The global decline in biodiversity remains alarming, despite agreement at the World Summit on Sustainable Development to significantly reduce the rate of loss by 2010. The main causes include deforestation, changes in habitat and land degradation, often linked to the growing impact of climate change. Another threat – the focus of this year’s observance of the International Day for Biological Diversity – is the spread of invasive alien species.

An unwanted by-product of globalization, non-native species are harming ecosystem services, livelihoods and economies throughout the world. The Government of South Africa alone is spending as much as $60 million per year in an attempt to eradicate plants, such as wattles, that are invading valuable farmland, river systems and economically important tourist sites such as the Cape Floral Kingdom.

In the Great Lakes of North America, zebra mussels are affecting shipping, fisheries and electric power generation. Throughout the islands of the Pacific Ocean, rats from foreign ships are exterminating indigenous birds. In many countries in Africa, water hyacinth is clogging lakes and rivers, to the detriment of aquatic wildlife and the communities and industries that profit from it.

There are many other examples of how invasive alien species can affect native biodiversity, agriculture, forestry, fisheries and even human health. Such threats stand to be exacerbated by the other drivers of biodiversity loss, and climate change in particular. The implications for poverty reduction, sustainable development and the Millennium Development Goals are profound.

The Convention on Biological Diversity is addressing the threat of invasive alien species by setting global priorities and guidelines, sharing information and expertise, and helping to coordinate international action. The most cost-effective and feasible method of control is prevention. To be successful, this strategy requires collaboration among Governments, economic sectors and non-governmental and international organizations. A country can only prevent invasions if it knows which species may invade, where they may come from and the best management options for dealing with them.

Individuals, too, have a responsibility. Abiding by local and international quarantine and customs regulations will prevent the spread of insect pests, weeds and diseases. A simple rule applies: leave living organisms in their natural habitats and bring home only memories.

Next year is the International Year of Biological Diversity. Highlights include a high-level segment of the United Nations General Assembly and the 10th meeting of the Conference of the Parties to the Convention on Biological Diversity, in Nagoya, Japan. These events will help to shape future strategies to preserve the planet’s ecosystems. Controlling invasive alien species and addressing the other causes of biodiversity loss is an increasingly urgent task. I urge all Governments, organizations and individuals to renew their efforts to protect life on Earth.