On Friday's "20/20," ABC's John Stossel presented the views of scientists who dissent from the Al Gore view of global warming, including two former members of the IPCC – the committee which shared the Nobel Peace Prize with Gore. These scientists disagreed with the selection process of the committee's members and some of its conclusions. The ABC host disputed some of the claims in "An Inconvenient Truth," and even presented the view that increased carbon dioxide levels are the result of global warming, rather than the cause, as he took on Gore's famous graph from the movie. Stossel: "But the real inconvenient truth is that carbon increases came after temperature rose -- usually hundreds of years later. Temperature went up first. I wanted to ask Mr. Gore about that and other things, but he wouldn't agree to talk about this." Video of the segment can be seen here. (Transcript follows)

The ABC host introduced his regular "Give Me a Break" segment: "You've heard the reports. The globe is warming. And it's our fault. And the consequences will be terrible. But you should know there is another side to this story. And scientists who've tried to tell it are often threatened. Which makes me say, 'Give Me a Break.'"

Then came a number of clips of journalists relaying the purported danger of global warming, and clips of children expressing their fears of the future. After arguing that "An Inconvenient Truth" was incorrect or misleading in the way it presented the dangers of rising sea levels and the plight of polar bears in the Arctic, the ABC host then got to the movie's famous graph that the former Vice President used to argue that higher carbon dioxide levels cause temperatures to increase. Stossel: "I knew that carbon dioxide's thought to amplify temperature increases, but this shows a clear cause an effect. For 600,000 years, when carbon rose, so did temperature. It suggests that carbon levels control temperature. But the real inconvenient truth is that carbon increases came after temperature rose -- usually hundreds of years later. Temperature went up first. I wanted to ask Mr. Gore about that and other things, but he wouldn't agree to talk about this."

Stossel presented several scientists who dispute contentions by Gore and others that "the debate is over" on global warming. These scientists included Paul Reiter of the Pasteur Institute, Tim Ball of the Natural Resources Stewardship Project, and John Christy and Roy Spencer of the University of Alabama. Stossel relayed their contentions that global warming and cooling trends have happened in the past, and related that the media had "fretted about that then, too." Stossel: "Climate changes, they point out. It always has -- with or without man. Early last century, even without today's big output of carbon dioxide, the Arctic went through a warm period. The media fretted about that then, too. And Greenland's temperatures rose 50 percent faster in the 1920s than they're rising now. Some scientists say the warming may be caused by changes in the sun or ocean currents or changes in cloud cover. Or other things we don't understand. The debate is not over."

More on the media's history of reporting on warming and cooling trends over the last century can be found in a May 2005 report by the MRC's Business and Media Institute.

Reiter and Christy had notably been members of the IPCC, and they were critical of the way governments chose the members of the committee, some of whom were merely activists instead of scientists, suggesting that politics had played too great a role.

STOSSEL: Paul Reiter of the Pasteur Institute and John Christy say they were members of the IPCC. That so-called group of scientists, they say, is not what people think it is.

REITER: The IPCC is the Intergovernmental Panel on Climate Change. It is governments who nominate people. You'll find in many chapters that there are people who are not scientists at all.

STOSSEL: Who are they?

REITER: They were essentially activists.

STOSSEL: Members of groups like Greenpeace were involved. And when the IPCC report came out, not all its members agreed with what was said.

Reiter further said that he had resigned from the committee in protest because he disagreed with some of the report's findings, and had to threaten a lawsuit against the IPCC to have his name removed from the report, although, according to Stossel, the IPCC disputes this account.

Stossel then dealt with the issue of these types of global warming dissenters being "smeared as deniers," as those who support the more liberal view of global warming seek to compare their way of thinking to that of Holocaust deniers.

STOSSEL: Today, scientists like these are often smeared as "deniers."

UNIDENTIFIED MAN: We have Holocaust deniers, we have climate change deniers. And to be honest, I don't think there's a great deal of difference.

LINDA DOUGLAS, ABC News: Deniers are confusing the issue and delaying solutions.

Last August, "Newsweek" ran a cover story attacking the global warming "denial machine," and the "NBC Nightly News" soon ran its own story with the same theme.

After recounting that many global warming activists, like Al Gore and Robert F. Kennedy Jr., try to discredit skeptics by accusing them of "being purchased by a 'well-funded denial machine,'"  these scientists were shown denying that they receive any money because of their views, as they contended that, rather than being rewarded for their views, they have faced harassment and threats.

Stossel summed up his report: "Is this what the global warming debate has come to? One side saying, 'Shut up, dissent must not be heard'? The truth is that, while everyone agrees the earth has warmed, lots of good scientists don't agree that it's mostly our fault, and don't agree that it's going to be a catastrophe."

Below is a complete transcript of Stossel's "Give Me a Break" segment from the Friday October 19 "20/20":

JOHN STOSSEL: You've heard the reports. The globe is warming. And it's our fault. And the consequences will be terrible. But you should know there is another side to this story. And scientists who've tried to tell it are often threatened. Which makes me say, "Give Me a Break."

MATT LAUER, Today Show: -the world is heating up fast, and we have ourselves to blame.

DAWNA FRIESEN, Today Show: -global warming is real, and we humans are almost certainly the cause.

STOSSEL: Books warn that the earth is under fire, a suicidal planet's approaching a boiling point and a toxic burn. Children are frightened.

UNIDENTIFIED GIRL #1: I worry. My mom worries.

UNIDENTIFIED GIRL #2: The water might rise, and it might flood the whole town.

UNIDENTIFIED BOY #1: We won't be able to survive for long.

STOSSEL: And people say since global warming is because of man, it must be fixed by man now.

UNIDENTIFIED MAN in ad, standing in front of a moving train: Some say irreversible consequences are 30 years away.

STOSSEL: This Ad Council PSA says ignoring the coming crisis is like putting our kids in front of a train.

MAN: That won't affect me.

[The man steps off the track and leaves his daughter in front of the moving train.]

STOSSEL: What do you most worry will happen?

UNIDENTIFIED BOY #2: We'll all die.

STOSSEL: Are there some people who say this isn't true?

[Several children who are gathered say, "Yes."]

STOSSEL: Might they be right?

[Nearly all the children gathered say, "No."]

STOSSEL: How do you know they're not right?

UNIDENTIFIED GIRL #3: Well, because the Earth is getting hotter.

STOSSEL: Where do you learn this?

UNIDENTIFIED BOY #1: I saw the Al Gore video.

JERRY SEINFELD, at the Academy Awards: And the Oscar goes to An Inconvenient Truth.

STOSSEL: The global warming documentary featuring Vice President Al Gore has been seen by millions. People have proclaimed him a prophet, a cultural icon, a conquering hero.

LEONARDO DICAPRIO: You are a true champion for the cause, Mr. Gore.

STOSSEL: And last week, he won a Nobel Peace Prize. The Oscars were followed by other worldwide media events.

GORE: You are Live Earth.

STOSSEL: With all this hoopla, it's no surprise that 86 percent of Americans say global warming is a serious problem.

JOHN EDWARDS: Global warming is now, by anybody's measure, a crisis.

STOSSEL: But is it a crisis? Yes, the globe is warming, but is it really all our fault? And is it true that the debate is over? No. What you think you know, may not be so. For example, in An Inconvenient Truth, Gore says if we allow the globe to warm, terrible things will happen. And:

AL GORE: Sea level worldwide would go up 20 feet.

UNIDENTIFIED BOY #3: Yeah, maybe like the height of this building.

UNIDENTIFIED GIRL #4: We'll probably just, like, drown, and we'll die.

GORE: This is what would happen to the sea level in Florida. This is what would happen to San Francisco Bay.

STOSSEL: Maybe. Maybe in thousands of years, says the IPCC, the group that shared last week's Nobel Prize with the Vice President. But in 100 years, the oceans might rise 7 to 24 inches, not 20 feet.

GORE: A faster buildup of heat here.

STOSSEL: Mr. Gore also talks about melting ice caps.

GORE: That's not good for creatures like polar bears-

STOSSEL: They show this heart-rending cartoon.

[Cartoon of a polar bear swimming to floating ice and trying to get on, but it breaks leaving the bear in the water.]

GORE: A new scientific study shows that for the first time, they're finding polar bears that have actually drowned.

STOSSEL: But I bet you didn't know that polar bears appear to be doing all right. Future warming may hurt them, but right now, the World Conservation Union and the U.S. Geological Survey say most populations of polar bears are stable or increasing.

GORE: There is one relationship that is far more powerful than all the others-

STOSSEL: The most impressive demonstration in Mr. Gore's movie is the big graph of carbon dioxide levels.

GORE: Here's what the temperature has been on our Earth. Now, one thing that kind of jumps out at you is: Did they ever fit together?

STOSSEL: My goodness! I knew that carbon dioxide's thought to amplify temperature increases, but this shows a clear cause and effect. For 600,000 years, when carbon rose, so did temperature. It suggests that carbon levels control temperature. But the real inconvenient truth is that carbon increases came after temperature rose -- usually hundreds of years later. Temperature went up first. I wanted to ask Mr. Gore about that and other things, but he wouldn't agree to talk about this. Why should he when he and others say-

GORE: The debate's over.

UNIDENTIFIED MAN: The science is agreed upon.

Governor ARNOLD SCHWARZENEGGER (R-CA): The debate is over, and the science is in.

PAUL REITER, Pasteur Institute: It's absurd for people to say that sort of thing. It's really wrong.

STOSSEL: These scientists are among those who say the debate is by no means over. John Christie and Roy Spencer won NASA's Medal for Exceptional Achievement for figuring out how to get temperature data from satellites. They agree that the Earth has warmed.

JOHN CHRISTY, University of Alabama: We all agree that it's warmed, I think. The big question is, and the thing that we dispute, is: Is it because of mankind?

STOSSEL: Climate changes, they point out. It always has -- with or without man. Early last century, even without today's big output of carbon dioxide, the Arctic went through a warm period. The media fretted about that then, too. And Greenland's temperatures rose 50 percent faster in the 1920s than they're rising now. Some scientists say the warming may be caused by changes in the sun or ocean currents or changes in cloud cover. Or other things we don't understand. The debate is not over. And, anyway, who's to say that yesterday's temperature was the perfect one. If temperatures keep rising now, these scientists say we don't know that that will be all bad.

TIM BALL, Natural Resources Stewardship Project: The fact is, when the climate changes, there are gains and there are losses.

STOSSEL: But Tim Ball, who studies the history of climate change, points out that all we hear about is the bad news from the IPCC, that massive group of global warming scientists.

RICHARD BRANSON: 2,000 scientists.

LESTER HOLT, NBC News: 2,000 scientists.

FREDRICKA WHITFIELD, CNN: 2,500 scientists say the globe is getting warmer and we are to blame.

REITER: There's the most unmitigated rubbish talked about-

STOSSEL: Paul Reiter of the Pasteur Institute and John Christy say they were members of the IPCC. That so-called group of scientists, they say, is not what people think it is.

REITER: The IPCC is the Intergovernmental Panel on Climate Change. It is governments who nominate people. You'll find in many chapters that there are people who are not scientists at all.

STOSSEL: Who are they?

REITER: They were essentially activists.

STOSSEL: Members of groups like Greenpeace were involved. And when the IPCC report came out, not all its members agreed with what was said.

ROY SPENCER, University of Alabama: We were not asked to look at a particular statement and sign our names to it at all.

REITER: I got very frustrated, and I resigned.

STOSSEL: But the IPCC still listed Reiter as part of the so-called consensus.

REITER: I contacted the IPCC and said, "Look, I've resigned. I don't want to have anything more to do with this." And they said, "Well, you've been involved, so you're still on the list."

STOSSEL: Only when he threatened to sue, he says, did they take his name off the report. The IPCC denies that that happened. Today, scientists like these are often smeared as deniers.

UNIDENTIFIED MAN: We have Holocaust deniers, we have climate change deniers. And to be honest, I don't think there's a great deal of difference.

LINDA DOUGLAS, ABC News: Deniers are confusing the issue and delaying solutions.

STOSSEL: Often they're accused of being purchased by a "well-funded denial machine."

ROBERT F. KENNEDY JR.: These corporate toadies lying to you and telling you that global warming doesn't exist.

GORE: The illusion of a debate has been purchased with millions of dollars a year-

STOSSEL: Aren't you guys all on the take?

BALL: I wish I was. I wouldn't be driving a 1992 car and living in a leaky apartment.

STOSSEL: These scientists all say they don't get any money from business, yet some have been threatened. One email said, "You will not live long enough to see global warming."

BALL: And even more direct than that.

REITER: We stick our necks out. We do get hurt.

STOSSEL: Is this what the global warming debate has come to? One side saying, "Shut up, dissent must not be heard." The truth is that, while everyone agrees the earth has warmed, lots of good scientists don't agree that it's mostly our fault, and don't agree that it's going to be a catastrophe. So when the Nobel Prize winner says-

GORE: The debate's over. The debate's over.

STOSSEL: I say, "Give Me a Break."

—Brad Wilmouth is a news analyst at the Media Research Center.