There is no silver bullet—no single solution to get us to a sustainable climate. There is, however, silver buckshot: a combination of political, technological, economic, and behavioral actions and interventions that will provide the necessary progress towards that goal. Far from being merely additive, behavioral interventions—i.e., changes in the “choice architecture” of environmentally-relevant decisions—have the potential to amplify and multiply the effectiveness of political, technological, and economic tools. Homo sapiens differ from homo economicus in ways that are both challenging and enriching. A more comprehensive understanding of human attention, motivation, judgment, and choice than that provided by the rational-economic model provides entry points for the design of decision environments that allow us—as consumers, citizens, or policy makers—to change our behavior in ways that bring us closer to a sustainable future.