A glacier with basal temperatures of around 0 °C. Warmth is provided by friction with the bedrock, by shearing within the ice mass, and from geothermal heat. Glacier flow is rapid because warm glaciers are lubricated at their base, and velocities of 20–30 m per day have been recorded. Warm glaciers are the most effective agents of glacial erosion. See D. Evans (2003) on active temperate glacier margins, and Lingle and Fatland (2003) Annal. Glaciol. 36, 1 on temperate glacier surges.