Inoculating the Public against Misinformation about Climate Change

"Just as a small dose of vaccine activates the body's immune system to protect against an infectious disease, so message inoculation can help protect the mind against the effects of disinformation."

This research investigated if and how public understanding of the scientific consensus on human-caused climate change can be protected ("inoculated") against real-world misinformation. "The idea is to provide a cognitive repertoire that helps build up resistance to misinformation, so the next time people come across it they are less susceptible," explains lead author Sander van der Linden. In brief, the study finds, although misinformation on climate change can psychologically cancel out the influence of accurate statements, if legitimate facts are delivered with a warning dose of misinformation, some of the positive influence is preserved.

The context is the researchers' observation that: "Effectively addressing climate change requires significant changes in individual and collective human behavior and decision-making. Yet, in light of the increasing politicization of (climate) science [especially in the United States (US), where it tends to be conservatives who deny the validity of climate science and block government policies to respond to global warming], and the attempts of vested-interest groups to undermine the scientific consensus on climate change through organized 'disinformation campaigns,' identifying ways to effectively engage with the public about the issue across the political spectrum has proven difficult....[I]n the face of political polarization, effectively communicating with the public about the scientific consensus [about the reality of human-caused climate change] requires knowledge about: (a) the way in which people attend to, process, and organize new information and (b) the structural nature of the information environment in which people form judgments and opinions about climate change."

To find a compelling climate change falsehood currently influencing public opinion, van der Linden and colleagues tested popular statements found on the internet, each of which was rated for familiarity and persuasiveness, with a nationally representative sample of 2,000 US citizens. The researchers divided participants into 6 groups. Group 1 was a control group. Group 2 received the (accurate) scientific consensus message (which is that 97% of climate scientists are convinced human-caused global warming is happening). This increased their own estimate of the consensus by about 20 percentage points, consistent with prior studies. Group 3 received a classic disinformation message (from the Oregon Global Warming Petition Project, a website claiming to hold a petition signed by "over 31,000 American scientists" stating there is no evidence that human carbon dioxide (CO2) release will cause climate change). This reduced participants' estimates of the consensus by about 9 percentage points. Group 4 received both messages, which canceled each other out. Groups 5 and 6, however, first received the consensus message and then either a shorter or longer inoculation message before receiving the disinformation message. The short inoculation warned that "some politically motivated groups use misleading tactics to try to convince the public that there is a lot of disagreement among scientists." The longer inoculation added details about the Oregon Petition specifically (e.g., explaining that some of the signatories are fraudulent, including Charles Darwin and members of a music band called the Spice Girls, and that fewer than 1% of the signatories have a background in atmospheric/climate science). For those "inoculated" with this extra data, the misinformation that followed did not cancel out the accurate message. The general inoculation saw an average opinion shift of 6.5 percentage points towards acceptance of the climate science consensus, despite exposure to fake news (the Oregon Global Warming Petition Project). When the detailed inoculation was added to the general, the shift was almost 13 percentage points - two-thirds of the effect seen when participants were just given the consensus fact.

The research team points out that, in the past, tobacco and fossil fuel companies have sought to sow seeds of doubt and to undermine scientific consensus in the public consciousness. The team says the present study demonstrates that such techniques can be partially "reversed" to promote scientific consensus, and work in favour of the public good.

"Practically, these findings suggest that, when possible, communicating the scientific consensus on human-caused climate change should be accompanied by information that forewarns the public that politically or economically motivated actors may seek to undermine the findings of climate science. In addition, audiences should be provided with the 'cognitive repertoire' - a basic explanation about the nature of disinformation campaigns - to pre-emptively refute such attempts. In short, these findings add to a growing body of research reporting that communicating a social fact, such as the high level of agreement among experts about the reality of human-caused climate change, can be an effective and depolarizing public engagement strategy."