This is a Blue Marble image from NASA, Earth at night is superimposed on this (NASA/GSFC), Using the lights as an indication of population density. The squares on the map highlight a representative number of cities within the regions of glacier-fed areas. All of these areas derive some benefit from melting glaciers. The implication is that if the glaciers melt away completely, or substantially, these areas would be affected. Image: Courtesy of NASA/GSFC, NOAA/NGDC, DMSP, GLIMS
