A Plot for Sustainability – The Sustainable Development Goals as A Narrative

The Sustainable Development Goals, while complex at first sight, express a simple narrative about the relationships between people and nature. This paper illustrates this in the context of a coral reef land or seascape supporting coastal people. Coral reefs, their health described by measures of coral and fish diversity and abundance, provide key services and benefits to people. These services directly support 10s of millions of jobs in multiple economic sectors in coastal and distant states, protect and harbor communities and cities across tropical coastlines, sustain use of living and nonliving resources, provide transport infrastructure and valuable natural products, and in future may provide energy solutions. Through these multiple benefits, coral reefs contribute to reducing hunger and poverty, thus improving health, and potentially strengthening gender and social equality. However, access and use result in pressures that may drive decline in coral reef health. Broader land and seascape factors also affect reef health and therefore delivery of benefits, including land-use change and altered freshwater flows, as well as climate change. Managing this complex system requires appropriate awareness and knowledge, governance mechanisms and investments by stakeholders. This ‘SDG narrative’ can be used from local to global levels, motivating actions and policy at and across these scales to sustain ecosystem function and use, for the oceans what is also increasingly called a blue economy.


Introduction
In recent years, 'blue economy' and sustainable development concepts have become core elements in national and international discussions and planning for development.The Sustainable Development Goals (SDGs) (fig. 1) identify priority goals selected by countries in the United Nations General Assembly in ratifying Agenda 2030, 'the future we want', in September 2017 [1].Due in 2030, they express global aspirations for a prosperous, equitable and sustainable future, based on an inclusive, 'soft', goal-setting, non-binding model [2].To make them more tangible, they have been elaborated into 169 targets, each of which may be assessed through 1 or more indicators [3].This complexity is daunting, particularly as success means achieving them all as an indivisible whole, not focusing exclusively on just one or a select few.Thus, since their ratification in 2017, countries and sub-national stakeholders and entities have been struggling to work out how to implement them successfully, and measure progress credibly [4].
The term 'blue economy' is analogous to the concepts of 'green economy' and 'sustainable development', focused on economic value generated from ocean (and freshwater) systems.Principles for a blue economy are widely accepted [5,6,7], though precise definitions of the blue economy have been very varied [6,8].The term 'ocean economy' is sometimes used synonymously, though this may often not include aspects of sustainability, with a focus on maritime transport, energy and other sectors that don't have a dependence on ecosystems and their productivity.Importantly, as for sustainable development, blue economy addresses the triple-bottom-line of achieving economic, social and environmental benefits simultaneously.In this sense, blue economy may be viewed as "the SDGs from an ocean perspective" and could be expressed as "rather than a focus on SDG14 (the ocean) itself, what do the other 16 goals look like through the lens of the ocean?".Reconciling the holistic nature of the SDGs within the confines of the current economic paradigm focused on Gross Domestic Product [9], based on monetary valuation and growth, is challenging, though valuation is a critical tool for assessing balance and interactions among multiple sectors.Monetary valuation focuses on tangible goods and/or human-derived services, and deals poorly with nature and complex social interactions.Blue economy and sustainable development concepts internalize limits to growth, where mainstream economic thinking seeks to maximize growth in value (wealth).The disconnect between the mainstream economic model and nature's limits are plain to see in coral reefs, in their widespread degradation near large and growing population centers [10], rapidly depleting coral reef fisheries worldwide [11], expanding dead zones and sedimentation from rivers and runoff that kill reefs [12], and climate warming that has induced 3 global bleaching events and mass coral mortalities between 1998 and 2017 [13].All of these multiple and interacting threats, from local to global scales, driven by population and economic growth combined, have resulted in the loss of 50% of coral reefs worldwide [14] and future projections of ocean warming all but assure reefs decline to < 1% of their original range unless massive transformations in global governance for sustainability are implemented [15].This fate is not unique to coral reefs, and other natural systems are projected to collapse with further climate change [15,16].There is growing consensus, expressed from local to global levels, that economic growth must be brought within the biophysical constraints of nature -for example in relation to pollution, exceedance of planetary boundaries, climate change, and other indicators of extreme and potentially irreversible impacts to nature [9,16].But the comprehensive nature of the SDGs [2] and the limitations of economic models to value nature-based and intangible benefits [17] impede progress.
Coral reefs are useful model for this analysis as they are a flagship ecosystem, recognized both for their great tangible and intangible values to people [18,19], as well as for their beauty, both resulting from their incomparable biodiversity and productivity.A microcosm of ocean systems and vulnerability, coral reefs illustrate the fate of other ecosystems in the ocean, as well as those on land.Their role as a canary for not just climate change, but human-nature interactions is at the forefront of international discourse, being highlighted in all major global assessments in recent years including the 5 th Assessment Report of 2014 [20], '1.5 C report' [15] and oceans and cryosphere [21] reports of the Intergovernmental Panel on Climate Change (IPCC), and the global assessment of the Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services (IPBES) [14].

Method
This paper transposes the aspirations expressed by the SDGs onto a model of ecosystem service provision and human use of a reef (Fig. 2a).It expresses our knowledge about ecological function, how this affects service provision and benefits received by people (both monetary and non-monetary), how these affect broader aspects of societal welfare, and the effects of people and service-use on nature and its ability to provide the services.I use coral reefs as the model system, and how they are embedded in a populated land-or seascape, whether rural or urban, developing or developed.The model is based on explicit and tangible interactions (e.g.extraction of fish) that can be measured to assess the sustainability of human-nature interactions, balance and reconcile monetary and other metrics that address the core dynamics of the system, and provide explicit guidance for decision-making.The model is applied at the level of a coral reef land-or sea-scape, addressing where the ecosystem and its broader spatial and temporal dimensions produce services used by people through varied economic sectors.The interactions and links in this model are well-supported by the literature through varied ecosystem [22,23] and human dimensions models [24].The IPBES conceptual framework [25,26] provides a foundation for this model, focused on the flows between nature and people, mediated through 'contributions from nature to people'.
The model also builds on recent work focused on interactions, at the level of goals and targets [27,28,29].But borrowing from the blue economy approach [6], rather than focusing on interactions with goal 14 and its targets, this model "looks through goal 14 as a window to the other 16 goals".This enables the holistic and indivisible nature of the SDGs to explicitly frame the resulting narrative, providing the big picture or birds eye view.Twinning this with the ecosystem-use model (Fig. 2a) forges a mechanistic focus that goes a level deeper than the goals and targets to specific variables and indicators, enabling quantification of these relationships.

Results
The model takes the form of a set of assertions (Box 1, Fig. 2b), in 140 words establishing the relationships among all 17 SDGs for an exploited coral reef.Looking through goal 14 towards the other 16 goals, the model provides a narrative, or storyline, for expressing the interactions and balance between nature and people.The narrative is simple and compelling, addressing the problem statement and gap identified for this paper, which is in resolving the complexity of the SDG model for practical application and measurement at multiple scales.
Box 1 -Coral reef SDG narrative.Goal numbers are cited between curly brackets {}.


Coral reefs {G14}, their health described by measures of coral and fish diversity and abundance, provide key services and benefits to people. These services directly support 10s of millions of jobs in multiple economic sectors {G8} in coastal and distant states, protect and harbor communities and cities {G11} across tropical coastlines, sustain use of living and non-living resources{G12}, provide transport infrastructure and valuable natural products {G9}, and in future may provide energy solutions {G7}. Through these multiple benefits, coral reefs contribute to reducing hunger {G2} and poverty {G1}, thus improving health {G3}, and potentially strengthening gender {G5} and social equality {G10}. However, access and use result in pressures that may drive decline in coral reef health.Broader land and seascape factors also affect reef health, including land-use change {G15} and altered freshwater flows {G6}, as well as climate change {G13}. Managing this complex system requires appropriate awareness and knowledge {G4}, governance mechanisms {G16} and investments by stakeholders {G17}.From this simple narrative the model can be built up with greater rigour around each goal (model component) and its interactions with others (Fig. 2b, Table 1), by defining the relationships and linkages more explicitly using the relevant scientific disciplines and their literature.

Discussion
A simple narrative model accessible for public and policy discourse is linked to a scientific evidence-based framework that supports monitoring and management of this complex socialecological system [30], on a firm foundation of sustainable development [27,31] and blue economy [5,6].The value of this 'coral reef SDG model' is in its simplicity -expressing how and why natural assets are fundamental to multiple aspects of human economy and society, and to help express how blue economy and sustainable development intersect.Two main benefits of this model are: Expressing common values [2] -first, having been endorsed by countries in the United Nations, the SDGs express the highest level of 'societal value' common to all countries and cultures across the planet.The 17 goals correspond broadly to the three pillars of sustainable development -environment, economy and society -as well as to governance and means of implementation (e.g.goals 16,17) and pressures on the environment (e.g.goals 6, 13) that economy and society impose.
What you measure is what you manage [3,32] -second, the goals can be deconstructed (here in the context of a coral reef) into specific elements (e.g.fish, income or health), which are quantifiable through metrics and indicators.Taken together, the targets and indicators across multiple goals help quantify what is meant by 'sustainability', as to meet sustainability criteria each metric will need to fall within certain ranges.Thus overall sustainability would not be achieved if any one or set of indicators do not meet their criteria.The model makes the relationships between ecological, economic and social compartments explicit, as well as identifying whether interactions are causal or correlative.Thus monitoring of these compartments and relationships provides the data necessary for informing management as well as assessing its effectiveness.
Each of these, the 'global' and the 'local', are expanded on further below.

The local context
Developing an SDG narrative at local levels for individual value chains helps elucidate the complex interactions and change factors that need to be considered in management of coral reefs at a local level.Two case studies illustrate this, for fisheries and coastal protection, following the structure identified by the model (fig.3, Table 2).
In both examples core relationships are relatively simple and direct, and each set of relationships can be measured by variables and indicators now relatively well established in natural and social sciences, and in relevant engineering and technology sectors.For example, interaction between the reef resource and fishers can be quantified by fish catch and/or income earned, or social dynamics may be illustrated through gender disaggregation of primary indicators such as fish catch or income earned.Indirect and secondary benefits (increasingly termed co-benefits [14,21,27]), the effect of social and enabling factors on coral reef health, and aspects of access to, utilization and management of the system, may be quite complex.These interactions may vary greatly from one location to another depending on local ecosystem dynamics, cultures and governance systems, and depending on the spatial scale at which the model is applied.Nevertheless, the common language of the model enables consistency among applications, as well as differentiation of the model to suit local contexts.The behavior and key thresholds for each variable may be identified empirically, or derived from the relevant literature, so the performance of each interaction can be assessed.For a holistic overview, aggregation can be done to varied levels, through multi-dimensional metrics.
Historically there has been greater investment in biophysical over socio-economic monitoring (e.g. for coral reefs [33,34], in large part due to greater complexity and variation in human dimensions over natural ones [35].Efforts to redress this have been varied, such as the SocMon programme of the Global Coral Reef Monitoring Network [36], and capacities for monitoring, data management and integration are improving to the point of making 'integrated monitoring' a reality [34,38].The SDG model supports these efforts, not only helping to identify key components of the model and variables defining their interactions that monitoring programmes should measure, but also providing a bridge to societal benefit priorities motivating large scale aggregation [35,38].The model may also facilitate integration of values and data from multiple knowledge systems and perspectives on nature [39,40], by enabling different stakeholder groups to populate the narrative model and linked mechanistic model (Fig. 2) with elements and measures important to their knowledge systems.S1).

The national and international context
Within countries, economic sectors have tended to develop in isolation, with little integration of metrics and data among them.Not only may different sectors use different methods and protocols for monitoring, they may use different variables for the same quantities.This hampers the development of multi-sectoral or integrated approaches.Thus, establishing a monitoring and evaluation framework for the SDGs is challenging.The indicator framework developed thus far [3], though ambitious, is hampered by this lack of integration, and in the absence of tangible common metrics has focused on process indicators (e.g.area covered by ecosystem based management measures for 14.2) rather than state variables (e.g. of ecosystem health measures, such as coral cover) [32].Coral reefs create physical structure {G14} that provide a wave barrier protecting the shoreline.

Direct benefits
Direct benefits are mediated through fish catch {G12}, supporting jobs, income and value chains {G8}.
This enables the development of settlements {G11} and economic activity {G8} on the shoreline, and natural waterways {G9} for navigation.

Cobenefits
These contribute directly to reducing poverty {G1}, and an increased or stable food supply {G2}.These directly (protein and nutrients)

Means of implementation
Fisheries need to be managed {G16}, require investment and participation by relevant actors {G17}, and are affected by general awareness and understanding among fishers and consumers, as well as managers and scientists {G4}.
Coastal development requires appropriate governance {G16} and public compliance affecting land-sea interactions {G11} and investment {G17}, and affects resource extraction {G12}.SDG indicator framework identifies indicators at three levels of indicator maturity, from low (Tier 3) to operational (Tier 1) [3], paralleling the 'readiness' framework of essential ocean variables [34,41], providing practical steps guiding how these indicators can be matured and made more ready for use.However, many of the proposed SDG indicators are not relevant to local contexts, or cannot readily be equated with more tangible/local indicators (Table S1).The model proposed here facilitates the identification of locally relevant and 'real' indicators (e.g.coral reefs managed and in healthy state, as shown by coral, fish and other indicators) that could be aggregated through higher level proxies (e.g.proportion of coral reef area under ecosystem-based management, for Target 14.2) to populate the official SDG indicators framework that countries must use to report on the SDGs [42].
A similar challenge is evident from experience with the 2011-2020 Strategic Plan for Biodiversity of the Convention on Biological Diversity (CBD).This plan was concretized through 20 targets (the Aichi Biodiversity Targets), and there has been mixed success in reaching them.Those closest to being achieved [43] are primarily process-oriented (e.g.Target 2.1 -'Biodiversity values integrated into national and local development and poverty reduction strategies').Those farthest from being achieved, or even suffering regression (e.g.Target 10.1 -'multiple anthropogenic pressures on coral reefs are minimized, so as to maintain their integrity and functioning') refer to actual drivers of decline but without any mechanism or mandate for the CBD to address them directly.This weakness has led to a call for a more comprehensive framework for the post-2020 CBD targets, though it is currently not yet clear what form such a framework may take [44].This model provides a solution, specifying how targets for the status of nature, which are the focus of objective 1 of the convention (on nature conservation), integrate with the other goals that relate to objectives 2 and 3 of the convention, on sustainable use and benefit sharing, as well as to means of implementation.This model will also explicitly assist alignment of the post-2020 CBD framework with the SDGs and their joint application from 2021 to 2030.A proposed pyramid framework tabled at the first meeting of the Open Ended Working Group of the CBD held from 27-30 August 2019 in Nairobi, Kenya (Fig. 4), provides a relevant framework to superimpose the groups of goals relating to a potential apex target on biodiversity, direct and indirect/co-benefits, and means of implementation.).This is superimposed with the SDG goal components of the coral reef SDG model, comprising the apex target (here focused on a coral reef), and the focus area of each goal of the CBD, on conservation (biodiversity goals), sustainable use (direct benefits), access and benefit sharing (indirect benefits) and means of implementation.Further elucidation of both the coral reef model and the proposed pyramid framework may result in a final 'integrated target framework' that is being sought for the post-2020 CBD framework aligned with the Sustainable Development Goals.
Formal implementation of the SDGs has to use the specified targets and indicators [3].This model provides an informal framework for 'soft' implementation and assessment of sustainability, where context-specific indicators and targets can be identified that meet the local context, yet make it clear the spirit of the SDGs is being followed (Table S1).This enables different stakeholders to document and assess how well their actions support (or not) implementation of the SDGs.These 'soft' metrics may be particularly useful to assess Voluntary Commitments [45], which vary greatly in nature, and for nongovernment partners, for whom the SDG headline indicators may not be relevant.This model may also be useful at sub-national levels, or adapted across different ecological systems, for example mangrove, seagrass and nearshore pelagic systems, or even terrestrial ones.It may help countries to aggregate from local to higher levels, then translate the results into the high level indicators contained in the formal indicator framework for national SDG reporting [3].

Conclusion
A model helps to make key relationships explicit, which is particularly useful in a complex context such as the nature-society domain of the Sustainable Development Goals.This model deconstructs the nature-society interactions in the 17 domains of the goals, by identifying key interactions within and across them, and thereby metrics that quantify them.This enables target-setting based on knowledge of these interactions and their inherent thresholds or limits, and the design of targeted monitoring to inform management and governance of the system.With nature as the entry point (a particular coral reef ecosystem service) the approach is equivalent to 'ecosystem-based management' [46] or in the specific case of fisheries, the 'ecosystem-approach to fisheries' [47].This paper has focused on coral reefs as a model system, but can be applied in any land-or seascape.Equally, the model may be constructed from the perspective of any of the 17 goals, for example health (goal 3) -in which case it A plot for sustainability -the Sustainable Development Goals as a narrative.Obura David O. v.2. may express a 'health-approach to the SDGs', or may even be applied to focus on a narrower challenge, such as a 'health-approach to fisheries' [48].
So long as the model is applied in a way that meets the vision of stakeholders in each goal, it enables a consistent approach across wide domains of economic and social sectors.The SDGs can therefore be used not just as a static framework, or just to look at interactions among goals [28], but as a way to view all goals from the perspective of any interest holder, and thereby develop fully integrated approaches to development that are coherent and complementary with one another.Viewed through SDG14 (i.e. an oceans perspective) the model provides a tangible way to forge equivalence between 'blue economy' and the SDGs [6].It also identifies specific requirements for monitoring, how science and knowledge can be used, and helps identify gaps [34,49].Among countries, where formal joint management may be impossible, commitment to the SDGs and application of a common model [2] could help assure alignment and mutually supportive actions [50,51].In regions with many countries this may also be helpful, enabling collective action without requiring over-complex multi-country agreements.
Table 1.The 17 Sustainable Development Goals (SDGs) interpreted for their dependence and effects on coral reefs, within a coral reef land-or seascape.The goals are interpreted for the strength and direction of their interactions.

Figure 2 .
Figure 2. a) Functional model of coral reef and societal interactions, extending from the spatial and temporal aspects of the seascape at bottom, through species and their ecological interactions (i.e.biodiversity) to resource and ecosystem provision to multiple economic and societal sectors (BMU -Beach Management Units), with overarching governance regimes reflecting values and principles held by the societal actors.b) Schematic of the 'coral reef-SDG model', showing the approximate correspondence with the functional model in (a), starting at the base with the coral reef as a natural asset, and moving upwards through the stages in the narrative model in Box 1, grouped as enabling factors, direct benefits, indirect benefits, and finally the means of implementation for the SDGs.

Figure 3 .
Figure 3.The coral reef SDG model parametrized for two examples of benefit flows: a) fisheries and b) coastal development.The number of each goal is given, with a suggested local indicator (and see TableS1).

Table 2 .
Coral reef SDG narrative adapted to fisheries and coastal development, corresponding to figure3.