CLIMATE CHANGE IN MOUNTAINS AND IN THE ARCTIC

It is critically important for society to understand how climate is changing in high-elevation regions and at high-latitudes because of the potential impacts in areas such as water resources, biodiversity, natural resources, recreation, frequency and intensity of rainfall, floods, droughts, snow, glaciers, permafrost, river flow, and sea-level rise. Because of the similarities between high- latitude and high-elevation regions, most of these impacts will be felt in both regions. For example, many of the major river systems on the planet have their sources in mountains which can lead to geopolitical conflicts in regions where large watersheds are affected by climate change and extend across national boundaries. The river drainage basins for the Arctic Ocean extend across vast land areas of the Northern Hemisphere and are a major source of freshwater as well as a major contributor to the freshwater in the Arctic Ocean. This proposal will focus on climate change in both high-elevation and high-latitude regions, and a particular emphasis on identifying and quantifying the roles of several important climate feedbacks and how they will change during this century. The reason for the focus on both high altitudes and high latitudes is the similarities between them, and of particular significance for this proposal the roles of similar climate feedback loops that contribute to enhanced rates of warming in both regions. Arctic temperatures have shown significant increases in recent decades as sea-ice cover and sea-ice thickness have been decreasing. The recent rapid loss of summer sea ice and its implications is among the most immediate concerns related to Arctic amplification. One of the most important positive feedbacks in the Arctic is the snow/ice-albedo feedback in which increasing temperatures cause ice to melt and more solar radiation to be absorbed in the ocean, thus increasing temperatures even more. Another important positive feedback relates to increasing atmospheric water vapor which increases the downward infrared radiation thus increasing surface temperatures.Observations have suggested that high-elevation regions have been relatively more sensitive to climate change than the global average and that many of the important climate feedbacks are similar to those in the Arctic. High-elevation regions have generally warmed at a greater rate than the global average during the last several decades, with greater increases in daily minimum temperatures than daily maximum temperatures. At present, studies of both high latitude and high elevation climate change are limited by a sparse network of surface observations. This can be partially addressed by using satellite observations. In the proposed research, we will use a combination of observations and climate models (both global and regional) to identify the most important climate feedbacks at high latitudes and at high elevations. Furthermore, we will use statistical techniques to quantify the components of several of these feedback loops. The overarching goal of this research is to use observations and both global and regional climate models to obtain a better understanding of how the hydrologic cycle interacts with the climate system globally and locally and how these interactions might change in the future. The proposed work is important at local, regional, national, and international levels because it will improve our understanding of how various components of the hydrologic cycle might change in the future. The public welfare depends on obtaining sound information upon which more informed decisions about future water resources can be made. Future climate change will affect people at spatial scales ranging from local to global in such diverse areas as agriculture, forestry, health, energy use, water resources, and coastal development. It is important to understand the interrelationships and feedbacks within the climate system at both high latitudes and high elevations in order to better plan for a future with a different climate than we have today. Climate change will be arguably among the most important societal challenges during the 21st century, and understanding how, why, and where it is changing is critical to our collective future.