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Economic valuation for policy support in the context of ecosystem-based adaptation to climate change: An indicator, integrated based approach

Ecosystem-based adaptation (EbA) includes a set of natural capital-based measures to adapt to climate change. UN Environment has called for measuring EbA costs and benefits before promoting the adoption of such a policy. Within such policy input, the paper objective is twofold. It first performs a critical survey of economic and valuation studies that measure the costs and benefits of undertaking EBA measures. It then proposes an integrated valuation approach, based on a set of 54 economic indicators that include ecological aspects and encompass the technical, financial and academic difficulties to perform thorough cost-benefit exercises, by providing policymakers with simple, though rigorous evidence.


Introduction
Ecosystem based adaptation (EbA) "uses biodiversity and ecosystem services as part of an overall adaptation strategy to help people and communities adapt to the negative effects of climate change at local, national, regional and global levels" (UNEP, 2012). Fundamentally, "EbA is the use of natural capital by people to adapt to climate change impacts, which can also have multiple co-benefits for mitigation, protection of livelihoods and poverty alleviation" (Munang et al., 2013c). EbA options increase the resilience and capacity of selected ecosystems to naturally adapt to changes, including climate induced changes, over time. Effective EbA is where ecosystem-based approaches replace or augment conventional adaptation approaches to deliver superior outcomes for people and the community. The overall outcome is envisaged as an adaptive approach to implementation of adaptation initiatives that have been formulated with the role of ecosystems services at their heart and is becoming broadly applied worldwide.
There is, however, a crucial issue at the heart of effective EbA. It consists in the application of a well-founded valuation methodology that supports decision-making process and enables comparisons between conventional adaptation options (i.e. typically delivering a smaller range of services that are easier to quantify) with EbA options (i.e. deliver a greater range of options that are more difficult to quantify). When undertaking EbA, in fact, the decision-maker is both (1) restoring and conserving ecosystems for adapting to climate change pressures (e.g. coral reefs restoration for storm protection), and (2) restoring the resilience, the ecological/economic productivity and the capability of the ecosystems to regenerate and adapt to changes and shocks. She is, hence, investing in conserving and increasing the value of national natural capital. EbA options, in fact, produce several (present and future) additional positive impacts, beyond climate change adaptation.
In this context, valuing EbA impacts becomes crucial. EbA options' measurement, however, is a far more complex process compared to valuing more conventional or technical adaptation solutions, since it involves an assessment of (potentially large) non-market values that are often-times inadequately measured or missing altogether from costbenefit assessments. This means that when deciding between options, technical adaptations might be unfairly favored or prioritized over ecosystem-based solutions. In addition, a critical challenge of economic valuations of EbA refers to the difficulties of valuing the (potentially large) array of benefits without market values. For example, urban green areas (such as parks) for adaptations to heat waves or storm events might provide a host of benefits such as cool shading, evaporative cooling, rainwater interception and storage, air pollution removal, habitat creation and biodiversity, as well as aesthetical, health and recreational values that do not have market prices. Improperly accounting for those values (or in some cases neglecting them altogether) definitely affects the economic valuations of EbA. Such an important area of research and policy warrants, therefore, greater attention.
In this context, the paper attempts to conceptualize a technical indicators-based framework that can correctly inform decision making on EbA adoption and implementation, The study presents a set of 54 economic indicators that encompass the technical, financial and academic difficulties to perform integrated and thorough economic valuation. The study aims at providing policymakers with simple, though rigorous evidence. The main objective of the technical framework aims at capturing the complexity of economic valuation of EbA costs and benefits, with computationally simple instruments. The proposed conceptual, methodological framework is applied to coastal EbA. When EbA is performed in coastal areas, ten different types of interventions may help addressing a range of climate change risks and impacts, as synthesized in Table 1 1 .
The paper is organized as follows. Section 2 critically surveys economic studies that value costs and benefits generated by different EbA options. In addition, it presents an original assessment framework (based on 54 synthetic indicators) for the understanding and computation of economic costs and benefits generated by undertaking EbA options to climate change drivers. The economic indicators are grouped in 3 main sub-categories. Section 3 discusses the proposed methodology from a policy perspective. Section 4 concludes.

Methods
The choice of undertaking one or more EbA options can generate (present and future) costs and benefits that need to be valued and balanced. This is instrumental to achieve an informed decision on whether and how implementing the selected option. Economic analysis and valuation of EbA options' costs and benefits helps providing technical instruments that allow to (1) assessing the overall outcome; (2) enabling comparisons among adaptation methods and (3) support decision-making.
From this perspective, the section first surveys existing valuation studies, based on the performance of economic cost-benefit analysis methods, and then proposes an alternative valuation assessment methodology.

Critical survey of EbA costs and benefits valuation studies
For the compilation of the critical survey, we have scrutinized the literature on economic valuation of costs and benefits of marine and coastal EbA options. An initial search on google scholar has shown more than 40k papers from the academic and grey literature. We considered studies, analysis, applications and case-studies from all over the world, with the only constrain of English as a language. When refining the     search by using more specific key words (for instance narrowing to "EbA options", "marine EbA options", "economic valuation" "state-of-the arts" economic valuation techniques of costs and/or benefits, e.g. contingent valuation, stated choice and so on), the output strongly decreased to around 100 works. The reading of the abstract of selected papers was the required step to understand the focus and topic of the study. In fact, most studies on EbA are qualitative, when using economic analysis. Finally, we ended up with a selection of papers (around 50), published in the period 2000-2016. Table 2 reports the main content of the studies on EbA options in marine and coastal systems, where costs and benefits are measured in qualitative, quantitative and monetary terms.
The purpose of the survey aimed at checking for empirical regularities and commonalities that allow to point out general highlights. The search shows that the literature is very fragmented and does not allow to "build" a rigorous, general framework. This occurs because units of measurements, types of EbA options, socio-economic characteristics, geographical applications and valuation techniques vary broadly and are very context specific.
In order to systemize and summarize the surveyed literature, we have counted the frequency of types of applications and the minimum and maximum monetary value of the selected valuation studies. This exercise is only finalized to provide a synthetic, if not visual sketchy, overview on the state-of-the arts of economic valuation of coastal EbA. Table 3 reports the main findings.
It does not exist a consistent corpus of studies that allows for direct comparability of values. In fact, most studies focus on the computation of costs or benefits only. Costs are often present, direct costs, generated by the concrete realization of and EbA intervention. Costs are computed on the margin. Benefits are mostly computed as avoided costs/damages and/or as additional benefits, indirectly generated by EbA on economic activities (mostly fishery and/or tourism). Benefits are computed as aggregated (discounted) values or just described and measured in qualitative terms 2 .
Among the surveyed cases and studies on EbA costs valuation, the most frequent application (31.25%) refers to the creation of marine protected area (MPAs), followed by coral reef conservation/restoration (21.87%). Among the surveyed cases and studies on EbA benefits valuation, the most frequent application (42.85%) refers to the conservation/ restoration of coral reef, followed by and mangroves conservation/ restoration (21.428%).
When the valuation in monetary terms of both (present and future) EbA costs and benefits is performed (i.e. South Thailand and Fiji Lamu cases, for mangroves restoration/conservation), the future discounted benefits highly offset the present costs of the undertaken options.
Finally, even when costs and benefits are expressed in monetary terms, one has to be cautious in interpreting and comparing the figures. The measurement of EbA costs and benefits in monetary terms, in fact, also depends on the macro-economic milieu of the geographical area where a selected EbA option is implemented 3 . The value of 1 dollar is very different in developing or wealthier countries. A "low value" in absolute terms might be very high in a concrete socio-economic context and has to be interpreted in the economic milieu where the EbA valuation is carried on.

Alternative methodology: EbA indicators
The section proposes to assess and value EbA options' costs and benefits by making the use of indicators. Indicators are measures that evaluate (indirectly) the level of a complex phenomenon, assessed by direct observation of other related phenomena, with a high common semantic content to the concept that one wants to measure. For this reason, we design a number of original indicators that compute economic costs and benefits generated when undertaking (each of the 10) EbA options.
As a general framework, the set of indicators were selected by the following criteria: (1) validity (the capability of effectively measuring the concept under study); (2) reliability (the ability to measure the concept in a stable manner across time); (3) sensitivity to changes of what one wants to measure (the capability to adapt to data changes in a flexible manner); (4) computational simplicity (the indicators are easily computable and do not require complex statistical/econometric operations); (5) applicability for decision making (the degree of acceptability and uptake of the information for policy/management decisions, including public investments). (6) applicability to each of the 10 EbA options, to engineering solutions and policy inaction.
In particular, the conceptualization and selection of indicators follow a precise reasoning. based on (1) the identification of the timing of the procedural steps required for EbA implementation and (2) the identification of all possible (present and future) direct/indirect costs and benefits, generated by EbA options' implementation. With respect to the timing of the EbA indicators, we have distinguished three different temporal dimensions: ex ante, contingent and ex post the selected EbA intervention. A set of indicators measures the status quo before performing the selected EbA option and provides an inventory (in simple physical terms and units of measurement) of the stock of natural capital in the area where EbA interventions have to be implemented. The ex ante assessment also values if and how much the stock of natural capital, and its capability to produce flows (e.g. ecosystem services), has been depleted by climate change events. Such operation is instrumental to the valuation of the efficacy and efficiency of the selected EbA options. Contingent to the EbA implementation, the indicators categorize the direct impacts of the adaptation option, including direct/indirect costs and benefits, measured in different ways, and possible negative externalities. For instance, the implementation of a selected EbA option can generate costs and benefits on local population during implementation (e.g. in coral reef restoration, fishers or scuba-divers could be forced to stop their activities as long as EbA operations have to be implemented. At the same time, local workers can be employed to collaborate with the EbA project). Finally, the set of indicators to be computed after the EbA option has been implemented, refers to maintenance and monitoring costs; a broad plethora of direct benefits generated from EbA with respect to adaptation to climate change, and a group of indirect benefits generated by well restored and conserved ecosystems beyond climate change adaptation. Those benefits include an improved economic productivity of the natural resource at stake, in a particular economic sector (e.g. dune and beach restoration can attract more tourists) and a new inventory of natural capital, after EbA intervention. Table 4 reports and summarizes the rationale of the 54 indicators for the computation of costs and benefits derived from EbA options. Appendix 1 explains the computation method for each indicator.
The 54 indicators can also be categorized in three main groups: social resilient indicators; (strictly) economic indicators and biodiversity/ environmental indicators, as synthesized in Figure 1.
The sub-categorization is important because the decision-maker and the stakeholders involved in a selected EbA option might attribute a

Discussion
The capability of costs-benefits methodologies and techniques to provide informative contents for decision-making is limited in the case of EbA. This occurs for two reasons. First, EbA is a context-specific, case-by-case exercise (UNEP, 2012) and so is the economic valuation of EbA costs and benefits that mostly depend on contingent scenarios and available data. Second, identifying and computing EbA costs and benefits is an integrated exercise that can be based on a plethora of economic, social and ecological aspects. Attaching a monetary value to EbA costs and benefits is only the final step of a thorough integrated procedure that should include the assessment of (1) climate change drivers, impacts and vulnerability 5 ; (2) socio-economic milieu and (3) geographical, ecological and environmental local peculiarities 6 . Such complexity may not be captured by standard economic valuation methodologies and related computational procedures.
The methodological heterogeneity and often incompleteness of many studies, in fact, may not provide a systematic, integrated support for policy decision making for EbA options. In addition to that, alternative ecosystem valuation methodologies can inform policy choices to better reflect local needs, improve living standards and facilitate more effective adaptation strategies to climate change. "Alternative ecosystem valuation methodologies, in fact, can enable new pathways towards climate change adaptation and the improvement of living standards that would be particularly suitable for low-income settings where natural resources are vulnerable and financial resources scarce" (Folkersen, 2018, p.1, p.1).
From this perspective, using indicators can overcome (at least some of) the difficulties, including the computational complexity, required by state-of-the arts economic valuation methodologies and techniques. Despite possible limitations, which will probably emerge with further research and the application of the assessment methodology to casestudies, the proposed indicators framework presents several advantages. Indicators are easy to compute, and the required data are often available and easy to gather and collect. In addition, the indicators are very flexible in application. The indicators attempt to gather and value information that might be neglected and not accounted when performing cost-benefit analysis with state-of the arts valuation methodologies, given that methodological protocols can be very rigorous but bounding and limitative in assessing complexity. The indicators attempt to cover the multi-faceted valuation reality, generated by EbA implementation.
The matrix of 54 indicators is conceived as a menu list. The analyst (scientists, practitioners and/or policy-makers) will use and will compute those indicators that are required by the valuation tailored to the specific case-study at issue (time period, geographical scale, macroeconomic milieu, ecological status, location and so on). The indicators are very effective in communicating the main message they have to convey. In addition., the same assessment structure can be used for computing costs and benefits of both EbA options and alternative options to climate change adaptation (i.e. engineering based adaptation intervention). This allows comparisons among different policies and climate change adaptation options.

Conclusions
In the last few decades, a considerable amount of work has gone into the monetary valuation of the services provided by the environment to human well-being. Based on the framework of economics, the monetization of ecosystem services has been advocated as a way to make visible the hidden benefits that nature provides. The hope is that if the services of nature (including adaptation to climate change) can be expressed in amounts of money, policy makers and markets will see their value and act to insure they are used in a sustainable way. Although frequently presented as a novel approach it actually has a very long history (Baveye et al., 2013).  (J4) 4 Such synthetic indicator can support decision-making scenario by employing a mathematical equation that results in a quantitative estimate. The estimate is useful to scope out the benefits of a situation against the costs of the situation. It is a ratio of benefits divided by costs. When we divide the value of the benefits by the value of the costs, the result indicates how much we get in benefits for every unit of money spent in the project. The computation of B/C ratio is based on estimation, and of course estimation is valid only if the data and the source that spawn the hypothesized numbers. 5 Climate Change Impacts Assessment refers to the selection of relevant climate change drivers and their most important impacts on coastal systems in the particular area under study. EbA options, in fact, depend on the peculiar climate change drivers and impacted sectors. Vulnerability Assessment refers to the quantitative assessment of the consequences of climate change drivers on human activities and the environment in coastal systems. This assessment is very important because can be interpreted as the cost of policy inaction. 6 The impacts of climate change on environment and human activities are mostly determined by two main elements: (1) the specific economic and environmental characteristics of the territory and population hit by the climatic event, and (2) the adaptation measures in place in the selected area. Adaptation measures vary depending on a plethora of factors. For instance, adaptation measures can be classified based on the sectors considered, the methodology, the timing, goal and motive of their implementation. Adaptation can include reactive or anticipatory actions, or can be planned or autonomous, engineering or ecosystem based.
From this perspective, the paper has provided an assessment framework for the identification and computation of economic costs and benefits generated by undertaking EbA options to climate change drivers. After having critically reviewed a broad literature in the topic of economic valuation of EbA costs and benefits, we have presented and illustrated 54 synthetic indicators, grouped in 3 main sub-categories (social resilient, economic and biodiversity/environmental). The proposed framework is instrumental to provide rigorous, but easy-tocompute valuation instruments that inform the policy supporting the implementation of EbA options. Ecosystems and natural capital present resilience and capability of self-restoration to adapt to climate change and are important production inputs in green economies and drivers of green economic growth. Investing in EbA options today, beyond climate change adaptation, implies increasing the value of the stock of natural capital in the future because EbA allows ecosystems to continue and provide their services and generate the related benefits. In addition, investing in EbA improves the quality, hence increases the value of the natural capital. Such feature might result appealing for those economies, like SIDS (Small Islands Development States), where environment is an important driver of economic growth (e.g. tourism). From this perspective, the technical calculation of EbA impacts, through the proposed methodological framework, can correctly inform decision making.

Author contribution statement
Laura Onofri: Conceived and designed the analysis; Analyzed and interpreted the data; Wrote the paper.
Paulo A.L.D. Nunes: Conceived and designed the analysis; Analyzed and interpreted the data.

Funding statement
This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors. Indicators:  D6, groups F, G, I1, I3-19  Economic Indicators:  groups C, D, E