ARTICLE Received 16 Feb 2016 | Accepted 28 Dec 2016 | Published 15 Feb 2017 No saturation in the accumulation of alien species worldwide Hanno Seebens et al. # Although research on human-mediated exchanges of species has substantially intensified during the last centuries, we know surprisingly little about temporal dynamics of alien species accumulations across regions and taxa. Using a novel database of 45,813 first records of 16,926 established alien species, we show that the annual rate of first records worldwide has increased during the last 200 years, with 37% of all first records reported most recently (1970–2014). Inter-continental and inter-taxonomic variation can be largely attributed to the diaspora of European settlers in the nineteenth century and to the acceleration in trade in the twentieth century. For all taxonomic groups, the increase in numbers of alien species does not show any sign of saturation and most taxa even show increases in the rate of first records over time. This highlights that past efforts to mitigate invasions have not been effective enough to keep up with increasing globalization. Correspondence and requests for materials should be addressed to H.S. (email: hanno.seebens@uni-oldenburg.de) or to F.E. (email: franz.essl@univie.ac.at). #A full list of authors and their affiliations appears at the end of the paper. DOI: 10.1038/ncomms14435 OPEN NATURE COMMUNICATIONS | 8:14435 | DOI: 10.1038/ncomms14435 | www.nature.com/naturecommunications 1