Energy supplies are central to human ecology and key to the sustainability of human communities, but the decline of fossil fuel resources is largely ignored in global environmental politics. Most political analysis of energy focuses on state-centered "energy security" while largely overlooking discourses of environmental or ecological security. Yet energy and the environment are intimately connected; in the 1970s and 1980s, energy resources were seen as very much a part of the environment to be secured, while today fossil energy is seen as an evident threat to the environment, especially through the medium of climate change. This article surveys the changing relationships among energy, the environment, and security, and suggests a framework for examining the discursive forces that have affected such changes. This framework offers guidance toward developing a more ecologically informed approach to energy and (state, global, and human) security under conditions of scarce and declining global fossil fuel supplies.