Biological invasions are a major threat to ecosystems, biodiversity, and human well-being, resulting in ecosystem degradation and causing economic costs in the multi-trillions of euros globally. A study led by McGill University sheds light on the stark economic cost resulting from biological invasions in the European Union (EU). Most invasive alien species are not adequately assessed for their actual and potential economic impacts therefore most cost estimates are grossly underestimated, say the researchers. To fill this gap, the team quantified the economic costs of biological invasions to the European Union, while estimating future invasion costs using predictive models.