It is estimated that there are over 180,000 islands in the world (about 50% of which have a surface area of less than 150 km²), a million if small islands and rocks were included. The importance of these unique environments is recognised worldwide: although they account for only 5% of the earth’s surface, islands host 20% of terrestrial plants and vertebrates and 600 million people depend on island ecosystem services for water, food, shelter, medicine, and the resources needed for their daily lives (CBD, 2010).
Various threats, originating from global changes, are endangering their natural, cultural, economic and social heritage, such as pollution (waste, water), biological invasions, worsened by poor connectivity with neighbouring ecosystems, climate change, in some cases is even threatening to submerge certain areas such as the coral islands of the pacific or the Indian oceans, and the destruction of habitats and landscapes, particularly due to land development.
Even though sustainable resource management problems (drinking water supplies and wastewater treatment, access to renewable energy sources, waste management, protection of local bio- and agro-biodiversity) and enhancing the value of heritage (natural, landscape and cultural) are not specific to islands, these issues are particularly acute there: isolation, rarity of resources, limited space, lack of locally available technologies, in other words their «insular nature» generally reduces their range of solutions.
Therefore, small islands share a range of issues and so, inevitably, share common solutions.