Bridging currents: an interdisciplinary source-to-sea approach is essential to align regional and national priorities with the future global plastics treaty ambitions

While it is vital to agree to a set of global objectives and targets to reduce plastic pollution as part of the Global Plastic Treaty, past negotiations have been troubled by differences in regional and national priorities and needs. To take these different priorities and needs into account, this letter proposes the adoption of an interdisciplinary source-to-sea approach. A source-to-sea approach emphasizes the connected nature between land-based sources of marine plastic pollution along the life cycle of plastic products on the one hand, and air, soil, and water cycles that determine marine plastic flows and associated sustainability risks on the other hand. It takes into account how we know more about the way in which production, use and plastic waste contribute to the pollution of rivers and seas in one location (e.g. in Europe), than we do for rivers and seas in other places (e.g. Africa). There are also regional and national differences in how much awareness exist about plastic pollution and how it is governed and regulated. These differences translate in different priorities and needs in terms of how to most efficiently and effectively reduce plastic pollution. The letter argues that these differences should be embraced and that an interdisciplinary source-to-sea approach can help to develop tailor-made regional and national targets and measures that in turn contribute to achieving the global ambitions of the Global Plastic Treaty. A key role is foreseen for existing governance institutions, such as river basin commissions and regional seas conventions (coordinated by UNEP Regional seas Programme), while the Global Plastic Treaty can become a platform for sharing of approaches, lessons and strategies between regions and countries so that over time, plastic pollution will be reduced worldwide.