Introduction

The global challenges posed by plastic pollution have emerged as a critical environmental and societal concern of the 21st century.1 Recent research demonstrates that plastic pollution aggravates the impacts on all planetary boundaries,2 and substantial evidence documents the adverse impacts of plastic pollution on human health, ecosystems, and biodiversity.3,4 This helps explain the growing attention toward plastic governance across academic, policy, and industry spheres. This growing attention is reflected in a proliferation of governance initiatives at multiple scales.

Perhaps most prominent is the multilateral effort to secure an international legally binding instrument to eliminate plastic pollution. The 2022 United Nations Environment Assembly (UNEA) resolution 5/14, mandating treaty negotiations, represents a critical opportunity to address the issue of plastic pollution systemically, moving beyond the historically fragmented approach of targeting individual environmental domains, product categories, or waste streams.5 While earlier interventions primarily focused on specific items such as plastic bags or single-use products,6 the UNEA resolution recognized that plastic pollution occurs from production and transportation to waste handling and mismanagement. Consequently, it acknowledges that effective governance requires a systemic approach, addressing the full life cycle of plastic feedstocks, products, and wastes.

Despite the initial recognition of the systemic nature of plastic pollution, the inconclusive treaty negotiations during the past three years reveal deep-rooted tensions between nations that frame the plastic challenge as primarily a waste management issue and nations that continue to insist the challenge must be addressed across the life cycle of plastics.7 This highlights the very challenging task of landing an ambitious global treaty on an issue with such strongly vested interests in the current geopolitical landscape.8 These interests reflect not only divergent policy preferences but also profound carbon lock-ins in the petrochemical-based plastics industry, which through technological, institutional, and behavioral phenomena shape the political feasibility of far-reaching life cycle interventions.9,10

However, while political will and vested interests are decisive factors shaping the scope of a future international agreement, the ability to govern plastics effectively is also constrained by substantial knowledge gaps (KGs) that persist across the life cycle of plastic.11,12,13,14 These gaps span production, use, end-of-life, and cross-cutting issues, and they encompass not only technical and scientific uncertainties but also social, political, and economic dimensions. The complexity of these KGs is further amplified by the rapid evolution of plastic materials, changing consumption patterns, and recycling challenges, all of which create uncertainty and shifting conditions for policy interventions.

Against the backdrop of the current global political deadlock, we present an analysis of key KGs that constitute barriers to effective plastic governance, accompanied by an action agenda for addressing these gaps. The analysis draws on a structured expert workshop and a synthesis of relevant literature focused on the institutional setting and governance legacy of the European Union (EU). The EU constitutes a relevant case given its ambition to advance life-cycle-oriented approaches to plastic governance, most notably articulated in the 2018 European Strategy for Plastics in a Circular Economy.15 In the context of the ongoing international treaty negotiations, the EU has further positioned itself as a leading proponent of ambitious global action, including through its participation in the High Ambition Coalition.16 As one of the actors likely to champion and implement ambitious provisions under a future global plastics agreement, the EU’s ability to address these KGs will be central to the credibility and effectiveness of such an instrument. This analysis thus proceeds from the assumption that addressing KGs can enable, but not on its own guarantee more effective plastic governance in a context shaped by strong political and economic constraints.12

Our analysis highlights that KGs are not the result of missing evidence alone. Rather, they also stem from the absence of standardized methodologies, limited transparency and disclosure, and insufficient systems for monitoring and tracing plastics across their life cycle. In this sense, KGs do not merely coexist with political deadlock; they also shape what can be proposed, implemented and enforced, and as such matter for the scope and legitimacy of plastic governance. This has important implications for how such gaps can be addressed. Our findings indicate that many of the identified gaps cannot be resolved through further research alone, but require interventions in how knowledge is generated, standardized, disclosed, and made accessible within governance systems. By identifying these KGs and linking them to concrete action areas, this study moves beyond mapping missing knowledge toward understanding how constraints can be addressed, providing actionable insights for researchers, policymakers, and practitioners working toward more sustainable plastic systems.

The remainder of the article is structured as follows. Section 2 describes the research process and methodology. Section 3 presents the results, identifying and characterizing key KGs and analyzing how these gaps impede effective governance across the plastics value chain, including production, use, end-of-life management, and cross-cutting life cycle themes. In section 4, we translate these findings into four strategic action areas to support more effective plastic governance, explicitly linking each action area to the KGs it addresses. Section 5 concludes by outlining key takeaways.