The number of new instances of non-native species documented is increasing around the globe — growth that shows no sign of slowing.

The introduction of alien species can disrupt ecosystems and even cause local extinctions. Hanno Seebens at the Senckenberg Biodiversity and Climate Research Centre in Frankfurt, Germany, Franz Essl at the University of Vienna and their colleagues assembled a data set of 45,813 records, dating back to the 1500s, detailing the first arrival of an alien species. They show that such 'first records' have increased in the past 200 years, from an average of 7.7 per year between 1500 and 1800 to a record 585 in 1996. The rise in these records in the past 200 years was found in all taxa, with the exception of mammals and fishes, in which rates have declined in recent decades.

Alien numbers will probably continue to rise for years to come, despite efforts to curb them.

Nature Commun. (2017)