In this slightly simplified version of a technical paper first circulated in 1970, Amory Lovins argues that “heat released by man’s rapidly increasing energy-use may seriously perturb global climate in less than 100 years. He argues that until the climate issue is completely understood, it is risky and imprudent to use nuclear power as the form of energy best suited for dealing with the climate problem. The paper provides a model of how the earth’s heat balance works, how humans contribute to a heated earth, and a discussion of policy implications. “