WASHINGTON -- Nonprofit organizations with ties to energy interests are promoting a controversial climate study as proof that prevailing views of global warming are wrong.

The scientists who authored the new study contend that the global warming of recent decades is not without precedent during the past 1,000 years, as other scientists have claimed. In fact, they say the Earth was even warmer during what is known as the "medieval warm period" between 900 and 1300 A.D.

The paper has touched off a worldwide storm of e-mail among climate scientists, some of whom have proposed organizing a research boycott of two journals that published the study.

The links among authors of the new study, the nonprofit groups and the energy interests illustrate a three-way intersection of money, science and policy. Energy interests underwrote the study and help finance the groups that are promoting it.

The study also illustrates a strategy adopted by some energy companies in the late 1980s to attack the credibility of climate science, said John Topping, president of the Climate Institute.

"They saw early on that what they had to do was keep the science at issue," said Topping, a former Republican congressional staffer who founded the institute in 1986.

By relying on the news media's inclination to include both sides of a story, the industries were able to create the impression that scientists were deeply divided over climate change, Topping said.

"It was all very shrewdly done," he added.

The Climate Institute takes the position that climate change threatens the global environment and promotes international cooperation on the issue. Less than 1 percent of its funding has come from oil industry sources, Topping said, with the rest coming from foundations.

To measure long-term climate patterns, scientists rely on "proxy" indicators, such as the content of air bubbles trapped centuries ago under ice packs in Greenland and Antarctica, the chemical makeup of ancient ocean sediments, and the relative widths of old tree rings.

These natural records have been used to portray a global climate that has been largely stable until the late 1980s, when temperatures started rising sharply.

A millennium of these temperature records presents what has been called a "hockey stick" graph, depicting centuries with little relative change, then a sharp and sudden rise during the past two decades.

Most climate scientists think the rise results from the atmospheric buildup of heat-trapping "greenhouse gases," especially carbon dioxide released by the combustion of fossil fuels such as coal and petroleum.

Industry-backed groups claim the new study challenges the validity of this view by presenting evidence of global warming at a time when fossil fuels were not being burned in appreciable quantities.

The new study, "Reconstructing Climatic and Environmental Changes of the Past 1,000 Years: A Reappraisal," was published several weeks ago in a British scientific journal, Energy and Environment.

The authors contend in the 65-page paper that their reanalysis of data from more than 200 previous climate studies provides evidence of global temperature shifts that are more dramatic than the current one, including during the "medieval warm period."

The research was underwritten by the American Petroleum Institute, the trade association of the world's biggest oil companies.

Two of the five authors are scientists who have been linked to the coal industry and have received support from the ExxonMobil Foundation.

Two others, who are affiliated with the Harvard-Smithsonian Center for Astrophysics, also have the title of "senior scientists" with a Washington-based organization supported by conservative foundations and ExxonMobil Corp.

The organization, the George T. Marshall Institute, is headed by William O'Keefe, a former executive of the American Petroleum Institute.

O'Keefe also was at one time the president of the Global Climate Coalition, a now-defunct organization created by oil and coal interests to lobby against U.S. participation in climate treaties, such as the Kyoto Protocol.

"Statements made about the warming trend of the 20th century and the 1990s do not withstand close scrutiny," O'Keefe declared at a recent luncheon held in the Dirksen Senate Office Building here.

The purpose of the luncheon was for Willie Soon, a physicist and astronomer with the Harvard-Smithsonian Center, to present a summary of the new research.

Promotion of the scientists' arguments began with a news release issued by the public affairs office of the Harvard-Smithsonian Center shortly after the paper was published. Headlined "20th Century Climate Not So Hot," the release declared that the scientists had "determined" that the current warming trend is neither the hottest nor the most dramatic change in the past 1,000 years.

Didn't publish the release

Major news organizations failed to publish the news release. However, it was picked up by the Discovery Channel Online, which declared that the 20th century may have been "just another bump in the climate road."

The Discovery Channel Online article was immediately copied and distributed by the staff of the Senate Environment and Public Works Committee, headed by Sen. James Inhofe (R-Okla.), an outspoken skeptic about climate change.

The committee also circulated a statement by the Competitive Enterprise Institute declaring that "the hockey stick theory has effectively been dismantled" and "the margin of error is so large that nearly any temperature trend could be drawn to fit within it."

The principal target of the paper by Soon and his co-authors was Michael Mann of the University of Virginia, whose landmark compilation of thousands of "proxy" indicators led to the conclusion that the last two decades have been unusually warm and to the first depiction of the "hockey stick" graph.

Mann said last week that the Soon study does not even attempt to reconstruct global average temperatures but simply highlights anecdotal evidence of isolated warming trends.

In a statement issued jointly with environmental scientist Michael Oppenheimer of Princeton University, Mann said that when all of these indicators are compiled and averaged, the "medieval warming period" fits within the long-range global trend. He said this was done not only in his study but also in nearly a dozen that have followed it.

Soon acknowledged during a question period at the Senate luncheon that his research does not provide such a comprehensive picture of the Earth's temperature record. He questioned whether that is even possible, and said he did not see how Mann and the others could "calibrate" the various proxy records for comparison.

"Then he needs to educate himself on several decades of very careful, painstaking research," Mann snapped.

The energy industry provides significant funding for groups that employ some of the authors or promote their new study.

Soon's four co-authors were Sallie Baliunas, also from the Harvard-Smithsonian center; Sherwood Idso and his son, Craig Idso, both of Tempe, Ariz., who are the past president and the current president of an organization called the Center for the Study of Carbon Dioxide and Global Change; and David R. Legates, a climate researcher at the University of Delaware.

The Idsos, who have previously been linked to Western coal interests, do not reveal the sources of financial support for their center, which on its Web site presents summaries of scientific studies purporting to raise questions about prevailing climate change theories.

The center had a budget of nearly $400,000 in 2001, the most recent year for which nonprofit statements to the Internal Revenue Service are available.

It operates from a post office box and offices in the homes of Craig and Sherwood Idso and a second son of Sherwood Idso, Keith Idso.

Identities of the four donors who provided the organization's $397,000 contributions in 2001 are blanked out of the Internal Revenue Service filing, and Sherwood Idso declined to name them.

"We generally do not say anything about our funding," he said. "The feeling is that what we produce there should be evaluated on its own merit, not where any funding comes from."

Records filed with the IRS by ExxonMobil Foundation show that it provided a grant of $15,000 to the Arizona center in 2000. These records and others show that ExxonMobil Foundation and ExxonMobil Corp. also have contributed $160,000 to the George T. Marshall Institute in the past three years and more than $900,000 to the Competitive Enterprise Institute.

In a telephone interview, Soon declined to say how much he is paid to serve as a "senior scientist" with the George T. Marshall Institute. Both he and Baliunas have that title.

The institute was organized in the 1980s and is chaired by Robert Jastrow, a retired scientist from the National Aeronautics and Space Administration who was an early and vocal supporter of former President Reagan's "Star Wars" missile defense initiative.

Other board members

Other members of the organization's board include O'Keefe; Baliunas; techno-suspense novelist Thomas Clancy Jr.; newspaper columnist Charles Krauthammer; Dr. Bernadine Healy, former director of the National Institutes of Health; and Frederick Seitz of Rockefeller University in New York, a former chairman of the National Academy of Sciences.

O'Keefe declined to identify the Marshall Institute's funding sources, but acknowledged it received money from ExxonMobil and the Sarah Scaife Foundation, headed by conservative Pittsburgh billionaire Richard Mellon Scaife.

He volunteered that it also receives funds from the Bradley Foundation, a large Milwaukee foundation known for its support of conservative causes.

Ross Gelbspan, once a Boston Globe reporter and editor whose 1997 book, "The Heat Is On," details industry efforts to discredit climate change science, said conclusions that greenhouse gases are causing the planet to heat up are the result of "the largest and most rigorously peer-reviewed scientific collaboration in history."

"The contradictory statements of a tiny handful of discredited scientists, funded by big coal and big oil, represent a deliberate -- and extremely reckless -- campaign of deception and disinformation," Gelbspan declared.