"Americans and Climate Change: Closing the Gap Between Science and Action" (PDF) is a report synthesizing the insights of 110 leading thinkers on how to educate and motivate the American public on the subject of global warming. Background on the report here. I’ll be posting a series of excerpts (citations have been removed; see original report). If you’d like to be involved in implementing the report’s recommendations, or learn more, visit the Yale Project on Climate Change website.

Below the fold is the second part of the chapter on the challenges science and scientists face in communicating to the public about global warming. There’s lots of good stuff, but I was particularly interested in the discussion of how to convey scientifically accurate information about the connection between global warming and today’s weather.



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Communicating the Risks or the Solutions

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There is, as well, a more basic question, discussed a great deal at the Conference, of whether communicating the risks associated with climate change to Americans is the correct route to go in the first place. Many contend that it is time to discontinue "scare-mongering" and alarmism, and instead portray a hopeful vision of solutions that will create jobs and pump up the economy. Those seeking to advance action will likely need to communicate both consequences and solutions. Finding the right balance and sequence to promote action commensurate with the science is a task that will need to draw not just on the natural sciences but also on the social sciences (see more on this theme later in Part I).

Meanwhile, many at the Conference intuitively recognized the potential value of better understanding and communicating local impacts of climate change so that Americans would grasp what this issue could mean for their well-being and that of their children. Recognizing that this is partly a function of the available science, Conference Recommendation #2 calls for research priorities on climate change to be more responsive to society’s information and decision-making needs, including acceleration of ongoing efforts to observe and model local impacts at greater resolution levels.

Scientific Conservatism Meets Today’s Weather

Weather extremes and anomalies increasingly provoke societal discussion about climate change. For example, the unusually warm East Coast January in 2006 appears, anecdotally at least, to have increased the general public chatter about climate change. At the time of our Conference in the fall of 2005, Hurricanes Katrina and Rita were utmost in the public’s mind.

Such events present what has become a recurring dilemma: Should those seeking to prompt action on climate change opportunistically exploit the spike in public concern? Or should they remain scientifically conservative and seek to disabuse people of the notion that individual weather events or seasons, alone, confirm that human-induced climate change is happening?

If such public concerns are treated as a "teachable moment," this may offer fleeting gains in the public’s propensity to act, while also incurring a significant risk that when the local weather turns again, concern will dissipate and even sustain a backlash.

Distinguished University of California scientist Richard Somerville discussed the recent hurricanes at our Conference and agreed to paraphrase his comments for this report. He writes that:

"A warmer climate means that, statistically, hurricanes may be stronger, on average. It does not mean we can definitely prove that any particular hurricane owes its strength to climate change, only that the odds of strong hurricanes have gone up. There is persuasive scientific evidence from observations, theory and models that higher sea surface temperatures should and apparently do increase the duration and the average maximum intensity, but not the frequency, of hurricanes. There has clearly been a big observed increase in the duration of hurricanes and in their average maximum wind speeds in recent decades. The number of Category Four and Five hurricanes globally has nearly doubled since 1970.

We know that hurricanes are highly variable, no two are alike, and next year’s hurricane season might be very different from this year’s. It is our natural inclination to wait a few more years, observe more hurricanes, improve our theories and models, until we have an airtight case to present. Science is inherently self-correcting, and later research can always confirm, extend or disprove earlier research. Nevertheless, the best current research tells us that all the oceans have recently warmed substantially, that human activities are the primary cause of that warming, that an increase in the average intensity of hurricanes is the expected result, and that we have indeed observed a remarkable increase in the numbers of the strongest hurricanes. No amount of waffling over probabilities and statistics can obscure these sobering results."

This is an example of clear scientific communication, which is more the exception than the norm in our society (and of course even this passage, for all its admirable clarity, is too long to be delivered as a sound bite on the TV news). Due to the inherent variability of the climate system, few if any specific weather events will ever meet the unrealistic standard of serving as definitive proof of climate change. But many can be described as "consistent with" or "indicative of " what we expect to see now or in the near future under a disrupted climate. And, as Somerville illustrates, such language can be used to describe how specific events fit — or don’t fit — a larger pattern.

In this spirit, a number of our Conference recommendations seek to improve the scientific literacy and communications capabilities of those best positioned to portray this high-stakes issue to Americans. Together, they promote ways for our journalists and editors, teachers, business leaders, religious leaders, TV weathercasters and the scientists themselves to have access to timely information that puts today’s weather events into context using clear language.

The Conference participants did not have time to craft any particular turns of phrase, but instead called for new institutions, capacity- building, training and even coordinated advertising initiatives that will evaluate these issues with great care and ultimately supply our society’s communicators with language that is scientifically accurate without being too reticent or opaque to gain wider notice and comprehension.

One metaphor that may bear expanded usage is that of the "human fingerprint," a clear way of summarizing the meaning of a flourishing body of research collectively known as "detection and attribution studies." This is a key ingredient often missing from the news coverage of observable effects, namely lucid and concise explanations of how scientists can, with increasing confidence, attribute the causes of observed effects to human rather than natural causes. Studies of the temperatures at different levels of the atmosphere (e.g., tropospheric warming versus stratospheric cooling), decreases in the day-night temperature range and land-sea temperature differences, among many others, provide mutually reinforcing observations that together distinguish the human fingerprint from natural causes such as solar or volcanic activity.

Nobody should expect Americans to cozy up for bedtime reading of such studies, but more can be done to translate these findings for broader accessibility. Exploring how this should be done is part of the task of the "bridging institution" called for in Recommendation #1. In short, this institution would be a science-led effort to use all media, the Internet, and other opportunities to translate and direct the scientific results on climate change in journals such as Science, Nature, Climatic Change and elsewhere to the alert, reachable public.

Observable versus Projected Impacts

All the above suggests the potential value of stepping back to a more basic question: What balance should those seeking to prompt action strike between information about currently observable consequences of climate change and the highly concerning projections of future impacts?

Popular news coverage about climate change is strongly biased toward highlighting emerging evidence that climate change is or may be underway today, namely, retreating glaciers and melting icecaps, European heat-waves and floods, and record-breaking hurricane seasons. Such stories are tangible and vivid. They counteract the public interpretation of the issue as a long-term threat only, and help to make it newsworthy. And yet coverage of observable climate change may be the toughest scientific turf to play on since it is relatively more uncertain than projections of future changes likely to transpire if we remain on our current emissions trajectory.

This may seem paradoxical: Shouldn’t something here today be more certain than something coming tomorrow? In fact, we have made major progress in identifying the human fingerprint evident today and distinguishing it from the natural variability of the climate. Yet our confidence in projections of future impacts, assuming continued increases in emissions, is still relatively greater. This point is encapsulated in a summary table in the Intergovernmental Panel on Climate Change’s Third Assessment Report from 2001 showing the scientists’ relative confidence levels in many climate change phenomena — ranging from drought risk to peak cyclone intensities to the frequency and maximum temperature of hot days. The confidence level associated with each phenomenon’s occurrence is shown to be equal or higher when considering future projections over the 21st century than retrospective observations from the latter half of the 20th century. To the extent that future projections contain uncertainty — and they do — the scientific debates center on how rapid and severe the changes will be, not whether they will transpire if we continue emitting greenhouse gases at growing rates.

And what do our future emissions look like? To date, humanity has increased the concentration of the primary greenhouse gas, carbon dioxide, in our atmosphere by just over 30 percent (i.e., from approximately 280 parts per million in the pre-industrial year 1750 to approximately 381 parts per million today). If we stay on a so-called "business-as-usual" trajectory, the range of illustrative scenarios from the IPCC show concentrations rising anywhere from 90 percent to 250 percent over that same benchmark pre-industrial level (i.e., 530 to 970 parts per million) by the year 2100. Current concentrations have not been exceeded in the past 420,000 years — and likely not in the past 20 million years — and they remain on a path of rapid and continuing increase.

Scientists as Messengers

Sustaining a scientific definition of a problem in the public’s mind can have maladaptive consequences. It partitions the issue into a zone where many people believe they are unqualified to come to their own conclusions. After all, most of us are not scientists. This means that we are relying on the testimonials of others, even if we recognize them to be underpinned by the scientific method, peer review, and a high degree of consensus.

Psychologists have documented how the identity and attributes of a "messenger" can be especially important in determining how an individual interprets a given piece of information. Is the source of information knowledgeable and trustworthy, the typical listener will ask? Do they share the listener’s interests, or are they operating under the influence of some disguised agenda?

If the issue is a scientific one, people generally regard scientists as the most credible messengers. Yet when we asked the scientists participating in our Conference about the expectation that they and their colleagues will communicate — and do so forcefully when societal well-being is at stake on an issue like climate change — their answers are often sobering. They describe a system of career incentives and norms that are powerfully inhibiting (see more on this below). But they also lament the lack of training and experience that would enable them to communicate effectively beyond their peer group to broader society, even if their incentives did incline them to do so.

It is crucial, however, to distinguish between the idea that one should not always rely on scientists as messengers and the notion that scientific findings should not constitute the core content of a message. In fact, perceptions of scientific consensus appear to be an exceptionally important driver of public readiness to support action on climate change.

Steven Kull, Director of the Program on International Policy Attitudes (PIPA) at the University of Maryland and a participant in our Conference, found in a 2005 poll that those who believe that there is a scientific consensus are much more inclined to believe that even high- cost steps are needed to mitigate climate change. Among those who believe that scientists are divided, only 17 percent favored high-cost steps, as compared to 51 percent of those who perceive there is a consensus.

The poll also found that when the American public was asked to "suppose there were a survey of scientists that found that an overwhelming majority have concluded that global warming is occurring and poses a significant threat," the overall percentage who said they would then favor taking high-cost steps increased dramatically from 34 percent to 56 percent. Accordingly, the "bridging institution" called for in Recommendation #1 is specifically tasked with conducting surveys of scientists, among many other functions.