Cleaning up plastic pollution in marine environ : a case study of Australian waters’

Plastic production, consumption, and subsequent management of plastic debris is one of the major environmental issues facing global society. Marine plastic pollution is extensively acknowledged as a severe anthropogenic threat to marine environments. Due to their low costs and great functional capabilities, plastics have become exceptionally essential in modern economies. For instance, the coronavirus disease (COVID-19) is a great illustration of the benefits and drawbacks of plastic use. Personal protective equipment such as face shields and medical equipment such as syringes are made of single-use plastics to help protect people worldwide, however, after their use, sustainable disposal and potential reuse is challenging. Research has documented their existence in oceans. Although plastic is consumed worldwide, the magnitude of waste mismanagement and pollution varies greatly across regions. Most of the global plastic debris is generated by high-income countries where per capita plastic consumption is particularly high.
Over time, the control of the massive increase in plastic debris has proven challenging. Waste mismanagement has tremendously exacerbated the likelihood of plastic leakage, particularly into the oceans where options for removal are extremely limited. Globally, marine plastic debris is found across beaches, floating on the ocean surface and in the water column, on deep ocean floors, inside marine wildlife, and frozen within polar ice. The commonly documented impacts of marine plastic pollution are detrimental effects on human health, wildlife, marine ecosystems, ocean waters, maritime activities as well as coastal economies. In addition, plastics in marine environments degrade and progressively fragment into smaller particles, microplastics, which further exacerbate the adverse effects of marine plastic pollution. Given the growing awareness of marine plastic pollution, governments are investing more resources in the development and implementation of policies and strategies to effectively manage and minimise this pollution and its related effects. A shift from the traditional linear economy of ‘take-make-dispose’ to a circular economy of ‘efficient resource use through a closed-loop system’ which aims to reduce waste and keep resources in use infinitely to promote sustainable development has increasingly gained attention from scholars, practitioners and policy makers.
In Australia, plastic pollution in the oceans is the most serious environmental threat to marine life after climate change. Australia’s marine environment is the world’s third largest marine jurisdiction which is home to a diverse array of marine species. Marine plastics are having an adverse impact on Australian marine waters with entanglement, ingestion, transportation of invasive species, seafood contamination, and reduced tourism revenue. To combat marine plastic pollution, Australia's Commonwealth government has developed a roadmap for transition from a linear economy to a circular economy for plastics at the national and state levels, to contribute to the Sustainable Development Goals (SDG) 14 and 12. However, the proposed or implemented policies, in Australia’s National Plastic Plan of 2021, aimed at promoting the transition from a linear to circular economy have been explored largely from a production or government policy perspective and less effort has focussed on the preferences of consumers and the wider society. A circular economy for plastics requires a participatory approach, and households are the largest source of municipal plastic debris in Australia, therefore, this information helps policymakers prioritise initiatives.
The overall aim of the thesis is to provide meaningful insights into the management of marine plastic pollution especially preferences for addressing marine plastic pollution and contribute to creating a circular economy in plastics. This thesis employs a number of methods to add to the environmental economics literature on this topic. The thesis begins with a general introduction to contextualise the problem. To understand the abundance of marine plastic pollution in oceans, Chapter Two presents a global review of literature on the abundance and distribution of microplastics across surface waters of the five world’s oceans including the Pacific, Atlantic, Indian, Arctic and Southern (Antarctic) Oceans. Using a systematic review approach, this chapter reviews a global dataset derived from 45 primary studies undertaken since the year 2010 following the Oslo and Paris Conventions (OSPAR) guidelines, under the North-East Atlantic Marine Environment Strategy Convention, to monitor and harmonize data collection about marine debris. The results are heterogeneous in terms of the concentration and distribution of microplastics in surface waters in the oceans.
Chapter Three presents a global overview with a meta-analysis of Willingness to Pay (WTP) to clean up coastal plastic debris. Over the years, researchers have estimated WTP for the reduction of beach debris using non-market valuation methods. This chapter utilises a worldwide dataset of 63 primary studies over 22 years to evaluate the overall effect size and assess the variability in the WTP estimates. The findings show that people are willing to pay $US0.71 per person per year for a one per cent reduction in beach debris. The observed heterogeneity in WTP estimates is associated with elicitation methods used, beach attributes, geographic locations, and per-capita income.
To assess the public perceptions of the outlined circular economy policies in the reduction of marine plastic pollution in Australian marine waters, a multi-state Discrete Choice Experiment (DCE) survey was conducted across six states in Australia (n=1274) and the data was utilized for analysis in chapters four and five. Chapter four identifies policy strategies that align with the 4R framework (Reduce, Recycle or Reuse and Recover) of a circular economy for plastics and Australia’s National Plastic Plan of 2021 to estimate the WTP for the reduction of plastics in Australian marine waters using a full correlation Multinomial Logit model— estimated in WTP space. The results indicate a preference for Redesigning (Reduce) and Recovering approaches over Recycling or Reuse policies.
Attitudes are thought to influence behavioural intentions and choices but there are limits to the number of attitudinal scales which could be used in a survey. A common media image associated with marine plastics involves entangled marine life or the impact of ingested plastic on marine life. In Chapter Four, the influence of attitudes towards animals on choices is explored through the Animal Attitude Scale (AAS), a 20-item scale on animal welfare. Chapter five utilises a Hybrid Choice Model (HCM) to estimate the influence of positive attitudes toward animal welfare on WTP to support circular economy policies. The findings indicate that a positive attitude towards animal welfare is associated with age, gender and membership in an environmental organisation, and influences respondents’ WTP for Ocean clean-ups initiatives aimed at reducing marine plastic pollution.
Overall, this thesis highlights the importance of developing reliable and standardised methods to enable efficient data comparisons of marine debris information at global, regional and national scales for government agencies. For researchers, these definitions would facilitate data comparability and reproducibility through benefit transfers in meta-analysis. The findings from the estimated WTP for circular economy-based initiatives could assist policymakers in their assessment and decision-making processes as Australia transitions to a sustainable circular economy for plastics. In a broader context, these findings could inform future approaches for strengthening the efforts and resources invested in circular economy strategies for the management of marine plastic pollution.