Aldo Leopold’s 1949 “The Land Ethic” is seminal in academic environmental ethics and the environmental ethic of choice among professional conservationists and environmentalists. After sixty years, the sciences (evolutionary biology and ecology) that inform the land ethic have undergone much change. The land ethic can be revised to accommodate changes in its scientific foundations, but it cannot be scaled up to meet the challenge of global climate change. Fortunately, given the prominent place of Leopold in all circles environmental, he also faintly sketched an Earth Ethic in a paper written in 1923, which was published posthumously in 1979. The Earth Ethic is informed less by ecology and evolutionary biology than by biogeochemistry and anticipates the Gaia Hypothesis, viz., that the Earth (or biosphere) is, as a whole, a living being. If so, Leopold thought it a worthy object of moral respect.