John D. Hamaker, a mechanical engineer and agronomist, argued that Earth's interglacial periods carry the seeds of their own end: soils lose minerals over thousands of years, plants weaken and absorb less carbon dioxide, the gas builds up in the atmosphere, and rising evaporation at the equator eventually piles snow at the poles until a new hundred-thousand-year ice age begins. Hamaker and co-author Donald Weaver laid this out in the book The Survival of Civilization, and the film follows Larry Ephron, who set out to popularize the theory in his own book, The End, and hired the narrator as a research assistant sent digging through UC Berkeley's libraries. The footage includes photographs of the Sierra Nevada the narrator shot as a teenage Boy Scout, images that survive only here after the Oakland firestorm destroyed the rest of his archive. The film closes with the Earth Regeneration Society's case for a crash program to cut atmospheric CO2 back to 280 parts per million, the pre-industrial baseline.