A new UN climate change report that concluded humans are responsible for most of the rise in global temperatures, immediately came under fire Friday from observers who questioned the report’s scientific credibility.

The U.N. Intergovernmental Panel on Climate Change (IPCC) report reaffirmed previous so-called scientific assessments of the nature of climate change and its potential impacts. However, a number of vocal critics raised specific questions about its methods, findings, and implied policy solutions.

It is “extremely likely” that humans are the primary cause of global warming, the report states. That wording is stronger than the “very likely” assessment from the IPCC’s last comprehensive climate change report, released in 2007. The U.N., however, also acknowledges another possibility; maybe it was wrong. “There may also be … an overestimate of the response to increasing greenhouse gas and other anthropogenic forcing,” the new report admits.

The report and contradictory statements show an “embarrassing lack of internal inconsistency,” according to an analysis by Patrick Michaels and Chip Knappenberger of the Cato Institute.

Michaels and Knappenberger argue that the IPCC declined to account for deviations between climate impacts predicted by IPCC models and actual temperature increases. They said the IPCC report fails to consider “the discrepancy between the observed effectiveness of greenhouse gases in warming the earth and this effectiveness calculated by the climate models that the IPCC uses to project future climate change.”

IPCC models have also come under fire for their failure to explain an ongoing pause in the rise of global temperatures, which in reality, have remained flat for approximately 15 years.

Scientists responsible for the report said they are confident in its findings.

“Our assessment of the science finds that the atmosphere and ocean have warmed, the amount of snow and ice has diminished, the global mean sea level has risen and the concentrations of greenhouse gases have increased,” Qin Dahe, who co-chaired the working group responsible for the report, told to Associated Press.

The study’s authors dismissed recent criticisms about the ongoing temperature leveling, claiming that 15 years is too small of a window to accurately gauge longer-term trends in global temperatures. “Due to natural variability, trends based on short records are very sensitive to the beginning and end dates and do not in general reflect long-term climate trends,” the new report reads.

That explanation did not satisfy American policymakers, as well as other skeptical scientists, who cite the stoppage in global warming as evidence of the shortfalls of IPCC models.

The group simply “glossed over” the fact, Sen. Jim Inhofe (R., Okla.), an outspoken skeptic of IPCC’s findings, said in a Friday news release. “With climate change regulations expecting to cost the U.S. economy millions of jobs and between $300 billion and $400 billion in lost GDP a year, we can’t afford to act on politically charged media alarmism,” Inhofe said.

Putting aside partisan considerations and observing the report solely through the scientific method, there are some serious concerns. According to one recent study that dissented from the IPCC’s findings, the IPCC’s latest report fails to account for the discrepancy between reality and climate models.

Conducted by scientists with the Science and Environmental Policy Project, the Center for the Study of Carbon Dioxide and Global Change and the Heartland Institute, the study found that the IPCC’s models “perform poorly when their projections are assessed against empirical data.”

The joint study was released under the umbrella of the Nongovernmental International Panel on Climate Change (NIPCC). Its scientists who authored the study say they want to fill a dissenting scientific role that, up until now, has been absent from IPCC’s academic work on climate change.

“NIPCC authors paid special attention to contributions that were either overlooked by the IPCC or that contain data, discussion, or implications arguing against the IPCC’s claim that dangerous global warming is resulting, or will result, from human-related greenhouse gas emissions,” explains a summary for policymakers accompanying the 1,200 page NIPCC report.

The report’s concludes, that “the human effect is likely to be small relative to natural variability, and whatever small warming is likely to occur will produce benefits as well as costs.”

The potential benefits of global warming is an often-overlooked aspect of the debate that Danish economist, Bjorn Lomborg, addressed in a Friday column on the IPCC report.

“Globally, and in almost all regions, many more people die from cold than heat,” Lomborg wrote. “With increasing temperatures, fewer cold deaths will vastly outweigh extra heat deaths.”

“Likewise, CO2 fertilizes crops and will increase production more in temperate countries than it will slow down crop increases in tropical countries. It will lower heating costs more than it will increase cooling costs,” he added.

In his column in the Wall Street Journal, James Taranto offered a scathing criticism of the media’s culpability in the climate change agenda as an “enterprise” of corruption. Citing a recent report by the Associated Press, he writes how “AP itself uses the term ‘climate skeptics,’ which is less pointed than ‘denialists’ but is still problematic. The purported opposition between “skeptics” and adherents to “the scientific consensus” is nonsensical, for skepticism is at the very heart of the scientific method. When the data call a theory into question, a scientist revisits the theory. Instead, the panel is employing the antiscientific method: It ‘is expected to affirm’ the theory ‘with greater certainty than ever.'”

There is clearly a fundamentally flawed approach to the science itself, as well as climate change as a public policy issue. Some environmentalists have acknowledged that the more sharp voices demanding action on climate change have ignored or even opposed technologies that could be the country’s most viable means to address the problem.

“One cannot logically claim that carbon emissions pose a catastrophic threat to human civilization and then oppose the only two technologies [natural gas and nuclear power] capable of immediately and significantly reducing them,” wrote Michael Shellenberger and Ted Nordhaus of the Breakthrough Institute, a prominent environmentalist group, on Friday. They added, “And yet this is precisely the position of Al Gore, Bill McKibben, the Sierra Club, [the Natural Resource Defense Council], and the bulk of the environmental movement.”