Yale Program on Climate Change Communication

2. Global Warming Beliefs

2.1 About seven in ten Americans think global warming is happening.

Americans who think global warming is happening outnumber those who think it is not by a ratio of 6 to 1.

About seven in ten Americans (72%) think global warming is happening. By contrast, only about one in eight Americans (12%) think global warming is not happening.

2.2 About half of Americans are “extremely” or “very” sure global warming is happening. Fewer than one in ten are as sure it isn’t happening.

Fifty-two percent of Americans are either “extremely” or “very” sure global warming is happening, the highest level since our surveys began in 2008. Far fewer (7%) are “extremely” or “very” sure global warming is not happening.

Over the last five years (since our October 2014 survey), the percentage of Americans who are sure global warming is happening has increased by 14 percentage points.

2.3 About six in ten Americans think global warming is mostly human-caused.

The 2018 U.S. National Climate Assessment (written and reviewed by hundreds of climate experts over the course of four years) states: “Greenhouse gas emissions from human activities are the only factors that can account for the observed warming over the last century; there are no credible alternative human or natural explanations supported by the observational evidence” (pp. 39-40).http://nca2018.globalchange.gov

About six in ten Americans (59%) understand that global warming is mostly human-caused, an increase of eight percentage points over the past five years (since October 2014). By contrast, three in ten (30%) think it is due mostly to natural changes in the environment.

2.4 More than half of Americans understand that most scientists think global warming is happening.

A review by John Cook and colleaguesCook, J., Oreskes, N., Doran, P. T., Anderegg, W. R. I., Verheggen, B., Maibach, E. W., Carlton, J. S., Lewandowsky, S., Skuce, A. G., Green, S. A., Nuccitelli, D., Jacobs, P., Richardson, M., Winkler, B., Painting, R., & Rice., K. (2016). Consensus on consensus: A synthesis of consensus estimates on human-caused global warming. Environmental Research Letters 11(4). found that six independent, peer-reviewed studies about the extent of the scientific consensus about global warming have reached similar conclusions: between 90% and 100% of climate scientists are convinced that human-caused climate change is happening. The most rigorous of these studies found that 97% of climate scientists are convinced that human-caused climate change is happening.

Now, more than half of Americans (55%) understand that most scientists think global warming is happening, an increase of 11 percentage points over the past five years (since October 2014). By contrast, about one in four Americans (24%) think there is a lot of disagreement among scientists about whether or not global warming is happening, the lowest level since our surveys began. Very few Americans (4%) believe that most scientists think global warming is not happening.

2.5 About one in five Americans understand that almost all climate scientists (more than 90%) have concluded that human-caused global warming is happening.

Although the majority of Americans now understand that most scientists think global warming is happening, fewer understand just how strong the level of consensus among scientists is. Only about one in five Americans (22%) understand that nearly all climate scientists (more than 90%) are convinced that human-caused global warming is happening. However, that number has increased by 13 percentage points over the last five years (since October 2014; see Report PDF, Data Table, p. 32).

About one in five Americans (21%) say they “don’t know” what percentage of climate scientists think human-caused global warming is happening.Respondents were asked to estimate the percentage of climate scientists who have concluded that human-caused global warming is happening by moving a simulated slider bar which appeared on the screen of their computer. This slider allowed respondents to move the marker from 0% on the left to 100% on the right, or to any whole number between the two. A “don’t know” response option appeared below the slider bar.

Public misunderstanding of the scientific consensus – which has been found in each of our surveys since 2008 – has significant consequences. Other research has identified public understanding of the scientific consensus as an important “gateway belief ” that influences other important beliefs (i.e., that global warming is happening, human-caused, and worrisome) and support for action.For more information, see: van der Linden, S. L., Leiserowitz, A. A., Feinberg, G. D., & Maibach, E. W. (2015). The scientific consensus on climate change as a gateway belief: Experimental evidence. PLoS ONE, 10(2).