Sorting out the truth on global warming
By BILL ADAIR
Published April 23, 2007
WASHINGTON - A major international study recently concluded there was overwhelming evidence that humans were causing global warming. But that didn't quiet the skeptics. They continue to raise doubts, suggesting that everything from sunspots to cattle flatulence is causing the earth to warm, and insisting that scientists were stretching the truth.
"Every weather extreme is global warming!" said radio host Rush Limbaugh three days after the release of the report. "These people, they're brilliant little socialists and communists. They know how to propagandize; they know how to keep this alive."
Global warming has been called the most dire issue facing the planet, and yet, if you're not a scientist, it can be difficult to sort out the truth.
Here's what scientists involved in the recent report from the Intergovernmental Panel on Climate Change say about the skeptics' points. The IPCC involved more than 2,500 scientists from 130 nations reviewing thousands of climate studies.
Cattle flatulence creates more greenhouse gas than cars.
Variations of this point have been made by Supreme Court Justice Antonin Scalia who made a crack about it in a recent dissenting opinion and conservative columnist George Will. There is some truth to it, although it is sometimes exaggerated.
Cattle and other ruminant animals are surprisingly large producers of methane, the No. 2 greenhouse gas. When they eat plant material, it combines with bacteria in their stomachs to produce methane. U.S. cows emit about 5.5-million metric tons of methane each year, accounting for 20 percent of the nation's methane emissions, according to the Environmental Protection Agency.
The skeptics often mention animal flatulence to trivialize the causes of warming, but Gavin Schmidt, a NASA climate scientist who was a reviewer on the IPCC study, says more gas comes from the front of the animals than the rear.
"It's not really flatulence," he said. "It's really burps."
The skeptics have sometimes exaggerated its effect as a greenhouse gas. The scientists' best estimate says the impact of all animal-produced methane worldwide is roughly the same as the carbon dioxide produced by cars and trucks in the United States. But some skeptics neglect to include those qualifiers and incorrectly contend that cows alone create more greenhouse gas than all cars, trucks and planes.
Sunspots are a major factor in global warming.
This theory, promoted by Sen. Ted Stevens, R-Alaska, and others, seems to make a lot of sense. We know there are fluctuations in heat from the sun, so it seems logical that they could make the Earth hotter.
But the landmark IPCC report released in February said solar fluctuations were not an important factor in the dramatic warming of the Earth in recent decades. Scientists say the amount of heat from the sun has not increased significantly in the past 30 years, even though global temperatures did.
Michael Oppenheimer, a professor of geosciences at Princeton University who worked on the IPCC report, said solar variations "are not the dominant contributor to warming in the past 50 years. Greenhouse gases are the dominant factor."
Studies show Antarctica is cooling, which contradicts the belief that the Earth is warming.
Like other points from the skeptics, this one - from novelist Michael Crichton, conservative author Ann Coulter and others - has a germ of truth, but has been exaggerated.
Indeed, a 2002 study found that a small, ice-free area of the Antarctic mainland had cooled over a five-year period. It also found that, from 1966 to 2000, more of the continent had cooled than had warmed.
The study, by University of Illinois at Chicago professor Peter Doran and other scientists, drew tremendous news coverage. It ran counter to people's assumption that global warming would occur uniformly throughout the planet, and quickly became a talking point for the skeptics.
Doran says his research was taken out of context and wildly exaggerated. Although it showed one portion of Antarctica was cooling, it was wrongly cited as evidence against global warming, he wrote in the New York Times.
Scientists say his findings reflected Antarctica's unique weather patterns, which keep one portion of the continent cooler while the peninsula, which stretches toward South America, has been warming faster than the global average.
Just 30 years ago, there was talk of an ice age coming.
Limbaugh, Sen. James Inhofe, R-Okla., and many others make this point to suggest that scientists are fickle. If the experts were pursuing ice-age theories 30 years ago, the skeptics ask, how can they now believe the Earth is warming?
Indeed, Newsweek published a story in 1975 headlined "The Cooling World."
"There are ominous signs that the Earth's weather patterns have begun to change dramatically and that these changes may portend a drastic decline in food production - with serious political implications for just about every nation on Earth," the article warned, citing a "sudden, large increase" in snow cover and a drop in the amount of sunshine reaching the continental United States.
Today, climate scientists say that was unfounded media hype. Although there were a few studies that suggested the possibility of global cooling in the 1970s, they did not represent a consensus of the world's scientists reviewing the thousands of studies, as the IPCC's reports do today.
"With all due respect to your noble profession," Schmidt said in an interview, "I would have to caution people not to believe everything they read in Newsweek or Time."
The "hockey stick" theory has been debunked.
Charts showing the increase in global temperatures resemble a hockey stick. They show temperatures relatively flat for centuries and then increase sharply in the last 100 years, like the blade on the stick. But skeptics such as Inhofe often say that this theory has been proven wrong and that "the hockey stick is broken."
Scientists involved with IPCC study acknowledge there were minor problems with supplementary information in the original 1998 study that became known as the hockey stick report. Those problems were identified and corrections were made.
But the scientists say the problems were insignificant and did not undermine the core finding of that study and many others since: The Earth's average temperature changed relatively little over centuries but then went up dramatically in post-industrial times.
Said Schmidt: "The hockey stick lives."
What's the big deal if average temperatures increase a few degrees?
This point has been raised by Thomas Gale Moore, a senior fellow at the Hoover Institution at Stanford University and the author of Climate of Fear: Why We Shouldn't Worry about Global Warming.
"It's absurd to believe that we live in the best of all possible times and that we can't adjust" to a temperature change, he recently told Newsweek. He says more people die from cold than warmth and says an increase of a few degrees could prevent thousands of deaths.
Indeed, scientists acknowledge that there are benefits from global warming. They noted at a news conference last week that some apples taste better because the growing season is longer. And as the Earth warms, frigid locales will be more temperate and presumably more desirable.
But the scientists who wrote the IPCC study say they are concerned because the Earth has been warming so fast.
"With just a small increase in the average temperature, you get a big increase in the extremes," said Gerald Meehl, a senior scientist at the National Center for Atmospheric Research and a lead author of the IPCC study.
Scientists believe that as the Earth warms, weather patterns will bring more intense droughts to certain areas and more powerful storms in other places. As temperatures warm, the atmosphere holds more water, leading to more intense rain and more frequent flooding.
Said Oppenheimer, the Princeton professor: "The more we learn, the more we find reasons to be concerned."
Researcher Angie Drobnic Holan contributed to this report. Washington bureau chief Bill Adair can be reached at firstname.lastname@example.org or (202) 463-0575.
For more information on the IPCC study, go to http://www.ipcc.ch/