Global forecasts of shipping traffic and biological invasions to 2050

Abstract

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. Shipments of natural resources and goods connect distant regions but sometimes move more than their intended cargo. This study models the growth of the global shipping network and the implications for spreading invasive species in a changing climate, forecasting substantial increases in ship movements and a 3- to 20-fold increase in invasion risk in coming decades.