In September, on a stage with a panel of fellow climate experts, NASA atmospheric scientist Kate Marvel said "We are more sure that greenhouse gas is causing climate change than we are that smoking causes cancer."
But while 97% of climate scientists are convinced that human-caused global warming is happening, most Americans are unaware of this scientific consensus. Recent surveys of more than 8,000 U.S. adults find that even those who have great concern about climate change tend to underestimate the scientific consensus by a large margin.
Our prior research has found that Americans can be categorized into six groups - dubbed Global Warming's Six Americas. People categorized as "Dismissive" and "Doubtful" tend to disbelieve climate science, so it is unsurprising that they believe the scientific consensus to be lower (44% and 52%) than it actually is (97%).
However, even people with the greatest concern about climate change-the "Alarmed" and "Concerned"-also give estimates (84% and 73%) that fall well short of the actual level of scientific agreement.
There are several reasons why so many Americans underestimate the actual level of scientific consensus, despite a majority believing in climate change. One is that people's opinions about climate change are influenced by many other factors (e.g., ideology; family and friends) that do not include scientific evidence. Another is that many of the misinformation campaigns that have spread doubt about climate change have specifically targeted the scientific consensus, falsely arguing that "there is still much debate among scientists" about whether climate change is happening or human caused. A third explanation is the simple fact that the scientific consensus is not well-publicized - that is, many people just haven't heard about it.
In fact, while 72% of survey respondents offered a guess about the level of scientific consensus, 28% instead said they "Don't Know." This answer was most often given by the "Disengaged" and least often by the "Alarmed."
These results suggest an important opportunity for climate change communicators. For example, more than 50% of Americans are comprised by the "Concerned" and "Cautious," who tend to already have moderate-to-positive opinions about climate change fundamentals (e.g., that it is happening and human-caused) - despite most being unaware of the true level of scientific consensus supporting the beliefs and attitudes they already hold. This indicates that pro-climate public opinion does not always require knowledge of the current state of climate science, but is also formed through other routes - such as trusted messengers, shared values, and social norms.
At the same time, however, there is a growing body of evidence supporting the "Gateway Belief Model," which demonstrates that improving people's estimates of the scientific consensus can have cascading effects on their beliefs that climate change is happening and human caused, which then increases their sense of worry, and in turn increases their support for climate policy.
In sum, even many people who understand climate change as the serious threat that it is currently misperceive the extent of the scientific consensus by a large margin. However, this presents an opportunity for climate change communicators - because existing pro-climate beliefs and attitudes can likely be strengthened and solidified with simple messages about the scientific consensus.