Despite an accumulation of scientific evidence on both the causes and consequences of climate change, U.S. public opinion on the subject has splintered sharply along party lines. While a vast majority of Democrats now believe that global warming is real, that its effects will happen within their lifetime, and that human activity is the dominant cause, Republicans have grown increasingly skeptical, creating a yawning gap that complicates efforts to communicate the urgency of the problem and the need for aggressive action. When attitudes harden and diverge, it is often driven by the behavior of political elites, who shape the frames and mental models that people use to interpret events. Scholars have long observed that people resort instinctively to heuristics to ease the burden of making decisions, especially on issues like climate, where there is an obvious disconnect between scientific understanding and mass competence. Those cues, however, are often unreliable and prone to cognitive bias. When voters act upon signals provided by their preferred political party and by selective exposure to preferred media outlets, they may do so mechanically, with little regard for the accuracy of the evidence that they receive, or they may ignore and distort information in a way that reinforces preexisting assumptions. In the end, beliefs about climate change are as complex as the issue itself, which suggests that awareness of the problem and an understanding of its effects will not translate automatically-or even easily-into increased concern, issue salience, or policy preferences. The "pictures in our heads," to borrow Walter Lippmann's famous phrase, are shaped less by factual knowledge than by a variety of other factors more difficult to control-by personal experience and assorted real-world cues (such as the weather), but also by opinion leaders, media narratives, and political rhetoric, each of which provides a competing frame of reference with the power to filter and mislead. Because climate change has become so heavily laden with values and so absorbed into partisan identity, it will be nearly impossible to build social consensus through conventional means. Once a "hard" issue for all, which seemed to demand sophisticated calculation or technical expertise, it has now become an "easy" one for many, where the reactions that it prompts are familiar, stable, and symbolic, increasingly polarized, immune to rational argument, and vulnerable to manipulation by elites.