It is argued that the facile electron field emission from carbon systems occurs primarily because surface groups such as C-H can produce large changes in local electron affinity, so that electric fields from the anode can be focused toward unhydrogenated surface areas of high affinity, the fields ending on negative charges in an underlying depletion layer. The resulting downward band bending creates large surface fields which allow Fowler-Nordheim emission, while not exceeding the material＇s breakdown field.