The personal safety and well-being of one fifth, and water supply for almost half of all people depend directly or indirectly on the functional integrity of mountain ecosystems, the key component of which is a robust vegetation cover. The green'coat' of the world's mountains is composed of specialized plants, animals and microbes, all nested in a great variety of microhabitats. Because a single mountain may host a series of climatically different life zones over short elevational distances, mountains are hot spots of biodiversity and priority regions for conservation. With their diverse root systems, plants anchor soils on slopes and prevent erosion. Both landuse and atmospheric changes such as elevated CO₂ and climatic warming affect mountain biodiversity. Sustained catchment value depends on sustained soil integrity, which in turn depends on a diverse plant cover. Whether landuse in mountains is sustainable is a question of its consequences for water yield and biodiversity. Given their dependence on mountains, lowlanders should show concern for the highlands beyond their recreational value.

Recent environmental changes are having, and are expected to continue to have, significant impacts in the Arctic as elsewhere in the world. Detecting those changes and determining the mechanisms that cause them are far from trivial problems. The use of multiple methods of observation can increase confidence in individual observations, broaden the scope of information available about environmental change, and contribute to insights concerning mechanisms of change. In this paper, we examine the ways that using traditional ecological knowledge (TEK) together with scientific observations can achieve these objectives. A review of TEK observations in comparison with scientific observations demonstrates the promise of this approach, while also revealing several challenges to putting it into practice on a large scale. Further efforts are suggested, particularly in undertaking collaborative projects designed to produce parallel observations that can be readily compared and analyzed in greater detail than is possible in an opportunistic sample.

High-mountain areas suffer from increasing environmental threats. The causes are often global in dimension but lead to specific impacts under conditions of steep and/or high-altitude terrain with strong effects from snow and ice. This paper presents a global perspective, focussing primarily on observed and projected changes in climate and then goes on to discuss key messages of greatest relevance to the highest belts of mountain regions. The paper finishes with a brief discussion of mitigation strategies

This paper presents an overview of mountain biodiversity at a multitude of scales in space, time, and function. Even though species richness is usually the focal component in nature conservation, genetic diversity within species is equally important. The small-scale distribution of species in the tropical Andes, as exemplified by the plant genera Calceolaria and Bartsia, contrasts against the situation in high-latitude mountains, e.g., the Scandes, where species have wide ranges and many are circumpolar. Recent studies on alpine plants based on molecular methods show that the intraspecific genetic diversity tends to increase with latitude, a situation brought about by the glaciation history with repeated contraction-expansion episodes of species' distributions. In tropical mountains, species distributions are geographically much narrower, often as a result of relatively recent, local speciation. Thus, whereas species richness in mountains decreases from the Equator towards the poles, genetic diversity shows the opposite trend. Finally, a comparison of ecosystem diversity in low- and high-latitude mountain ranges (tropical Andes vs. Scandes) shows that the landscapes differ profoundly with regard to timberline ecotones, snow distribution, and climate variables, and are subject to widely different impacts of global change

Mountains as “Water Towers” play an important role for the surrounding lowlands. This is particularly true of the world's semiarid and arid zones, where the contributions of mountains to total discharge are 50–90%. Taking into account the increasing water scarcity in these regions, especially for irrigation and food production, then today's state of knowledge in mountain hydrology makes sustainable water management and an assessment of vulnerability quite difficult. Following the IPCC report, the zone of maximum temperature increase in a 2 × CO₂ state extends from low elevation in the arctic and sub-arctic to high elevation in the tropics and subtropics. The planned GCOS climate stations do not reach this elevation of high temperature change, although there are many high mountain peaks with the necessary sensitive and vulnerable ecosystems. Worldwide, more than 700 million people live in mountain areas, of these, 625 million are in developing countries. Probably more than half of these 625 million people are vulnerable to food insecurity. Consequences of this insecurity can be emigration or overuse of mountain ecosystems. Overuse of the ecosystems will, ultimately, have negative effects on the environment and especially on water resources. New research initiatives and new high mountain observatories are needed in order to understand the ongoing natural and human processes and their impacts on the adjacent lowlands.

Mountainous regions offer not only essential habitat and resources, including water, to the earth's more than 6 billion inhabitants, but also insights into how the global human habitat works, how it is being changed at the moment as global climates are disrupted, and how the disruption may lead to global biotic and economic impoverishment. At least 600 million of the earth's more than 6 billion humans dwell in mountainous regions. Such regions feed water into all the major rivers of the world whose valleys support most of the rest of us. At least half of the valley dwellers receive part or all of their water from montane sources, many from the melt water of glaciers, others from the annual snow melt. Glaciers are retreating globally as the earth warms as a result of human-caused changes in the composition of the atmosphere. Many are disappearing, a change that threatens municipal water supplies virtually globally. The warming is greatest in the higher latitudes where the largest glaciers such as those of Greenland and the Antarctic Continent have become vulnerable. The melting of ice in the northern hemisphere raises serious concerns about the continued flow of the Gulf Stream and the possibility of massive climatic changes in Scandinavia and northern Europe. Mountains are also biotic islands in the sea life, rich in endemism at the ecotype level. The systematic warming of the earth changes the environment out from under these genetically specialized strains (ecotypes) which are then maladapted and vulnerable to diseases of all types. The process is systematic impoverishment in the pattern conspicuous on mountain slopes with increasing exposure to climatic extremes. It is seen now in the increased mortality and morbidity of plants as climatic changes accumulate. The seriousness of the global climatic disruption is especially clear in any consideration of mountains. It can and must be addressed constructively despite the adamancy of the current US administration.

The lands surrounding the North Atlantic Region (the SCANNET Region) cover a wide range of climate regimes, physical environments and availability of natural resources. Except in the extreme North, they have supported human populations and various cultures since at least the end of the last ice age. However, the region is also important at a wider geographical scale in that it influences the global climate and supports animals that migrate between the Arctic and all the other continents of the world. Climate, environment and land use in the region are changing rapidly and projections suggest that global warming will be amplified there while increasing land use might dramatically reduce the remaining wilderness areas. Because much of the region is sparsely populated—if populated at all—observational records of past environmental changes and their impacts are both few and of short duration. However, it is becoming very important to record the changes that are now in progress, to understand the drivers of these changes, and to predict future consequences of the changes. To facilitate research into understanding impacts of global change on the lands of the North Atlantic Regions, and also to monitor changes in real time, an EU-funded network of research sites and infrastructures was formed in 2000: this was called SCANNET—SCANdinavian/North European NETwork of Terrestrial Field Bases. SCANNET currently consists of 9 core sites and 5 sites within local networks that together cover the broad range of current climate and predicted change in the region. Climate observations are well replicated across the network, whereas each site has tended to select particular environmental and ecological subjects for intensive observation. This provides diversity of both subject coverage and expertise. In this paper, we summarize the findings of SCANNET to-date and outline its information bases in order to increase awareness of data on environmental change in the North Atlantic Region. We also identify important gaps in our understanding and identify where the roles of existing infrastructures and activities represented by SCANNET can facilitate future research, monitoring and ground-truthing activities.

In the late 19^th century, mountaineer and essayist Sir Leslie Stephen wrote that the Alps were “Europe's Playground.” His words were prescient: the Alps are today one of the continent's most valued recreation areas. However, the importance of Stephen's words can only be appreciated when set in historical context. One hundred years earlier, his remark would have been laughed at. Until the late 18^th century the Alps were a source of fear to travellers and of mystery to scientists. They were an uncharted wilderness at the heart of the world's most crowded continent. Yet, within a remarkably short space of time, they were mapped, developed and exploited. Their current status as “playground” is bound intrinsically to a shift in imagination, beginning in the 16^th century and accelerating dramatically between the years 1800 and 1914, that has transformed them, in popular perception, from a realm of terror and superstition to one of beauty, relaxation and contemplation. Driven by fresh perspectives in the fields of science, music, literature and aesthetics, the metamorphosis has affected our appreciation not only of the Alps but of every mountain range in the world.