When scientists communicate with other scientists, they begin with background, offer details and then deliver their conclusion. When talking to the public, they should begin with the bottom line. Explain why people need to care and then offering supporting details (Somerville & Hassol, 2011). Facts are meaningless if people don't understand why they should care about those facts.
Use metaphors to explain difficult concepts. Some people ask how scientists can predict how the climate will behave 50 years from now when they cannot predict the weather two weeks from now. Those people are confusing climate and weather.
To explain this, a scientist might compare our warming climate to a pot of boiling water. When you set a pot of water on a hot stove, you can know the water will boil in about 10 minutes even if you don't know when and where each tiny bubble will appear (Hassol, 2008).
Use real-world analogies (Loewenstein, Weber, Hsee, & Welch, 2001). Illustrate the science in a way that will resonate with your audience on an emotional level. Explain, for example, that every day humans release enough greenhouse gases into the atmosphere to trap an amount of energy equal to detonating 400,000 atomic bombs like the one dropped on Hiroshima.
Use plain language. Avoid jargon. Your goal should be to describe the science, not label it (ecoAmerica, 2013).
Be wary of uncertainty. A scientist might describe her projection as "uncertain" because she can't say with absolute certainty how carbon pollution will shape the climate. The problem is that, to the public, "uncertain" sounds like "unsure" (See Marshall, 2014), but it often means something closer to "very likely." This can breed wishful thinking. People will expect the best if there is no guarantee of the worst (Markowitz & Shariff, 2012).
Compare scientific uncertainty to medical uncertainty. If you were "very likely" or even "somewhat likely" to develop cancer, you would not hesitate to seek treatment. If your audience still feels unsure, remind them that it's better to be safe than sorry. We should prepare for the worst, not the best.
When, not if. Scientists could project a range of impacts at a fixed point in time (e.g. "The sea will rise three to five feet by 2050.") They could also project a specific impact at an uncertain time (e.g. "The sea will rise by three feet between 2030 and 2050.") It's better to do the latter. People will feel more concerned and will be more likely to support climate action (Ballard & Lewandowsky, 2015). This may be especially true of conservatives (Rickard, Yang, & Schuldt, 2014).
Explain that scientists agree about climate change. The large majority of Americans underestimate the scientific consensus on climate change (Leiserowitz et al., 2018). Explain that 97 percent of climate scientists agree that humans are causing climate change (Cook et al., 2016), and warn that politically motivated groups are trying to sew doubt about the scientific consensus (Linden, Leiserowitz, Rosenthal, & Maibach, 2017). If possible, use a pie chart when making explaining this fact (Van der Linden, Leiserowitz, Feinberg, & Maibach, 2014).
When people understand the scientific consensus on climate change, they are more likely to accept climate science, more likely to worry about climate change, and more likely to believe that people should take action. This is particularly true among conservatives (van der Linden, Leiserowitz, & Maibach, 2019).
Be warm. Scientists are generally judged as competent but not warm. As a result, people envy them, and this hurts their trustworthiness (Fiske & Dupree, 2013). Convey warmth by showing concern for people and the environment.
Debunk myths. Climate deniers have floated a number of myths about climate change. For example, some have said that Earth is becoming cooler, not warmer. When confronted with a myth, don't repeat it. Instead, lay out the evidence in simple language. The facts should feel simpler and more intuitive than the myth. (Cook & Lewandowsky, 2011).
Begin with the facts. The Earth is becoming warmer over time.
Reinforce the facts. The ten hottest years on record all came in the last 16 years. 2014 was the hottest year ever recorded.
Point to the myth. Some have suggested the Earth is actually getting cooler.
Explain why the myth is false. This is patently false. We are seeing record high temperatures year after year in all corners of the globe.
Connect local weather to global climate. Explain how a local drought, flood or severe storm is connected to climate change. Personal experience with extreme weather can make people feel more concerned about climate change (Konisky, Hughes, & Kaylor, 2015).
Explaining the science isn't enough. Progressives who know a lot about science are more likely to trust evidence of climate change, but conservatives who know a lot about science are actually more likely to dismiss evidence of climate change (Kahan et al., 2011). People seek out information that confirms what they already believe. That's why you cannot simply convey the facts of climate change. You must also speak to people's values. Information is the least important part of persuasion. See Persuading Conservatives.