Anton Nahman

In addition to its direct impacts on marine ecology and biota, marine plastic debris can affect the delivery of ecosystem services, with resulting impacts on human well-being, society and the economy. It is important to quantify these impacts in economic terms, so as to be able to provide evidence-based support for an appropriate policy response. We review the South African literature on the impacts of marine plastic debris on ecosystem services and on the economy, in order to identify relevant knowledge gaps. The gaps are found to be significant. Some research has been conducted in terms of impacts relating to recreation, aesthetics and tourism and the costs of beach and harbour clean-ups. However, there is a significant lack of research regarding impacts on ecosystem services relating to fisheries and aquaculture, heritage, habitat provision, biodiversity, and nutrient cycles. There is also a significant lack of research regarding direct economic impacts on the transport/shipping and fisheries industries, indirect economic impacts (such as costs associated with health-related impacts), and non-market costs (e.g. impacts on scenic, cultural and spiritual values). More research is needed in South Africa to address these gaps, in order to inform policy aimed at addressing plastic waste and marine plastic debris. Significance: This review highlights the knowledge gaps in terms of the impacts of marine plastics on ecosystem services and on the economy in South Africa, which are important to understand in order to be able to direct funding for future research in this domain. Without better knowledge of the economic impacts of marine plastic debris, it is difficult to assess the costs of inaction, and therefore to inform an appropriate policy response for tackling the problem of marine plastic debris.

Given the broad (economic, social and environmental) objectives of a green economy, and the limitations associated with mainstream measures of economic performance (such as gross domestic product), an alternative or expanded set of indicators is required for measuring progress toward a green economy. This article develops a composite index for measuring green economic performance, based on 26 indicators across the economic, social and environmental dimensions. The index will enable comparison of a country's green economic performance both over time and relative to other countries. Furthermore, the index is constructed in such a way as to allow for disaggregation (i.e. for scores on individual components to be seen at a glance), such that areas of specific concern can be easily identified and addressed, and progress in each area monitored over time. The index was tested on data from 193 countries, and the resulting country rankings were assessed.