The world's mountain systems, including the people in them, have gained international attention in the last few decades. The United Nations' International Year of Mountains-2002 can be regarded as the culmination of a long process involving research, development of research networks, a greater awareness by various sectors of society of the critical importance of mountain regions for a sustainable future, and recognition of that fact by policy makers. This volume reviews recent climatic trends in high elevation regions of the world, assessing the reliability of various environmental indicators that can be used for monitoring climatic change, and assessing whether physical impacts of climatic change in high elevation areas are becoming evident, and to discuss a range of monitoring strategies needed to observe and to understand the nature of such changes.