Abstract
The Offshore Renewables sector is expanding rapidly, with the growth of the sector motivated by policies to mitigate anthropogenic climate change and increase energy security, driven by ambitious targets including the delivery of 43-50GW of offshore wind at a UK level by 2030. Assessments of the potential ecological impacts of developments must be undertaken to meet the legislative requirements of the EIA Directive (2011/92/EU), Marine Strategy Framework Directive (EC/2008/56), Habitats Directive (EC/92/43), Birds Directive (EC/79/409) and derived legislation. Ornithological impacts are of particular concern, given the global importance of UK seabird populations and the sensitivity of protected seabird species to offshore wind developments.
Assessments of ornithological impacts are complex and typically involve substantial uncertainty. Within this context, the legislative framework requires a precautionary approach to decision-making. Reduction of uncertainty offers direct potential to reduce consent risk by reducing the necessity for precaution. Improved quantified of uncertainty is also crucial, however, since a failure to properly quantify uncertainty, or effectively use information on uncertainty in decision-making, introduces the risk that precaution will be applied inappropriately. Improved quantification of uncertainty reduces this risk, and allows potential approaches for the reduction of uncertainty (e.g., via additional data collection or novel methods of analysis) to be evaluated and prioritised, leading to the reduction of consent risk as new evidence become available.
The key objective of the AssESs Project ("Assessing the extent and significance of uncertainty in offshore wind assessments") is to evaluate the extent and significance of uncertainty within ornithological offshore wind impact assessments, and subsequently provide recommendations for how priority sources of uncertainty can be reduced and how precaution should be applied within the assessment process. The main objectives of this work are to:
- Identify and assess uncertainty and approaches to evaluating uncertainty in ornithological offshore wind impact assessments.
- Evaluate the significance of parameter uncertainty on the outputs of ornithological impact assessments, including how sources of uncertainty interact through the assessment process for both individual projects and cumulatively.
- Seek stakeholder views on how precaution should be applied, accounting for the extent and significance of uncertainty. Define a set of recommendations to address a) the reduction of uncertainty in assessment methods, and b) the treatment of uncertainty within ornithological offshore wind impact assessments.
The AssESs Project is divided into four work packages. Within Work Package (WP) 1 we review the approaches and tools that are commonly used in ornithological assessments within the UK context, review evidence around levels of uncertainty within inputs to assessments, and provide an updated version of the roadmap for reducing and better quantifying uncertainty developed in Searle et al. (2021, 2023a). WP2 then undertakes sensitivity analyses to evaluate the sensitivity of key outputs from assessments to the values of input parameters, with the structure of these analyses being informed by both stakeholder engagement and the outputs of WP1. The outputs from these two work packages are then used within WP3 to inform a structured process of stakeholder engagement (workshops and interviews) to explore the use of uncertainty and precaution within assessments. Finally, WP4 will develop recommendations around (a) changes to treatment of uncertainty within assessments and (b) future research priorities.
This report summarises WP1. Section 2 (“Commonly used tool and methods”) focuses on reviewing Statutory Nature Conservation Body (SNCB) guidance in order to summarise the approaches and tools that are commonly used in ornithological assessments within the UK context. Note that this review was conducted in August 2024, and so is not able to capture changes to guidance that have occurred subsequent to this: in particular, it does not include the updating of NatureScot guidance on collision risk modelling (CRM) to reflect JNCC et al. (2024). Section 3 (“Sources of uncertainty in parameters”) reviews sources of evidence that are used to specify the values of biological parameters used within these approaches and tools, and the uncertainty within these values - the focus is both of quantified levels of uncertainty and reporting of the metrics used to character this (standard errors, standard deviations, confidence intervals, ranges, bootstrap samples) and on broader, more qualitative, sources of uncertainty (e.g. around selection of underlying sources of information, evaluation of transferability, and selection of model structures). Section 4 (“Update to uncertainty roadmap for ornithological offshore wind impact assessments”) provides an update of the roadmap in Searle et al. (2023a) to account for both research activities that have begun since publication of that paper, and to identify knowledge gaps that have emerged, or increased in importance, since publication of that paper.