Disturbances caused by offshore wind can come from various sources, the most prevalent of which are noise and light. Noise from pile driving during the construction phase is the most significant source. Overall noise levels are lower during the operation phase; noise from an operational offshore wind turbine is lower than ship noise in the same frequency range but remains constant over the turbine’s 20 to 25-year lifespan. Despite this, the cumulative effect of many wind turbines in one area must be monitored and studied to mitigate their possible impact on fish and marine mammals.97,98 This includes potential changes to their behaviour, such as swimming patterns or acoustic abilities. Marine mammals like whales and dolphins, which rely on sound for navigation and communication, can be particularly susceptible to this.99,100 Light disturbance must also be considered. Attraction to lighting, combined with poor weather conditions, can lead birds to fly at lower altitudes, increasing the risk of collision.101 Light disturbance from onshore cable installation may also disrupt the nesting behaviour of marine turtles and disorientate hatchlings.102 Furthermore, electromagnetic fields created by subsea cables can affect sensitive species, though there is still a significant gap in knowledge in this area.103,1042.3 Disturbances 2.4 Pollution Other areas of concern are chemical, plastic and debris pollution. Offshore structures are often coated with antifouling paints, which can leach toxic substances into the water and potentially harm marine organisms. There are also risks associated with service vessel operations, such as the accidental leak of hazardous fluids and the potential for collisions with marine mammals.105 Construction and maintenance activities can generate plastic waste and other debris, which can enter the marine environment if improperly managed. Further up the supply chain, the demand for offshore wind may drive potential land, freshwater and ocean pollution. This occurs when chemicals, heavy metals and highly saline or acidified wastewater from mining activities leach into nature. This can also happen with air pollution from steel production. While approximately 90% of wind turbines are recyclable, their blades are made from polymer composite, primarily reinforced with glass fibre, which makes them extremely hard to break down. As the first wave of early commercial offshore wind installations approach their end of life, there is a risk that most of the blades will end up in landfills or be incinerated. Research by the University of Cambridge shows that turbine blades are set to account for 43 million tonnes of waste in 2050.106 It is worth noting, however, that there have been significant advancements in recycling options as the industry increases commitments to circularity. Offshore wind developers like Iberdrola, Ørsted and RWE, alongside wind turbine manufacturers such as Siemens Gamesa and Vestas, have tested new solutions on the ground and committed to reusing, recycling and recovering 100% of decommissioned blades.107,108,109 Furthermore, with composite materials being used by multiple sectors, the wind industry is also exploring cross-sector collaboration with other composite-using sectors, such as maritime transport, aviation and automotive.110 The cumulative effect of wind turbines in one area must be monitored and studied to mitigate possible impact on seabirds, fish, and marine mammals. Nature Positive: Role of the Offshore Wind Sector 22

Nature Positive Role of the Offshore Wind Sector