Skeptics of climate change -- a good number of them about to take seats in Congress -- often point to uncertainties or holes in the science as reasons for delaying or not taking action.
But uncertainty is the modus operandi of science, as Vaughan Turekian, chief international officer at the American Association for the Advancement of Science, describes it. Scientists report not only what is known but to what degree it is known.
"Science is never an open and closed case," Turekian said.
Still, there is a fundamental difference between the way the public and policymakers see uncertainty and the way scientists do, which creates a gap that needs constant bridging, scientists say.
"When scientists talk about results they rarely focus on the things they know with great certainty. It seems counterintuitive to people who are not scientists, talking so much about what we don't know," said James McCarthy, a professor of oceanography at Harvard University.
"If you were to hear someone say, 'I know with 100 percent certainty that the Earth's climate will change or not,' that would be a statement to walk away from because you would know right away that a scientist hasn't made that statement."
There are several coordinated efforts under way to bridge the gap. John Abraham, an associate engineering professor at Minnesota's St. Thomas University, is creating a "climate rapid response team" of scientists who are open to addressing the politics of global warming. The American Geophysical Union, separately, is establishing a bank of climate scientists to serve as experts on global warming.
It is probably no coincidence that policy debates involving environmental issues have often been long and contentious. A number of environmental debates, including those over acid rain and the depletion of the ozone layer, have centered on scientific uncertainties.
Judith Curry, chairwoman of the School of Earth and Atmospheric Sciences at the Georgia Institute of Technology, blames climate scientists. She said the reason uncertainty has been especially played up in climate science is because "climate scientists were so vehement in their overconfidence, which just didn't stand up given the complexity of the problem. ... Trying to hide uncertainties just ends up compromising the scientists and confusing the policymaking process."
Uncertainty, she said, should be used as information in the decisionmaking process. But for lawmakers, it is not easy to incorporate uncertainty into policy or to prove to constituents that an action is necessary. Moreover, the public is not well aware of how uncertainty is handled in science, according to Robert Costanza, director of the Institute for Sustainable Solutions at Portland State University In Oregon.
"That's part of the problem, and that's why the public opinion can be so easily manipulated because of that lack of basic understanding," he said.
In the 1970s and 1980s, the United States had an Office of Technology Assessment, which analyzed complex scientific concepts, producing studies for Congress on subjects like the nation's energy future and ecosystem management and giving advice on how to address issues. The office was defunded during the anti-big government wave that followed the release of the 1994 Republican document called "Contract with America" and the Republican takeover of the Senate during the first term of the Clinton administration.
Many other countries in Europe still have similar mechanisms, though, to assess the quality of scientific information. It is something the United States should consider again, said Thomas Dietz, vice chairman of the science panel in America's Climate Choices, a study done by the National Academy of Sciences.
"We need to have a mechanism to take scientific understanding and make it available both to policymakers and to the public," said Dietz, assistant vice president for environmental research at Michigan State University. "A lot of issues we don't seem to have much space for a public discussion that doesn't become heated and a matter of talking points and pundits."
Scientists are waiting for integrity standards to come out of the Office of Science and Technology Policy, required by President Obama in a March 2009 executive order and a year-and-a-half overdue. Public Employees for Environmental Responsibility recently filed a lawsuit to obtain documents relating to the overdue standards. Without them, it has been difficult for government agencies to agree on policies for transparency, collaboration and public participation in data gathering and decisionmaking based on that data.
With the lack of government mechanisms, boosting science education in the United States might help the public understand the state of science and how to make decisions in the face of uncertainty, Dietz said. The most recent World Economic Forum report ranked the United States 48th in math and science education.
Strengthening science education, agreed Turekian, would strength critical thinking. And that, he said, is necessary to understand the complexity around climate change because the better you understand how scientific information is gathered, the better you understand the information itself.
"When you think about critical thinking, you don't take as given either facts or counterfacts that are just imposed on you," he said. "Rather, you take the time to sort of critically assess which uncertainties are more important and which uncertainties have nothing to do with the broader trends."
The broader trends, he said, are understood: If atmospheric carbon dioxide is increased, there will be certain increases in temperature. The uncertainties that need more understanding are the feedback effects from increasing temperature, such as what warming would do to the makeup of clouds, and if clouds would lead to even more warming if they change.
That level of detail does not need to be known to put in place measures akin to insurance policies to guard against the range of effects, scientists tend to agree, though they also tend to stay out of the policy debate.
Costanza has tried to combine a precautionary principle with a polluter-pays principle in incorporating uncertainty into policy. The concept can also apply to environmental disasters like oil spills.
In his idea, companies that pollute or emit carbon dioxide must take out bonds that cover worst-case scenarios that would be held until uncertainty is removed. This would create an incentive for emitters to reduce uncertainty by funding independent research or adopting cleaner practices.
"If they don't see it in financial terms, they're going to try to avoid it or manage or manipulate the uncertainty rather than reducing it," he said. "All it takes is a little muddying of the water so there's not a clear answer to delay action for years and years. It takes a lot less money and effort to muddy the water than it does to clear the water."