A lot of today’s widespread confusion about climate change—some of it unwitting, some of it deliberately cultivated—stems from the critical miscommunication of two little words: risk and uncertainty. To most of the public, risk means a danger that must be addressed, whereas uncertainty means a lack of clarity about whether there is any meaningful danger at all. To scientists and economists like myself, uncertainty has a starkly different meaning. It is worse than risk; it indicates the possible range of just how bad a (very real) danger will be. You can think of uncertainty as a risk multiplier.
As a result of this confusion, our efforts to share our research findings with a broad audience have often backfired spectacularly. If we want to speak more clearly and effectively about the grave threats facing the world, we need to unlearn our academic communication habits and embrace the language of everyday speech. It is certain that unmitigated climate change will—and to a large extent already does—affect everyone on Earth; the impacts are uncertain only in the sense that they might be even more destructive than we expect. Failure to respond aggressively will make the danger worse. That is another certainty, one that becomes more likely every time climate change drops down on the list of public priorities.
The words we choose can have an enormous impact. Mention that climate change is inherently uncertain and an oft-heard response is “Oh, looks like we don’t quite know yet. Better to wait and see, do more research.” That one word has become a powerful tool for sowing doubt about climate action. In the early 2000s, pollster Frank Luntz famously counseled Republican leaders to make a supposed “lack of scientific certainty a primary issue in the debate,” following in the tradition of fossil-fuel interests that have pursued a similar strategy to stave off carbon-limiting policies or regulations. Luntz understood that “should the public come to believe that the scientific issues are settled, their views about global warming will change accordingly.”