Petroleum supplies have heretofore been abundant and inexpensive, but the world petroleum production peak is imminent, and we are entering an unprecedented era of petroleum scarcity. This fact has had little impact on policies related to climate, energy, the built environment, transportation, food, health care, public health, and global health. Rising prices are likely to spur research and drive efficiency improvements, but such innovations may be unable to address an increasing gap between supply and demand. The resulting implications for health and the environment are explored in the articles we have selected as additional contributions in this special issue. Uncertainty about the timing of the peak, the shape of the production curve, and decline rates should not delay action. The time for quick, decisive, comprehensive action is now.