Invasive species and climate change: a perfect storm

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Following on from an IUCN call for greater action on addressing invasive species in order to protect biodiversity – the Honolulu challenge, presented at the 2016 IUCN World Conservation Congress – the latest IUCN brief presses home the links between invasive species and climate change.

Climate change facilitates the spread and establishment of many alien species and creates new opportunities for them to become invasive. Climate change also reduces the resilience of habitats to biological invasions However, the inverse is also true: invasive species reduce the resilience of natural habitats, agricultural systems and urban areas to climate change.

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Water hyacinth; photo: CABI

The IUCN brief uses the water hyacinth (Eichhornia crassipes), a global invasive species originating from South America, as a case in point. The plant forms dense cover on the surface of freshwater bodies. Its populations are known to double in as little as 12 days, blocking waterways, limiting boat traffic, and affecting fishing and trade. In Lake Victoria in eastern Africa, it can grow to such densities that ships are unable to leave docks. The brief also highlights the devastating effects of the emerald ash borer beetle (Agrilus planipennis), native to Asia and decimating North American ash species. This species can kill entire forest stands within six years of infestation.

These pests’ negative impacts can be increased by climatic changes. More frequent occurrences of hurricanes, floods and droughts can transport species to new areas and decrease the resistance of habitats to invasions. An increase in global temperatures leads to emerging Arctic shipping passages, which will greatly reduce the time taken for ships to travel from Asia to Europe. This in turn increases the risk of alien species surviving the shorter journey.

These issues are all important as these invasive species are a major threat to global food security, and disproportionately affect low- to middle-income countries which lack the capacity to prevent and manage biological invasions. In order to address these global, regional and national issues, a number of actions are required:

  • National and regional capacity should be increased, in order for countries to be able to directly manage invasive species through scaled-up best practice solutions.
  • Climate change policies should ensure that measures to address climate change do not increase the threat of invasive species. For example, native tree species could be used for carbon sequestration or erosion control rather than introducing species, such as Acacia or Eucalyptus, outside their native range.
  • Climate change considerations should also be explicitly incorporated into invasive species risk assessments, to help identify those species that could become a threat in the future.
  • Ecosystems need to be prioritised according to their vulnerability to climate change, making it possible to establish measures that will prevent invasive species introductions. For example, establishing effective biosecurity measures to manage priority pathways of introduction, supported by early warning and rapid eradication to tackle species before they become invasive.
  • Finally, species also need to be prioritised and managed according to the likelihood they become a global invasive threat due to climate change.

CABI, with its decades of experience dealing with invasive species, is leading the way in the response to this global issue. We are about to launch a new programme, Action on Invasives, which will assemble a coalition of stakeholders to adopt a systems-based approach to tackling invasive species across regions and economic sectors. By developing climate-smart best practise frameworks, we hope to empower low- to middle -income countries to be able to defend against invasive species, detect them if they do break through, and ultimately defeat them.

Find out more about CABI’s work on invasive species by visiting www.invasive-species.org

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