occurs at the cost of eco-systems degradation and consequently also lower per capitaecosystem services.

The individual development paths of the scenarios arefundamentally different and do not converge. They differwith respect to the paths of many of the drivers of globalchange. In particular, the scenarios differ with respect towhether the world becomes more or less interconnectedand whether environmental management is reactive or pro-active. Global Orchestration is connected and reactive,Order from Strength is disconnected and reactive, AdaptingMosaic is disconnected and proactive, and TechnoGarden isconnected and proactive.

These basic differences are explored in more detail inthe full storylines. The scenarios differ with regard to insti-tutions, technology, social organization, and ecologicalchange. None of these four development paths leads to afull transition to sustainability, even though the two proac-tive scenarios include response to ecosystem change.TechnoGarden follows a ‘‘technology strategy’’ to deal withthese threats, while Adapting Mosaic takes a more institu-tional and behavioral path. A complementary mixture ofthese two different strategies is required for the sustainabil-ity transition and a future where the loss of ecosystem ser-vices is avoided both through substitutions by other servicesor through human change itself. In contrast, the two reac-tive scenarios put more emphasis on material human well-being but take different strategies toward this goal. GlobalOrchestration is a world where globalization of economicactivities is fairly successful and results in the highest eco-nomic growth rates of all four scenarios. Order fromStrength is a fragmented world where economic and mate-rial interests are focused on more local and regional solu-tions.

This rudimentary and ‘‘caricature-like’’ brief descriptionof the scenarios illustrates the fundamentally different natureof their development paths. Chapters 8 and 9 provide a richqualitative and quantitative image of these four futures. De-spite this detail, each scenario represents a kind of ‘‘pure’’strategy. In reality, elements of each described possibleworld will be presented in some aspects of the future devel-opment but not others. Therefore, it should be noted thatthe scenarios jointly give the full range of heterogeneity offuture developments. Some combinations of them are a realpossibility, especially at the more local and regional level.Even though they portray divergent development paths,they jointly hold the full richness of future ecosystem ser-vices and human well-being.

One common finding is that all these different possibili-ties lead to a general decrease of regulating and supportingecosystem services per capita while ecosystem managers tryto maintain provisioning services. However, the chosen de-velopment paths all lead to different outcomes for the fivecomponents of human well-being. Global Orchestration

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leads to the greatest improvement in human well-being.TechnoGarden improves all but one element of humanwell-being. Adapting Mosaic significantly improves humanwell-being in the South with little change in the North. InOrder from Strength, human well-being is decreased.

While basic human conditions generally improve acrossthree scenarios and decline in one scenario, they all result,to a varying extent, in perilous paths of ecosystem changesand lower per capita ecosystem services. This illustrates thecomplex linkages and feedbacks of ecosystem servicechanges with human well-being. While material elementsof human well-being generally increase, loss of ecosystemservices leads to higher inequalities in some of the scenariosand even degradation of some aspects of human well-beingin others. Degradation and loss of some ecosystem servicesalso affects the relationship between provisioning and regu-lating functions of ecosystem services.

The Global Orchestration scenario has the highest ratesof economic development associated with lowest popula-tion increase. This leads to a high capacity to both invest inthe future and respond to potential threats. However, thiscarries an environmental price as it leads to the highest ratesof global change, including the highest rates of forest landdisappearance and the highest levels of energy consump-tion. Nevertheless, the overall improvement of humanwell-being is the highest with this scenario, particularly inthe currently developing countries. This may be becauseincreases in wealth and equity lead to a high capacity torespond to changing circumstances and offset some loss ofecosystem services.

But the key uncertainty of the Global Orchestrationpath is whether or not the impressive rates of economicdevelopment and human well-being can be sustained if allexternalities are accounted for. It remains unclear whetherthis development path is only achieved at the cost of endan-gering the biosphere and other planetary systems irrespec-tive of apparent improvement of human well-being, thusundermining economic systems in the long term. Full con-sideration of the feedbacks from ecosystems to human sys-tems in the quantitative models might reduce the level ofeconomic development and the relative improvement ofhuman well-being.

The Order from Strength development path comesclose to disaster. It is the world with the highest populationgrowth, some of the highest adverse environmental im-pacts, and the lowest rates of economic development. Theincome disparities in this possible future are similar to thosethat prevail today. Ecosystem services are seriously eroded.Society lacks the economic or technological capacities toadapt or respond to these threats to human well-being. Forexample, while high trade boundaries reduce the chance ofinvasive species, the risk of adverse impacts on human well-being when invasions do occur is high due to low socialcapacity for adaptation.

There is an utter disregard, under Order from Strength,for human interference in the biophysical processes and ageneral erosion of the main pillars of sustainability: environ-ment, equity, and development. The consequences are thesecond highest demand for energy services (after Global

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Orchestration) associated with the highest greenhouse gasemissions for all scenarios, the highest levels of water ab-straction, and the lowest per capita incomes. It is not sur-prising that the incidence of disease, poverty, loss of securityand freedom, and other adverse human conditions are mostprevalent in this scenario.

The Adapting Mosaic development path is the most pro-active about emerging challenges. It sets parallels betweenthe adaptive development of humans and ecosystems. Fromthis perspective it appears to be most attractive. It achieveshigh levels of human well-being with relatively low risksand intrusion on ecosystems and nature. Only Techno-Garden has lower impact on ecosystems. But Techno-Garden has high and unknown risks of collapse due totechnology failure, while Adapting Mosaic is low risk. Thisdevelopment path highlights the benefits of evolutionaryresponses fostered by investments in social, natural, andhuman capital at local and global levels. There is recogni-tion that natural capital underpins other forms of capital,such that property rights are attached to ecosystem services.In other words, they are internalized in decision processes.

Thus, Adapting Mosaic is the scenario with the highestdegree of assumed feedback from nature to the humansphere and that includes explicit consideration of ecosys-tems. In the other three scenarios, ecosystems are reducedto the benefits provided by ecosystem services. In this sense,Global Orchestration and TechnoGarden come closest toachieving a sustainability transition, but somewhat ironi-cally, Global Orchestration does so without vigorous diffu-sion of new technologies and TechnoGarden without highrates of economic development. This might indeed consti-tute a possible internal contradiction between these twostorylines.

TechnoGarden also improves human well-being, butwith higher risk and uncertainty. Technological approachesalone, without appropriate institutional and social embed-ding, cannot resolve the challenges of the future. In addi-tion, technology itself may be the source of additionalproblems due to the potential for breakdowns in highlycontrolled systems. Also, the assumption in this scenario isthat the described changes toward ‘‘greener technologies’’might take some time to occur. Therefore, technology doesnot lead to a higher level of economic growth right away.

In the past, technological change has generally been themain driver of economic development in the long run. InTechnoGarden, technological change is used to improveprovision of ecosystem services and does not provide themeans for rapid rates of development and elimination ofpoverty, as in the Global Orchestration strategy. The differ-ence is primarily in the focus in Global Orchestration onglobal institutions to improve equality and eliminate pov-erty. For example, technology leads to a rapid shift awayfrom the current reliance on fossil energy in this scenario sothat its consequences for climate change are lower than inother scenarios; however, there is no attempt to improveaccess to energy sources for all people. It is possible that therealized rates of development in this scenario would behigher if some of these positive environmental externalitieswere included as a resource. The cumulative effect of tech-

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nological change and lower environmental impacts in thisfuture world could indeed lead to the highest level ofhuman well-being. However, the high risk of collapsewould remain.

The Order from Strength development path is the leastsustainable both because of its disregard for the impacts onecosystems and because of the lack of development. Itcomes close to embodying many of the fears associated witha perilous development path or a failure in human develop-ment. It is indeed surprising that despite these monumentalfailures, the development path manages to improve someaspects of human well-being in the currently rich countries.(See Chapter 11.)

The scenarios also do not include a development pathcharacterized by a ‘‘best case’’—a success of sustainable de-velopment associated with a high degree of environmentalprotection at all scales. This would be a scenario that combinessome of the positive characteristics of Global Orchestration,TechnoGarden, and Adapting Mosaic into a developmentpath that is both evolutionary and has high social and tech-nological innovative capacities without a disregard for naturalor human capital, such as where there is a high dependencyby the poor on biodiversity. Such a scenario might serve toillustrate the policies and strategies that would be requiredover the next decades to reduce human intrusion on naturewhile improving human well-being for all future genera-tions. The MA nevertheless chose not to develop this‘‘rosy’’ scenario, as for each country and in each location-specific case the mix of these different elements is likely todiffer.

The MA scenarios show increasing pressures on biodiv-ersity and many other adverse impacts on ecosystems up to2050 and beyond. However, ecosystems play a crucial rolein overall biophysical processes. For example, they are animportant regulating component of the global carbon cycle.The potential impacts of ecosystem service changes onglobal and climate change are twofold. They include theinterplay of ecosystem services and other service in co-determining water, air, and land use as well as the emissionsof greenhouse gases. They also include the regulating func-tion of ecosystems in global and climate change. MA sce-narios describe the former impacts explicitly. The latter onesare more difficult to capture in the models. For example,climate models do not include changes in the carbon cyclethat might emerge due to anthropogenic causes of ecosys-tems changes, nor do they include the effects of albedochange arising from land use change.

13.3 Robust Findings of the MA ScenariosA striking feature of the four MA scenarios is that they allshow increased demand for ecosystem services and placeincreased pressure on ecosystems to supply those services.People in each scenario pursue different methods for amel-iorating the increased pressure on ecosystems. In some sce-narios, such as TechnoGarden, the greater pressure onecosystems is somewhat relieved through technological ad-vances to improve efficiency of service delivery. In GlobalOrchestration, society focuses on equal access to ecosystem

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services in the hopes that this will eventually lead to greatercare of ecosystems. In general, scenarios in which increaseddemand for ecosystem services is coupled with disregard forregulating and supporting services (Order from Strengthand Global Orchestration) suffer from high risk of break-downs in access to provisioning ecosystem services. Thosescenarios in which learning about ecosystem function is apriority (TechnoGarden and Adapting Mosaic) tend to dobetter in maintaining supporting services.

Together, the scenarios illustrate that it is difficult to re-place the provision of ecosystem services with alternativeswithout fundamentally changing human well-being. Thatis, replacing one service with another often creates demandson ecosystems in another place, in a future time, or for adifferent service. For example, we can replace biofuels withfossil fuels, which may improve local forests but which mayalso lead to increased demand for carbon sequestrationglobally. One of the most common types of these trade-offsis to favor provisioning services at the expense of supportingservices. As noted earlier, however, ignoring supporting ser-vices leads to high risk of future breakdown in access toprovisioning services. One of the implications of this maybe that ecosystems may not be able to support large humanpopulations at high levels of material human well-being—levels that are associated with increasing consumption andproduction patterns.

Highlighting this trend is an important message for policy-makers. Describing irreversible trends, such as the loss offorest area, which occurs in all scenarios, can help to focusattention on developing strategies to ameliorate the conse-quences of these developments and devise adaptation mech-anisms. The MA scenarios provide some hints about howthis might be done. In addition, the scenarios alert policy-makers to possible unexpected irreversibilities that theymight foster through the decisions they take today.

A major driver for the portrayed irreversible trends inthe MA scenarios is increasing land use for human purposes,which in return reduces the area available to unmanagedecosystems. This trend is further exacerbated by climatechange and other adverse environmental developmentssuch as loss of water and air quality. For example, changes inland use are expected to be the major driver of biodiversitychanges (based on quantitative assessment of species-area re-lationships in the next century across all four scenarios), fol-lowed in importance by changes in climate, nitrogendeposition, biotic exchanges, and atmospheric concentra-tions of carbon dioxide. (See Chapter 10.)

Storylines and qualitative assessment of ecosystem ser-vices and their impacts on human well-being provide moreinsights into possible future events and developments thatmodels are not currently capable of quantifying. As notedearlier, human well-being has five key, reinforcing compo-nents: basic material needs for a good life, health, good so-cial relations, security, and freedom and choice. Ecosystemsunderpin human well-being through their supporting, pro-visioning, regulating, and culturally enriching services. (SeeChapter 11.) World populations increase in all four MA sce-narios along with incomes and material consumption,which help determine human well-being. The tacit as-

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sumption is that there are biophysical limits to ecosystems’ability to produce services for human use. In scenarios, thisdecline cannot be completely compensated for by techno-logical and social changes. This critical result is associatedwith high scientific confidence. (See Chapter 11.)

In some ways, this important result unearths one of themost interesting findings of the MA scenarios. All four sce-narios support larger populations with higher levels of in-come and consumption, which puts increasing stress onecosystem services. Ecosystems in the MA scenarios aregenerally able to support the increasing demand for services,but at the cost of supporting and regulating services andtherefore at the cost of increased risk of breakdowns in pro-visioning services. This seeming contradiction raises a ques-tion: Is it possible to imagine sustainable futures with morepeople on the planet all enjoying higher human well-beingcompared with today but without further degradation ofecosystems and their services? Such a future would implythat the human ‘‘footprint’’ on the planetary processeswould need to decrease through more efficient provision ofservices or that provisioning ecosystem services would needto be substantially decreased without affecting human well-being. The ultimate limits in the substitutability of ecosys-tem services is a critical research topic that clearly emergesfrom the findings of the MA scenarios.

The MA scenarios explore management and policy op-tions that are currently being discussed by decision-makers.In this way, the scenarios provide a long-term perspectivefor different near-term decisions about ecosystem manage-ment and use. This can give useful concrete policy guidanceto decision-makers along with the options discussed today.For example, new technologies could be developed that areable to improve the efficiency of ecosystem service provi-sion. Bioengineering and tremendous progress in geneti-cally modified organisms are one possibility for reducing theburden on natural ecosystems to meet human demands, butthis is already controversial. The scenarios show that thereare possible benefits, as well as enormous risks to use ofthese technologies. They hold the promise of limitinghuman demands for space and ecosystem services. At thesame time, they may lead to a multitude of unintended ad-verse consequences.

The possible convergence of some new technologiesdiscussed in Chapter 7 could lead to revolutionary changesand a new wave of economic development not based oncurrent consumption patterns. There is a considerable re-search effort on the possible benefits, risks, and ethics ofnano, genetic, information, and new cognitive science andtechnologies. Their convergence toward meeting newhuman needs and providing services could be a powerfuleconomic drive that could in principle reduce the impacton ecosystems. However, they carry great risk of problemsand unforeseen consequences on ecosystem services andhuman well-being. A lower risk possibility is a fundamentalchange in human behavior that leads to much better ecosys-tem management and more humble demands on ecosystemservices despite more affluent and larger future populations.

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13.4 Lessons Learned about Policy, Planning,and Development Frameworks

13.4.1 Global Policies in Context of Other ScalePolicies

A complex and interacting set of processes that span envi-ronmental, economic, technological, social, cultural, andpolitical dimensions drive the global system. Policies aimedat one aspect, such as poverty alleviation, may exacerbateother problems, such as environmental degradation. Con-tradictory sectoral policies can negate one another or back-fire. Scenario analysis helps identify opportunities formutual reinforcement between sectoral policies.

Policies need to be consistent across scales as well asacross sectors. For instance, national policies should neitherinhibit local initiatives nor undermine global policies.Moreover, since each human community and ecosystem isunique, policies should allow for and encourage adaptationsto the local context and conditions. Again, the integratedscenario approach can illuminate the requirements for amultilevel policy framework. In the new century, environ-mental problems will continue to cross borders. Water pol-lution, air pollution, and depletion of the stratosphericozone layer are problems that do not respect national bor-ders. Neither does the buildup of greenhouse gases in theatmosphere that contributes to climate change. Nor do thebirds, fish, and zooplankton that may be contaminated inone country but become part of the food web in another.Facing these challenges will require cooperative regional,continental, and global solutions.

Dealing with cross-border problems requires much thesame kind of institutional apparatus at the local and nationallevels as described earlier: problems must be detected anddiagnosed, interests must be balanced within and across bor-ders, and agreements need to be implemented. There is,however, one big difference: at the global level, commit-ment is a more difficult problem, and there is no centralauthority to enforce agreements, although the emergenceof a world environment organization could be envisagedunder certain scenarios.

Social, political, economic, and ecological processes canbe more readily observed at some scales than others, andthese may vary widely in terms of duration and extent. Fur-thermore, social organization has more- or less-discrete lev-els, such as the household, community, and nation, whichcorrespond broadly to particular scale domains in time andspace.

A long time horizon is an obvious requirement for poli-cies that aim to affect development over many decades. Butlong-term policy is often, by default, the cumulative resultof a series of policies with a shorter-term outlook. There-fore, the long-range impacts of short-term policies shouldbe designed and assessed in advance. Alternative policiesmay achieve similar short-term goals but have very differentlong-term impacts. Ideally, policies should create a platformfor the next round of new and more advanced policies. Thescenario approach is particularly appropriate for incorporat-ing long-term considerations into today’s policy discussions.

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New social actors are becoming increasingly important,complementing traditional modes of decision-making andaction. In particular, NGOs encompass a broad variety ofinterests, including educational organizations, trade unions,religious organizations, aid and development organizations,charities, and the media. The policy process needs to in-volve and mobilize all relevant institutions, tapping intotheir diverse capacity and potential for interaction, synergy,and complementarity. This means that participation, nego-tiation, and the articulation of multiple goals should substi-tute for antagonism and exclusion. Again, a scenario-building process that can cultivate contrasting visions andperspectives is a critical technique for fostering pluralisticdialogue.

13.4.2 The Usefulness of the MA Scenarios forStakeholders

This section explores what we learned about the usefulnessof scenarios (development, modeling, analysis) for generat-ing policy-relevant information. It also assesses the useful-ness of the information in the scenarios for preparing policyanalyses for selected stakeholder groups discussed in greaterdetail in Chapter 14. Most of the selected indicators, how-ever, refer to the quantitative results of the scenario model-ing exercise. Understanding many of the assumptions thatthe qualitative storylines portray in more detail and theirconsequences for different stakeholder groups can add sub-stantially to the analysis. Chapter 14 also addresses what dif-ferent user groups are likely to find most useful or missingwhen they conduct their own policy analyses of the MAscenarios.

13.4.2.1 Background

Scenarios have become a popular tool in environmental as-sessment and management in the past two decades. Theyplayed a limited role in the 1960s, when local and largelyshort-term problems dominated the environmental agendas.Increasing concerns over multifaceted, continental- toglobal-scale, and especially long-term problems led to thegrowing use of scenarios. Although policy-making is onlyone of many possible uses of scenarios, an increasing num-ber of scenario applications attempt to provide useful infor-mation for decision-makers in public policy or privateentities. Global scenarios represent a special cluster withinthis realm.

The work of the MA Scenarios Working Group hasbuilt on other global environmental assessments to design arelatively ‘‘user-driven’’ process. This is an ambitious objec-tive. The range of targeted stakeholders includes the maininternational environmental agreements explicitly con-cerned with specific ecosystems or their services (the U.N.conventions on biodiversity, desertification, and wetlands),national governments (both parties to the internationalagreements and regulators of domestic policies), the privatesector (extending from local resource operators to multina-tional companies using ecosystem services), and civil society(communities crucially depending on the local ecosystemsand their services as well as NGOs protecting specific com-

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munity interests or broader environmental values). Thisuser-driven objective has been pursued from the beginningof the overall MA process.

Representatives of this wide-ranging and diverse in-tended audience have been surveyed concerning the infor-mation they would most need from the MA. The userquestions have been sorted, analyzed, and summarized inChapter 5.

Yet this goal of stakeholder participation must confrontthe reality of the scenario development process (scenaristsgetting carried away by their own storylines and visions ofthe future) and, most important, the constraints of the toolscurrently available to obtain the information users require.In this respect, an important question is related to the dis-tance between the variables in the models and scenarios onthe one hand and the indicators related to the stakeholdersinterests, values, and mandates on the other.

The quickest way to obtain information from the sce-narios for policy analysis is when the indicators of interestare directly available as input (assumptions about drivingforces) or output (results of the model calculation or thequalitative assessment based on the input assumptions) vari-ables in the storylines or in the assessment models. An al-most equally simple way to acquire information is whenscenario or model variables can serve as precursors that canbe converted by generally accepted procedures into policy-relevant indicators. Post-processing is required when therelationship between scenario variables and policy indica-tors are indirect. This can take the form of statistical proc-essing of model output or running additional models fed bythe primary model output to generate the required policy-relevant indicator. Inferred indicators require expert judg-ments and special procedures to be derived from one orseveral scenario or model output variables. Finally, distantindicators are those on which some sparse information isavailable in the model results but obtaining them wouldentail special post-processing arrangements (such as an ex-pert panel). Given the limited time and resources availableto conduct the policy analyses in Chapter 14, most indica-tors were taken directly from scenario storyline and modelresults (Chapters 8 and 9) and their interpretation and anal-ysis by fellow experts in Chapters 10, 11, and 12.

13.4.2.2 Usefulness of the MA Scenarios to Specific StakeholderGroups

The United Nations Convention on Biological Diversityhas evolved into a complex web of thematic issues. A de-tailed comprehensive assessment of the implications for allthemes and subprograms is not possible here. However, agood deal of relevant information on biodiversity is avail-able in the scenarios.

Among the major threats to biodiversity, habitat trans-formation is the most important one, and quantitative re-sults are available on key drivers: population growth andurbanization, fossil fuel extraction, change in agriculturalarea, forest conversion, and land fragmentation. Agricul-tural intensification and water withdrawal are available asindicators for the threat of overexploitation and inappropri-ate management. The information about pollution as a

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threat to biodiversity is limited to SO2 and NOx emissions,critical load excess, and return flows as proxies for waterpollution. Climate change as a threat is characterized bychanges in temperature and precipitation and by biomeshifts. In contrast, there is no quantitative scenario outputthat would indicate the evolution of invasive species that isan increasing concern among threats to biodiversity.

The Convention on Wetlands (the Ramsar Convention)is concerned with wetlands, which exist in all continents,are diverse, and provide important functions and services.The quantitative model output of the scenarios does notcontain direct or precursor indicators of wetlands change.This is because global models are designed to capture broadpatterns of global change and because modeling techniqueshave not advanced much for wetlands processes, whichgenerally take place at much smaller scales. One good wayto generate wetland-related indicators would be to use theoutput of the global models operated in the MA scenariosexercise as input to drive general or location-specific wet-land models to explore the potential impacts of differentglobal scenarios. This was not possible in the present assess-ment. Therefore, conceivable impacts for wetlands are as-sessed on the basis of coarse indicators like regional waterwithdrawal, return flows, and water quality. This leads to arather rough assessment of the emerging risks to wetlands,but the characteristic differences among the scenarios areapparent even at this level.

The mandate of the United Nations Convention toCombat Desertification is to address and alleviate degrada-tion of land in arid, semiarid, and dry subhumid areas. Thecauses and processes of desertification are multiple and di-verse. The desertification process itself is not directly de-picted in global models because the process involves manylocal biophysical and socioeconomic factors that the globalmodels cannot address. One possibility could be to use suchmodels as post-processors of the global model runs. Thiswas not feasible in the present assessment. Instead, an at-tempt was made to define suitable proxy variables fromwhich indicators of desertification could be inferred. Oneof the main socioeconomic drivers behind desertification isunsustainable land use in arid areas. Models provide outputthat can be used to generate indirect indicators by takingthe extent of arid areas under agriculture in different regionsas a proxy to assess the desertification risk. These indicatorsdo not provide a rich information base, but they are suitablefor conducting a broad assessment of desertification risk andresponse options under the MA scenarios.

The main insights from the MA scenarios for nationalgovernments are analyzed at two time horizons in Chapter14. The medium-term assessment looks at the implicationsfor the prospects of reaching the Millennium DevelopmentGoals. The long-term assessment seeks to estimate the pros-pects for implementing the long-term objectives of sustain-able development as confirmed and proclaimed by theJohannesburg Declaration at the World Summit on Sustain-able Development in 2002.

The MA scenarios and model results contain a lot ofuseful information about the evolution of ecosystem ser-vices that is related to the achievement of these near- and

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long-term objectives. In some cases, the information isavailable on the relevant MDG indicator or its close proxyor precursor version (such as the proportion of land areacovered by forests or of population with sustainable accessto an improved water source). For many MDG indicators,implications of the scenarios can be assessed from indirectindicators. Good examples are the indicators defined tomeasure progress on Target 2: ‘‘halve the proportion ofpeople who suffer from hunger.’’ The indicator of preva-lence of underweight children is well approximated by themodel output indicating the percent of malnourished chil-dren (a composite indicator, see Chapter 14 for details),while the indicator on the proportion of population belowminimum level of dietary energy consumption can be in-ferred, albeit roughly, from the model output indicating theamount of calories available per capita per day.

A lot of qualitative information can also be used as in-ferred indicators relating to the MDGs, like income growthin regions for the prospects of achieving Target 1: halvingthe proportion of people whose income is less than $1 aday. In contrast, the scenarios are rather vague about generaldevelopment issues like education (school enrollment, liter-acy rates), overall health status (under-five and infant mor-tality rates, immunization against measles). Finally, the MAscenarios are totally silent about the financial aspects of de-velopment, such as the prospects for official developmentassistance, for debt and debt relief, especially for heavily in-debted developing countries, or for foreign direct invest-ments.

The situation is similar in the case of the indicators thatcan be used to measure progress on the objectives of theJohannesburg Declaration up to 2050. General economicdevelopment indicators (GDP growth, for example, or thegap between rich and poorer regions), many directly or in-directly environment-related social indicators (food secur-ity, hunger, access to energy), and many environmentalindicators are readily available and provide useful informa-tion for policy analysis. However, the more specific charac-terization of the economic and financial development(access to financial resources, sharing the benefits fromopening markets, or access to health care) is omitted due tothe primary focus on global ecosystems futures.

One of the most useful aspects of the scenarios for com-munities and NGOs is the effort to assess the relationshipbetween ecosystem changes and human health and well-being. Given their global nature, however, the scenarios arenot able to fully model all the trade-offs and interactionsbetween ecosystem services and human well-being, espe-cially in reaction to specific response options and adapta-tion. Given the scenarios’ inability to fully model allecosystem services (cultural and supporting, along with pro-visioning and regulating), as well as the complex interac-tions between ecosystem services, human well-being, andresponse options over time, it is difficult to address thethresholds at which further ecosystem degradation and re-ductions in human well-being might occur. The scenariosdo not fully meet the needs of civil society stakeholders tohave the MA address the impact of ecosystem change onthe vulnerability and resilience of human communities and

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on their cultural concerns. These issues are more success-fully addressed in the sub-global assessments. Communitiesare interested in learning about site-specific impacts in rela-tion to global changes, but the scenario methodology is notsufficiently advanced yet to make such cross-scale assess-ments readily possible.

There is a wealth of information in the MA scenariosthat is useful and relevant for the private sector, but it is noteasy to extract and summarize it. First, virtually all issuesthat are important in these scenarios are likely to have somedegree of private-sector implications, for the private sectorthat is closely related to or has indirect stakes in ecosystemservices is widespread and diverse—from large multina-tional companies to small local resource operators. Second,the MA scenarios address a large number and diversity ofecosystems and human well-being issues. The intersectionof these features implies that it is a major challenge to con-solidate the complex ecological data, analytical information,and modeling results in a succinct assessment for the privatesector. There are two principal ways this task could be ac-complished. The first is to focus on the specific interests ofa small and carefully selected set of stakeholders (loggingcompanies interested in timber, pharmaceutical firms pursu-ing genetic resources, and so on) and to prepare targetedassessments of the implications of different scenarios forthem. The second possibility is to consider the interests ofthe private sector as a whole in ecosystem services and thenderive general insights about the risks and opportunitiesemerging under different assumptions about the future. Thesecond option was taken in Chapter 14, which means thatthere remains a lot of unveiled information in Chapters8–12 that might be useful for the private sector and worthexploring.

In summary, the MA scenarios provide rich and usefulpictures of broad patterns of possible futures at the globalscale and at the level of world regions. However, it is im-possible to perform detailed quantitative analyses of localprocesses and impacts with the set of models adopted in thepresent endeavor. The qualitative scenarios and storylinesaddress many issues that the models cannot, providing amore rich and detailed investigation. One crucial improve-ment for the quantitative models in future assessmentswould be to soft-link sector- and region-specific models byusing the global scenario framework and outputs of globalmodels to drive them. A particularly useful feature of thecurrent effort is that scenarios provide information aboutsocioeconomic and technological development patterns,which is necessary for the assessment of the viability andeffectiveness of various instruments and response strategies.Such tools may be currently available or might becomeavailable in the future for different stakeholder groups toprotect their interests or fulfill their mandates in the con-texts of widely diverging but plausible futures.

13.4.3 Path-dependencies, Irreversibilities, andTheir Implications

Most complex systems display non-linear behavior in whichrelevant phenomena drastically change after certain thresh-

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old values are exceeded or where initially small but cumula-tive effects become ever more important as the systemevolves. They also display hysteresis (a history or path de-pendence of systems behavior, which in the case of complexsystems means that they do not return to their original stateeven when the influence of the driving forces that changedthem ceases), leading to important irreversibilities in theirbehavior. This is often referred to as path-dependency.Many systems are characterized by such irreversibilities;examples include technological change, global climatechange, and biodiversity loss. Often very similar initial con-ditions can lead to fundamentally different outcomes, andthese are usually very sensitive to the actual developmentpath taken. They can be characterized by emergent proper-ties that can evolve in fundamentally different ways alongalternative future development paths.

The MA scenarios are themselves examples of suchpath-dependencies. By the end of the twenty-first century,they have evolved and branched out into fundamentally dif-ferent futures that depend on a myriad of interveningchanges and decisions taken along the way. Some of thepath-dependent phenomena could undergo abrupt changesover the time frames considered in the MA scenarios.Climate-related abrupt changes could include loss of theGreenland ice sheet, shutdown of the North Atlantic Ther-mohaline Circulation, or the release of methane from per-mafrost or from deep sea clathrates deposits. In technology,abrupt and path-dependent changes could include rapiddeployment and improvement of renewable energy tech-nologies leading to low emissions futures, but also majorbreakthroughs in availability of fossil energy sources render-ing them practically inexhaustible (such as methane clath-rates as energy source). Similarly, overfishing could irreversiblydeplete stocks, while new fish farming methods with lowenvironmental impacts could allow for a recovery of now-endangered fish stocks. Finally, desertification could be-come irreversible beyond some critical levels of vegetationand soil loss.

Future anthropogenic climate change is characterizedboth by path-dependencies and numerous irreversibilities.Human activities have caused and will continue to causeclimate change. The main direct causes are the global emis-sions of greenhouse gases primarily due to energy and landuse changes. Emissions of particulate matter, aerosols, andmany other substances also affect current and future climatechange. For the wide range of IPCC emissions scenarios(Nakicenovic et al. 2000), Earth’s mean surface temperaturechange is projected to warm 1.4–5.8� Celsius by the end ofthe twenty-first century, with land areas warming morethan the oceans and the high latitudes warming more thanthe tropics (Cubasch et al. 2001). The associated sea levelrise is projected to be 9–88 centimeters.

The range of future mean surface temperature changesfor the MA scenarios is narrower, with 1.6–2� Celsius by2050 because of two important factors, namely that one sin-gle integrated assessment model and one climate modelwere used to estimate future climate changes. Six differentIAMs and different climate models were used by the IPCC,adding significantly to the range of uncertainties and widen-

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ing the range up to 5.8� Celsius. It is indeed possible thatthe full range of climate change for the MA scenarios wouldbe comparable if the scenario approach were extended to awider range of models and quantifications. An importantindication that this may be the case is that cumulative car-bon emissions across scenarios are comparable with theIPCC ranges. In other words, the climate implications arelikely to be underestimated through the approach taken bythe MA.

The seemingly small changes in temperature and sealevel rise across the scenarios mask the more fundamentalpath-dependencies. For example, the scenario with thehighest emissions by 2050, Global Orchestration, leads toalmost five times higher emissions than the scenario withthe lowest emissions, TechnoGarden. It is clear that reduc-ing Global Orchestration emissions fivefold would dramati-cally change the nature of the scenario, requiring massiveemissions mitigation measures and policies ranging fromradical technology change to modified human behavior. Inother words, greenhouse gas emissions (and many otherscenario characteristics) differ in their emerging properties,associated irreversibilities, and resulting development paths.

Despite this possible underestimation of the future cli-mate changes across MA scenarios (given the current uncer-tainties), the impacts on ecosystem services and humanwell-being will be significant and pose a major reason forconcern. For example, anthropogenic climate change willhave fundamental impacts on biodiversity. It affects individ-ual organisms, populations, species distributions, and eco-system composition and function both directly (throughincreases in temperature and change in precipitation, forinstance, and in the case of marine and coastal ecosystemsalso through changes in sea level and storm surges) and indi-rectly (through changing the intensity and frequency of dis-turbances such as wildfires, for example). Processes such ashabitat loss, modifications, and fragmentation and the intro-duction and spread of non-native species will affect the im-pacts of climate change.

The general effect of human-induced climate change isthat the habitats of many species will move poleward(toward higher latitudes) or upward (toward higher alti-tudes) from their current locations (Gitay et al. 2002). It isclear that such significant impacts on biodiversity by an-thropogenic climate change would also lead to significantadditional loss of ecosystem services beyond those thatoccur due to other pressures of human development onecosystems in MA scenarios.

Ecological systems can also be involved in abruptchanges both at small and large scales, usually acting in con-cert with physical and chemical components of the Earthsystem and frequently also due to the influence of humansystems. One of the best-known examples from the past ofsuch an abrupt change is the transition from a green to anarid Sahara in the mid-Holocene (Claussen et al. 1999; de-Menocal et al. 2000). About 6,000 years ago, the climate innorthern Africa was much more humid than today, sup-porting savanna vegetation throughout the region, with lit-tle or no desert. The change that occurred was both abruptand severe, leading to a complete desertification of much of

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this area—the formation of the present Sahara Desert. Theultimate trigger for the shift was a small change in the distri-bution of incoming solar radiation in the region due to asubtle change in Earth’s orbit (Steffen et al. 2004). Thischange by itself was not significant enough to drive the veg-etation shift but rather nudged the Earth system across athreshold that triggered a number of biophysical feedbacksthat led rapidly to a drying climate and then to an abruptchange in vegetation (Steffen et al. 2004). This episodedemonstrates the complexity of the dynamics that lie be-hind threshold-abrupt change behavior.

The behavior of the terrestrial carbon cycle is an aspectof Earth-system functioning that may experience abruptchange, particularly in the second half of this century, whichis over the time frame adopted in the MA scenarios. Atpresent, terrestrial ecosystems absorb about 25–30% of theCO2 emitted by human activities, thus providing a valuablefree ecosystem service that slows the rate of climate change.Simulations of the evolution of terrestrial carbon sinks from1850 to 2100 (Cramer et al. 2001) show the developmentof the current strong sink through the second half of thetwentieth century. The sink will continue to grow in sizethrough the first half of this century, according to these sim-ulations, but is likely to saturate around 2050, with no fur-ther increase. One simulation shows a rapid collapse of thesink through the second half of the century, with the terres-trial biosphere as a whole (Cox et al. 2000) perhaps evenbecoming a net source of CO2 to the atmosphere by 2100because of a much drier climate in Amazonia and a subse-quent loss of the remaining forests there (Steffen et al.2004). This again indicates the possible irreversibilities asso-ciated with high carbon emissions paths such as those ofOrder from Strength and to a lesser extent Global Orches-tration and Adapting Mosaic futures.

Marine ecosystems commonly show threshold-abruptchange behavior, sometimes called regime shifts. For exam-ple, there appear to have been dramatic and synchronouschanges to marine ecosystems in the North Pacific Oceanin the late 1970s. Such changes cannot be ascribed to localecological interactions only. They involve many differentbiological and environmental parameters (over 100 in thecase of the North Pacific), show coherence over large spatialscales, and are correlated to very large-scale external forc-ings, often teleconnections in the climate system. The 1977regime shift in the North Pacific, for example, is correlatedto a sharp increase in mean global surface temperature (Stef-fen et al. 2004).

Human impacts can also trigger abrupt changes in ma-rine ecosystems, particularly through overfishing and eutro-phication. Recent reports (Myers and Worm 2003) claimthat about 90% of the large predatory fish biomass has beenremoved from the world’s oceans, with removal rates beinghighest with the onset of post–World War II industrialfisheries. Given the importance of top-down controls onthe dynamics of marine ecosystems, there is the possibilitythat such overfishing could lead to regime shifts in marineecosystems, with reverberations through to lower trophiclevels such as zooplankton. On a smaller scale, overfishing

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is already known to cause sharp regime shifts in coastal eco-systems (Jackson et al. 2001).

Human-dominated waste loading on the coastal zonehas also led to abrupt changes (from an Earth system per-spective) in the functioning of marine ecosystems in theform of eutrophication. If the level of nutrient loading ishigh enough, significant changes can occur to the speciescomposition of the ecosystem, often leading to a simplifi-cation of ecosystem structure (domination by one or a fewspecies) (Gray et al. 2002). Severe eutrophication can leadto the formation of hypoxic (oxygen-depleted) zones, inwhich the dissolved oxygen concentration is below thatnecessary to sustain animal life (Rabalais 2002), usually re-sulting in drastic changes to ecosystem structure. The re-gion of the Gulf of Mexico near the mouth of theMississippi River and the Baltic Sea in northern Europe areregions where hypoxic zones commonly occur (Steffen etal. 2004). In certain cases, hypoxic zones such as those thatseasonally occur on the west Indian shelf release nitrogenoxide, a greenhouse gas (Naqvi et al. 2000).

It remains to be seen how overfishing and eutrophica-tion in concert will alter global biogeochemical cycles andthe resulting global inventories of carbon, nitrogen, phos-phorus, and silica. Despite the seemingly large capacity ofmarine ecosystems to assimilate the impacts of waste loadingand overfishing, the imminent collapse of many coastal eco-systems is a warning that human and systemic global pres-sures may act synergistically to trigger large-scale regimeshifts in global marine ecosystems (Steffen et al. 2004). Theloss of such ecosystem services and their possible adverseimpacts on human well-being cannot be treated adequatelyin the current IAM approaches. The MA has made a sig-nificant contribution by linking a fisheries model to itsIAM. This is an important area and direction for future im-provements in our capacity to model complex global sys-tems and their future development paths.

Critical thresholds and irreversible changes are probablyhidden in the largely unexplored domain of interactionsamong climate and environmental change, socioeconomicdevelopment, and human and animal health. Scenarios re-main the main tool for gaining a better understanding ofthese critical interactions and numerous feedbacks. Humanactivities have already become a geophysical and biogeo-chemical force that rivals natural processes, and this is likelyto increase, but to differing degrees, across all four MA sce-narios. This implies that major discontinuities in the socio-economic domain may lead to corresponding disruptions inthe biogeochemical/physical and ecosystem domains—thatis, that abrupt changes can be expected in the coupledhuman-environment system. Thus abrupt changes in socio-economic systems could attenuate or amplify changes oc-curring in other aspects of the coupled system (Steffen et al.2004).

Abrupt changes in coupled socioeconomic and naturalsystems have occurred in the past. The archeological andpaleoecological records indicate that major shifts in societalconditions in the past often appear to have been linked withabrupt changes in the biophysical environment (Alverson etal. 2003), including, perhaps, the collapse of the Classic Pe-

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riod and lowland Maya civilization and various ‘‘pulses’’ ofMongul expansion from Mongolia, which had significantconsequences for Imperial China and eastern Europe (Stef-fen et al. 2004).

One of the most important potential discontinuities isthe spread of a new disease vector, resulting in a pandemic.High population densities in close contact with animal res-ervoirs of infectious disease facilitate rapid exchange of ge-netic material, and the resulting infectious agents can spreadquickly, with few barriers to transmission through a world-wide contiguous, highly mobile human population. The al-most instantaneous outbreak of SARS in different parts ofthe world is an example of such potential, although rapidand effective action contained its spread. Warmer and wet-ter conditions as a result of climate change may also facilitatethe spread of diseases such as malaria. Malnutrition, poverty,and inadequate public health systems in many developingcountries provide large immune-compromised populationswith few immunological and institutional defenses againstthe spread of an aggressive infectious disease. An event simi-lar to the 1918 Spanish Flu pandemic, which is thought tohave killed 20–40 million people worldwide, could nowresult in over 100 million deaths within a single year. Sucha catastrophic event, the possibility of which is being seri-ously considered by the epidemiological community, wouldprobably lead to severe economic disruption and possiblyeven rapid collapse in a world economy dependent on fastglobal exchange of goods and services (Steffen et al. 2004).

Another important area of emergent properties and apossible source of abrupt and irreversible changes is the in-teraction of technological change and the natural environ-ment, including ecosystems. An obvious case is the currentadvances in bioengineering that can affect and interact withnatural ecosystems. The possible interactions include ad-verse and irreversible impacts on regional ecosystems. His-torical examples are many, including the introduction ofnew species into foreign environments leading to dramaticecosystem changes and shifts. The other possibility is pro-duction of resistant and better-adapted species to overcomesome future challenges. MA scenarios explore many but notall possibilities that might emerge during the twenty-firstcentury as the result of technological changes that may ei-ther directly affect ecosystem services or indirectly affectboth ecosystem services and human well-being.

A century is ample time for pervasive diffusion of funda-mentally new technologies and systems. In fact, whole newtechnoeconomic paradigms have emerged in the past oversimilar time scales—from the emergence of the coal, steam,steel, and telegraph eras to the ages of oil, gas, internal com-bustion, gas turbines, petrochemicals, pharmaceuticals, massproduction, and so on. Also in the future, new technologiescould lead to new combinations of technologies and humanactivities. Today, the possible convergence of nano-,cogno-, bioengineering, and information technologies isseen as a possible way of enhancing human performance,modifying organisms into components of larger technoeco-nomic systems, and directly interacting with many micro-and nano-scale systems of both inanimate and biologicalorigin.

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All four MA scenarios consider further economic devel-opment in the world despite increases in human population.Much of the increased human productivity would stemfrom ecosystem services, some of which might indeed beenhanced by convergence of advanced technologies intonew paradigms during the twenty-first century. At the sametime, many of these future technological possibilities maybring with them unanticipated effects—some that mightthreaten human well-being and ecosystems and some thatmight enhance them and reduce human interference withnatural systems. MA scenario storylines tackle many of thesecomplex issues. However, dramatic effects of such techno-logical developments were not pursued in scenario quanti-fications, presumably partly because models used in the MAwere not designed for the assessment of technologicalchanges and technology diffusion. Technology might in-deed prove to be one of the most fundamental drivers offuture human development and ecosystem services.

The question of how robust an increasingly interlinked,globalized world economy is must be addressed urgently(Steffen et al. 2004). There will almost surely be significantincreases in need in the future for the provisioning of natu-ral resources and ecosystem services. And despite techno-logical advances, meeting these needs will have impacts onthe Earth system and especially on many already-threatenedecosystems. There is a high probability that droughts,floods, and severe storms will occur more frequently, andan increasing probability that the more drastic, abruptchanges of the type described earlier could also occur.Coping with such stresses would take an increasing share ofeconomic activity away from the evolution and growth ofthe economy in general (Steffen et al. 2004). How manysuch stresses, occurring when and where, would it take forthe global economic system to begin a downward, self-reinforcing spiral that would lead to a rapid collapse? Shouldsuch a collapse occur, it could lead to a significant and prob-ably long-lasting change in the fundamental human-ecosystemrelationship.

13.5 Information Gaps and Research NeedsThis section describes the research needed to improve thedevelopment of global scenarios in the future. It includesboth research needed in the formal sense as well as im-provements that could be made in methodology and in themanner in which the scientific community operates.

13.5.1 Global Storyline Development

Determining the nature of the MA global storylines bychoosing the key drivers that would vary across scenariosand those drivers that would follow the same trend in allscenarios was a long and sometimes difficult process. Thiswas partly the result of divergent views on the use of scenar-ios, and partly the result of divergent disciplinary ap-proaches to science. Here, we describe some research andchanges in research methods that could improve the devel-opment of global storylines in the future.• Development of regional and local scenarios linked to

the global scenarios would help create better global sce-

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narios. Regional and local scenarios can use more accu-rate local information and might represent some systemdynamics more accurately. They can also pinpoint spe-cific variables of interest. Expanding methodologies forlinking scenarios developed at different geographicalscales or nesting them within one another to foster theexchange of information across scales will be an impor-tant step to help improve scenario development methods.

• Better communication and interaction with policy-makers would help inform the development of thestorylines by indicating the key variables that are of in-terest to decision-makers. Improved communicationwith policy-makers would be useful both for under-standing policy-makers’ most pressing questions and forcommunicating results to them at the end of the process.Having a greater presence of policy- and decision-makerswithin the working group may be one way to improvethis communication.

• Better communication and interaction across scientificdisciplines would help facilitate future global scenariodevelopment projects. During the MA scenario devel-opment process, it turned out that the differences amongdisciplines’ core beliefs about how the world functionswere also often the critical issues that policy-makerswanted to have addressed in the scenarios. (See a moredetailed discussion in Chapter 5.) However, it took ourworking group several meetings to come to a full under-standing of the differences of core beliefs among disci-plines. Better interdisciplinary communication prior toinitiation of this project might have made this processeasier.

13.5.2 Modeling Complex Systems

The response of complex systems to environmental changeis assessed using models that are based on multiple drivingvariables, along with their interactions. Models currentlycan provide part but not all of the information needed forscenarios of ecosystem services. For example, temperaturetrends at the broad scale can be assessed relatively wellthrough current climate models, whereas rainfall patternscannot. Nevertheless, rainfall is important for many ecosys-tem services in many regions, often more important thantemperature. The assessment therefore is incomplete andcan be improved once more-reliable rainfall simulations aremade or the uncertainty range of rainfall simulations areconsidered explicitly (which was not possible within theMA models).

While the assessment models can provide useful infor-mation to scenarios, their coverage of the Earth system isincomplete, and their description of essential ecosystemfunctioning is better for some processes than others. Cli-mate and carbon cycle impacts are relatively well under-stood while even the most basic nutrient cycles are lessreliable in current models.

With regard to analyzing ecosystem services, the currentmodels have a critical deficiency in that they are not able tosimulate the important feedbacks—the changes, often small,

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in ecosystems, that feed back and affect social systems,sometimes in large ways—that were described in the MAstorylines. Therefore, the qualitative assessments by thestorylines of some of these feedbacks loops became an im-portant means to describe likely changes under the four MAscenarios.

The models are also incomplete in the sense that weneed to better understand the interactions among variablesacross models. For example, we urgently need better mod-els that link likely changes in such things as land cover tolikely changes in essential ecosystem processes, includingnutrient cycles, primary production, energy flow, and keycommunity dynamics, as well as the relationship of thesechanges to ecosystem services. One of the important weak-nesses of our current understanding is the lack of data forbroad-scale (long-term and large-scale) ecological dynam-ics. Improved models and approaches are required to betterunderstand ecosystems and their interaction with humansystems, but such more-advanced models will still not leadto a complete and full integration and may never lead tofull understanding of the complex interactions. The bettermodels based on broad-scale dynamics would enhance ourunderstanding of the ecosystem patterns and ecosystemprocesses. The benefits and requirements for these im-proved models and approaches are as follows:• Better models for the relationship between ecosystem

change and provision of ecosystem services wouldgreatly improve quantification of the scenarios. Even incases where we can develop decent models of the eco-system, it is extremely difficult to predict the end resultfor provision of ecosystem services.

• Much better models for the relationship between eco-system services and human well-being are desirable. Incases where we were able to model changes in ecosys-tem services (only provisioning and regulating services),we were rarely able to estimate the impact on humanwell-being. Most of the quantifiable indicators of humanwell-being related to population and demographics. Itproved much more difficult to estimate spiritual well-being, recreation opportunities, or even impacts onhuman health.

• Models currently estimate only provisioning and regu-lating services. As pointed out in Chapter 12, this alignsperfectly with our understanding that provisioning andregulating services are often given greater priority thancultural and supporting services in management deci-sions. Certainly not by accident, the models focus on theecosystem services that are perceived by society as moreimportant (driving research agendas and funding); theygive less attention to cultural and supporting services.There are two consequences of this bias.First, cultural and supporting services are left out of the

quantitative modeling exercise altogether: changes in theseservices simply are not quantified. This has critical implica-tions. Supporting services are necessary for the productionof all other ecosystem services, yet we cannot quantify howthey may change in the future. If supporting services aredeclining, we may face severe and possibly sudden loss ofprovisioning and regulating services in the future.

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Second, the fact that models are able to only explore asmall subset of ecosystem services (even within provisioningand supporting services) means that a smaller set of potentialtrade-offs can be quantified. Thus, even if the models wereable to perfectly characterize all the trade-offs among theecosystem services that they considered, this would plainlyunderestimate the consequences of any societal choice, asmany other trade-offs would remain unquantified. Theconsequence is that model results, at best, represent a crudelower bound of the expected consequences of any specificscenario.• Improvements in modeling interactions among drivers

or services would improve the quantification of scenar-ios. For example, it was very difficult to model howchanges in agricultural production interacted withchanges in water quality.

• Developments are needed to improve comparison of re-sults across different models. Because the models weused calculated different variables or used different re-gion boundaries, many variables were not comparable.Even in cases where two models calculated, say, landcover change, we could not always easily compare theresults across models to ensure that our models were giv-ing similar results. Comparison across models was evenmore difficult in the cases where the models were calcu-lating different variables.

• There is a great deal of research needed on focused sci-entific topics. This is covered in Chapter 4.

13.5.3 Harmonizing Models and Storylines forUnderstanding Complex Systems

A major challenge for future scenario exercises will be toimprove the level of harmonization between storylines andquantifications of the scenario. This involves three maintasks.

First, adequate time has to be given between the devel-opment of storylines, deriving model inputs from the story-lines, running the models, interpreting model output, andrevising the storylines. Perhaps two or three full iterations ofthis cycle are required to achieve a high level of consistencybetween the storylines and model calculations. Iterations arealso required for achieving convergence among varioussubcomponents of the scenarios in addition to facilitatingscenario consistency.

Second, the models need to be able to incorporate someof the important factors in the storylines, such as cross-scalefeedbacks, thresholds, and small-scale changes. We knowthat these types of changes, which the models cannot fullyaddress, are important determinants of the future. If themodels are not able to address these factors, they will nevermatch the richness or plausibility of the storylines in devel-oping pathways to the future.

Third, it is important to make the conversion of infor-mation between the storylines and models more transparentand less arbitrary. Currently, information from the storylineis used to prescribe model inputs in an ad hoc (althoughconsistent) fashion. For example, general statements abouttechnological progress in the storylines were used to specify

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important input parameters to the modeling exercise, suchas the rate of change of crop yield and the rate of improve-ment of domestic water use efficiency. Likewise, resultsfrom the modeling exercise (such as estimates of land use orcover change) are used ad hoc to modify or enhance thequalitative statements of the storylines. Rather than performthis conversion ad hoc, systems analysis techniques shouldbe used to make the conversion more transparent and scien-tifically rigorous. For example, future exercises should con-sider the usage of fuzzy sets or agent-based approaches toconvert from the linguistic statements of the storylines tothe numerical information needed for model inputs, andfrom numerical model outputs to linguistic statements. Var-ious techniques of qualitative modeling may also be usefulfor this conversion of information.

13.5.4 Research on Vulnerability

Further research on ecosystems and human well-being isneeded. At the moment, scientific models for assessingthresholds of vulnerability in ecosystems are very few andnot sufficiently developed (Peterson et al. 2003). Similarly,possible ways these thresholds will affect human well-beingcould be better understood. Research on thresholds isneeded to more fully understand socioecological resilienceand human well-being.

While we can sometimes quantify the trajectory of pro-vision of a given ecosystem service, we cannot always deter-mine whether the trajectory will continue the same way orwhether it will change radically upon crossing some un-known threshold. Yet these threshold changes are often themost important changes in ecosystem services to under-stand. Research about thresholds and socioecological resil-ience would greatly improve our understanding of how toquantify and anticipate thresholds in management. A keyissue here though is whether we have enough informationto assess the thresholds or the vulnerability of ecosystemsand human well-being to extreme events (ecological andsocioeconomic surprises). Integrated assessments can be oneof the main tools used to understand the resilience (buffer)of ecosystems and human well-being.

13.6 ConclusionsThe MA scenarios have broadened global scenario exercisesin their scope and methodology. By including and focusingon the many services that ecosystems provide to sustain an-thropogenic systems, the MA scenarios explore the mani-fold linkages that exist between ecological and humansystems. Previous scenario exercises have focused on someof the links between specific driving forces of environmen-tal change and their impacts. For example, the IPCC ex-plored connections among energy and land use and climatechange. However, previous scenarios have not includedecological dynamics in their storylines or analysis and havenot attempted to understand the effects of change on a suiteof ecosystem services and human well-being. The MA sce-narios expand the reach of analysis by including multipleecosystem services and by linking environmental changes totheir impacts on human well-being.

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In addition, the MA scenarios contribute to the method-ology of scenario analysis in various ways. They advancethe role of qualitative and quantitative information andhighlight the advantages of combining the two in the sce-nario development process. The scenarios also demonstratethe importance of integration across various disciplines toderive internally consistent, detailed pictures of the future.They also stress the significance of including various stake-holder perspectives in the scenario development process, sothat the scenarios focus on questions about the future thatare relevant for their potential users. Furthermore, the sce-narios reveal the imminent path-dependencies and irrevers-ibilities of plausible development pathways, which helpshighlight the implications of decisions taken today.

With this analysis, the MA scenarios provide importantinsights for various stakeholder groups, such as the U.N.conventions, national governments, NGOs, local commu-nities, and the private sector. Each group can derive impli-cations from the set of scenarios in order to develop robuststrategies for their policy decisions.

The MA scenario analysis can be improved in futurescenario projects for ecosystem services. Modeling complexsocioecological systems with their interactions and feedbackloops remains a key challenge. Providing information notjust on services with the highest immediate priority formany people and organizations (provisioning and regulatingservices) but also on supporting and cultural ecosystem ser-vices will enhance the level of analysis for decision-making.Furthermore, linking global models to models that operateat smaller geographical scales can enhance the consistencyand quality of the derived information.

The qualitative analysis of ecological feedback loops,thresholds, risks, and vulnerabilities as part of scenario de-velopment can provide important insights that existingglobal ecological change models have so far not been able tocapture. Global modeling and integrated assessment efforts,though, can provide important consistency checks of as-sumptions on key driving forces and their interactions. En-hancing the methodology for combining quantitative andqualitative analysis in the future will greatly improve ourability to deal with the complexities that lie ahead of us.

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