A decision framework for estimating the cost of marine plastic pollution interventions. With more marine plastic interventions, there is a need for evaluating the cost-efficiency of each of the efforts for smart investments of conservation efforts. The article presents a framework with an approach to compare cost-effectiveness of interventions across sociopolitical and economic contexts. The framework was tested in six case studies: two quantitative and four comparative case studies. 

Authors

Erin L. Murphy, School of Life Sciences, Arizona State University; Miranda Bernard, School of Life Sciences, Arizona State University; Gwenllian Iacona, Center for Biodiversity Outcomes, Arizona State University; Stephanie B. Borrelle, David H. Smith Conservation Research Program, Society for Conservation Biology; Megan Barnes, Centre for Environmental Economics & Policy, School of Agriculture and Environment, University of Western Australia; Alexis McGivern, School of Geography and the Environment, University of Oxford; Jorge Emmanuel, Institute of Environmental and Marine Sciences, Silliman University; Leah R. Gerber, School of Life Sciences, Arizona State University.

Highlights

• A framework to evaluate cost-effectiveness of marine plastic interventions is important to reach conservation goals and can also help decision-makers to prioritize right efforts.
• In this study, relative costs of implementations of mitigations were calculated in quantitative case studies, exploring the effects across different socioeconomic conditions.
• To better understand what affects the net costs of interventions, comparative case studies were developed – where either temporal, spatial scale or socioeconomic conditions varied, and the other two factors were kept constant.
• Overall, the study found that socioeconomic context, and spatial and temporal scale were important factors that influence the costs and its distribution across stakeholders.
• For future research, the efficacy of the framework should be further explored by decision-makers in various socioeconomic and geopolitical contexts, and at different temporal scales of action.

“Employing our approach facilitates deliberation about the possible costs that may influence the efficiency of an intervention, allowing decision makers to compare an intervention to a business-as-usual scenario or other possible interventions before their implementation.”

RESEARCH BRIEF

Marine plastic interventions are increasingly introduced all over the globe to reduce the problem of marine plastic pollution.  Although the investments to address plastic pollution are growing, the funds for conservations efforts are limited.

While benefits of marine plastic interventions can be assumed to be many, the cost-efficiency of each intervention should be evaluated before implementation. Both benefits and costs can be social, economic, and ecological, and on different levels.

An overview of the net costs of interventions can help decision-makers to prioritize their actions to reach their conservation goals. The article presents a decision support framework with an approach that estimates and compares cost-effectiveness of interventions across sociopolitical and economic contexts.

Method for calculating costs and benefits

In the framework, relevant cost and benefit categories for interventions was identified before the net cost was calculated with an equation including direct, indirect, and nonmonetary costs, as well as monetary and nonmonetary benefits produced by the intervention.

In addition to calculating the actual costs, the framework provided sections for describing the intervention with its objectives, spatial-temporal scale of evaluation and which stakeholders are involved or affected by the intervention. The framework was further applied to case studies.

Six case studies

The framework was tested in six case studies, in which two of the case studies were quantitative. These case studies were applied to demonstrate how the framework can be used to examine relative costs of alternative interventions, and for providing a perspective on how interventions by different actors (under contrasting socioeconomic conditions) can differ.

The first case study was on an implementation of a solid waste management (SWM) plan over 10 years in a coastal city on an island in the Philippines, where the key objectives were to prepare the city for anticipated population growth and urbanization. Interventions included expanding waste management services, increasing recycling and composting rates, and reduction of open burning.

The second case study was on the implementation of a trash wheel in Baltimore over a 10-year evaluation period, with a key objective to improve sanitation and quality of water in the coastal city.

The four comparative case studies were developed to better understand three key factors that influence the net costs of intervention: temporal scale of analysis, spatial scale of implementation and socioeconomic conditions. Temporal scale was explored on a time scale of 1 to 20 years. Spatial scale was explored in beach cleanups in municipalities vs. national scale in a developed country over one year.

Socioeconomic conditions were explored by comparing costs of a waste-to-energy (WTE) plant in a municipality in a developed country and a developing country. In each case study scenario, the relative costs for each cost and benefit category were compared. The effectiveness of each intervention was assumed to be consistent in each scenario.

Different groups affected

Results from the two quantitative studies provided insights into which public group benefitted the greatest in net costs of the implementation, and whether anyone was negatively affected. The study of the solid waste management (SWM) plan in the Philippines showed that the costs would probably fall on the city. Marine sectors, recycling sectors and the public would benefit the greatest.

The direct costs appeared to affect the low-income and rural communities negatively more than the rest of the public, as they now had to pay for waste management, or they would receive fines. Also, a small group of citizens whose income was based on waste picking would be affected by fewer opportunities for waste picking. These findings contrasted with the second quantitative study, the implementation of a trash wheel in Baltimore, where all stakeholder groups reported that they benefitted from the intervention.

Costs vary with length of the intervention

The comparative studies highlighted differences in net costs related to the length of the intervention. Comparative studies on beach cleanups found that over a longer time scale, implementations will lead to more work, as plastic production and pollution increases. This will demand more hours and more costs for the beach cleaners.

This also included an anticipated increase in hourly wages and costs for disposal of waste. Same outcomes and constant work would not lead to the same results, but rather reduced benefit of cleanups, including decreased monetary benefits over time. These findings on effects over time contrasted with the results from the WTE plants, where net costs decreased when operational time increased.

Higher costs in developing countries

When relative costs of beach cleanups over different scales were compared, net costs were found to be higher per unit cleaned when coastal cleanups were implemented nationally compared to locally.  In this example, the direct costs were higher when more isolated areas were included, and less monetary benefits found for tourism and health as per kilometer cleaned would decrease.

The comparative studies found that the net cost of implementing a WTE plant was higher in municipalities in developing countries than in developed countries. Labor costs were low, but infrastructure costs were higher, used old technology and challenges like waste with high moisture content also led to increased maintenance costs. These findings suggest that for developing countries, more efforts and investments were needed for installing a plant of good quality.

Overall, the authors suggests that three main factors influence the total and distribution of costs across stakeholders and should be considered when implementing interventions: 1) Socioeconomic context of implementation, 2) spatial scale of implementation, 3) time scale of evaluation.

Inclusion of stakeholders

A standardized framework can be helpful for any actor planning a marine plastic intervention. It can bring understanding to the relationship between costs and efficacy, and between different socioeconomic contexts.

Socioeconomic and environmental context should be identified as a first step, to enable planning the time frame of the intervention and who should be included. Including all stakeholders early in the process will give a realistic overview of costs and benefits and further considerations for equally shared costs.

For an even better overview and to ensure all objectives for the implementation are met, net costs for each stakeholder group can be quantified. For decision makers, this provides an opportunity to get a better overview of all stakeholders involved, and their respective costs and benefits.

The researchers suggest that the temporal objective of the analysis should be in line with the objective goal of the implementation:

• Is it for long-term sustainability? Then the temporal scale of the evaluation should be longer.
• Is it for short-term benefits? Then the temporal scale of evaluation should be shorter.

Ultimately, the authors argue, communities would benefit from aiming to achieve objectives with different time scales.

“Future research should seek to engage decision makers in various geopolitical and socioeconomic contexts and at different scales of action to validate the efficacy of this tool and generate cost data that can be compared across contexts.”

Using the framework

Though efficiency might be the primary goal in many decision-making processes, the framework can help estimate potential costs over time, and how they may differ for each implementation in a consistent way.

Predicting costs over a longer time scale also involves a great deal of uncertainty and can be challenging. The framework can also be used to compare efforts and costs of the same intervention at different locations or over spatial scales. It provides a step towards a more standardized approach to evaluate and compare implementations, putting the objectives in the right context, and makes choosing the right investments for reaching conservation goals easier.

The empty version of the framework is available and can be downloaded here (Appendix 3).

The full article is available here. (link)

Watch the public presentation of this work: 

A decision framework for estimating the cost of marine plastic pollution interventions from Society for Conservation Biology on Vimeo.