Climate Variability and Change in High Elevation Regions: Past, Present & Future: Past, Present and Future (Advances in Global Change Research Book 15)

Glaciers in the Andes are particularly important natural archives of present and past climatic and environmental changes, in significant part because of the N-S trend of this topographic barrier and its influence on the atmospheric circulation of the southern hemisphere. Strong gradients in the seasonality and amount of precipitation exist between the equator and 30° S. Large differences in amount east and west of the Andean divide also occur, as well as a change from tropical summer precipitation (additionally modified by the seasonal shift of the circulation belts) to winter precipitation in the west wind belt (e. g. , Yuille, 1999; Garraud and Aceituno, 2001). The so-called 'dry axis' lies between the tropical and extra­ tropical precipitation regimes (Figure 1). The high mountain desert within this axis responds most sensitively to the smallest changes in effective moisture. An important hydro-meteorological feature on a seasonal to inter-annual time-scale is the occurrence of EN SO events, which strongly control the mass balance of glaciers in this area (e. g. , Wagnon et ai. , 2001; Francou et ai. , in press). The precipitation pattern is an important factor for the interpretation of climatic and environmental records extracted from ice cores, because much of this information is related to conditions at the actual time of precipitation, and this is especially so for stable isotope records. Several ice cores have recently been drilled to bedrock in this area. From Huascanin (Thompson et ai. , 1995), Sajama (Thompson et ai. Front Matter....Pages i-vi Climate Variability and Change in High Elevation Regions: Past, Present and Future....Pages 1-4 Climatic Change in Mountain Regions: A Review of Possible Impacts....Pages 5-31 Variability of Freezing Levels, Melting Season Indicators, and Snow Cover for Selected High-Elevation and Continental Regions in the Last 50 Years....Pages 33-52 Comparison of Lower-Tropospheric Temperature Climatologies and Trends at Low and High Elevation Radiosonde Sites....Pages 53-74 20th Century Climate Change in the Tropical Andes: Observations and Model Results....Pages 75-99 The Impact that Elevation has on the ENSO Signal in Precipitation Records from the Gulf of Alaska Region....Pages 101-121 The Health of Glaciers: Recent Changes in Glacier Regime....Pages 123-135 Tropical Glacier and Ice Core Evidence of Climate Change on Annual to Millennial Time Scales....Pages 137-155 Glaciers and Climate in the Andes between the Equator and 30° S: What is Recorded under Extreme Environmental Conditions?....Pages 157-175 Large-Scale Temperature Changes Across the Southern Andes: 20th-Century Variations in the Context of the Past 400 Years....Pages 177-232 Frequency-Dependent Climate Signal in Upper and Lower Forest Border Tree Rings in the Mountains of the Great Basin....Pages 233-244 Upper Yellowstone River Flow and Teleconnections with Pacific Basin Climate Variability during the Past Three Centuries....Pages 245-262 Taking the Pulse of Mountains: Ecosystem Responses to Climatic Variability....Pages 263-282 Back Matter....Pages 283-283 Glaciers in the Andes are particularly important natural archives of present and past climatic and environmental changes, in significant part because of the N-S trend of this topographic barrier and its influence on the atmospheric circulation of the southern hemisphere. Strong gradients in the seasonality and amount of precipitation exist between the equator and 30° S. Large differences in amount east and west of the Andean divide also occur, as well as a change from tropical summer precipitation (additionally modified by the seasonal shift of the circulation belts) to winter precipitation in the west wind belt (e. g., Yuille, 1999; Garraud and Aceituno, 2001). The so-called 'dry axis' lies between the tropical and extraƯ tropical precipitation regimes (Figure 1). The high mountain desert within this axis responds most sensitively to the smallest changes in effective moisture. An important hydro-meteorological feature on a seasonal to inter-annual time-scale is the occurrence of EN SO events, which strongly control the mass balance of glaciers in this area (e. g., Wagnon et ai., 2001; Francou et ai., in press). The precipitation pattern is an important factor for the interpretation of climatic and environmental records extracted from ice cores, because much of this information is related to conditions at the actual time of precipitation, and this is especially so for stable isotope records. Several ice cores have recently been drilled to bedrock in this area. From Huascanin (Thompson et ai., 1995), Sajama (Thompson et ai 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