Hans Estrup Andersen

In 2007 HELCOM launched a plan for transboundary management of the Baltic Sea.
This plan, called the Baltic Sea Action Plan (BSAP), aims amongst other things, to
reduce eutrophication in the different regions of the Baltic Sea by reducing incoming
nutrient loads from all discharging drainage basins. This paper investigates the costeffective
distribution of nutrient abatement measures between drainage basins and
Baltic Sea regions, where the aim is to achieve the BSAP nutrient load reduction
targets. The cost-minimisation model BALTCOST, an interdisciplinary development
involving economists and natural scientists, is used to identify the most cost-effective
configuration of abatement measures. BALTCOST utilises detailed regional and
spatial data down to 10 x 10km grid cell level for all Baltic littoral countries.
Modelling results suggest that it should be possible to achieve the BSAP load
reduction targets for N and P in most Baltic Sea regions, with the exception of the P
load target in the Baltic Proper and the N reduction target in the Danish Straits, where
only 74% and 88% respectively, of the desired BSAP load reductions can be
delivered. BALTCOST results indicate that the BSAP targets appear difficult to
achieve, and that additional abatement measures are likely to be required to fulfil
these targets. The minimised total cost of delivering the achievable load reductions
across the 9 Baltic littoral countries is estimated to be 4.69 billion Euros, annually,
with substantial differences in the cost burden between the countries. Comparison of
N and P reductions at source and at sea shows that groundwater and surface water
nutrient retention is highly influential over the costs incurred in fulfilling the load
reduction targets. Disregarding spatial variation in nutrient retention is clearly
unrealistic, and the detailed modelling of nutrient retention, together with the spatially
detailed dataset behind the cost-estimates, are novel features of this study; previous
studies have used more aggregated estimates of retention and regional costs.