A ‘biological invasion’ of alien species is threatening life on Earth – with risks to human health, crops and infrastructure, a new report has found.
About 37,000 alien species have invaded new areas – 3,500 of which are classified as ‘invasive’ with ‘documented impacts’ – including accelerating climate change and wiping out native animal and plant species.
A 2019 estimate of the financial impact of non-native invasive species worldwide was more than $423 billion, but the UN warned this is likely a “gross underestimate.”
The UN ecology body IPBES warns: ‘People and nature in all parts of the world are threatened by invasive alien species.
‘More than 37,000 established alien species have been recorded worldwide, including more than 3,500 invasive alien species with documented impacts. The number of alien species is increasing worldwide at an unprecedented and increasing rate.’
Invasive species that threaten native species include the gray squirrel, which threatens the native red squirrel with extinction, and the Asian hornet, which kills bees.
In Britain, the invasive Asian hornet (pictured) is a threat to native insects, especially honey bees
In Britain, invasive species that threaten native species include the gray squirrel, which threatens the native red squirrel with extinction, and the Asian hornet, which kills bees.
The panel of 90 experts from the Intergovernmental Panel on Biodiversity and Ecological Services (IPBES) warns: ‘Invasive alien species are a major direct driver of change, causing biodiversity loss, including the extinction of local and global species.
‘Invasive alien species alone or alongside other drivers of change have contributed to 60 percent of recorded global extinctions of animals and plants (and at least 218 invasive alien species have caused 1,215 documented local extinctions.’
Ingar Andersen, head of the UN Environment Programme, said that ‘invasive species have become one of the ‘five horsemen of the biodiversity apocalypse’ that is ‘descending harder and faster on the world’.
In Britain, the gray squirrel (pictured) is considered invasive because it outcompetes the native red squirrel for resources
The invasive red fire ant was first found in Europe in 2023 and posed a significant threat to agriculture, ecology and human health
A 2019 estimate of the financial impact of non-native invasive species worldwide was more than $423 billion, but the UN warned this is likely a “gross underestimate.”
“While the other four horsemen – changing land and sea use, exploitation, climate change and pollution – are relatively well understood, knowledge gaps remain around invasive species,” she said.
Species listed in the report as a global threat include Japanese knotweed, European shore crab and Nile perch, a freshwater fish.
Meanwhile, the gray squirrel has been singled out by the British Ecological Society as a major invasive alien species in Britain – both because of the spread of the disease squirrel pox and because it kills young trees by eating their bark.
The report warns that to date, 1,061 alien plants (6 percent of all established alien plants), 1,852 invertebrate alien animals (22 percent), 461 vertebrate alien animals (14 percent) and 141 alien microbes (11 percent) are known to be invasive.
It warns that an additional 200 new non-native invasive species are entering new areas every year, and that by 2050 the number of invasive species will be 36 percent higher than today.
Invasive alien species, alone or together with other drivers of change, have contributed to 60 percent of recorded global animal and plant extinctions
In the Mediterranean, the venomous lionfish has spread so widely that authorities in many areas have been forced to cull the local population
The invasive Japanese knotweed is widespread in Britain and is extremely difficult to remove once the plant has become established
Co-chair of the IPBES panel, Professor Helen Roy from the UK Center for Ecology and Hydrology and the University of Exeter, said the panel of 90 experts from around the world all “drew the same conclusion about the need for urgent action on the of climate change’. and the growing threat of invasive alien species.”
The report states that no single driver of climate change acts in isolation.
Climate warming allows alien species to establish and spread poleward on sea and on land, including in the Arctic and Antarctic regions.
And in mountainous areas, climate change has allowed invasive alien species to expand their range to higher elevations twice as quickly as native species.