Stanford University Public Opinion Surveys on Global Warming (2013): Has past global warming been caused by humans?

Percentage of Americans who believe past global warming has been caused by humans or in equal part by humans and natural fluctuations 

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:  Do you think a rise in the world’s temperature is being caused mostly by things people do, mostly by natural causes, or about equally by things people do and by natural causes?  2012:  Do you think that the increase in the world’s temperature over the past 100 years was caused mostly by things people did, mostly by natural causes, or about equally by things people did and by natural causes?  2012:  Assuming it’s happening, do you think a rise in the world’s temperature would be caused mostly by things people do, mostly by natural causes, or about equally by things people do and by natural causes? 2012:  If the world’s temperature did increase over the past 100 years, do you think this increase was caused mostly by things people did, mostly by natural causes, or about equally by things people did and by natural causes? 1997-2011:  Do you think a rise in the world’s temperature is being caused mostly by things people do, mostly by natural causes, or about equally by things people do and by natural causes? 1997-2011:  Assuming it’s happening, do you think a rise in the world’s temperature would be caused mostly by things people do, mostly by natural causes, or about equally by things people do and by natural causes?

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