 Counterculture environmentalists were quick to grasp the implications of Ehrlich's writings on overpopulation, the Hubbert "peak oil" prediction, and more general concerns over pollution, litter, the environmental effects of the Vietnam War, automobile-dependent lifestyles, and nuclear energy.More broadly they saw that the dilemmas of energy and resource allocation would have implications for geo-politics, lifestyle, environment, and other dimensions of modern life.The "back to nature" theme was already prevalent in the counterculture by the time of the 1969 Woodstock festival, while the first Earth Day in 1970 was significant in bringing environmental concerns to the forefront of youth culture.