Renewable and nuclear energy are two plausible alternatives to fossil fuel-based energy production. This study reports students' beliefs about the usefulness of these two options in reducing global warming and their willingness to undertake actions that would encourage their uptake. Using a specially designed questionnaire, students' (n > 12,000; grades 6 to 10) responses were obtained from 11 countries. Links between their beliefs about these energy options and their willingness to act were quantified using a range of novel derived indices: significant differences between beliefs and willingness to act were found across the various counties. One derived index, the "Potential Effectiveness of Education," measures the extent to which enhancing a person's belief in the effectiveness of an action might increase their willingness to undertake that action: this indicated that education may impact willingness to act in some countries more than others. Interpretations are proffered for the reported differences between countries including whether the extent of students' concern about global warming had impacted their decisions and whether cultural attributes had any influence. Pedagogical ways forward are related to the findings.