Reducing nutrient pollution in European river basins under climate change and evolving EU policy

In Europe, nutrient pollution from intensive farming and high population density degrades water quality, undermining the water needs of humans and natural ecosystems. Water quality outcomes result from the interaction of management actions and a changing climate, making it difficult to separate the influence of each driver. To devise effective mitigation strategies, a clear understanding of river basin dynamics, nutrient source distributions, and projected climate evolution is required, together with region specific load targets that respect the source to sea continuum—including surface water, groundwater, and marine discharge. Water quality models offer tools for exploring future trajectories that consider changes in climate and nutrient source management.

We (i) compiled existing nutrient load targets for European river basins, highlighting their spatial variability; (ii) developed a set of coupled climate change and EU policy scenarios extending to 2050, representing plausible trajectories of precipitation and policy stringency; (iii) applied a scenario modelling framework that links these drivers to basin scale nutrient fluxes, allowing us to quantify the reductions needed to meet the defined targets; and (iv) evaluated a suite of basic nutrient reduction measures (e.g., optimized fertilizer application, enhanced riparian buffers, upgraded wastewater treatment) for their effectiveness in delivering the required load cuts.

This research highlights the nutrient loading reductions needed to achieve European water policy targets for both inland and coastal ecosystems in a changing climate, offering guidance for sustainable water resource strategies.