The Netherlands request on Cumulative Impact Assessment, on behalf of the Greater North Sea Basin Initiative (GNSBI)

<p dir="ltr">ICES reviewed selected cumulative impact assessment (CIA) methods and applications. These methods provide contrasts in terms of purpose, spatial resolution, and requirements for qualitative, semi-quantitative, or quantitative data and information. All methods are cross‑sectoral and identify or quantify risk. Risk is defined, in this context, as the likelihood and magnitude of impact on an ecosystem component.</p><p dir="ltr">The basis of all CIAs is a linkage framework, comprising impact chains that link stressors to receptors via human activities, pressures, and ecosystem components. Data demands increase with more highly resolved activities, pressures, and ecosystem components, or with increased spatial resolution. In relatively data‑rich regions, which are a focus for the Greater North Sea Basin Initiative (GNSBI), applications of more complex CIA methods with more highly resolved impact chains are feasible and documented. Spatially resolved CIA methods are necessary to provide a link to marine spatial planning (MSP) processes and give flexibility to provide outputs at different scales and resolutions.</p><p dir="ltr">CIAs estimate risks of impacts that may compromise achievement of policy objectives. To guide management, assessments must be applied in the context of relevant policies and the associated social–ecological system (e.g. objectives, targets, and governance). If CIAs are to support management in GNSBI regions, ICES emphasizes the importance of progressively strengthening links between the assessments and other parts of the management framework and process. ICES also emphasizes the importance of process-based models to assess and refine the selection of candidate management measures for activities at project and/or sectoral levels.</p><p dir="ltr">ICES proposes common principles for CIA methods. These define good practice in CIA method development and application. The principles apply to CIAs in general and address terminology; uncertainty, confidence and transparency; flexibility and transferability; integration; and implementation practice.</p><p dir="ltr">ICES developed evaluation criteria for CIA methods. These criteria were applied to evaluate whether CIA methods were suitable to address questions and applications listed by GNSBI. This evaluation did not consider whether CIA methods fulfilled purposes originally defined by their developers and proponents.</p><p dir="ltr">No CIA method met all evaluation criteria. To address GNSBI questions and applications, a CIA method needs to be spatially resolved. Spatial Cumulative Assessment of Impact Risk for Management (SCAIRM) is a spatially resolved CIA method and met most other evaluation criteria. SCAIRM is structured in a way that can be incrementally extended while remaining operational and has been applied in the Greater North Sea. For these reasons, ICES advises that it is a suitable method to begin addressing GNSBI questions and applications. For subsets of the questions and applications, especially those requiring ordinal comparison of risk, other CIA methods are also appropriate.</p><p dir="ltr">None of the reviewed CIA methods were developed to address the questions and applications identified by GNSBI. However, ICES notes that repurposing and developing existing CIA methods for GNSBI provides efficiencies. This is because existing CIA methods fulfil some evaluation criteria, and significant time and resources are needed to develop new CIA methods.</p><p dir="ltr">CIA methods usually allow new data and information to be added in a stepwise way without compromising operability. Priorities for collection of data and information may be determined from qualitative and semi-quantitative CIAs, which identify impact chains linked to the greatest risks. There is a trade-off between the benefits of increasing the resolution of impact chains and the costs of acquiring data and information needed to complete the assessments.</p>