Invasive Alien Species a Major Threat

Over 37,000 alien species have been introduced by humans around the world and the threat posed by these invasive alien species are underappreciated, according to a groundbreaking report by the Intergovernmental Platform on Biodiversity and Ecosystem Services (IPBES).

The report sheds light on the severe and often underestimated threat posed by invasive alien species. These species were introduced to various regions and biomes due to human activities. Among them, more than 3,500 are considered harmful and invasive, jeopardizing nature, its contributions to humanity, and the quality of life. Despite their significant impact, these invasive species are frequently ignored until the consequences become dire.


The report, approved by representatives from 143 member states in Bonn, Germany, reveals alarming findings. The global economic cost of invasive alien species exceeded $423 billion annually in 2019, a figure that has quadrupled every decade since 1970. This cost includes not only economic burdens but also profound ecological and social consequences.


Invasive alien species were identified as one of the five primary drivers of biodiversity loss, alongside land- and sea-use changes, species exploitation, climate change, and pollution, in the 2019 IPBES Global Assessment Report. Subsequently, governments tasked IPBES with providing evidence and policy recommendations to address this critical issue. The resulting report, compiled by 86 experts from 49 countries over four and a half years, constitutes the most comprehensive assessment of invasive species worldwide, incorporating insights from Indigenous Peoples and local communities.

Professor Helen Roy, co-chair of the Assessment, underscores the significance of this threat, stating, “Invasive species are a major threat to biodiversity and can cause irreversible damage to nature, including local and global species extinctions, and also threaten human wellbeing.”


The report clarifies that not all introduced alien species become invasive; only a subset establishes and spreads, causing negative impacts on ecosystems and often people. Approximately 6% of alien plants, 22% of alien invertebrates, 14% of alien vertebrates, and 11% of alien microbes are recognized as invasive. Indigenous Peoples and local communities, who depend heavily on nature, face heightened risks, with over 2,300 invasive species affecting their lands, threatening their lifestyles, and even their cultural identities.

Historically, many species were introduced intentionally for perceived benefits, but when they become invasive, the negative consequences are substantial for both nature and society. Professor Anibal Pauchard highlights that invasive species have played a major role in 60% of global animal and plant extinctions and are solely responsible for 16% of these extinctions. Their impacts on native species are predominantly negative, accounting for 85% of documented effects.


In addition to ecological disruptions, invasive alien species have adverse effects on human livelihoods. They damage food supplies, lead to health issues, and harm local economies. For example, the European shore crab has severely affected commercial shellfish beds in New England, and the Caribbean false mussel has damaged vital fishery resources in India. Invasive alien mosquitoes like Aedes albopictus and Aedes aegyptii contribute to the spread of diseases such as malaria, Zika, and West Nile Fever. Invasive alien species also harm livelihoods, as seen in Lake Victoria, where fisheries have suffered due to the spread of water hyacinth.

The report emphasizes that invasive alien species pose a global challenge with local impacts, affecting people in every country, from all backgrounds, and even reaching Antarctica. The Americas, Europe and Central Asia, and Asia Pacific are among the regions with the highest reported impacts, mostly occurring on land, particularly in forests, woodlands, and cultivated areas.


To make matters worse, the report anticipates that the threat from invasive alien species will continue to grow. This is partly due to increasing global trade and human travel, which have led to the introduction of new alien species. Climate change will exacerbate the problem by creating conditions more conducive to the spread of invasive species. Additionally, interactions between invasive alien species and other environmental drivers can amplify their effects, such as invasive alien plants contributing to more intense wildfires.

The report reveals that while many countries have targets related to managing invasive alien species in their national biodiversity plans, only 17% have specific national laws or regulations addressing these issues. Furthermore, 45% of all countries do not invest in the management of biological invasions.

Despite these challenges, the report offers hope, emphasizing that invasive alien species can be managed effectively through a range of measures. Prevention, early detection, and rapid response are key strategies. Eradication has been successful for some species, especially in isolated ecosystems like islands. Containment and control are options in various contexts, and biological control has been effective in specific cases.

The report calls for a holistic, integrated approach across countries and sectors, focusing on policies, governance, public awareness, research, and inclusive governance. It highlights the importance of prevention, preparedness, and engagement with stakeholders and Indigenous Peoples. By taking concerted action, the world can mitigate the threats posed by invasive alien species and protect both nature and human wellbeing.



  • 37,000: alien species established worldwide
  • 200: new alien species recorded every year
  • 3,500: invasive alien species recorded globally, including 1,061 plants (6% of all alien plant species), 1,852 invertebrates (22%), 461 vertebrates (14%) and 141 microbes (11%)
  • 37%: proportion of known alien species reported since 1970
  • 36%: anticipated increase in alien species by 2050 compared to 2005, under a “business-as-usual” scenario (assumes past trends in drivers of change continue)
  • 35%: proportion of alien freshwater fish in the Mediterranean basin that have arisen from aquaculture
  • Impacts
  • 34%: proportion of impacts reported in the Americas (31% Europe and Central Asia; 25% Asia Pacific; 7% Africa
  • 75%: impacts reported in the terrestrial realm (mostly in temperate and boreal forests and woodlands and cultivated areas)
  • 14%: proportion of impacts reported in freshwater ecosystems 
  • 10%: proportion of impacts reported in the marine realm
  • 60%: proportion of recorded global extinctions to which invasive alien species have contributed
  • 16%: proportion of recorded global extinctions in which invasive alien species have been the sole driver
  • 1,215: local extinctions of native species caused by 218 invasive alien species (32.4% were invertebrates, 50.9% vertebrates, 15.4% plants, 1.2% microbes)
  • 27%: invasive alien species impacts on native species through ecosystem properties changes (24% through interspecific competition; 18% through predation; 12% through herbivory)
  • 90%: global extinctions on islands attributed mainly to invasive alien species
  • $423 billion: estimated annual economic cost of biological invasions, 2019
  • 92%: proportion of economic costs of biological invasions attributed to invasive alien species damaging nature’s contributions to people and good quality of life (with the remaining 8% of costs related to biological invasion management)
  • 2,300: invasive species documented on lands managed, used and/or owned by Indigenous Peoples
  • 4x: rise in the economic cost of biological invasions in every decade since 1970          

Policy and management

  • 80% (156 out of 196): countries with targets in national biodiversity strategies and action plans for managing biological invasions
  • 200%: increase in the last decade in the number of countries with national invasive species checklists, including databases (196 countries in 2022)
  • 83%: countries without specific national legislation or regulations on invasive species
  • 88%: success rate of eradication programmes (1,550) conducted on 998 islands

60%: success rates of biological control programs for invasive plants and invertebrates   


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