It happened again. Vice President Al Gore held a press conference on July 14 to hype his favorite topic -- global warming -- and ABC and NBC snapped to attention. Both networks’ evening news shows highlighted Gore’s opinions without giving any time at all to Gore’s critics. Of the big three nightly newscasts, only CBS Evening News refused to take the bait.

On ABC’s World News Tonight, correspondent Ned Potter told viewers that "many scientists, and some politicians as well, say something larger is happening. They say we are seeing early signs of global warming -- the trapping of heat in the atmosphere caused in part by pollution from cars and industry." Potter ran a quote from government scientist Tom Karl, then concluded: "Naturally, the debate over these predictions is as hot as the actual temperatures, but many Americans say something about the weather is amiss and the question is, how seriously?"

Correspondent Robert Hager, on NBC Nightly News, had a similar take: "The government says it’s all an indication that global warming is real and not only brings heat, but also brings more heavy rain because of the evaporation of water into the atmosphere, which comes back down in storms." Hager also ran a quote from Karl, as well as one from Gore. Neither Potter nor Hager let a climate-change skeptic respond.

Climate scientist S. Fred Singer, for instance, could have told viewers that throughout the 1990s there has been a slight cooling trend. In a July 25, 1997 op-ed for The Wall Street Journal, he noted that "weather satellite observations, independently backed by balloon-borne sensors, have shown no global warming whatsoever in the past 20 years." Only surface-based temperature readings have shown warming, according to Dr. Singer, because of such variables as the "urban heat island" effect. (The first half of 1998 has been an exception, with satellite temperatures rising because of El Nino. Candace Crandall of the Science and Environmental Policy Project tells MediaNomics that they have again started to fall.)

Why do reporters so consistently ignore global- warming skeptics? A story on the Time.com web site gives a clue to journalistic thinking. The unbylined story opines that "moves by the fossil-fuel-burning corporations to line up scientists to pooh-pooh global warming may distort conventional wisdom in the scientific community." The story quotes Time science correspondent Michael Lemonick: "You can always find a handful of scientists who’ll say whatever you want to hear...But it’s not as if the scientific community is divided on this issue -- the overwhelming majority of scientists believe that global warming is occurring, and that carbon dioxide is trapping heat."

But 15,000 scientists have signed a petition this year questioning climate-change theories. The petition drive, which was organized by the Oregon Institute for Science and Medicine, accepted no contributions from industry. The petition reads, in part: "There is no convincing scientific evidence that human release of carbon dioxide, methane, or other greenhouse gases is causing or will, in the foreseeable future, cause catastrophic heating of the Earth’s atmosphere and disruption of the Earth's climate."

Perhaps Lemonick is the one finding scientists saying what he wants to hear.

— Rich Noyes