Cumulative effects of offshore renewables: From pragmatic policies to holistic marine spatial planning tools

To alleviate climate change consequences, the UK government is pioneering offshore renewable energy developments at an ever-increasing pace. The North Sea is a dynamic ecosystem with strong bottom-up/top-down natural and anthropogenic drivers facing rapid climate change impacts. To ensure the compatibility of such large-scale developments with nature conservation obligations, regulatory processes set out that all effects need to be evaluated through cumulative impact assessments (CIA). However, by excluding climate change impacts and bottom-up effects of renewable developments, the CIA lacks spatio-temporal baselines linking oceanic ecosystem indicators to population dynamics, leading to uncertain predictions at population levels. CIA is currently required in Europe under the Strategic Environmental Assessment and the Marine Strategy Framework Directive (MSFD), suggesting that these two policy areas should be more closely aligned. This study presents an overview of the current CIA policy framework, enabling an ecosystem-based approach linking lower ecosystem components to top-predator populations using the UK as a case study. At the UK level, CIA requirements mirror the EU ones under the Marine and Coastal Access Act, the UK Marine Policy Statement, and the UK National Policy Statement. Firstly, we show how CIA and MSFD requirements are integrated into the UK licensing and maritime planning frameworks. Secondly, we provide policy pathways embedding the MSFD as a baseline for CIAs with European and UK regulations. Thirdly, we propose a framework encompassing a shared monitoring effort, an ecosystem modelling approach connected with two existing online databases supported with funds from Contracts for Difference. This integrated approach will enable a holistic and pragmatic ecosystem-based framework for more accurate and rapid methods for producing CIAs for offshore renewable energy developments.