Rick Piltz in 2002. (Photo by Nicky Sundt)

Rick S. Piltz, a longtime climate policy analyst who exposed how top-level George W. Bush administration officials edited scientific reports to minimize the link between human activity and climate change, died Oct. 18 at a hospice center in Washington. He was 71.

The cause was complications from bladder cancer, said his wife, Karen Metchis. He was a resident of Bethesda, Md.

For a decade, Mr. Piltz held a senior post with the U.S. Global Change Research Program, through which U.S. government agencies coordinate their support for research on climate. He quit in March 2005, citing frustration with the Bush administration’s efforts to change the testimony of federal officials and the reports they submitted documenting the impact of global warming.

The edits — in some cases subtle, in others as bold as crossing out whole sentences — altered descriptions of climate research written by government scientists and their supervisors with the apparent intent of raising doubts where many climate experts think there are none.

Many of the fixes were made by Philip A. Cooney, a onetime lobbyist for an oil industry trade group who was then working as executive director of the White House Council on Environmental Quality.

Cooney reportedly eliminated a passage from a 2002 draft summarizing government climate research that described the impact warming might have on water availability and flooding. He wrote that the language about a projected reduction of mountain glaciers and snowpack was “straying from research strategy into speculative findings/musings.”

Mr. Piltz, who packed a trove of documents into a box and gave them to the New York Times for publication in June 2005, sent a scathing memo to senior officials at a dozen agencies.

“Each administration has a policy position on climate change,” he wrote. “But I have not seen a situation like the one that has developed under this administration during the past four years, in which politicization by the White House has fed back directly into the science program in such a way as to undermine the credibility and integrity of the program.”

Cooney announced shortly after the documents’ publication that he was leaving the administration to join the gas giant Exxon Mobil Corp.

After the Democrats took control of the House and Senate following the 2006 elections, Mr. Piltz testified before both chambers on the muzzling of federal scientists. Some of the edited documents he disclosed were included in a probe by the House Committee on Oversight and Government Reform, which in December 2007 concluded after a 16-month investigation that the Bush administration had “engaged in a systematic effort to manipulate climate change science and mislead policymakers and the public about the dangers of global warming.”

Meanwhile, in summer 2005, Mr. Piltz used his own funds to start the group Climate Science Watch under the umbrella of the D.C.-based public watchdog organization Government Accountability Project.

At the time he turned whistleblower, Mr. Piltz came under criticism from conservatives, including Sen. James M. Inhofe (R-Okla.) and the late columnist Robert Novak, who noted that Mr. Piltz had once served as a Democratic congressional staffer. As a House Science Committee aide, Mr. Piltz had helped write the 1990 Global Change Research Act, which calls for a regular national climate assessment, a 10-year climate research plan and annual progress updates to Congress. The act also created the U.S. Global Change Research Program.

Michael MacCracken, who served as the program’s executive director when Mr. Piltz joined in 1995, said Mr. Piltz pushed repeatedly for the Bill Clinton administration to conduct the national climate survey to evaluate how global warming was affecting the country. The federal government published its third such assessment in May.

“He persisted by asking questions, calmly and doggedly, and urging that things get done,” MacCracken said.

Frederick Steven Piltz was born on July 29, 1943, in Detroit. He was a 1965 graduate of the University of Michigan, where he also earned a master’s degree in political science in 1967, motivated in part by the anti-Vietnam War movement on campus.

One of his first professional jobs was as a legislative analyst in Austin. According to MacCracken, one of Mr. Piltz’s tasks was determining who was benefiting from provisions “then-state Rep. Tom DeLay would put in late in the afternoon” as a bill was being finalized.

His first marriage, to Charlotte Crafton, ended in divorce. He then spent seven years as a companion of Lynn Hayden. Survivors include his wife of 24 years, Karen Metchis, and their daughter, Shayne Piltz, both of Bethesda.

Mr. Piltz was a firebrand who often would speak out at public forums about the suppression of federal scientists and the U.S. government’s unwillingness to move swiftly enough to cut carbon emissions linked to climate change. He spoke of fossil fuel extraction continuing at a “full-tilt boogie” and argued the Obama administration had failed to live up to its own pledge of respecting scientific integrity.

Even during his final days, while hooked up to an oxygen tank and on morphine, he insisted on discussing future policy priorities when friends dropped by for a farewell visit.

“He was saying we couldn’t let the administration get away with this and that policy,” said Nicky Sundt, who directs climate change science and policy integration at the World Wildlife Fund. “He was saying, ‘This is the torch that you need to carry.’ It was a fitting way to end.”