Key messages:

The thematic assessment of invasive alien species and their control produced by the Intergovernmental Science Policy Platform on Biodiversity and Ecosystem Services (IPBES) critically evaluates evidence on biological invasions and impacts of invasive alien species. In alignment with the UN Sustainable Development Goals and the Kunming-Montreal Global Biodiversity Framework adopted by the Conference of the Parties of the Convention on Biological Diversity, the assessment outlines key responses and policy options for prevention, early detection, and effective control of invasive alien species and mitigation of their impacts in order to safeguard nature, nature’s contributions to people, and good quality of life.

More than 37,000 established alien species, including more than 3,500 invasive alien species with documented impacts, have been recorded worldwide. In 2019, global annual costs of biological invasions were estimated to exceed $423 billion, with variations across regions, but this is likely a gross underestimation. Ninety-two per cent of this cost is attributed to the damage that the invasive alien species have caused to nature’s contributions to people and good quality of life; only 8 per cent is related to the management expenditures for biological invasions. The benefits to people that some invasive alien species provide do not mitigate or undo their negative impacts, which include harm to human health (such as disease transmission), livelihoods, water security, and food security, with reduction in food supply being by far the most frequently reported impact (more than 66 per cent).

Invasive alien species are a major threat to nature, nature’s contributions to people, and good quality of life

• People and nature are threatened by invasive alien species in all regions of Earth.

• Invasive alien species cause dramatic and, in some cases, irreversible changes to biodiversity and ecosystems, resulting in adverse and complex outcomes across all regions of Earth, including local and global species extinctions.

• The economy, food security, water security, and human health are profoundly and negatively affected by invasive alien species.

• Invasive alien species can add to marginalization and inequity, including, in some contexts, gender-and age-differentiated impacts.

• Overall, policies and their implementation have been insufficient in managing biological invasions and preventing and controlling invasive alien species.

Globally, invasive alien species and their impacts are increasing rapidly and predicted to continue rising in the future

• Many human activities facilitate the transport, introduction, establishment, and spread of invasive alien species.

• The threats from invasive alien species are increasing markedly in all regions of Earth, with the current unparalleled high rate of introductions predicted to rise even higher in the future.

• The ongoing amplification of drivers of change in nature may substantially increase the number of invasive alien species and their impacts in the future.

• The magnitude of the future threat from invasive alien species is difficult to predict because of complex interactions and feedback among direct and indirect drivers of change in nature.

Invasive alien species and their negative impact can be prevented and mitigated through effective management

• The number and impact of invasive alien species can be reduced through management of biological invasions.

• Prevention and preparedness are the most cost-effective options and thus crucial for managing the threats from invasive alien species.

• Eradication has been successful, especially for small and slow-spreading populations of invasive alien species, especially in isolated ecosystems.

• Containment and control can be an effective option for invasive alien species that cannot be eradicated for various reasons in terrestrial and closed water systems but most attempts in marine and connected water systems have been largely ineffective.

• The recovery of ecosystem functions and nature’s contributions to people can be achieved through adaptive management, including ecosystem restoration in terrestrial and closed water systems.

• Engagement and collaboration with stakeholders and Indigenous Peoples and local communities improves outcomes of management actions for biological invasions.

Ambitious progress to manage biological invasions8 can be achieved with integrated governance 

• Through a complementary set of strategic actions, integrated governance can limit the global problem of invasive alien species throughout the biological invasion process and at local, national, and regional scales.

• The threat of invasive alien species could be reduced with closer collaboration and coordination across sectors and countries to support the management of biological invasions.

• The Kunming-Montreal Global Biodiversity Framework provides an opportunity for national governments to develop or update aspirational, ambitious and realistic approaches to prevent and control invasive alien species.

• Preventing and controlling invasive alien species can strengthen the effectiveness of policies designed to respond to other threats to biodiversity and contribute to achieving several Sustainable Development Goals.

• Open and interoperable information systems will improve the coordination and effectiveness of management of biological invasions, within and across countries.

• Public awareness, commitment and engagement and capacity-building are crucial for the prevention and control of invasive alien species.

• There is compelling evidence for immediate and sustained action to manage biological invasions and mitigate the negative impact of invasive alien species.