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Current and projected global extent of marine built structures


The sprawl of marine construction is one of the most extreme human modifications to global seascapes. Nevertheless, its global extent remains largely unquantified compared to that on land. We synthesized disparate information from a diversity of sources to provide a global assessment of the extent of existing and projected marine construction and its effects on the seascape. Here we estimated that the physical footprint of built structures was at least 32,000 km2 worldwide as of 2018, and is expected to cover 39,400 km2 by 2028. The area of seascape modified around structures was 1.0–3.4 × 106 km2 in 2018 and was projected to increase by 50–70% for power and aquaculture infrastructure, cables and tunnels by 2028. In 2018, marine construction affected 1.5% (0.7–2.4%) of global Exclusive Economic Zones, comparable to the global extent of urban land estimated at 0.02–1.7%. This study provides a critical baseline for tracking future marine human development.

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Fig. 1: Global extent of marine construction.
Fig. 2: Global distribution of the physical footprint of marine construction (2018).
Fig. 3: Global distribution of wind, wave and tidal farms.

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Data availability

The marine construction inventory produced by the authors and original data sources that support the findings of this study are available at An inventory of offshore wind, tidal and wave farms can be found at Source data are provided with this paper.

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No custom computer code or algorithm was used to generate results.


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This research was supported by the Australian Research Council through a Linkage Grant (no. LP140100753) awarded to K.A.D., L.A. and E.L.J. A.B.B. was funded by a Maple Brown Foundation grant awarded to K.A.D. and R.A.C. and an Ian Potter Foundation grant to K.A.D. E.M.A.S. received funding from the World Harbour Project, The Ian Potter Foundation and The New South Wales Government Office of Science and Research. L.A. received funding through the Macquarie University FSE Visiting Researcher Fellowship Scheme. This is Sydney Institute of Marine Science (SIMS) publication no. 259.

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All authors contributed to the original concept of this manuscript, helped in the data-gathering effort and commented on the manuscript. A.B.B., K.A.D., M.M.-P., L.A. and E.L.J. led the implementation of the initial concept and manuscript preparation. A.B.B. led the data-gathering effort, analysed data and prepared the manuscript.

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Correspondence to A. B. Bugnot.

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Extended data

Extended Data Fig. 1 Global distribution of physical footprint of marine construction as of 2018.

Data for aquaculture a, artificial reefs c, marinas d, and oil and gas pipelines e, are expressed per km2 within each Exclusive Economic Zone (grey: missing data). The location of commercial ports and their size (estimated considering physical size and traffic) were sourced from the World Resources Institute b. Oil and gas rigs f, are expressed per km2 within each offshore field. Location of each structure (blue dots) is shown for tunnels and bridges g, breakwaters h, and artificial islands i.

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Bugnot, A.B., Mayer-Pinto, M., Airoldi, L. et al. Current and projected global extent of marine built structures. Nat Sustain 4, 33–41 (2021).

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