Plastics and the Ocean: understanding a global crisis

On the eve of the launch of the discussion series "Plastics: a systemic poison", Henri Bourgeois Costa, plastics expert at the Tara Ocean Foundation, and Fabiana di Paola, head of the Oceans Programme at the Fondation Maison des Sciences de l’Homme (FMSH), bring their perspectives together to shed light on the scientific, political and economic drivers of a crisis that has become global.

The Tara Ocean Foundation is known for its expeditions and educational programmes such as "Plastics at Sea under the Microscope". How do these initiatives help us better understand and tackle plastic pollution, and what are some of the Foundation’s most significant findings?

Henri Bourgeois Costa. When you study, as the Tara Ocean Foundation does, ocean life and especially plankton—the very first link in the food chain—plastic quickly becomes an unavoidable subject. With every net haul used to sample marine microorganisms, we also collect significant quantities of plastic, particularly microplastics. These tiny fragments of artificial polymers, smaller than a grain of rice, usually escape our attention, which tends to focus on macro-waste, particularly that linked to mass consumption.

In 2013, the Tara Mediterranean expedition focused on these microplastics, which originate from the breakdown of larger plastic debris, but also from industrial pellet losses or deliberately released microplastics, such as those used in cosmetics or agricultural applications. This mission revealed pollution on a vast scale and showed that the Mediterranean Sea was sadly one of the most polluted seas in terms of plastics. It also challenged assumptions by highlighting the major contribution of countries along the northern Mediterranean coastline, despite their complex and costly waste management and water treatment systems.

A few years later, in 2019, the Tara Microplastics expedition sought to understand the flow of plastic from land to sea by sampling nine of Europe’s largest rivers, from their estuaries upstream to major metropolitan areas. Everywhere, the same conclusion emerged: widespread microplastic pollution and significant upstream sources, even at the edge of major cities. In other words, land-based pollution represents a potentially enormous reservoir of microplastics, which are carried by rainfall events through river systems into the marine environment—not to mention atmospheric plastic pollution.

The conclusion is clear: we are not cleaning up the sea or rivers of a pollution that is simply the result of individual negligence or poor waste management. Plastic pollution is inherent to the production, marketing and use of plastics themselves. This is all the more true given that plastic pollution is not only physical; it is also chemical, involving a cocktail of 16,000 compounds that threaten ocean health—and, by extension, human health. It is partly for this reason that the latest Tara Europa mission was launched to study this chemical dimension of plastic pollution, with initial results expected by the end of 2026.

The FMSH programme "Oceans – Social worlds, living worlds" focuses on the human dynamics behind ocean degradation: plastic pollution is one of its most striking examples. How do the social sciences illuminate aspects that natural sciences alone cannot address?

Fabiana di Paola. In the Anthropocene era, where the human footprint is permanently inscribed in the ocean, microplastic pollution raises a central question: through which production, consumption and governance models have our societies made this phenomenon possible, and how can they change course? The social sciences make an essential and complementary contribution to environmental and life sciences. They do not merely observe the phenomenon: they explain why it persists and identify the political, economic and social levers needed for effective action.

Social sciences first show that plastic is not only a material, but a system of uses, habits, cultural norms and economic structures. In environmental sociology, for example, the study A new approach from public behavioural attitudes and perceptions towards microplastics (2024) demonstrates that individual and collective behaviours directly influence support for plastic reduction policies and the ability to change everyday practices. Sociology highlights social relations, inequalities and power dynamics that shape the plastics industry. Environmental law provides concrete tools, such as extended producer responsibility and the "polluter pays" principle, to transform these structures. Economics, through the concept of the circular economy, shows why recycling alone is insufficient and argues for reducing production at source. Finally, an anthropology of plastics anchors solutions in local contexts while questioning the macroeconomic logics behind pollution.

Interdisciplinarity is a structural condition for effectiveness. The social sciences translate scientific knowledge into socially acceptable, politically robust and sustainably effective action. By linking scientific knowledge, human behaviour and collective decision-making, they make it possible to respond to the challenge of microplastics in the ocean.

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How do you analyse the root causes of the plastic crisis?

HBC. The plastic crisis is that of a model which separates humans from their environment, treating economy and ecology as distinct when the former should be grounded in the latter to ensure genuine sustainability. We must no longer see this crisis as the sum of individual behaviours, but as the result of industrial and political choices that must be rethought, along with the levers needed to build alternative systems. This requires accepting the uncomfortable yet stimulating challenge of profound societal change.

FdP. Plastics became embedded in our daily lives because they were designed, promoted and regulated as an obvious solution. In the social sciences, we examine precisely this normalisation: how industrial and political decisions end up shaping social practices over the long term. Understanding the plastic crisis means confronting what, within our institutions, our narratives of progress and our governance systems, makes this model so resistant to change, and considering the social and political conditions required for genuine transformation.

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What led to the creation of a joint conference series in 2026 between the Fondation Maison des Sciences de l’Homme and the Tara Ocean Foundation?

FdP. It is worth recalling that the Tara Ocean Foundation has, since its creation, embodied an exemplary commitment to ocean protection and scientific research. We greatly admire its work. Its interdisciplinary approach resonates with our vision of research and the development of effective solutions. From our very first discussions, we shared a desire to have an impact, to reach a wide audience and to mobilise public attention around plastic pollution in the ocean. Our shared conviction that it is essential to bring together natural sciences and the social sciences gave real meaning to our collaboration. Through the new FMSH "Oceans" programme, we fund interdisciplinary research in the social sciences, life sciences and environmental sciences, including expertise from civil society, to achieve a comprehensive understanding of ocean systems.

HBC. There is, of course, deep respect for the scale and quality of the FMSH's work in promoting social science research. This respect is even greater because at the Tara Ocean Foundation we are equally convinced of the complementarity between natural sciences and social sciences. I would even say that the separation between them is somewhat artificial. The Foundation increasingly involves social science researchers in its strategic and advocacy work, particularly on plastics and toxic substances.

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What message would you like to convey to the general public through this conference series, and how do you hope it will be taken up?

HCB. The paradox of ocean plastic pollution is that it offers a tangible, visible reality—the macro-debris at sea—which obscures other forms, starting with the invisible pollution generated by plastics (climate, chemical and microplastic pollution). But it also reveals the reality on land: exponential production generating a systemic form of pollution, the scale of which is deliberately downplayed by certain industrial actors. This reality is masked by an excessive focus on individual responsibility and by the promotion of false solutions such as recycling or bioplastics. These issues are precisely what the social sciences help to uncover, and what we wish to make visible to decision-makers. We do not aim to stop at diagnosis, but to build on it to outline possible solutions informed by current social science knowledge.

FdP. Reducing plastics is now a vital necessity. With the social sciences, data produced by environmental sciences becomes more usable for decision-makers and the public. The social sciences analyse how such knowledge is received, identify social and political barriers, and propose concrete levers for action: transforming social norms, designing targeted communication strategies, and reforming regulatory frameworks. It is by linking knowledge, social behaviour and decision-making that we will be able to provide a sustainable response to microplastic pollution. The diversity of contributions in this conference series illustrates the need to combine different approaches to achieve real impact.

HCB. Plastic production affects planetary health. This is a difficult reality that must be acknowledged. But acknowledging it does not mean accepting it as inevitable. On the contrary, it means examining the underlying logics that produce it in order to better expose and challenge them. It also means avoiding simplistic solutions and instead collectively building responses. Reducing plastics is now imperative. While it may seem complex in our daily lives, we must remember that these materials are merely an accident in human history—just 75 years that do not underpin our happiness, creativity, or even the health of our species.