Earth's land surface is constantly changing and interacting with its interior and its atmosphere. In response to the interior, plate tectonics deform the surface, causing earthquakes, volcanoes, mountain building, and erosion—including landslides. These events can be violent and damaging. Forests, growing on the land surface, store carbon, which can be released into the atmosphere through logging and burning. Our ice sheets, sea ice, and glaciers are key indicators of our climate, and they have been undergoing dramatic changes. These land surface processes can be characterized and monitored from space using synthetic aperture radar (SAR) and light detection and ranging (lidar).