Stanford University Public Opinion Surveys on Global Warming (2013): Has Global Warming Been Happening?

Percentage of Americans who believe global warming has been happening

Source: Map created by Stanford Geospatial Center based on data compiled by Stanford University Visiting Scholar Bo MacInnis and Stanford University Professor Jon Krosnick.  Professor Krosnick is the Frederic O. Glover Professor in Humanities and Social Sciences at Stanford University and a Senior Fellow at the Stanford Woods Institute for the Environment.  For more information, visit http://climatepublicopinion.stanford.edu.

Survey Question: 2012-2013: What is your personal opinion? Do you think that the world's temperature probably has been going up over the past 100 years, or do you think this probably has not been happening?  2012: What is your personal opinion? Do you think that the world's temperature probably has been going up slowly over the past 100 years, or do you think this probably has not been happening? 2012: What is your personal opinion? Do you think that the world's temperature probably has been going up over the past 100 years, or do you think this probably has not been happening?  1997-2011: You may have heard about the idea that the world's temperature may have been going up slowly over the past 100 years. What is your personal opinion on this? Do you think this has probably been happening, or do you think it probably has not been happening? 

Methodology: For more than a decade, many surveys have measured Americans' opinions about various issues related to global warming.  These surveys have involved interviewing truly random samples of the American adult population and have been designed to yield estimates for the country as a whole.  Many of these surveys have asked the same questions repeatedly.  To generate the state level analysis, MacInnis and Krosnick first combined these surveys, yielding a large number of respondents, selected randomly, for almost every state in the country.  MacInnis and Krosnick then applied a statistical modeling procedure to estimate what public opinion would be in each state today.  This procedure modeled differences between states, effects of survey mode (e.g., telephone interviewing vs. self-completion of online questionnaires), differences between results obtained by different interviewing firms, and trends in opinions over time.  This methodology produced estimates of the results that would be obtained by random digit dialing telephone interviews in 2013.

Nov 13, 2013