Unlike peer nations’ residents, Americans are less accepting of, and concerned by, (especially anthropogenic) climate change. Reinforced Theistic Manifest Destiny theory (RTMD; e.g., Ranney, 2012) explains many such “U.S.-exceptionalist” phenomena by combining geopolitical history with six belief constructs: afterlife, deity, nationalism, creation, evolution, and global warming. We assess predictions that climate change acceptance is increased by mechanism-explaining interventions. A 270-participant survey established widespread mechanistic ignorance, and an experiment with 149 other Americans (Californians and Texans) showed that a 400-word description of climate change’s mechanism dramatically reduced ignorance and increased climate change acceptance. The mechanism, briefly, is: (a) Earth’s surface absorbs (mostly visible) sunlight and subsequently emits infrared light, which (b) greenhouse gases selectively absorb and retain (because these molecules can become asymmetrical), so (c) heat energy leaves more slowly, warming Earth. Our intervention yielded desirable conceptual changes and science-coherent attitude changes. RTMD-predicted between-construct relationships were obtained and/or again replicated.