How to tell policymakers about scientific uncertainty

Uncertainty is part of science but it’s no excuse for indecision, according to Chandrika Nath, scientific advisor at the Parliamentary Office of Science and Technology.

Scientists know that uncertainty is intrinsic to scientific investigation whether as a result of inherently variable natural systems, incomplete knowledge of complex mechanisms, or statistical probability.

Uncertainty drives science forward, and keeps scientists looking for answers. Policymakers, however, like to have definite answers, especially around controversial choices on the environment. So where uncertainty drives scientists into action, it can lead policymakers to indecision, delaying in the hope of eliminating uncertainty or providing an excuse not to make unpopular decisions.

The Intergovernmental Panel on Climate Change (IPCC) has developed a “likelihood scale” that can help link probabilities to everyday language. For example, when the IPCC reports states that “it is extremely likely that humans have exerted a substantial warming influence on climate”, they mean there is a “more than 95 per cent probability” of that being the case.

Scientists often have limited control over how policymakers use their findings but they must still communicate clearly and openly about any uncertainty in the information they present. Making sure that uncertainty is communicated clearly with policymakers should mean that, over time, they become more familiar with the concept, and more confident about making decisions despite it.

Text adapted from an article on the Science and Development Network website.