Global shipping will have a bigger effect than climate change on the spread of non-native life forms.

A rise in ship traffic along important sea routes threatens to boost the spread of invasive species.

Sea transport accounts for the bulk of international trade in finished goods and raw materials. But ship traffic also allows non-native species, such as the microorganisms and algae that accumulate on ship hulls, to spread to distant places where they can cause severe harm.

Using models of economic growth to predict global trade, Anthony Sardain at McGill University in Montreal, Canada, and his colleagues estimate that ship traffic will at least triple, and possibly increase more than twelvefold, between 2014 and 2050. Models of marine biological invasion suggest that this projected surge in ship traffic could dramatically raise the risk of invasion. The team’s modelling pinpoints Northeast Asia, which exports huge volumes of cargo, as the most important source of invasive species.

The researchers found that shipping growth will likely have a far greater effect on the spread of non-native species than the environmental effects of climate change.