The CodeBlue project addresses the growing challenge of eutrophication in the North-East Atlantic Ocean and the Baltic Sea, where decades of nutrient enrichment, combined with accelerating climate change, have degraded marine ecosystems. Although international conventions such as HELCOM and OSPAR have defined maximum nutrient inputs to achieve good environmental status, existing data systems and assessments remain fragmented, inconsistent across regions, and insufficient for modern policy needs. Against this backdrop, CodeBlue provides a coherent, transboundary scientific framework to understand how climate change, long-term nutrient cycling and transboundary fluxes shape present and future eutrophication.
The project’s overarching objectives are to determine the relative roles of anthropogenic nutrient loads and climate change in shaping current eutrophication patterns; to assess whether “Maximum Allowable Inputs” remain adequate under projected environmental change; and to analyse how mitigation measures influence blue-economy sectors such as aquaculture and local marine management. The research is guided by fundamental questions such as whether climate change has already altered the effectiveness of current policies and how future scenarios may require revised thresholds or new management approaches.
Methodologically, CodeBlue deploys a multi-model, multi-basin approach unprecedented in scope. By integrating observations, satellite data, hydrological information and model outputs from national and international repositories, the project will develop harmonised atmospheric and riverine nutrient forcing and robust biogeochemical data layers. Long-term hindcasts will assess sediment nutrient storage and cycling, while forward-looking simulations will evaluate future conditions and nutrient reduction scenarios. These outputs will be merged using a weighted ensemble modelling framework to quantify uncertainties and produce consistent eutrophication diagnostics across both basins. Stakeholder participation is embedded through a co-design board, involving key policy stakeholder groups such as OSPAR, HELCOM enabling continuous communication between scientists, environmental agencies and policy bodies, and ensuring that the scientific outcomes respond directly to decision-makers’ needs.
The project’s potential impact spans science, society, economy, and policy. Scientifically, CodeBlue will deliver the first inter-comparable, basin-wide datasets and modelling tools capturing biogeochemical processes from local to regional scales. Economically and societally, the project supports sustainable blue-economy development by analysing how nutrient management affects aquaculture, coastal management, and food security. Environmentally, improved assessments and scenarios will underpin more effective restoration of marine ecosystems, contributing to global and European targets including the EU Green Deal, the Marine Strategy Framework Directive and the UN Sustainable Development Goals. For public authorities, the project will harmonise assessment methods across conventions, strengthen policy coherence, and provide updated evidence to revise definitions of good environmental status. CodeBlue also adds value culturally and institutionally by enabling coordinated stewardship of Europe’s marine environment and enriching the data holdings of major scientific institutions.
The expected final results include large-scale, harmonised multi-model datasets; long-term and future scenario simulations; refined assessment tools; methodological guidelines; a suite of policy briefs; scientific analyses and peer-reviewed publications; and a user-oriented Decision Support Tool accessible through EMODnet and aligned with Digital Twin of the Ocean initiatives. Short-term valorisation will arise through direct integration into ongoing HELCOM and OSPAR processes, as well as stakeholder workshops and blue-pilot case studies. Medium-term benefits include adoption of improved nutrient thresholds, better spatial planning for aquaculture and coastal industries, and transferable modelling and assessment approaches applicable to other European seas. Ultimately, CodeBlue will deliver a durable scientific and governance framework to guide effective, climate-resilient eutrophication management across interconnected marine regions.
