Before Spencer Christian, a weather forecaster with KGO-TV Channel 7 in San Francisco, steps before the camera during the station's 6 p.m. newscast, he scrutinizes a computer screen to analyze the latest forecasting data.
But unlike some of his counterparts, Christian doesn't view his extensive knowledge of storm fronts and high-pressure systems on the week's weather as credentials to assess the effects of greenhouse gases on the Earth's climate in the coming decades.
"The climatologists are the experts in this field," said Christian, who started weather reporting in 1975 and worked for 12 years as the weather anchor on "Good Morning America" in New York City before joining KGO-TV in 1999.
Christian is among the majority of TV weathercasters — but a slim majority, only 54 percent — who believe that the planet is warming, according to a new survey.
About one-quarter of the 571 weathercasters surveyed also said they've seen evidence of climate change in their local weather patterns. The survey was released this month by researchers at George Mason University and the University of Texas at Austin.
Nonetheless, while other surveys have reported that more than 90 percent of climate scientists think that human-generated greenhouse gases are a major contributor to climate change, just under one-third of weathercasters think human activity is behind the rise in average global temperatures in recent decades. And about a quarter of those polled agreed or strongly agreed with the statement, "Global warming is a scam."
These divided views between climate scientists and weathercasters matter, the surveyors said, because TV weather anchors have become the de facto science reporters on most TV newscasts. Only 10 percent of TV stations have a dedicated news reporter covering the topic, and two-thirds of the weathercasters were eager to add reporting on climate science to their coverage.
Almost half of them reported discussing climate science with news anchors during broadcasts, and nearly 90 percent said they had spoken on the subject in a public forum, according to the survey.
"Some of the people who do weather on TV actually may have a degree in meteorology and some of them don't," said David Easterling, chief of the scientific services division with the National Oceanic and Atmospheric Administration and chair of the American Meteorology Society's Climate Variability and Change committee. "But they have an important role to play in the whole climate change issue," he said. "People see them as a credible source of information on TV."
The American Meteorology Society concurs with the assessment by the Intergovernmental Panel on Climate Change that human-generated greenhouse gases are behind the steady rise in temperatures since the dawn of the Industrial Age.
The society confers its esteemed meteorological certification for broadcasters, which it now awards to those who have earned at least a bachelor's degree in meteorology and have passed a written exam offered by the society. The certification process is designed "to encourage a broader range of scientific understanding, especially with respect to environmental issues," the society states on its Web site.
That certification, or even just the college degree, distinguishes meteorologists from weather forecasters — who may or may not have training in the field. About half the TV weather forecasters nationwide are meteorologists. The schism in beliefs identified by the university researchers is borne out in the Bay Area, where past and present weather anchors offer differing views on climate change.
The most outspoken local meteorologist insisting that global warming is a hoax is Brian Sussman, a former KPIX-TV meteorologist who now hosts the morning show on conservative talk radio show KSFO-AM. Nationwide, a few other weather forecasters, such as John Coleman of KUSI in San Diego, are well-known for challenging assertions that human activity is altering the climate, and they're in demand as commentators on conservative talk radio and cable television. They're also courted as scientific experts on the speaker circuit.
That role for a weathercaster, though, doesn't sit well with Bill Martin, chief meteorologist with KTVU-TV in Oakland.
"I do hear other meteorologists, some who are ex-meteorologists and some who are now working in industry, talking about global warming being a sham," Martin said. "It frustrates me. For a lot of us it does."
Martin said evidence is clear that the planet has been warming steadily in modern times.
"If you look at the math and the numbers and the charts and the graphs, and say the planet's not warming, then you're not following the scientific method," Martin said.
The 2007 IPCC report noted that 11 of the previous 12 years were the warmest since temperature record-keeping began around 1850. Average temperatures have risen steadily over the past century, with most of the warming occurring during the past 50 years. Christian, the weather forecaster for KGO-TV, is also dismayed by the skeptics of climate science in the weather forecasting field.
Meteorologists, Christian said, have the same political biases as found among the public, "which may shape their views on climate change."
Sussman, however, was surprised that so many weather forecasters supported climate scientists' views that the planet is warming, with much of it linked to the burning of fossil fuel, which releases the heat-trapping gas carbon dioxide. He believes many more doubt that humans are causing global warming, and "a lot of them are worried about their job security should they come out and declare that."
He believes meteorologists are well-qualified to speak to, and debunk, climate science. "I think climate and the weather are very easy to understand."
Sussman, who has a book called "Climategate" scheduled for release on Earth Day, April 22, said the book challenges scientific assertions about climate change, and that it's "bulletproof" with its hundreds of scientific citations.
He said CO2 is "truly the least potent" greenhouse gas, and that it in fact will help promote plant growth, since plants absorb CO2 and process it into carbohydrates.
And "the biggest crock in all of this," he said, is that water vapor is in fact the primary greenhouse gas. Yet Sussman said none of the climate models used to predict warming trends take that into account.
"Ninety-five percent of all greenhouse gas is water vapor, and none of those models consider that," Sussman said.
Easterling, of the NOAA, was quick to counter Sussman's claims.
"It appears Mr. Sussman is as uninformed as I suspect most TV weathercasters are," he said. "Of course (the models) consider water vapor."
Stephen Schneider, a Stanford University climatologist, described as "laughable" the percentages used by Sussman. "The potency of the greenhouse gas matters, not the quantity," he said. "A tiny amount of Ebola virus can kill you."
Water vapor, Schneider explained, is a weak heat-trapping gas, compared with CO2 and certainly with more potent greenhouse gases like methane. Since the 1960s, climate models have factored in water vapor as the most abundant greenhouse gas, he said.
"He is misfiring on all cylinders," Schneider said.
William Hooke, the director of the American Meteorological Society, staked out a middle ground on the legitimacy of weathercasters and meteorologists speaking out on the subject of climate change.
"As with any other subject, we should be free to speak our mind," Hooke said.
But "all of us need to do our homework and make sure our statements are factual."