A United Nations report on climate change that has been lambasted for its faulty research is under new attack for yet another instance of what its critics say is sloppy science -- adding to a growing scandal that has undermined the credibility of scientists and policymakers who back the U.N.'s findings about global warming.

In the Fourth Assessment Report (AR4), issued in 2007 by the U.N.'s Intergovernmental Panel on Climate Change (IPCC), scientists wrote that 40 percent of the Amazon rainforest in South America was endangered by global warming.

But that assertion was discredited this week when it emerged that the findings were based on numbers from a study by the World Wildlife Federation that had nothing to do with the issue of global warming -- and that was written by a freelance journalist and green activist.

The IPCC report states that "up to 40 percent of the Amazonian forests could react drastically to even a slight reduction in precipitation" -- highlighting the threat climate change poses to the Earth. The report goes on to say that "it is more probable that forests will be replaced by ecosystems ... such as tropical savannas."

But it has now been revealed that the claim was based on a WWF study titled "Global Review of Forest Fires," a paper barely related to the Amazon rainforest that was written "to secure essential policy reform at national and international level to provide a legislative and economic base for controlling harmful anthropogenic forest fires."

EUReferendum, a blog skeptical of global warming, uncovered the WWF association. It noted that the original "40 percent" figure came from a letter published in the journal Nature that discussed harmful logging activities -- and again had nothing to do with global warming.

The reference to the Brazilian rainforest can be found in Chapter 13 of the IPCC Working Group II report, the same section of AR4 in which claims are made that the Himalayan glaciers are rapidly melting because of global warming. Last week, the data leading to this claim were disproved as well, a scandal being labeled "glacier-gate" or "Himalaya-gate."

The Himalaya controversy followed another tempest -- the disclosure of e-mails that suggested that leading global warming scientists in the U.K. and the U.S. had conspired to hide a decline in global temperatures.

"If it is true that IPCC has indeed faked numbers regarding the Amazon, or used unsubstantiated facts, then it is the third nail in the IPCC coffin in less than three months," Andrew Wheeler, former staff director for the U.S. Senate's Environment and Public Works Committee, told FoxNews.com. "For years, we have been told that the IPCC peer review process is the gold standard in scientific review. It now appears it is more of a fool's gold process."

Wheeler, who is now a senior vice president with B&D Consulting's Energy, Climate and Environment Practice in Washington, said the latest scandal calls into question the "entire underpinnings" of the IPCC's assessment and peer review process.

The U.N. did not return calls seeking comment on the scandal.

Jean-Pascal van Ypersele, vice chairman of the IPCC, was quoted in the European press as saying, "I would like to submit that this could increase the credibility of the IPCC, not decrease it. Aren't mistakes human? Even the IPCC is a human institution."

But not everyone agrees. Ross McKitrick, a professor of economics at the University of Guleph in Ontario, said the U.N. needs to start from scratch on global warming research and make a "full accounting" of how much of its research findings have been "likewise compromised."

McKitrick said this is needed because the U.N. acknowledged the inaccuracy of the data only now that its shortcomings have been exposed. "They are admitting what they did only because they were caught," he told FoxNews.com. "The fact that so many IPCC authors kept silent all this time shows how monumental has been the breach of trust."

Lubos Motl, a Czech physicist and former Harvard University faculty member, said the deforestation of the Amazon has occurred, but not because of global warming. He said it was due to social and economic reasons, including the clearing of cattle pastures, subsistence agriculture, the building of infrastructure and logging.

"Such economically driven changes are surely unattractive for those of us who prefer mysterious and natural forests," says Motl. "But they do help the people who live in Latin America."

The rapidly accumulating scandals surrounding climate change research appear to be driving the public away from its support for government measures to intervene. On Wednesday, Yale University and George Mason University released a survey showing that just 57 percent of respondents believe global warming "is happening." That was down 14 percentage points, from 71 percent, in October 2008. Fifty percent of people said they were "very" or "somewhat" worried about global warming, down 13 points from two years ago.

Another poll released Monday by the Pew Research Center for the People and the Press asked respondents to rank 21 issues in terms of their priority. Global warming came in last.