The research team, led by Leon A. Green-Tkacenko with Michael C. Allen and Julie L. Lockwood, conducted an evidence-mapping exercise using Tethys, a comprehensive repository of marine energy research maintained by the Pacific Northwest National Laboratory. Of the approximately 9,920 publications in the database, the team filtered, screened, and synthesized 354 empirical studies on offshore wind effects on birds, spanning publication dates from 1997 to the present. Each study was then mapped against a widely cited framework for understanding cumulative adverse effects, developed by Goodale and Milman in 2016, which identifies the categories of information required to assess how wind development affects wildlife at the population level rather than the level of a single project.

The framework distinguishes three broad categories of evidence. The first is hazards, meaning the physical changes wrought by human activities that could cause harm, including other wind farms and unrelated anthropogenic stressors. The second is vulnerable receptors, which encompasses identifying which species are most at risk, establishing clear baseline population data before construction, and stating thresholds of mortality that populations can tolerate. The third is exposure, covering the spatial and temporal boundaries over which birds encounter wind facilities, including the lifespan of installations, future development pressures, the life histories and phenology of the birds themselves, and the spatial dynamics of populations and development areas. The researchers subdivided these into eleven measurable subcategories to create a fine-grained picture of what the literature does and does not contain.

The results expose a field that has mastered its fundamentals while leaving its most consequential questions almost untouched. Nearly half of all studies, 46 percent, focused on refining which bird species are vulnerable to offshore wind effects, and 40 percent provided pre-construction baseline data. These are the building blocks of any cumulative assessment, the “known knowns” of the evidence base. But the picture darkens dramatically at the analytical frontier. Only four publications, a mere 1 percent of the dataset, examined the nature of effect pathways, that is, whether impacts from multiple wind farms are additive, synergistic, or countervailing. Just 10 studies, roughly 3 percent, attempted to define acceptable mortality thresholds beyond which bird populations would decline.

The distinction among effect pathways is far from academic. If the mortality caused by individual wind farms simply sums up as more facilities are built, an additive pathway, then current projections may be roughly sound. But if effects are synergistic, meaning they compound non-linearly so that combined impacts exceed the sum of individual facilities, population-level harm could be far worse than anticipated. Conversely, countervailing pathways could partially offset one another; for example, if birds displaced from one wind farm area experience reduced collision risk elsewhere, the combined effect would be less than the sum of its parts. The review found that additive mortality is the default assumption in most analyses, frequently without evidence to justify that choice, and at least one cited study openly acknowledged the lack of support for the assumption. If reality follows a multiplicative or countervailing pathway, cumulative effects are being systematically under- or over-estimated.

The threshold question is equally urgent. Setting a ceiling on tolerable mortality, the point at which additional deaths from wind development would push a population into decline, requires detailed knowledge of species’ life histories and demographic rates. The authors point to potential biological removal, a method originally developed for marine mammal management and later adapted for seabirds, which estimates a maximum sustainable yield of inadvertent mortality in a manner analogous to fisheries models. The technique has been applied only sparingly to offshore wind contexts, but the authors argue it could be deployed far more widely, particularly since the baseline population data it depends on are among the better-studied elements of the evidence base. Individual-based models and population viability analyses offer complementary routes, though uncertainty will always demand a precautionary approach.

Geography skews the evidence base as much as topic does. Of the 305 country-specific publications, 250, or 71 percent, came from Europe, followed by 92 from North America and just four from Australasia. The United Kingdom led with 104 publications, the United States followed with 89, and Belgium, Denmark, Germany, and the Netherlands each contributed ten or more. When the researchers compared publication counts against installed turbine numbers, the United States and United Kingdom emerged as disproportionately well represented, while China and Vietnam, the former hosting the largest number of offshore wind turbines in the world, were conspicuously absent. No publication in the dataset provided evidence on cumulative effects on birds in Chinese offshore waters, and none came from Vietnam at all. Less than 10 percent of studies considered waters beyond the Atlantic Ocean and its adjacent seas.

This spatial bias carries a hidden taxonomic cost. Petrels, shearwaters, and albatrosses, the order Procellariiformes, are far more species-rich in the Pacific than the Atlantic, and the East Asian-Australasian Flyway is the most diverse and threatened migratory bird corridor on Earth, home to critically endangered species such as the Spoon-billed Sandpiper. The review also found that the single-order studies it examined clustered heavily on a few groups: Charadriiformes, the gulls, terns, and shorebirds, with 34 publications; Anseriformes, the waterfowl, with 26; and Suliformes, the cormorants and gannets, with 13. Procellariiformes, despite their reliance on offshore habitats, were the subject of just one study.

The divide between marine and non-marine birds proved equally telling. Of the 354 publications, 189 focused exclusively on marine birds, only 20 on non-marine birds, and 145 on both. For landbirds and other non-marine species that migrate over the ocean, evidence for four entire categories was completely absent: effect pathways, mortality thresholds, facility lifespan effects, and development-area siting. The authors attribute this gap in part to a research bias toward breeding-season studies and to the technical limits of tracking small passerines, which are often too small for high-precision GPS tags. Understanding their over-ocean migrations instead relies on light-level geolocators, radar, and Motus tags, none of which deliver comparable spatial or taxonomic resolution.

The review also highlighted an underappreciated role for so-called gray literature. Government and industry reports, which made up 208 of the 354 included documents, were far more likely than peer-reviewed articles to contain baseline population data, appearing in 50 percent of reports versus 25 percent of journal articles, and discussions of facility-lifespan timescales were nine times more common in reports. Peer-reviewed papers, by contrast, more often addressed spatial patterns at broader scales. The authors argue that both streams of evidence are indispensable and that incorporating underrepresented countries’ gray literature into accessible databases such as Tethys would deliver some of the greatest gains. With 68 gigawatts of offshore wind already installed and a pipeline of 454 gigawatts, and with nearly half of all bird species already in decline, the team concludes that building a more balanced and complete evidence base is essential to decarbonizing the grid without deepening the toll on biodiversity.

The research, published in Communications Earth & Environment, investigates the projected effects of offshore wind development on coastal precipitation across one of Europe’s most densely populated and economically important regions. The Northwest European shelf includes the shallow seas surrounding the United Kingdom, Ireland, the North Sea and neighboring continental coasts. These waters are already central to Europe’s renewable-energy plans, with thousands of turbines expected to be installed or expanded over coming decades. The study asks whether the cumulative presence of these structures could modify regional weather patterns in ways that matter for water resources, flooding, agriculture and climate adaptation.

Wind turbines extract kinetic energy from the atmosphere. As air passes through a large wind farm, the turbines slow the flow and generate turbulence, creating what scientists call a wind-farm wake. The wake can stretch for many kilometers, particularly under stable atmospheric conditions, when relatively cool air near the sea surface is capped by warmer air above. In such situations, vertical mixing is limited, allowing the disturbance created by the turbines to persist and spread downstream. The resulting changes in wind speed, turbulence and vertical motion can affect the transport of heat and moisture through the lower atmosphere.

Rain does not form simply because air contains water vapor. Moist air must usually rise, cool and condense into clouds, and the details of that process depend on atmospheric stability, wind direction, temperature contrasts and the location of weather systems. Offshore wind farms can influence these conditions by changing near-surface friction and redistributing momentum between different layers of the atmosphere. Even a modest alteration in the marine boundary layer—the lowest part of the atmosphere directly affected by the ocean surface—can shift the convergence of air or modify the uplift needed for cloud formation. These effects may then appear as changes in precipitation along the coast.

The study’s projections focus on the combined influence of future wind-farm development rather than treating each turbine as an isolated object. That distinction is important. Individual turbines produce small atmospheric disturbances, but arrays containing hundreds or thousands of machines can behave as a broad, roughened surface. When several wind farms are placed along prevailing airflow pathways, their wakes may interact, amplify or partially offset one another. The atmospheric response can also vary with season and weather regime. A storm crossing the North Sea will interact with turbines differently from a calm, stable winter night or a convective summer shower.

According to the analysis, the projected changes are not expected to create a simple blanket of wetter or drier conditions across northwestern Europe. Instead, the influence is likely to be spatially uneven, with precipitation responses depending on wind direction, the position of the farms and the atmospheric structure above them. Areas immediately downwind may experience altered moisture transport and vertical mixing, while some coastal locations could see changes in rainfall intensity or timing. This is a crucial finding for interpreting the research: the issue is not that offshore wind farms would control the region’s weather, but that large-scale development could subtly reshape existing precipitation patterns.

The potential consequences become more significant because the affected coastline is highly exposed and heavily developed. Cities, ports, transport networks, farmland and industrial zones line the shores around the European shelf. Many coastal communities already face rising sea levels, heavier rainfall extremes and growing pressure on drainage systems. A small average shift in precipitation may have limited practical importance in isolation, but changes in the location or intensity of rainfall could matter when they coincide with high tides, storm surges or saturated soils. For water managers and urban planners, understanding these secondary effects could become part of evaluating the wider footprint of renewable-energy infrastructure.

The researchers’ work also highlights the complexity of representing offshore wind farms in climate and weather models. A numerical model cannot simulate every blade and tower across thousands of square kilometers at the same resolution as the surrounding atmosphere. Scientists therefore use parameterizations, mathematical descriptions that represent the collective effects of turbines on momentum, turbulence and energy exchange. The reliability of the projections depends on how accurately these schemes capture wake behavior, atmospheric stability, sea-surface conditions and interactions between neighboring wind farms. Model resolution, the choice of future energy scenarios and natural climate variability all contribute to uncertainty.

That uncertainty does not make the findings irrelevant. Rather, it shows why offshore energy planning must be connected to atmospheric science. The same modeling frameworks used to estimate precipitation responses can help identify conditions under which wind-farm effects are strongest and determine whether impacts remain local or spread toward the coast. Better observations from research vessels, weather stations, aircraft, satellites and instruments mounted on offshore platforms could improve these estimates. Long-term monitoring would also help distinguish turbine-related signals from ordinary fluctuations caused by storms, seasonal circulation and broader climate change.

The expansion of offshore wind remains a central component of Europe’s strategy to reduce greenhouse-gas emissions, and the study does not suggest that renewable-energy development should be halted. Instead, it adds a new layer to the question of how such infrastructure should be designed. Future planning could consider the spacing and orientation of wind-farm clusters, prevailing wind pathways, sensitive coastal watersheds and regions already vulnerable to flooding. As offshore arrays grow from individual projects into interconnected industrial landscapes, their atmospheric influence may become an increasingly important part of environmental assessment. The message is not that turbines will suddenly rewrite Europe’s weather, but that the clean-energy transition is interacting with the atmosphere in ways scientists are only beginning to map.

Subject of Research: Projected effects of future offshore wind farms on coastal precipitation and atmospheric processes over the Northwest European shelf.

Article Title: Projected impacts of future offshore wind farms on coastal precipitation over the Northwest European shelf.

Article References: Akhtar, N., Elizalde, A., Geyer, B. et al. “Projected impacts of future offshore wind farms on coastal precipitation over the Northwest European shelf.” Communications Earth & Environment 7, 651 (2026). https://doi.org/10.1038/s43247-026-03852-x

Image Credits: AI Generated

DOI: https://doi.org/10.1038/s43247-026-03852-x

Keywords: offshore wind farms, coastal precipitation, Northwest European shelf, wind-farm wakes, atmospheric modeling, renewable energy, climate impacts, rainfall, weather systems, Europe