Permafrost, a form of ice that influences nearly 25% of the northern hemisphere landmass, shows substantial change, mostly in the form of thermal decomposition due to warming air temperatures. Permafrost degradation affects local ecology and hydrology as well as coastal and soil stability. Decomposition of permafrost will mobilize reserves of frozen carbon, some of which, as methane, will increase the global greenhouse effect. Researchers will focus on changes in hydrological systems, on vegetation changes, on wildlife populations and on the overall habitability of the Arctic, and will use integrated geophysical, ecological and economic models to determine thresholds of critical change in, for example, human-Rangifer (caribou) systems. Geologists and geophysicists will work to understand factors that initiated and guided formation of Antarctic ice sheets, particularly in the region of the ice-covered Gamburtsev Mountains.