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Global forecasts of shipping traffic and biological invasions to 2050


Socioeconomic factors, including population growth, global trade and the worldwide transport of materials, interact with environmental drivers to determine the sustainability of natural systems. We focus on the global shipping network, which is central to invasive species spread worldwide. We explain 90% of the variation in global shipping traffic and a twofold increase in shipping using basic socioeconomic indicators and a temporal validation set. Combining our model with global economic development scenarios, we project global maritime traffic to increase by 240–1,209% by 2050. Integrating our predictions with global climate change projections and shipping-mediated invasion models, we forecast invasion risk to surge in middle-income countries, particularly in Northeast Asia. Shipping growth will have a far greater effect on marine invasions than climate-driven environmental changes: while climate change might actually decrease the average probability of invasion, the emerging global shipping network could yield a 3- to 20-fold increase in global invasion risk.

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Fig. 1: Decadal projections of total inter-SER traffic.
Fig. 2: Shipping vessel movements.
Fig. 3: Invasions into each SER under different conditions.
Fig. 4: Breakdown of invasion risk by source SER for each destination SER in 2050 under ‘status-quo’ shipping projections (SSP2: ‘middle-of-the-road’).

Code availability

Code underlying the results will be made available upon request.

Data availability

Historical GDP and population data were obtained from the World Bank Databank (, and forecasted values are accessible through the IIASA SSP database ( Data on inter-country distance, trade agreements, common language, common border and common colonial history are obtainable through the CEPII research centre’s GeoDist and Gravity datasets ( Data on historical ballast releases can be accessed through the NBIC Database ( Current and forecasted environmental variables used in this study are available from the AquaMaps Environmental Dataset ( Data on ship movements and attributes were purchased from IHS Sea-web, are used under license and cannot be publicly shared by the authors. However, these data can be purchased from IHS (


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We thank L. Della Venezia, E. Hudgins, G. Inglis, E. Johnston, D. Nguyen, G. Ruiz and S. Varadarajan for helpful discussions. This research was supported by an NSERC-CGSM grant to A.S., and an NSERC-CAISN and NSERC-Discovery grant to B.L.

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A.S. and B.L. designed the study, analysed the data and wrote the manuscript. E.S. contributed experience and perspectives relating to socioeconomic, shipping and trade components. All of the authors reviewed and commented on the manuscript.

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Correspondence to Anthony Sardain.

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Supplementary Results, Supplementary Discussion, Supplementary Tables 1–4, Supplementary Figures 1–5, Supplementary References.

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Sardain, A., Sardain, E. & Leung, B. Global forecasts of shipping traffic and biological invasions to 2050. Nat Sustain 2, 274–282 (2019).

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