How to Tell Policymakers about Scientific Uncertainty

"Uncertainty drives science forwards, and keeps scientists looking for answers....But for policymakers, uncertainty is problematic, particularly around controversial choices on the environment or public health. Policymakers like to have definite answers - an impossibility in science."

Designed for scientists, this resource shares strategies for communicating uncertainty to policymakers. "Some uncertainties can be reduced by collecting more or better data. But uncertainties in complex natural systems, like the Earth's weather, mean no practical amount of research will give certainty." It is suggested here that scientists communicate to policymakers that uncertainty does not equate to flawed science. For example, the vast majority of scientists are certain that climate change is happening, even if they remain uncertain about the exact outcomes.

Along these lines, the resource makes reference to the Intergovernmental Panel on Climate Change (IPCC)'s "likelihood scale" that can help link probabilities to everyday language. But because people can interpret qualitative phrases ("it is extremely unlikely that...") as included in the IPCC scale, this resource suggests that scientists also communicate actual percentages ("there is more than 95% probability").

Other recommendations include: "Be transparent about the assumptions that have been made in each case, and about the quality of the evidence. It may help decision-making if you present a range of outcomes that also take into account different actions. For example, climate change scientists present the possible outcomes of severely cutting greenhouse gases, cutting them a little and not cutting them at all....Be as neutral and objective as possible and let the facts speak for themselves. Don't paint either a 'doom and gloom' picture or an overly positive picture if the data don't back it up."

In conclusion: "when formulating messages for policymakers, make sure you always include something about the unknowns, however tempting it is to omit them for potentially more interesting messages. And try to share what you have learned about communicating uncertainty with colleagues so other scientists don't 'reinvent the wheel'. Consider giving a group talk in your department or producing some written guidance. Offer yourself as a mentor to colleagues looking to do the same thing. Finally, keep looking out for opportunities to give another briefing."