Catálogo de publicaciones - libros

Mountains are complex and fragile ecosystems characterised by vertically, highly differentiated climatic conditions and often by an abundance of water and rich biodiversity. Mountains are high-risk environments: avalanches, glacial lake outbursts, landslides and earthquakes threaten life in mountain areas. Remoteness and difficult access hamper development in mountain regions. Therefore, mountain areas are often marginalized. Despite these constraints, mountains offer significant opportunities. Mountain dwellers have adapted to life in steep and harsh conditions and have developed sophisticated techniques for farming, water use, forestry and communication. The agro-biodiversity as a function of altitude, exposition and farmers’ crop selection is huge. Mountain inhabitants have also developed a rich cultural diversity. Therefore, people living in lowland areas or in big cities increasingly prefer mountains for recreation.

Mountain paleoarchives, including glaciers, laminated lake sediments, and trees near the limits of their habitable range, provide much information relevant to the study of past climatic changes (Alverson and Kull 2002). Properties recorded in these archives offer quantitative climate-related information at annual or higher temporal resolution. In addition, by nature of their occurrence at high elevation, they provide information about climate variability in the free atmosphere, not just its surface expression. However, interpreting these proxy records in terms of large-scale climatic change is a difficult task. Mountains are generally regions of strong climatic gradients and inherently high natural variability, making interpretation of local records difficult. Additional difficulties exist due to the fact that the proxies do not respond to climate alone, but are influenced by myriad additional factors. In this chapter, we highlight two methods which use dynamical constraints, either from the climate system or the underlying archives themselves, to help tease out the climatic information contained in point-based proxy timeseries. Although the examples that we present are applied in conjunction with ice core records, the techniques are relevant to the interpretation of annually resolved climate proxy timeseries in high altitude regions. Past climatic changes are often either reconstructed using paleoproxy data or modeled using a numerical representation of the underlying dynamics of either the climate system or paleoarchive development.

One of the challenges for global environmental change research is to understand how future climate changes will be expressed in mountain regions. The physiographic complexity of mountains creates environments that can be highly variable over relatively short distances. This spatial heterogeneity reflects a hierarchy of environmental controls. At regional scales, insolation and atmospheric circulation features determine the dominant regional climate patterns that affect mountain regions. At finer spatial scales, substrate, aspect, elevation, and a number of other environmental factors influence ecosystem dynamics. Vegetation, for example, is affected by all levels of this hierarchy, from regional-scale climate regimes down to site-specific features, such as substrate type (cf. Körner, this volume).

The 20 century has seen the acceleration of unprecedented global and regional-scale climatic and environmental changes to which humans are vulnerable, and by which we will become increasingly more affected in the coming centuries. One-half of the Earth’s surface area lies in the tropics between 30°N and 30°S, and this area supports almost 70% of the global population. Thus, temporal and spatial variations in the occurrence and intensity of coupled ocean-atmosphere phenomena such as El Niño and the Monsoons, which are most strongly expressed in the tropics and subtropics, are of worldwide significance. Unfortunately, meteorological observations in these regions are scarce and of short duration. However, ice core records are available from low-latitude, high-altitude glaciers, and when they are combined with high-resolution proxy histories such as those from tree rings, lacustrine and marine cores, corals, etc., they provide an unprecedented view of the Earth’s climatic history over several millennia. This paper provides an overview of these unique glacier archives of past climate and environmental changes on millennial to decadal time scales. Also included is a review of the recent, global-scale retreat of these alpine glaciers under present climate conditions, and a discussion of the significance of this retreat with respect to the longer-term perspective, which can only be provided by the paleoclimate records.

Moraines are non-continuous short-term records of ice marginal positions. Moraines help provide important paleo-glaciological mass balance information (e.g. glacier surface area, ice volume, terminus elevation, snowline altitudes, longitudinal ice surface gradient below the paleo-snowline) which in part controls the geometry of the glacier and the rate of advance and retreat of an ice margin. Therefore, chronologies on these ancient glacial landforms can be directly tied to local paleo-temperature and paleo-precipitation estimates for specific times during and after a glaciation. In the past two decades, the terrestrial cosmogenic nuclide (TCN) exposure dating method has made a revolutionary contribution to the study of alpine paleo-glacial histories and paleoclimatology. (i) Exposure dating of boulders on moraines provides the time since a boulder was deposited from an ice margin. It directly determines when the glacier reached a measurable mass-balance condition, whereas other chronometers, such as radiocarbon, U-series, and luminescence dating, typically provide only minimum or maximum limiting ages on ice margin positions, (ii) The method can provide a precise estimate of the timing of initial ice retreat. Timing of when an alpine glacier reaches its maximum position is not only a function of local climate but also of numerous glaciological and hydrological conditions. Initial retreat is the most discrete short-lived climate-response event in a moraine record. Unlike the timing of initial retreat, initial advance is not recorded in moraine records because glaciers override their moraines during advance (Gibbons et al. 1984).

Glacier fluctuations provide important information on climate variations as a result of changes in the mass and energy balance at the Earth’s surface. Variations in glacier mass balance (e.g. Paterson 1994) are the direct reaction of a glacier to climatic variations. Fluctuations in the length of valley and cirque glaciers, on the other hand, are the indirect, filtered, and commonly enhanced response. Available mass balance records are, however, relatively short compared to the longer records of glacier length variations.

Pollen analysis, C and lichenometric dating of moraines, former elevations of the upper tree limit, and dendroclimatological and limnological data are some of the most relevant proxies for the reconstruction of climate variability and glacier behavior during the last millennium. A considerable number of paleoclimate reconstructions exist for the mountains of the Former Soviet Union. In this paper, we provide a regional overview of these datasets. Only regions with chronologically controlled and, preferably, high-resolution reconstructions will be considered here, namely, the Khibiny, the Urals, the Cherskogo Range, the Putorana Plateau, the Birranga Mountains, the Suntar-Khayata, the Kamchatka, the Caucasus, the Pamir-Alay, the Tien Shan, and the Altay Mountains (Fig. 1). This paper is a brief summary of the glacier and climate history of the last millennium and identifies achievements as well as gaps in our knowledge of paleoclimate in these regions. Ultimately, the identification of regional patterns of past climate changes will allow us to gain a better understanding of the causes behind climate variability on inter-annual to centennial timescales.

The regional distribution of precipitation in a mountain range like the European Alps is a good indicator for continental-scale atmospheric circulation patterns. This is particularly true when precipitation is primarily caused by the advection of air masses to the Alps from the North Atlantic or the Mediterranean Sea, as is the case under cold conditions. Alpine precipitation patterns during the Lateglacial period can hence be interpreted in terms of past atmospheric circulation patterns in continental Europe. In this paper, glacier-climate models are used for the reconstruction of Younger Dryas precipitation patterns based on changes in equilibrium line altitudes of Alpine glaciers. This type of research provides important information concerning the range of past precipitation variability against which present climatic changes in the Alps can be assessed. Also, unravelling the spatial patterns of Alpine precipitation allows us to gain a better understanding of forcing mechanisms behind precipitation changes.

The South Asian Monsoon system is one of the most important and influential of the Earth’s major climate systems. The people of the most heavily populated Asian countries have adapted many aspects of their society to the subtleties of the monsoon rains, and are thus highly susceptible to small changes in the timing and intensity of monsoon precipitation. A monsoon failure can have disastrous effects, and flooding related to extreme monsoon rains has proven to be one of the most deadly of natural catastrophes (e.g. in Bangladesh, China, India and Nepal). These vulnerabilities are likely to increase in the future with continued population growth, intensified land-use and sea-level rise. Although there is a growing effort to improve seasonal to interannual monsoon prediction skills via new research, the largest threats to human health and livelihood could come from unanticipated decade- and longer-scale extremes in monsoon. A major goal of this paper is to summarize the state-of-the-art regarding century to millennium-scales of monsoon variability, and to identify the paleoenvironmental research that is most urgently needed in the Himalayan-Tibetan Plateau if society is to be served effectively in the 21 century.

The Atacama Desert of the Central Andes (18°S to 28°S) has become a focal point of environmental research in recent years. Indeed, this area is a key site in several respects. It is located between the tropical and extratropical precipitation belts; the vertical gradients of ecozones range from sea level at the Pacific Coast up to high mountains that reach into the mid-troposphere at 6000 m elevation. The prominent mountain chain of the Andes stretches N-S, perpendicular to the zonal westerly airflow of the mid-latitudes, which creates distinct environmental gradients at meso-and micro-scales. Due to their sensitive location at the juncture between tropical and extratropical climate zones, paleoclimate records from this area may potentially provide important insights into the dynamics of the large-scale atmospheric circulation in the Central Andes in the past. This region therefore provides an ideal natural laboratory for paleoclimatologists.