When a panel of influential scientists visited Capitol Hill this month to talk about climate change, they offered none of the barbed words or emotional confrontation that have been the lingua franca of recent political discourse.
The impact of warming. Muir and Riggs glaciers in southeastern Alaska receded dramatically from 1941 (top) to 2004 (bottom). Credits: U.S. Geological Survey. (top panel) W.O. Field; (Bottom Panel) B.F. Molnia
Instead, at a briefing organized by AAAS, they answered climate change skeptics as they've been trained to do: with extensive data, and with a reminder that the scientific process, though imperfect, remains the best available tool for understanding the complex workings of the natural world.
“Skepticism is an integral part of the progress of science, and it helps keep the science on the correct path, ” said veteran climate researcher Warren Washington, former chairman of the U.S. National Science Board. “However, skepticism without specifics, alternate hypotheses, and facts is worthless. It does not advance the science. ”
But Washington and others acknowledged that the reputation of climate scientists has been tarnished by the perception that they are hostile to those who reject the scientific consensus. The panelists urged their colleagues to listen carefully to skeptics and to publish their research when it meets scientific standards.
The 11 May briefing attracted more than 100 staffers from congressional offices and foreign embassies, along with representatives of the U.S. State Department, the Congressional Budget Office, research universities, and nongovernmental organizations. It was sponsored by 13 mainstream American science organizations representing fields ranging from chemistry and meteorology to statistics and agriculture.
AAAS's Center for Science, Technology, and Congress was the lead organizer, with U.S. Senator Mark Udall (D—CO) serving as honorary host.
The briefing was the science community's latest effort to answer sustained attacks based on a handful of errors discovered in the massive 4th Assessment Report of the Intergovernmental Panel on Climate Change and by e-mails apparently hacked from the Climate Research Unit at the University of East Anglia in the U.K. It came just a day before U.S. Senators Joseph Lieberman (I—CT) and John Kerry (D—MA) introduced a broad energy and climate bill.
Such context made the event “tremendously important, ” said moderator Alan I. Leshner, chief executive officer of AAAS. “We all have come to believe that the issue of climate change and what we do about it—particularly as it relates to the issue of energy—is among the most pressing and important issues facing not only American society, but global society as well. ”
In addition to Leshner, who also serves as executive publisher of Science, and Washington, who formerly headed the Climate Change Research Section at the National Center for Atmospheric Research, the panel included two extensively published climate researchers: Richard Alley, the Evan Pugh Professor of Geosciences at Pennsylvania State University, and Richard Smith, the Mark L. Reed III Distinguished Professor in the departments of statistics and biostatistics at the University of North Carolina at Chapel Hill.
The 90-min session served as a short course on what is known, and not known, about the changing climate.
Washington listed arguments commonly offered by skeptics—there is no global warming, or humans are not causing it, or temperature records are inaccurate. Smith and Alley deconstructed those arguments, concluding that they are largely in error.
Warming, Alley said, is a matter of basic physics: Increase the concentration of carbon dioxide, methane, and other greenhouse gases in the atmosphere, and the atmosphere will hold in more heat.
Analysis of the atmospheric gases shows that steadily rising CO2 concentrations come not from volcanoes, he said, but from the burning of organic matter, especially fossil fuels. Thousands of scientists at research centers in many countries have taken thermometer readings on land, at sea, in the atmosphere, and by satellite, and others have documented shrinking glaciers. The inescapable conclusion: The world is getting warmer.
“A lot of what of what they [skeptics] say, at first sight it might appear that they're making reasonable points, ” Smith said. And yet, he added, “a lot of what they say doesn't stand up to scrutiny. ”
Said Alley: “The whole climate community has spent 30 years trying to find a way out of this. Could the Sun be doing it? Could the volcanoes be doing it?... [But] we can't explain what has happened recently without us—it has our fingerprints. ”
Even so, the panelists agreed, data alone won't build support for climate science.
“We have to continue to improve our methods and the accuracy of scientific information that's given to policy-makers, ” Washington said. “Skeptics must be encouraged and allowed to publish their research results in the scientific literature if the science is sound...because that would be better for science. ”