I see that other reviewers, including a non-scientist blogger, have used this forum to accuse Iain Stewart of bias, but if you actually watch this documentary you'll find that Stewart shows lots of restraint in his handling of skeptics and/or deniers. He merely echoes what the scientific consensus has shown over time, and does it calmly and methodically. It comes down to whether or not you have a personal motive to challenge the consensus, e.g. how evolution has been challenged for 1.5 centuries (for many of the same anthropocentric reasons).
Since Stewart is a scientist himself, one would expect him to have a "bias" toward critical thinking, and criticisms of him not giving "equal weight" to conspiracy theories are weak. He comes across as honest and thoughtful about the whole thing, never hastening to ignore the skeptics without giving their side. The segment on sunspots was a good example of balance.
The difference between skeptics and deniers is that skeptics will (grudgingly) accept evidence but deniers will change the subject or use ad-hominen attacks on climatologists out of desperation. This documentary shows Patrick Michaels to be more forthright than I expected, with admissions at a conference that it IS warming and Man IS causing it. Michaels now seems to be working the angle that not much can be done about AGW. There are a few scenes with hard-line deniers like Lord Monckton, but he was not shouted down.
I would strongly recommend this production above the overly-dramatic Al Gore film, which caused polarization by the very nature of its drama. How it got to be the gold standard for this sort of info is a mystery, outside of its movie-theater release vs. TV. I found Stewart's rendition of the same topic more watchable, and you can understand 99% of what he says despite a thick Scottish accent!
He does an especially good job of focusing on the potential for rapid climate shifts, citing Greenland ice cores and the rapid departure of a seven century southwest cave-dwelling society. Plenty of solid examples of Arctic ice retreat are shown. Massive ice-loss keeps getting ignored by people who insist it's been "cooling since 1998," etc. How can they claim any rational credibility? Other notable segments focus on Charles Keeling's pioneering CO2 measurements and the precarious future of U.S. desert cities.
I'd like to see an equally well-done documentary by psychologists about the human propensity for denial in the face of massive evidence. Science denial is becoming an increasingly dangerous trait for civilizations to indulge.
