Future socioeconomic conditions may have a larger impact than climate change on nutrient loads to the Baltic Sea

The BalticSea is suffering from eutrophicationcaused by nutrient discharges from land to sea, and these loads might change in a changing climate. We show that the impact from climate change by mid-century is probably less than the direct impact of changing socioeconomicfactors such as land use, agricultural practices, atmospheric deposition, and wastewater emissions. We compare results from dynamic modelling of nutrient loads to the BalticSea under projections of climate change and scenarios for shared socioeconomicpathways. Average nutrient loads are projected to increase by 8% and 14% for nitrogen and phosphorus, respectively, in response to climate change scenarios. In contrast, changes in the socioeconomicdrivers can lead to a decrease of 13% and 6% or an increase of 11% and 9% in nitrogen and phosphorus loads, respectively, depending on the pathway. This indicates that policy decisions still play a major role in climate adaptationand in managing eutrophicationin the BalticSea region.