Anne Waiguru

Kirinyaga Governor Anne Waiguru (left) confers with her Embu counterpart Cecily Mbarire (right) during the opening ceremony of the Africa Climate Summit in Nairobi yesterday.

| Francis Nderitu | Nation Media Group

Climate talks: Red alert on invasive alien species

What you need to know:

  • Invasive alien species are the subset of non-native species that are known to have become established, spread and negatively impact nature and people.
  • More than 37,000 alien species have been introduced into regions and biomes around the world through a variety of human activities.

Scientists have found more than 3,500 harmful invasive alien species whose global economic costs will exceed $423 billion annually, according to a new report.

This comes after nations globally agreed last December to reduce the introduction and establishment of priority invasive alien species by at least 50 per cent by 2030 as part of the new Kunming-Montreal Global Biodiversity Framework, a vital but ambitious commitment.

Invasive alien species are the subset of non-native species that are known to have become established, spread and negatively impact nature and people.

The 86 experts from 49 countries, who worked for more than four and a half years on the report, which they say was based on more than 13,000 references, also found that invasive alien species are one of the five most important direct drivers of biodiversity loss, along with changes in land and sea use, direct exploitation of species, climate change and pollution.

According to the Intergovernmental Platform on Biodiversity and Ecosystem Services (IPBES), more than 37,000 alien species have been introduced into regions and biomes around the world through a variety of human activities. This conservative estimate is now rising at an unprecedented rate.

At the formal adoption of the Assessment Report on Invasive Alien Species and their Control in Bonn, Germany, which was released on Saturday in Bonn, representatives of the 143 member states of IPBES noted that, in addition to dramatic changes in biodiversity and ecosystems, the global economic cost of invasive alien species exceeds $423 billion annually, with costs increasing at least fourfold every decade since 1970.

The report also highlights that invasive species pose a serious threat to nature, with 85 per cent of documented impacts negatively affecting people’s quality of life; for example through health impacts, including diseases such as malaria, Zika and West Nile fever, which are spread in Kenya and the rest of Africa by invasive alien mosquito species such as Aedes albopictus and Aedes aegyptii. Invasive alien species are also damaging livelihoods, for example in Lake Victoria, where fisheries have declined due to the depletion of tilapia as a result of the spread of water hyacinth (Pontederia crassipes), the world's most widespread terrestrial invasive alien species. Lantana (Lantana camara), a flowering shrub, and the black rat (Rattus rattus) are the second and third most widespread in the world, with far-reaching impacts on people and nature.

The experts note that, while many alien species have been deliberately introduced in the past for their perceived benefits to humans, the negative impacts of those that do become invasive are enormous for nature and people.

"Invasive alien species have been a major factor in 60 per cent and the sole driver in 16 per cent of the global animal and plant extinctions we have recorded, and at least 218 invasive alien species have been responsible for more than 1,200 local extinctions. In fact, 85 per cent of the impacts of biological invasions on native species are negative," said Prof Pauchard.

He believes that it would be an extremely costly mistake to think of biological invasions as someone else's problem.

"Although the specific species causing damage vary from place to place, these are risks and challenges with global roots but very local impacts, affecting people in every country, from every background and in every community;  even Antarctica is affected,” says Prof Pauchard.

“The report shows that 34 per cent of the impacts of biological invasions were reported from the Americas, 31 per cent from Europe and Central Asia, 25 per cent from Asia and the Pacific, and about seven per cent from Africa," he highlighted.

Prof Helen Roy (UK), co-chair of the assessment, urged governments to take these findings very seriously.

"Invasive alien species are a major threat to biodiversity and can cause irreversible damage to nature, including local and global extinctions, as well as threatening human well-being," she said.

Prof Anibal Pauchard (Chile) and Prof Peter Stoett (Canada) agree with the co-chair, but point out that not all alien species become invasive.

"About six per cent of alien plants, 22 per cent of alien invertebrates, 14 per cent of alien vertebrates and 11 per cent of alien microbes are known to be invasive and pose major risks to nature and people. People with the greatest direct dependence on nature, such as indigenous peoples and local communities, are at even greater risk," the scientists said, adding that more than 2,300 invasive alien species are found on lands managed by indigenous peoples.

"But business as usual is unlikely," Prof Roy continues. "With so many key drivers of change predicted to worsen, the increase in invasive alien species and their negative impacts is likely to be significantly greater.”

“The accelerating global economy, intensifying and expanding land and sea use changes, and demographic shifts are likely to lead to an increase in invasive alien species worldwide. Even without the introduction of new alien species, established alien species will continue to expand their ranges and spread to new countries and regions," she explained, noting that "climate change will exacerbate the situation".

The IPBES experts are worried that there are not enough measures in place to address these challenges.

"While 80 per cent of countries have targets for managing invasive alien species in their national biodiversity plans, only 17 per cent have national laws or regulations specifically addressing these issues. This also increases the risk of invasive alien species to neighbouring states, as the report finds that 45 per cent of all countries are not investing in the management of biological invasions," they said.

"Prevention is absolutely the best and most cost-effective option; but eradication, containment and control are also effective in certain contexts. Ecosystem restoration can also improve the outcomes of management actions and increase the resilience of ecosystems to future invasive alien species," the experts said.

Prof Pauchard listed preventive measures such as border biosecurity and strictly enforced import controls that the report says have worked in many cases, such as in Australasia in reducing the spread of the brown marmorated stink bug (Halyomorpha halys).

“Preparedness, early detection and rapid response have been shown to be effective in reducing rates of alien species establishment, and are particularly important for marine and associated water systems.”

“The PlantwisePlus programme, which supports smallholder farmers in Africa, Asia and Latin America, is highlighted in the report as a good example of the importance of general surveillance strategies to detect new alien species. The immediate urgency of invasive alien species makes this report valuable and timely," said IPBES Executive Secretary Anne Larigauderie.