The U.S movement began to take off after World War II, as people began to recognize the costs of environmental negligence, disease, and the expansion of air and water pollution through the occurrence of several environmental disasters that occurred post-World War II. Aldo Leopold published A Sand County Almanac in 1949. He believed in a land ethic that recognized that maintaining the "beauty, integrity, and health of natural systems" as a moral and ethical imperative.
