The 2,500 or so scientists, economists and other experts of the U.N. Intergovernmental Panel on Climate Change (IPCC) call global warming "unequivocal" and think it "very likely" that humans have contributed to the problem. The world's governments agree with the panel, which also shared last year's Nobel Peace Prize.

Then there's the Non-Governmental International Panel on Climate Change (NIPCC). These 23 individuals from 15 countries, including a handful of scientists, disagree. Led by physicist S. Fred Singer—best known for his denial of the dangers of secondhand smoke—they argue the reverse: "Natural causes are very likely to be the dominant cause" of climate change.

The NIPCC goes on to contend: "We do not say anthropogenic greenhouse gases cannot produce some warming. Our conclusion is that the evidence shows they are not playing a significant role."

In other words, even skeptics, deniers, contrarians—pick your favorite term—agree that global warming is real, or so it appears from the recent three-day conference in New York City put together by the Heartland Institute, a bastion of free-market thinking on the perils of junk science and government economic regulation. They just disagree—even amongst themselves—whether it is man-made.

On the one side sits Patrick Michaels, the recently resigned state climatologist of Virginia who ascribes global warming to fluctuations in the sun's energy output aided and abetted by human activity. In his conference dinner address, Michaels said: "Global warming is real and people have something to do with it."

On the other side is astrophysicist Willie Soon of the Harvard–Smithsonian Center for Astrophysics in Cambridge, Mass. He lays the blame on the sun for all the agreed-on warming. And meteorologist William Gray of Colorado State University in Fort Collins believes the sun will soon reverse its effect. "We should begin to see cooling coming on," he predicts. "I'm ready to make a big financial bet."

If you are interested in seeing a contrarian in action, here is your chance:

See the president and co-founder of the Heartland Institute, Joseph Bast, explain how the science of climate change is shifting, how a little global warming would be a good thing, and the reason not to vote. (download the original)

Watch meteorologist William Gray explain hurricane prediction, the perils of computer models and the coming global cooling. (download the original)

Marc Morano, spokesman for the U.S. senator who called global warming the "greatest hoax ever played on the American people," answers the question, "Is doubt your product?" (download the original)

Watch meteorologist Roy Spencer discuss the pitfalls of scientific publishing, the climate consensus and intellectual honesty. (download the original)

See civil rights campaigner Roy Innis equate environmental regulation to racism. (download the original)

ABC reporter John Stossel speaks on what he calls the socialist media, the religion of environmentalism and scare stories. (download the original)

These are interviews, not debates, and posted essentially unedited. They have been condensed in some cases, but the point is to let you experience some of the breadth of the contrarian viewpoint and use it as you see fit. In fact, please feel free to experiment with this video: hone it, recut it, amplify it, do with it what you will.

For example, here's what John Pavlus cobbled together from other conference participants to highlight the emerging threat that polar bears pose to the American way of life and the U.S. economy.

Even for the contrarians, the main argument is no longer whether climate change is happening—in fact, their main remaining scientific function is to bolster the understanding, and dreaded modeling, of the global climate. Instead, the argument has shifted to what to do about it and, as Marc Morano, Republican communications director for the U.S. Senate Committee on Environment and Public Works, noted: there are "a lot of reasons to move beyond carbon: energy security, energy independence."