Why do climate scientists who speak to the public face a paradox?

Robert Gifford.

Scientists understand that climate models inherently have uncertainty. But as soon as the public experiences some uncertainty in the message, people begin to dither and to say, “Well, I guess it's not so urgent — the experts aren't so sure of themselves”.

How can climate campaigners make themselves heard?

Messages have to be carefully targeted to different demographic groups, based on their self-interest. For the older generation, it's about their children and grandchildren; and for the younger generation, it's about them and their generation.

How useful are phrases such 'climate justice'?

For people with social-justice concerns, such a phrase will work. It resonates with members of Greenpeace and of left-leaning political parties; people more on the right side of the political spectrum will say, “You take care of your problems, we'll take care of ours”.

What five elements make up an effective message?

First, it has to have some urgency. Second, it has to have as much certainty as can be mustered with integrity. Third, there can't be just one message: there must be messages targeted to different groups. Fourth, messages should be framed in positive terms. Evidence from a recent thesis I co-supervised shows that people are less willing to change their behaviour if you tell them they have to make sacrifices. If you tell them they can be in the vanguard, be a hero, be the one that helps — that works. Fifth, you have to give people the sense that their vote counts and that their effort won't be in vain.

If some commentators are right and we are past the point of no return, how could we mobilize people into action?

The same five elements would apply, except that the messages would emphasize adaptation and mitigation. We would need to tell people they can lessen the impact and be someone who helps our own and other species — but with a tilt towards communicating that there will be huge impacts.

How do we communicate difficulties while making clear there are myriad options to be constructive?

We can learn from the success of other campaigns, such as seat-belt, anti-alcohol or anti-smoking campaigns. The fear-appeal approach can be overdone to the point where it has a counteractive effect. Things should be presented more in terms of asking how each person is going to help us face the challenge. Saying “It's all over” makes people give up.