A glacier is a huge body of ice formed naturally from snow accumulation over long periods of time. A glacier is always flowing outward or downward, depending on the landscape. If the flow exceeds the melt-off, the glacier advances, and the front edge moves in a forward direction. If the melt-off exceeds the flow, the glacier retreats, and the front edge recedes, making the glacier grow visibly smaller. By observing glaciers, scientists can learn about changing climatic conditions. Glaciers are a big influence on freshwater availability too.

Several spacecraft study glaciers and ice on Earth. Many satellites monitor different factors of Earth all the time. The Global Climate Observing System (GCOS) monitors glaciers. GCOS has been studying the glaciers in the Himalaya mountain range, the highest mountains of Earth. The Himalayan glaciers are retreating, or melting, rapidly. The larger glaciers haven’t changed much, but the smaller, debris-free glaciers have retreated. Ice margin lakes, made from melting glacial water, are adjacent to some glaciers. The lakes are growing bigger with the increased melting. There are some negative results of increased glacial melting. Rivers that carry glacial water run-off can overflow their banks and flood large areas. Heavy run-off can cause tremendous damage and high rates of erosion.

ESA’s CryoSat spacecraft was just launched from the Cosmodrome to study Earth’s ice fields and map ice thickness over water and land. It will help study the climatic changes in different areas of Earth. It has an all-weather microwave radar altimeter. It will determine changes in the thickness of floating sea ice and polar land ice sheets.