Title: International policy options to reduce the harmful impacts of alien invasive species
Summary: Alien invasive species are a negative outcome of the closer integration of the global economic system. Trade and travel increase human welfare but also lead to the introduction and establishment of alien species. These species are transported intentionally as objects of trade (e.g., exotic animals for the pet trade) and unintentionally as contaminants (e.g., plant diseases introduced on crop germplasm). As ecosystems become more connected by human activities the number of alien species continues to grow. Impacts from invasive species are likewise growing, and are now recognized as a significant global economic burden, and one of the main drivers of global environmental change. Amongst the most significant costs of invasive alien species are their effects on human health, whether as direct agents of infection, or through their effects on water supply, food security and other ecosystem services. Although coordinated international action is required to manage species invasions, existing international agreements stop short of supporting such action for most invasive species.
All nations are affected by invasive alien species. These range from fungal crop diseases that decrease food production and security, to mollusks that infest power plants and force their temporary closure, to large predatory reptiles established in natural areas after release by pet owners. Collectively, alien invasive species are estimated to cause over a trillion dollars in global annual damages. They reduce human health and welfare, as well as the provision of ecosystem services and biodiversity. All major crops suffer large yield losses from the effects of alien species, and farmers expend much time and expense to mitigate those losses. Most human diseases, including the current H1N1 swine flu pandemic, are caused by alien species that arise in one region and spread, often very rapidly via the airline network, to other nations. The environmental impacts of invasive species are widespread and as variable as the species themselves. They include, for example, the extinction of native species, the transformation of forests to grasslands, and the reduction in the quality and quantity of freshwater supplies.
Developing nations bear a disproportionately large burden from invasive species. These nations have fewer resources both for preventing the arrival of new invaders and for controlling those already established. Agricultural pests in developing countries decrease food security more severely because these nations have greater reliance on domestic food production. Alien invasive human diseases also have greater impacts in developing nations where there is less capacity for sanitation measures and disease treatment.
Finally, emerging infectious diseases such as SARS are appearing more often in developing nations, partly because of close contact between humans and animals that carry and transmit zoonotic diseases.
Preventing the spread and establishment of alien invasive species is an international public good. The risk facing any nation depends both on the efforts made by its trading partners to ensure alien species are not exported, and on its own programs for preventing the arrival and spread of new species. But although the actions of each country confer benefits on other countries, they have little incentive to take these benefits into account and every incentive to free-ride on the preventive actions of others. The result is that invasive species control is everywhere undersupplied. Addressing this problem requires coordinated action to identify and control the spread, through trade and travel, of potentially harmful species. It also requires the generation and dissemination of information on invasive species risks to enable nations to more fully utilize available international treaties (e.g., the SPS agreement) to restrict trade when risks are unacceptably high. Detailed global risk profiles for alien species are already generated for organisms that cause human diseases, and some animal and plant diseases. These support the internationally coordinated actions of the World Health Organization and Centers for Disease Control. Information about the international risks of most other alien species is rarely available, however, and there are few international agreements or agencies that could support coordinated international action based on those risks.
The problem is exacerbated since invasive species control is frequently a ‘weakest-link problem’. That is, the international control of harmful species is only as good as the control exercised by the least effective nation. International action should therefore have a focus on raising the capacity of the weakest links in the chain. This could be achieved in part by establishing an international and publicly available database of known invasive species, detailing their current and potential locations and how they can be transported.
This would allow all nations to modify their trade practices to reduce global invasion risks. At the same time, confronting industries with the full costs of the invasive species that they transport would encourage innovative efforts to prevent invasions, and would prevent the transfer of invasive species costs to broader society.
Many benefits would flow from strengthening international policy for preventing the spread of alien invasive species. The International Health Regulations (IHR) provide a good model for addressing the global risks posed by many invasive species. Harmonization of other international policy instruments, such as the Sanitary and Phytosanitary (SPS) Agreement, with the IHR would both recognize the common processes involved in the transport of all alien species, and provide stronger mechanisms for preventing the spread of all invasive species. There is also scope to strengthen the role of regional trade agreements in containing the risks posed of spreading invasive species within the areas covered by the agreement.
Source: Keller R. and Perrings C. (2010) International policy options to reduce the harmful impacts of alien invasive species, UNEP Ecosystem Services Economics Working Papers,Nairobi, UNEP PDF