Mais comment s'écoule donc un glacier ? Aperçu historique

Ice and snow have often helped physicists understand the world. On the contrary it has taken them a very long time to understand the flow of the glaciers. Naturalists only began to take an interest in glaciers at the beginning of the 19th century during the last phase of glacier advances. When the glacier flow from the upslope direction became obvious, it was then necessary to understand how it flowed. It was only in 1840, the year of the Antarctica ice sheet discovery by Dumont d'Urville, that two books laid the basis for the future field of glaciology: one by Agassiz on the ice age and glaciers, the other one by canon Rendu on glacier theory. During the 19th century, ice flow theories, adopted by most of the leading scientists, were based on melting/refreezing processes. Even though the word ‘fluid’ was first used in 1773 to describe ice, more the 130 years would have to go by before the laws of fluid mechanics were applied to ice. Even now, the parameter of Glen's law, which is used by glaciologists to model ice deformation, can take a very wide range of values, so that no unique ice flow law has yet been defined. To cite this article: F. Rémy, L. Testut, C. R. Geoscience 338 (2006).     

Results from a Multi-disciplinary Sedimentary Pilot Study of Tectonic Lake Iznik (NW Turkey) – Geochemistry and Paleolimnology of the Recent Past

A limnogeological reconnaissance study was carried out on Lake Iznik, located in the southeast of the Marmara region of Turkey, involving a seismic survey and collection of short sediment cores. This lake is located on the middle branch of the North Anatolian Fault Zone (NAFZ), a transform plate boundary between the Eurasian and Anatolian Plates. It is, therefore, tectonically active and offers an opportunity to investigate the interplay of sedimentary and seismo-tectonic processes, as well as climate change and human impact in the region. Short cores of the three sub-basins, maximum length of 35.5 cm, recovered non-laminated, blackish clays and silts with varying amounts of biogenic and minerogenic (allochthonous, autochthonous) material, which documented almost the last 80 years of deposition and environmental history. High sedimentation rates in the deeper core sections are accompanied by changes in land use (conversion of woodland to farmland) in the northern areas of Lake Iznik, which caused the deposition of more weathered material (high K/Na ratios) and higher contents of Mn in the lake. A tendency towards eutrophic conditions within the last 20 years is indicated by high nutrient content (N, TOC, P), decreasing C/N-ratios, and characteristic diatom and cladoceran associations. Also increased pollution is revealed by higher Pb, Cu, and Zn contents and increased supply of human and animal faeces (high coprostanol content) during the last two decades. But simultaneous lower sedimentation rates towards the core tops complicate the reconstruction of recent and past eutrophication and pollution states of Lake Iznik. This requires an extension of the pilot study and deeper sediment cores, to recover non-anthropogenic influenced sediment levels.     

Asking the right questions: environmental conflict in the case of Azerbaijan

This paper contributes an empirical test of key themes of the literature on natural resource conflict. Survey and interview data from an ongoing project in Azerbaijan provide insights into an unexpected lack of conflict in Azerbaijan related to the environment, resources and energy despite the predictions of resource conflict literature. We contend that questions about public perceptions about the environment and other daily concerns are critical if we are to understand who is likely (or unlikely) to be involved in conflict and why. The data presented in this paper demonstrate that Azerbaijani citizens rank environmental and resource issues among their immediate concerns and their top concerns for the country. However, compared to other day-to-day concerns such as the Nagorno-Karabakh conflict and economic concerns, environment-related concerns do not appear to be sufficient to motivate widespread violent conflict or citizen dissent related to environmental or natural resource conditions.     

Where the buffalo roam: Boundaries and the politics of scale in the yellowstone region

For more than twenty years, the state of Montana has pursued a controversial policy of lethal control to manage winter migrations of bison from Yellowstone National Park. In the late 1990s, as the state and a number of federal agencies attempted to cooperatively outline a more palatable scenario for bison management, local environmental groups became active participants in the debate. This paper examines the strategies pursued by these organizations in the course of their attempt to construct a new, ecosystem-level territorial space and jurisdictional scale for bison, and places their struggle within the context of existing work in geography on the politics of scale. Ultimately, the failure of their efforts illustrates some of the important constraints faced by social groups that attempt to create new territorial regimes and new scales of resistance in the interstices of existing political structures.     

区域环境变迁与持续发展的互动关系

区域历史进程中持续发展与环境变迁表现出了复杂的互动关系，两种动态过程紧密地交织在一起，通过人类活动互相作用，互相影响，持续发展，环境变迁与人类活动的内容在不同时代表现出不同的主题，并受到自然和人为因素的调节与控制，文中还简要阐明了当代可持续发展的主题，指出解决PRED问题要注意控制人口数量，提高人口素质；消除贫困，达到全球环境共有共治共保共享。     

The geography of water conflict and cooperation: internal pressures and international manifestations

Studies on transboundary water conflict and cooperation generally consider interstate relations over shared water resources as distinct from intrastate relations. While connections have been made between international water relations and regional relationships in general, it is conceivable that international water conflict and cooperation may also be influenced by domestic water events and vice versa. This paper seeks to investigate the dynamics of water interactions across geographic scale and their relationship to broader international affairs. The research approach involves the creation of an analytical framework for assessing possible linkages between external and internal interactions over freshwater resources. The framework is applied to three case studies – the Middle East, South Asia and Southern Africa – utilizing 'event data'. To validate the findings from the quantitative analyses, the results are compared with conventional qualitative understandings of water and overall relations in the three regions. The comparison demonstrates not only the efficacy of the analytical framework in general, but also highlights, at least in terms of the specific case studies selected, the disparate water dynamics across geographic regions and the importance of considering water events, both national and international, within larger political and historical contexts.     

Book Reviews

Books Reviewed Colbert C. Held, Middle East Patterns: Places, People, and Politics Barbara A. Weightman, Dragons and Tigers: A Geography of South, East, and Southeast Asia Henry J. Bruman, Alcohol in Ancient Mexico Brian W. Blouet, Geopolitics and Globalization in the Twentieth Century M. A. B. Siddique (ed.), International Migration into the 21st Century: Essays in Honour of Reginald Appleyard Michael R. Haines and Richard H. Steckel (eds.), A Population History of North America Emilio Moran, Human Adaptability: An Introduction to Ecological Anthropology Jeremy Leggett, The Carbon War: Global Warming and the End of the Oil Era Susan B. Marriott and Jan Alexander (eds.), Floodplains: Interdisciplinary Approaches William S.Logan, Hanoi: Biography of a City Alex Krieger and David Cobb (eds.) with Amy Turner, Mapping Boston Eric Sandweiss, St. Louis: The Evolution of an American Urban Landscape Carl Abbott, Greater Portland: Urban Life and Landscape in the Pacific Northwest Arthur D. Murphy, Colleen Blanchard and Jennifer A. Hill (eds.), Latino Workers in the Contemporary South Yanek Mieczkowski, The Routledge Historical Atlas of Presidential Elections     

Natural environmental changes and human impact reflected in sediments of a high alpine lake in Switzerland

From the high alpine Sägistalsee (1935 m a.s.l.), 13.50 m of continuously laminated sediments comprising the last 9050 years, were analyzed. Even though Sägistalsee is a high elevation site, human-induced environmental changes start as early as 4300 cal. BP and leave a clearly detectable signal in the mineralogy of the sediments, which is much stronger than the signal from natural environmental changes that occurred before this time. Variations in the physical and mineralogical sediment properties of this clastic sequence reflect erosional changes in the catchment, where almost pure limestone contrasts with carbonaceous, quartz-bearing marl, and shist. The calcite/quartz (Cc/Qz) ratio was found to be most indicative of these changes, which occurred around AD 1850 and at 650, 2000, 3700, and 6400 cal. BP. The first four are interpreted as erosion events, which are related to human-induced changes in the vegetation cover and land use. We associate them to the recent development of tourism and grazing, the medieval intensification of pasturing, Roman forest clearance, and Bronze Age forest clearance, respectively. The Cc/Qz-ratio increases significantly within less than 100 years during these events, reflecting the erosion of unweathered or poorly weathered soils. The time intervals in between are characterized by a gradually decreasing Cc/Qz-ratio and reflect the stabilization or formation of new soils. Only the change at 6400 cal. BP, which represents the initial gradual stabilization of the catchment, is related to the immigration of Picea abies.     

晚更新世以来青海北部的人类活动与湖泊演变

作为高海拔生态环境的青海北部是青藏高原的重要组成部分。晚更新世晚期以来 ,青海北部气候环境一直处于冷暖、干湿波动过程之中 ,湖泊水域也发生了相应的扩张和收缩 ,成为高原人类迁移和发展的自然背景。约 3 0kaB .P .,在晚期智人出现和迁徙的关键时期 ,青海北部开始有了最早的人类活动 ;更新世末—全新世初 ,气候转暖 ,古人类再次来到青海北部 ;进入全新世中期 ,气候暖湿 ,湖水位回升 ,细石器技术变得十分普通 ,青海北部的人类活动渐趋频繁。     

人类活动中温室气体的排放对气温影响综述

本文广泛参阅了国内外科学家的研究成果，综合论述分析了几种主要温室气体的源、汇及其浓度变化特征，研究分析了其增暖潜力，温室效应的强度和对人类社会各方面的影响，提出人类为保护自身的生存环境，必须严格控制温室气体的排放量。