Multi-criteria risk assessment of maritime traffic and offshore wind farms in the Northern Baltic Sea

Assessing maritime risk in seasonally ice-covered seas is challenging, particularly where dense shipping activity, severe ice conditions, and offshore wind infrastructure interact. This study develops a regional-scale framework integrating geographic information systems and multi-criteria decision analysis to assess interaction risks between maritime traffic and offshore wind farms (OWFs) in the Northern Baltic Sea. The framework combines 17 hazard, exposure, and vulnerability parameters to generate relative maritime risk index maps under wintertime and open-water scenarios. A scenario-based design compares the influence of ice-related parameters and OWFs on relative risk index patterns while maintaining consistent analytic hierarchy process-derived weights across scenarios. Under baseline ice conditions, high relative risk index areas increased from 2.10% without OWFs to 3.41% with OWFs. Under extreme ice conditions, high and very high relative risk index classes covered 68.73% without OWFs and 76.89% with OWFs, while the very high class increased from 5.69% to 15.52%. These results show that ice-related parameters are the dominant drivers of regional-scale risk increase, while OWFs mainly contribute to local increases in the relative risk index, particularly near existing fairways. The framework supports maritime spatial planners and OWF developers in identifying interaction zones between shipping routes and planned OWF areas in ice-affected seas.