Mountains occupy 24 percent of the Earth?s land surface (Kapos et al., 2000) and are home to a large part of the world?s people. It is difficult to say exactly how large a part, because there is no widely accepted definition of mountains. For many years, it has been estimated that one-tenth of the world?s population ? about half a billion people ? lives in mountain areas. Yet a recent study estimates that 26 percent of the world?s population live within or very close to mountain areas. This figure includes not only remote, poor and disadvantaged people and communities, but also urban centres inside and immediately outside mountain valleys, including even such mega-cities as Mexico City, Mexico and Santiago, Chile (Meybeck, Green and Vörösmarty, 2001).
However the mountains and their populations are defined, there is no doubt that mountains influence the lives of billions ? not only those living there, but those in the lowlands as well (Messerli and Ives, 1997). In particular, as the source of much of the world?s water supply (for example, 80 to 100 percent of freshwater in the arid and semi-arid regions of the tropics and subtropics), mountains have a fundamental role for global food security. In some areas of the world as much as 95 percent of available freshwater is used for irrigation and food production; most of this water originates in the mountains. Thus mountains are vital to a large part of the global population.
Yet until a decade ago, mountains played but little part in global discussion on environment and development. The United Nations Conference on Environment and Development (UNCED), held in Rio de Janeiro, Brazil in 1992, presented a unique opportunity for mountains to emerge from the wings (Price, 1998). The inclusion of a specific chapter on mountains in Agenda 21, the plan for action endorsed at UNCED by the Heads of State or Government of most of the world?s nations, placed sustainable mountain development on a comparable footing with other major issues such as climate change, tropical deforestation and desertification. In the decade that followed UNCED, international momentum for support of mountain areas has gathered steadily, culminating in the declaration of 2002 as the International Year of Mountains (IYM).
This article considers the evolution of the inclusion of mountains in the global agenda, the emergence of sustainable mountain development as a development priority, and the primary mountain issues, considered in five basic categories of environment, culture and gender, risk, economics, and policies and legislation.
