Climate change 'understanding' and knowledge

Recent surveys find that many people report having "a great deal" of understanding about climate change. Self-assessed understanding does not predict opinions, however, because those with highest "understanding" tend also to be most polarized. These findings raise questions about the relationship between "understanding" and objectively-measured knowledge. In summer 2011 we included three new questions testing climate-change knowledge on a statewide survey. The multiple-choice questions address basic facts that are widely accepted by contrarian as well as mainstream scientists. They ask about trends in Arctic sea ice, in CO2 concentrations, and the meaning of "greenhouse effect." The questions say nothing about impacts, attribution or mitigation. Each has a clear and well-publicized answer that does not presume acceptance of anthropogenic change. About 30% of respondents knew all three answers, and 36% got two out of three. 34% got zero or one right. Notably, these included 31% of those who claimed to have "a great deal" of understanding. Unlike self-assessed understanding, knowledge scores do predict opinions. People who knew more were significantly more likely to agree that climate change is happening now, caused mainly by human activities. This positive relationship remains significant controlling for gender, age, education, partisanship and "understanding." It does not exhibit the interaction effects with partisanship that characterize self-assessed understanding. Following the successful statewide test, the same items were added to a nationwide survey currently underway. Analyses replicated across both surveys cast a new light on the problematic connections between "understanding," knowledge and opinions about climate science.