Table 1 Measures of key variables about global warming.

From: Support for climate policy and societal action are linked to perceptions about scientific agreement

  Questions Coded responses
Independent variable   
Perceived scientific agreement ‘Which comes closer to your own view?’ 1=Consensus understood (‘most scientists think global warming is happening’)
   0=Consensus not understood (‘a lot of disagreement among scientists about whether or not global warming is happening’, or ‘most scientists think global warming is not happening ’ or ‘do not know enough to say’)
Dependent variables   
Injunctive beliefs ‘Do you think each of the following should be doing more or less to address global warming?’ (7 items*, α=0.971). 5-point scale: 1–5 (should do: much less, less, about the same, more, much more)
Policy support ‘How much do you support or oppose the following policies?’ (6 items, α=0.878) 4-point scale: 1–4 (strongly oppose, oppose, support, strongly support)
Mediators (key beliefs)   
Belief certainty ‘Do you think that global warming is happening?’ ‘How sure are you that global warming is/is not happening’ 9-point scale: 1 (complete certainty that global warming is not occurring) to 5 (not certain/don’t know) to 9 (complete certainty that global warming is occurring)
Human causation ‘Assuming global warming is happening, do you think it is…’ 3-point scale: (1) ‘global warming is not happening’ or ‘it is caused mostly by natural changes in the environment’; (2) ‘global warming is caused by both human activities and natural change’; (3) ‘global warming is caused mostly by human activities’.
Collective efficacy ‘Which of the following statements comes closest to your view?’ 4-point scale: (1) ‘global warming is not happening’ or ‘Humans cannot reduce global warming even if it is happening’; (2) ‘Humans could reduce global warming, but people are not willing to change their behaviour, so we are not going to’; (3) ‘Humans could reduce global warming, but it is unclear at this point whether we will do what is needed’; (4) ‘Humans can reduce global warming, and we are going to do so successfully’.
Harm timing ‘When do you think global warming will start to harm people in the United States/other people around the world?’ (2 items, α=0.969) 6-point scale: 1–6 (never, in 100 years, in 50 years, in 25 years, in 10 years, right now)
Harm extent ‘How much do you think global warming will harm’ (7 items, α=0.967) 4-point scale: 1–4 (not at all, only a little, a moderate amount, a great deal)
  1. *Seven items included: local government officials, state legislators, governors, the US Congress, the president, corporations and industry, and citizens themselves.
  2. Six policy items included: regulating carbon dioxide as a pollutant; signing an international treaty that requires the United States to cut its carbon dioxide emissions by 90% by 2050; adding a surcharge to electrical bills to establish a fund to help make buildings more energy efficient and to teach US citizens how to reduce energy use; requiring electric utilities to produce at least 20% of their electricity from renewable energy sources; providing tax rebates for people who purchase energy-efficient vehicles or solar panels; and increasing taxes on gasoline (by 25 cents per gallon) and returning the revenues to taxpayers by reducing the federal income tax.
  3. Seven items included: respondents themselves, their family, people in their community, people in the United States, people in other modern industrialized countries, people in developing countries and future generations.
  4. α is Cronbach’s α.