He emphasises that the narrative of Hot Air is about politics.
"It starts out with saying at the beginning of the film, it's 1988 and suddenly climate change managed to get on to the political agenda for the world, really. Obviously scientists had been aware of the growing problem up to that point, but in 1988 the American president and government sat up and took notice, and the rest of the world followed on quickly after that."
Barry says Hot Air starts quite hopefully. "In the late 1980s and early 1990s we could address the problem. But as time went on by, those who didn't want to see any action on climate change - because it was going to effect their profits, essentially - began to get themselves politically organised."
New Zealand's current Climate Change Issues Minister Tim Groser has recently implored the public for input into climate change policy after the year 2020. Barry believes the Minister may genuinely be concerned about climate change, but that he is an example of corporate interests preventing any real action.
"I think that Tim Groser probably is concerned about climate change," he says. "He's certainly well informed about the subject, but he is in a political situation where he has to, if you like, literally pay tribute to the large corporations that sustain the National government in power, that will jump down very heavily on it if he takes what corporations would call a radical view of the issue."
You can watch Hot Air - climate change politics in New Zealand below:
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