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Any management strategy for the Baltic Sea must take into consideration possible future changes of the range of drivers affecting the state of the Sea including climate change.

The Baltic Sea has changed drastically during the last century due to succes- sively higher pressures from human activities. Increasing nutrient loads have made the Sea shift from oligotrophic (nutrient poor) to eutrophic (nutrient rich). This has caused increased production of phytoplankton, which in turn has influenced the ecosystem functions in several ways. Potentially dangerous algal blooms have increased tenfold, as have sea bottoms with low or no oxygen and thereby poor conditions for fish spawning. Due to these changes and to overfishing the food web has undergone regime shifts from seal domi- nation in the early 20th _{century to cod domination after the 1950s. An abrupt}

shift from cod to domination by sprat and herring occurred in the late 1980s. See Figure 9.1.

Sea traffic has increased and caused unintentional and intentional oil spills, as well as releases of other hazardous chemicals. Vessels bring alien species to the Sea and warmer sea temperature increases the possibilities for invasive species to survive. Increases in consumption, production and waste have lead to littering of the coasts and the Sea.

Through the HELCOM agreement (HELCOM, 2007a) on the Baltic Sea Action Plan (BSAP) the nine littoral countries have undertaken to reduce nutrient loads and are struggling to implement the plan. BalticSTERN research has shown that doing so will provide clear welfare benefits. BSAP also sets goals regarding biodiversity conservation, hazardous substances and shipping.

At the same time new challenges appear. Recent modelling shows that climate change will lead to a warmer and less saline Sea and that climate effects will be seen earlier than previously thought. Some scenarios for long- term development envisage significant increases of drivers such as agricultural production and traffic (sea and land transports).

Climate change is not taken into account in the scenarios developed within the Cost-Benefit Analysis (CBA) of the BalticSTERN as it was supposed to have little effect up to the year 2050, which was the time span of the scenarios. Furthermore, the Business-As-Usual (BAU) scenario of the CBA is based on a fairly marginal increase of drivers. Nevertheless, this scenario envisages a gloomy development for large parts of the Baltic Sea. As illustrated in the maps in Figure 11.1 (see also Chapter 2.1) only two of the basins – Bothnian Bay and Kattegat – would be in an acceptable state in 2050. The Baltic Proper would be in a really bad condition with very turbid water, blue-green algae blooms in large areas every summer and with constant oxygen shortages in sea bottoms in large areas. Underwater meadows would be almost lost and non-suitable for fish spawning. There would be almost no cod, fewer sprat and herring but lots of roach, carp and bream.

BAU 2050 BSAP 2050

Figure 11.1. Maps showing the situation in the Baltic Sea 2050 in a BAU (11a) and a BSAP

(11b) scenario respectively.

The modelling made within ECOSUPPORT (see Chapter 10) indicates that in a worst-case non-action scenario, with substantial increases of drivers and where climate change is accounted for, the consequences will be even more drastic. An even larger increase of nutrient loads, subsequent rise of algae blooms and cod populations close to extinction in the whole Baltic Sea may be the result. Risks for, maybe not yet fully understood, feedback mechanisms may enhance the risk of surpassing thresholds and may trigger the ecosystem into a situation that is even worse.

In Chapter 1 a table was presented (Table 1.1) indicating that outcome of measures has to be looked at assuming both a best-case and a worst-case scenario for development of drivers. It was also indicated that the Cost- Benefit-Analyses (CBA) of the BalticSTERN action and non-action scenarios would be based on a best-case scenario regarding the development of drivers. In Table 11.1 the results from the BalticSTERN CBA are presented. Subse- quently Table 11.1 illustrates costs and benefits for action and non-action in a best-case scenario.

Table 11.1. Costs and Benefits of Action and Non-action regarding mitigation of eutrophication in a time perspective of 2050, assuming best-case development of drivers.

Best – case scenario

Costs Benefits

Action towards BSAP targets for nutrient loads

< 2 300-2 800 million Euros > 3 800 million Euros

No further action Only Bothnian Bay and Kattegat would be in a good condition. All other basins would be in an unaccept- able condition. Baltic Proper would be worst off with very turbid water, blue-green algae blooms over large areas every summer, underwater meadows almost lost and unsuitable for fish spawning, almost no cod, fewer herring and sprat, constant oxygen shortage in large bottom areas and extinction of bottom animals. Loss of recreational and existence values

> 3 800 million Euros annually

As the required measures under a best- case scenario are not implemented the costs of these are avoided (<2 300 – 2 800 million Euros annually)

The costs and benefits for action+ and non-action in a worst-case scenario, based on the outcome of ECOSUPPORT, is illustrated in Table 11.2.

Table 11.2. Costs and Benefits of Action and Non-action regarding mitigation of eutrophication in a time perspective of 2050, assuming worst-case

development of drivers.

Worst – case scenario

Costs Benefits

Action+ The required measures under a Worst-case scenario would be larger than in the Best-case scenario, implying larger costs

> 3 800 million Euros to infinite

No further action

Continuous increase of nutrient loads and subsequent increase of algae blooms in the whole Sea. Cod almost extinct and fewer sprat and herring. Adding a longer time perspective (2100) and non-action regarding additional environmental problems, there may be system collapses – and costs may be infinite

As the required mea- sures under a Worst- case scenario are not implemented, the costs of these are avoided, costs that would be compared to in the Best- case scenario

Regardless of how the drivers will evolve in the future (i.e. worst-case or best-case), Tables 11.1 and 11.2 indicate that it is motivated to take further action aimed at improving the state of the Baltic Sea. As this report has illu strated, the environmental problems of the Baltic Sea are complex and interlinked, and there are uncertainties regarding future drivers and risks of regime shifts.

The implications of these preconditions when setting up management strategies will be discussed in the following.