Changing world temperatures influence views on global warming, Stanford scholar says

The year after temperatures rise, people are more likely to believe in global warming, says Jon Krosnick, a Stanford professor of communication and of political science. The latest polling shows that 73 percent of Americans believe global warming is real and 79 percent favor some sort of government intervention on the issue. But, only 49 percent favor mandates to reduce greenhouse gas emissions by power plants.

Ian Terpin Jon Krosnick portrait

Jon Krosnick, professor of communication and of political science, conducts research on public opinions about climate change.

What do the American people really think about global warming? To gauge public opinion on the issue, the Stanford News Service interviewed Jon Krosnick, a Stanford professor of communication and of political science who conducts survey research on how people view climate change.

It is a timely issue in light of the White House's recent proposal, the "Blueprint for a Secure Energy Future," to reduce carbon emissions by the nation's biggest source of pollution blamed for global warming: power plants. Krosnick is the Frederic O. Glover Professor in Humanities and Social Sciences and a senior fellow at the Stanford Woods Institute for the Environment, which has provided support for much of his research.


Do most Americans believe global warming is happening? What are the trends?

A remarkable number of Americans believe that the Earth has been warming over the last 100 years. In our latest survey (June 4-8, 2014), that proportion was 73 percent, exactly what we saw back in December 2013 and June 2012 and just slightly lower than the 77 percent we observed back in 1997.

This percentage peaked in 2006 and 2007 at about 85 percent. That was a time when the news media were paying a tremendous amount of attention to the issue and the time when Al Gore's movie, An Inconvenient Truth, was in theaters. There are many possible explanations for the 10 percentage point decline that occurred between 2007 and 2009, including the economic recession, the "climategate" controversy and more. (In 2009, a hacker illegally obtained emails from an English university that skeptics used to argue that global warming was a manufactured crisis. Scientists countered that the emails were taken out of context. The incident became known as "climategate.")

But our research indicates that the explanation most likely is changing average world temperatures. About one-third of the country does not trust environmental scientists, and those citizens decide whether global warming has been happening by paying close attention to the last year's average world temperature.

The year after that temperature rises (as when 2010 was the warmest year on record), those individuals are more likely to say that global warming has been happening.


How does climate change rank among the issues Americans are most concerned about?

This is a very interesting question that can be answered in different ways. First, when Americans are asked what is the most important problem facing the United States today, essentially no one says global warming (see Table 1 in this study). But when people are asked what they think will be the most serious problem facing the world in the future if nothing is done to stop it, global warming/the environment is the most frequently cited problem.

And when we asked survey respondents how important the issue of global warming is to them personally, in our latest survey, 18 percent said "extremely important." This is the group of truly passionate activists on the issue, and that activist group is as large or larger than the activist groups in the American public who are passionate about gun control, abortion rights and lots of other issues that have been high on the legislative agenda. Almost one in every five Americans is passionate about global warming, and about 90 percent of those passionate people are on the green side of the issue.


Is there public support for the Obama administration's proposed carbon and energy regulations?

President Obama campaigned in 2008 saying he wanted to reduce greenhouse gas emissions in the U.S. by 80 percent by the year 2050. Large majorities of Americans have favored that goal in our surveys, and when we told our survey respondents how much this would cost them in higher prices for goods and services, we found that Americans were willing to pay the amount of money that federal analyses said would be the incurred costs.

In our 2013 survey, only 10 percent of respondents said that the federal government should do nothing about global warming, and 79 percent said that the government should do some, quite a bit or a great deal. Also, 81 percent of Americans said the federal government should limit the amount of greenhouse gasses that American businesses emit. And in our surveys, large majorities of Americans have favored government intervention in various ways to achieve that goal.

However, in our most recent survey, only 49 percent of Americans said they favor government mandates reducing greenhouse gas emissions by power plants, which is exactly what the President's recent Environmental Protection Agency regulations do. So, public support for this particular action is not even a majority.


Do people have concerns about future generations being hurt by climate change?

Yes. When asked how much global warming will hurt future generations, 67 percent said a lot or a great deal, whereas only 32 percent said that global warming will hurt them personally a lot or a great deal. So, most people seem to see the effects as playing out more dramatically after they themselves have passed away.

In terms of political party affiliation, who are the most likely to believe in global warming and the least likely?

Interesting question. There's a split between Republicans and Democrats – 57 percent of Republicans believe [in global warming] whereas 86 percent of Democrats do so, and 71 percent of independents do. But notice that even a majority of Republicans think that the Earth has been warming over the last 100 years.


How will this affect the 2014 national elections?

In 2008 and 2010, candidates' statements about global warming influenced voting in the presidential election and in congressional elections. Candidates who took what might be called "green" positions won votes as a result, and candidates who expressed skeptical views lost votes as a result. We expect to see the same happening in 2014 – candidates who believe that global warming has been happening and is a threat that deserves government attention stand to benefit at the polls if they express those views early and often to voters.

Jon Krosnick, Communication, (650) 725-3031,

Clifton B. Parker, Stanford News Service, (650) 725-0224,