The paper analyzes three cross-sectional polls conducted by the Gallup Organization at ten-year intervals (1990, 2000, and 2010) to examine the growing significance of partisan identification in shaping environmental concerns among the American public. It notes that polarization regarding global warming has intensified, particularly in comparison to other social, economic, and political issues, and that this party sorting occurs as individuals gain information and respond to cues from political elites. The authors discuss the implications of these findings for the U.S. environmental movement and the strategies it employs in addressing climate issues.