Officials and scientists who write and review the nation's chief climate analysis say they are struggling to get across the risks of climate change to policymakers and the public.
Finding ways to portray risks in time scales and language that people understand remains a challenge, they said this week at a two-day meeting of the National Academies of Sciences, Engineering and Medicine.
And it's as difficult to explain risks on a localized level as it is to show, without facing accusations of fearmongering, that climate change is an existential threat to the human race, they added.
So far, "we're missing the mark," said Alice Hill, a member of President Obama's National Security Council and ex officio member on the last climate assessment.
The U.S. Global Change Research Program, a 13-agency effort, is responsible for assembling the national climate assessment. The report is meant to be a comprehensive look at climate change impacts on the United States.
The third report, released in 2014, found increased evidence of human-made warming and warned of heavy precipitation and extreme heat events. It also found increased confidence that recent trends in sea-level rise were due to humans.
Agencies are starting to assemble teams to create the fourth assessment, while the National Academies' Committee on Advice to the U.S. Global Change Research Program is providing guidance for officials (Greenwire, Feb. 19).
Thomas Karl, chairman of the Subcommittee on Global Change Research, which is the steering group for the 13-agency program, said at the meeting that framing climate risks within the assessments remains one of the key challenges.
"You have all these cascading effects that really lead to those big risks," Karl said, "and I think we need to ask ourselves, how do we communicate most effectively in the next national assessment what those are?"
Hill, a former judge, called herself a "huge fan" of the climate assessment but said it appeared that the public and policymakers were not comprehending the risks that it portrayed.
She said she frequently speaks to groups of engineers, infrastructure operators and local policymakers and asks whether they've read the national assessment. She said that only about "two or three hands out of an audience of 100 people" ever say they have.
"If the people who need to care about this -- an architect or an environmental lawyer who's working on [the National Environmental Policy Act] -- are not paying attention to this," she said, "we need to figure out a way to make this resonate so that they do care."
Hill said that it's difficult, though, to convey the full scope of risks when people only home in to the impacts that will touch them most locally. She also said the report was hampered by the fact that it relies on consensus and thereby misses some of the more uncertain impacts that are on the extreme end of scenarios.
"We need to be more willing to talk about that tail end," she said, "because if you talk, if it's completely consensus, are we at risk for understating the risk?"
The authors of the report agreed that they also struggle with portraying risks where the science isn't certain yet.
"There are a number of extreme events where the science isn't quite there yet, but communicating risk could be very important," Karl said.
One such area: How will the electrical distribution system be affected by more frequent ice storms and lightning?
"It's not like we're totally ignorant" of those effects, Karl said. "How we don't just push that aside" by saying the science is still uncertain is a struggle that the authors of the report face.
Timelines and solutions
At this week's National Academies meeting, White House science and technology adviser John Holdren said that one of the areas that's also been difficult to convey is the time frame of risks and potential solutions.
"There are all these different time scales in the climate problem," he said. "Folks on the whole just don't get that."
He noted that studies have begun to show risks on longer time scales, including recent research that has shown sea-level-rise risks associated with human activity and climate change will last over the next 10,000 years.
Bradley Udall, director of the University of Colorado's Getches-Wilkinson Center for Natural Resources, Energy and the Environment, said those longer time scales may be helpful in getting more people concerned about the findings of the assessment.
"It seems like we do not convey the existential risk to society in these assessments," said Udall, who participated in the second national climate assessment. "When they see the irreversibility of this, they wake up. That's a different kind of risk, and it's one that we haven't conveyed adequately."
At the same time, the time scales for solutions are also still not clearly understood, Holdren said.
"The time scale that I think is probably most important and the least understood by most members of the public and most policymakers is exactly how long the energy system takes to be transformed," he said.
According to Holdren, the total investment in the world's energy system is about $25 trillion. Of that investment, about 80 percent is still fossil fuel infrastructure.
"Which means if you want the energy system in 2050 to look very different than it looks today," he said, "you better be changing it rapidly now because no matter how badly you want it, you can't transform a $25 trillion infrastructure that is now 80 percent fossil fuel very quickly."
Robin Gregory, an adjunct professor at the University of British Columbia, said that one reason the report may not be resonating is that it's asking people to form opinions about a subject -- climate change -- that they still know nothing about.
"We're asking them to step outside their usual role. We're asking them to step inside a new arena," Gregory said. "It takes time."
He suggested that the report make more use of pictographs and case studies that bring in local knowledge and community values.
The authors of the national assessment should also frame their report around "dramatic" risks and costs, said Robyn Wilson, associate professor of risk analysis and decision science at Ohio State University. According to Wilson's research, that's a strategy that generally resonates more for issues where the political status quo is against taking action.
But the report's authors will have to walk a fine line to avoid being labeled fearmongers, said Kristie Ebi, a professor of environmental and occupational health sciences at the University of Washington.
"Any of us who have worked on this field for a long time," she said, "have been accused of scaremongering when we try to talk about risk."
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