Fundamentals

Exploring public opinion about global warming begins by gauging how many Americans believe that the planet has been warming, what people think has been causing warming, and whether people believe warming is a threat.  If most people believe that warming has not been happening or is not a threat, then public support for government action to address the issue seems likely to be minimal.  Thus, beliefs about existence and threat may be important determinants of policy preferences.

THE EXISTENCE OF WARMING

Since 1997, large majorities of Americans have believed that the earth has probably been warming.  In 1997, 77% of Americans said so. This percentage rose and fell during the ensuing years: rising to 84-85% in 2006-2007, dipping to 75% in 2009, rising to 83% in 2011, dropping to 69% in 2015, and rising again in 2018 to 74% (see the figure below).   These percentages suggest remarkable and consistent agreement among Americans on this question.


Question wording for all years can be found here.

CERTAINTY ABOUT EXISTENCE

In her book, Merchants of Doubt, historian Naomi Oreskes asserted that the fossil fuel industry and their supporters had been engaged in efforts to reduce the certainty with which some American believed that global warming has been happening and to increase the certainty with which others believed that it has not been happening (1). Our surveys suggest that since 1997, there has been no systematic shifting of certainty in either of these ways.

Among Americans who have believed that warming probably has been occurring, the proportion expressing this view with high certainty was quite consistent between 1997 and 2015, ranging from 43% to 57% (see the figure below).  And it reached an all-time high of 59% in 2018.


Question wording for all years can be found here.

Among people who believed that warming has probably not been happening, the percent expressing high certainty between 1997 and 2015 was typically in the low 30%s, and was 36% in 2018.  The two outliers were 47% in 2009 and 53% in 2011.  But those moments of higher certainty did not last.


Question wording for all years can be found here.   

People who have believed that warming probably has been happening have been more certain than people who believed warming probably has not been happening.   In only one of the fourteen surveys (in 2009) shown in the two figures above was certainty higher among people who doubted the existence of warming than among people who believed that warming has been occurring. In the other thirteen surveys, the proportion of individuals expressing high certainty was greater among individuals who believed in the existence of warming than among people who did not.

FUTURE WARMING

Large majorities of Americans have believed that warming will probably occur in the future if nothing is done to prevent it.  This percentage ranged from a low of 72% in 2011 and 2012 to a high of 76% in 2013, as shown in the figure below.


Question wording for all years can be found here.   

Certainty about future warming has increased since 1997.  Among people who said that the earth’s temperature will probably go up during the next 100 years if nothing is done to prevent it, the proportion who expressed high certainty increased from 45% in 1997 to 59% in 2015 (see the figure below).


Question wording for all years can be found here.   

CAUSE OF GLOBAL WARMING

In 2014, The Intergovernmental Panel on Climate Change (IPCC) asserted that human-caused greenhouse gases emitted during the last century “are extremely likely to have been the dominant cause of the observed warming since the mid-20th century” (2).  How many Americans have held that opinion?

Since 1997, large majorities of Americans have held this view, ranging from a low of 70% in 2009 to a high of 83% in 2007.  Identical numbers appeared in 1997 and 2015 (81%), suggesting no secular trend in this figure over the years.


Question wording for all years can be found here

WILL WARMING BE GOOD OR BAD?

One way to explore perceptions of threat is to ask people whether they believe that warming in the future will be good, bad, or neither good nor bad.  Answers to this question suggest majorities have perceived warming to be threatening.

The proportion of Americans who said that warming of five degrees Fahrenheit in the next 75 years would be bad has ranged from a low of 58% in 1998 to a high of 70% in 2008 (see the figure below).


Question wording for all years can be found here.

Very large majorities of people have believed that global warming will be a very serious or somewhat serious problem for the United States in the future, ranging from 73% in 2009 to 82% in 2006 (see the figure below).


Question wording for all years can be found here.

Even larger majorities of people have believed that global warming will be a very serious or somewhat serious problem for the world, ranging from 76% in 2009 to 85% in 2006, as shown in the figure below.


Question wording for all years can be found here.

References

  1. Oreskes, N., & Conway, E. M. (2010). Merchants of doubt: How a handful of scientists obscured the truth on issues from tobacco smoke to global warming. New York: Bloomsbury Press.
  2. Intergovernmental Panel on Climate Change (November 2014). The IPCC’s Fifth Assessment Report (AR5). Retrieved from https://www.ipcc.ch/pdf/press/ipcc_leaflets_2010/ipcc_ar5_leaflet.pdf