Available translations: Not specified


In a new study, scientists from around the world warn that the threats posed by invasive alien species are increasing. They say that urgent action is required in order to prevent, detect, and control invaders at both local and global levels.

Alien species are plants, animals and microbes that are introduced by people, accidentally or intentionally, into areas where they do not naturally occur. Many of them thrive, spreading widely with harmful effects on the environment, economy, or human health.

The study, published in Biological Reviews, was carried out by an international team of researchers from 13 countries across Africa, Asia, Australasia, Europe, North and South America. It states that the number of invasive alien species is increasing rapidly, with over 18,000 currently listed around the world.

The researchers attribute the escalation in biological invasions to the increase in the number and variety of pathways along which species spread, and to the increasing volume of traffic associated with those pathways. They highlight the role of emerging pathways such as the online trade in unusual pets, and the transport of species across oceans on rafts of plastic.

The study also shows how other drivers of global change, such as climate change, land-use change, alongside international trade are exacerbating the impacts of biological invasions. For example, species transported through shipping can now thrive in new regions, owing to climate warming; and the permanent opening of the Arctic Ocean with global warming is allowing marine species to move between the Atlantic and Pacific Oceans.

The paper is a part of the World scientists’ warning to humanity: a second notice initiative* calling for urgent change in our stewardship of the Earth and the life on it. The authors stress that biological invasions can be managed and mitigated. They point to approaches that are working around the world and make specific recommendations for improved management. For example, the introduction of more stringent border controls, including X-ray machines and detector dogs, has led to a progressive decline in the rate of fungal plant pathogens entering New Zealand.  

Professor Petr Pyšek of the Czech Academy of Sciences and Charles University in Prague, lead author of the paper, says: "As our knowledge about invasive alien species increases, the problems associated with biological invasions are becoming clearer. The threats posed by invasive alien species to our environment, our economies and our health are very serious, and getting worse. Policy makers and the public need to prioritize actions to stem invasions and their impacts."

"The threats posed by invasive alien species to our environment, our economies and our health are very serious, and getting worse. Policy makers and the public need to prioritize actions to stem invasions and their impacts." Professor Petr Pyšek, Czech Academy of Sciences

Professor David Richardson of the Centre for Invasion Biology at Stellenbosch University in South Africa, the other lead author, adds: "Nations such as Australia and New Zealand have made biosecurity a national priority. South Africa has invested heavily in a massive national programme focussed on reducing the negative impacts of widespread invaders on ecosystem services, especially the delivery of water from catchments invaded by alien trees. But action is needed more widely at both national and international levels in order to tackle the challenges effectively."

Professor Helen Roy, an ecologist at the UK Centre for Ecology & Hydrology, who contributed to the paper and is co-chairing a global IPBES study into invasive alien species, says: "It has been so exciting to see developments in our knowledge and understanding of biological invasions in recent decades, achieved through truly inspiring global collaborations. It is so important that we continue to share our knowledge and engage with relevant stakeholders across sectors and borders."


Notes for editors

Full paper reference: Pyšek P, Hulme P E, Simberloff D, Bacher S, Blackburn T, Carlton J T, Dawson W, Essl F, Foxcroft L C, Genovesi P, Jeschke J M, Kühn I, Liebhold A M, Mandrak N E, Meyerson L A, Pauchard A, Pergl J, Roy H E, Seebens H, van Kleunen M, Vilà M, Wingfield M J & Richardson D M: Scientists’ warning on invasive alien species. Biological Reviews. DOI: 10.1111/brv.12627

* World scientists’ warning to humanity

The paper is a part of the World scientists’ warning to humanity: a second notice, an initiative calling for urgent change in of the natural world. 

In 1992, a community of eminent scientists from around the globe put their names to a document warning of that humanity was on a collision course with the rest of the natural world (Union of Concerned Scientists, 1992). Twenty-five years later, Ripple et al. (2017) evaluated the human response and in a ‘second warning’ concluded that humanity had failed to make sufficient progress in dealing with the environmental challenges. Indeed, they found that most of these problems had worsened.

The original 1992 call was supported by more than 1,700 scientists, while in 2017 over 15,000 scientists added their signatures to the declaration.

What is the scale of the problem?

A recent analysis of global extinctions in the IUCN Red List database (IUCN, 2017) revealed that alien species contributed to 25 per cent of plant extinctions and 33 per cent of terrestrial and freshwater animal extinctions. Meanwhile, annual environmental losses caused by introduced species in the United States, United Kingdom, Australia, South Africa, India and Brazil have been calculated at over US$100 billion.

Action against invasive alien species

Since 1992, the importance of taking action against invasive alien species globally has been widely recognized (Millennium Ecosystem Assessment, 2005). The recent global assessment report on biodiversity and ecosystem services by the Intergovernmental Science Policy Platform on Biodiversity and Ecosystem Services (IPBES) ranked invasive alien species fifth among direct drivers of change in nature with the largest relative global impacts, after changes in land and sea use, direct exploitation of organisms, climate change, and pollution.

About the UK Centre for Ecology & Hydrology (UKCEH)

The UK Centre for Ecology & Hydrology is a centre for excellence in environmental science across water, land and air. Our 500 scientists work to understand the environment, how it sustains life and the human impact on it – so that together, people and nature can prosper. We have a long history of investigating, monitoring and modelling environmental change, and our science makes a positive difference in the world.

www.ceh.ac.uk / @UK_CEH