Invasive species - if climate change adaptation goes wrong

To “transplant” certain plant or animal species may be a feasible strategy in farming or forestry to cope with changing regional climate and weather conditions. But this also increases the risk of the introduction – intentionally or unintentionally – of invasive species and accompanying organisms into other ecosystems. The threat from release of so-called “invasive species” which cause environmental, human or economic damage, may accumulate on account of the climate change-induced vulnerabilities of the host natural ecosystems.

The global economic costs linked to the introduction of invasive species are already huge.¹Invasive species cost global agriculture an estimated USD 540 billion annually.²The US economy alone faces a hit of more than USD 100 billion per year.³ There is evidence that a trend of rising losses will continue.

Invasive alien species, creatures and organisms that have spread beyond their original habitat — whether through human agency or not — can have significant negative impact on existing species diversity, the natural ecosystem and human health, as well as on the economy as a whole. Climate change and globalisation can add to the proliferation of invasive species. Rising temperatures, rainfall, humidity and drought can facilitate their spread andestablishment, thereby strengthening their invasive ability.⁴

The resulting damage can include yield loss in agriculture, illnesses such as the West Nile Virus (carried by invasive mosquitos), land alteration, infrastructure damage and/or income reduction. There are large management costs (eg, research and control) associated with mitigating or eradicating invasive influences.

Climate change challenges the resilience of natural habitats to biological incursions, while simultaneously making natural habitats, agricultural and urban areas more vulnerable.⁵ The development of effective control and mitigation strategies are being hampered by the lack of awareness on the part of the general public and decision-makers about the consequences of bringing non-native species into new habitats. A historic example is the afforestation efforts of emperor Menelik II who introduced Eucalyptus trees to Ethiopia in the 1890s. Whilst they have several advantages, eucalyptus trees can negatively impact biodiversity and consumes a lot of water, thus reinforcing water scarcities already aggravated by climate change.⁶

Invasive plants and pests threaten food security, particularly in low- and middle-income countries that lack the means to prevent or manage such invasions. One example is the proliferation of the water hyacinth, an invasive species that has degraded aquatic ecosystems in many warmer regions of the world, causing environmental and cultural problems. It spreads rapidly, forming dense cover on the surface of freshwater bodies, blocking waterways, limiting boat traffic, and affecting fishing and trade. In Lake Victoria in eastern Africa, it can grow to such densities that ships cannot leave docks. The same could happen in other parts of the world.