A common type of biological particles is foraminifers, single-celled, amoeba-like protists that have a shell and either live on the sea bottom or float in the upper water column. There are an estimated 4,000 species living today. Foraminifers are sensitive to changes in their environment such as temperature and salinity, which makes them useful indicators (proxies) of past climate changes. Satellite Hydrology This group uses satellite-based measurements to study rivers, lakes, wetlands, and floodplains. Led by Profs. Douglas Alsdorf and Michael Durand, group members primarily use passive and active microwave measurements such as radar to measure surface water and snowpack. This group is working to better quantify the amount of water stored in snowpacks in the United States using satellite measurements. This group is helping define an upcoming satellite, Surface Water and Ocean Topography. Rivers are fundamentally two-dimensional in their structure and function. This is evident in the Amazon River, where the floodplain width is measured in kilometres. Sensitive to climatic changes, arctic lakes pose another hydrologic measurement challenge. SWOT measurements will enable new under- standing of these complex systems. SWOT will track freshwater resources, and measure ocean currents. SWOT is a joint effort between NASA, the Jet Propulsion Laboratory, and the French space agency, CNES. Glacier Environmental Change The Glacier Environmental Change group researches patterns, processes, and impacts of environmental change, mostly in glaciated regions. We integrate methods of glacial geology, climatology, hydrology, and biogeochemistry. Specializing in tropical mountain regions, we study sites along the entire American Cordillera, in Africa, and in Central Ohio. Glaciers impact environments and societies on different scales, from valleys to mountain ranges, spanning far into Earth’s past. Understanding glacier environmental changes requires many techniques and perspectives. Precise measurements from sensors on satellites and airplanes quantify ongoing glacier volume changes; landforms and lake sediments reveal past glacier-climate changes; the hydrochemistry of surface waters reflects glacier melt contribution; and computer simulations help explain past and future dynamics. Polar Meteorology The Polar Meteorology group has developed a model (Polar MM5) that is used to forecast weather conditions in the polar regions. The model has been used to stimulate conditions on the North American continent during the last ice age. In addition to weather prediction, the Polar MM5 model has been used for several simulations that examine the current and past climates over ice sheets, including one that illustrates conditions on the North American continent during the last