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expert reaction to IPBES invasive alien species assessment report

The Intergovernmental Platform on Biodiversity and Ecosystem Services (IPBES) have published a new report on the rising threat of invasive species.

This Roundup accompanied an SMC Briefing.


Professor Dame Angela McLean, Government Chief Scientific Adviser, said:

“The new IPBES report on Invasive Alien Species provides robust scientific assessment of the challenges we need to overcome to halt and reverse global biodiversity loss.”


Prof John Spicer, Professor of Marine Zoology, University of Plymouth, said:

“That invasive species are a major proximate cause of biodiversity loss and disruption has been known for a while. What is new and most shocking in this latest IPBES report is the scale of the estimated global economic cost of these invaders. That cost has quadrupled each decade since 1970, and is now much greater than $400 billion each year, a sum slightly greater than the GDP of Denmark last year. Here, and with each new evaluation of threats to biodiversity, there is a common, a persistent message. The scale of, and rate of projected change in, threats to our very existence increase at an even more alarming rate, while the window of opportunity to act shrinks.  You can only hit the ‘snooze’ button so many times!”


Professor Robin Pakeman, senior plant ecologist at The James Hutton Institute, said:

“By bringing together scientific experts in invasive species, IPBES have again produced an informative, rigorous and comprehensive account of the huge problems that invasive species are around the world. These issues are global, but even in a wealthy, intensively managed country like the UK, we have serious issues with invasive species. These include serious losses of biodiversity as a result of the invasion of western woodlands by rhododendron or of moors and heaths by Sitka spruce, but also serious economic issues due to Japanese knotweed affecting buildings and grey squirrels damaging growing trees. These are all obvious invasive species, but we are also seeing the loss of many of our ash trees due to an invasive fungal disease – ash dieback.

“The report is clear that prevention is cheaper and better than cure. We need better systems to prevent the spread of invasive species. This, ultimately, boils down to the real issue that biodiversity and ecosystem services are not part of everyday thinking in a globally connected world where trade drives the movement of species around the world.

“Much more effort is needed globally to address the potential movement of species and to try and identify and respond to invasions before they become a serious issue. In reality, once an invasive species becomes a problem, then it is too late for an easy solution. We need the issue treated seriously locally, nationally and internationally.”


Dr David Cooke, research leader, cell and molecular sciences, The James Hutton Institute, said:

“The IPBES summary report is well-researched and comprehensive. It is a damning statement on the current huge impact and ongoing and unrelenting threats of invasive species to nature, economies, food security and human health. But it also offers glimmers of hope in terms of some preventative measures that can be taken.

“A concern for all will inevitably be whether the report will be noted and acted on – and by who – when seen against so many other current global challenges. It is, however, crucial that action is taken. It may be optimistic to dismiss the following statement in the report as hyperbole: “… invasive species have become one of the five horsemen of the biodiversity apocalypse that is riding down harder and faster upon the world.”

“The report summary could place more stress on the impact of “free trade”, which sometimes seems to come at any price. As the report shows, the relative impact of transport on invasive species spread is almost off the chart at “massive”, compared to other drivers, in Figure SPM.5 (page 19).

“As a plant disease expert, I feel the report may under appreciate the impact of threats from microorganisms to crops and plant communities. The COVID pandemic, representing a dramatic example of a biological invasion that spread from wild animals to humans, should surely focus our minds on the potential for spread between humans and plants.

“Co-evolution of pests, diseases and plants over time leads to stable environments, but global trade, taking disease and pests with it, can upset the equilibrium with ecologically dire consequences. We are already seeing clear cases where microbial diseases, that appear harmless on native hosts, cause devastation on crops or plants in natural environments elsewhere. These events are generally driven by a trade in plants that would benefit from greater investment in regulation and inspection to prevent the next pandemic.”

“The report’s authors acknowledge weaknesses in governance (see section below from page 27) and stress the need for better alignment to help reduce threats, such as the risk to native plant and crop ecosystems from microbial diseases such as Xylella (a bacteria causing severe death of olive trees), Phytophthora (including P. ramorum, which is causing damage to larch trees, P. austrocedri, which is impacting juniper trees, and others) and Hymenoscyphus (the ash die back fungus).

“Ambitious progress to manage biological invasions can be achieved with integrated governance. The work under various relevant international organizations, partnerships and multilateral environmental agreements (e.g., the Convention on Biological Diversity, World Trade Organization, International Maritime Organization, International Plant Protection Convention, World Organisation for Animal Health, Convention on the Conservation of Migratory Species of Wild Animals and Convention on International Trade in Endangered Species of Wild Fauna and Flora) is not adequately aligned to address the problem posed by invasive alien species (well established).”


Professor Rick Stafford, Chair of the British Ecological Society Policy Committee, said:

“This report is a wakeup call for the world on the growing threats that invasive alien species pose for nature, human health and livelihoods. It lays out the growing economic costs of biological invasions and provides a comprehensive overview of their many negative impacts on people and nature, yet policies for controlling and preventing them have so far been insufficient.

“With the knowledge that human activities have already led to 37,000 alien species worldwide, it is alarming that the rate of introductions is still increasing. Invasive alien species seriously jeopardise the UK and other countries’ efforts towards meeting the commitment agreed at COP15 to halt and reverse biodiversity loss by 2030.

“On a positive note, the report gives compelling evidence for the success of immediate and sustained action to manage biological invasions and mitigate their negative impacts. It is clear that prevention is the most successful and cost-effective management option, and this should mark a turning point in our management of invasive alien species. The report provides a strong message that to combat the negative consequences of invasive species, coordinated collaboration across sectors and countries is key, including raising awareness and engaging with local communities.”


Dr James Bell, Quantitative ecologist, Rothamsted Research, said:

“This report represents a significant milestone and provides much needed evidence on how people and nature are under extreme pressure from more than 3,500 invasive alien species across the globe.”

“Professor Helen Roy is a world-leader in invasive alien species monitoring and her team provides the evidence base to underpin the UK’s policy response and species alerts.”

“Early detection and monitoring of these invasive species is key to success, yet still we are very exposed.”

“Effective control is often absent or too complicated, and therefore prevention is better than cure. Take, for example, the Box Tree Moth caterpillar which has spread rapidly from East Asia through continental Europe and now is systematically defoliating native box plants in southern England, not to mention our beloved garden box plants too – we can only stand and watch.” 

“The UK is not keeping pace with the rapid increase invasive alien species and effective, coordinated control at the national level is imperative.”

“Significant new investments in monitoring infrastructure and control measures are needed to help nature conservation identify and then mitigate against the growing threats.”

“Several recent invasions into the UK should have us worried about the near future and beyond. These include the impact of the Asian Hornet on our honey bees, the devastating effects of the fast-spreading Himalayan Balsam on our treasured nature reserves and the growth of ‘crayfish plague’, a disease spread by the invasive American signal crayfish, that sets to wipe out our native white-clawed crayfish.”


Dr Alexander Lees, Reader in Biodiversity at Manchester Metropolitan University, said:

“By moving species around the planet, inadvertently or otherwise, humanity is fundamentally reshaping the ecology of the biosphere, driving biodiversity loss and impoverishing vital ecosystem services at a vast financial cost. The new IPBES report on Invasive Alien Species should be a wake-up call to governments and policymakers of the pressing need to both control – and eradicate if possible, existing invasions and to stop further arrivals. Yet many of the pathways for invasion such as shipping, forestry, agriculture, horticulture, aquaculture and the pet trade still facilitate these introductions. At present, the laissez-faire attitude from decision-makers means we are sleepwalking towards the establishment of a generic global ‘McWildlife’ dominated by invasive species in many areas. The report should stand as a strong rebuttal to the creeping scourge of ‘invasive species denialism’, which may create consensus gaps on the need to eradicate such species. This may include in the UK subjectively beautiful but habitat-altering plants like invasive Rhododendron, or culls of introduced mammals which are a threat to native species, like American Mink. Clearly, we should not demonise species for our own actions in facilitating their spread beyond their native ranges, but we have a clear choice to both right these historical wrongs and stop facilitating further biological invasions.”   



The report ‘IPBES invasive alien species assessment report’ was launched at 13:00 UK time on Monday 4 September 2023.



Declared interests

Dr Alexander Lees: “I have no competing financial interests or personal relationships that have influenced these comments.”

For all other experts, no reply to our request for DOIs was received.

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