Simon Lamb quizzed 40 of the world's leading climate scientists to bring their work to film.
But it was the indigenous people of one of fastest warming regions on Earth who offered the most eye-opening insight into what is happening to our planet.
The Victoria University geologist's collaborative documentary Thin Ice - the Inside Story of Climate Science, six years in the making, took him from Antarctica to the Arctic Circle.
The Sami people had lived in northern Norway for thousands of years and were all too familiar with changes in their environment, Dr Lamb said.
"I didn't actually expect the people there to be particularly aware of it, but if you spoke to people in their 70s and 80s, they were very aware of it.
"They were looking back to their 20s and they could see the area had changed a lot."
Long periods in winter that had once plunged the region into temperatures of -40C were no longer common. Rains were often now falling in December - when the climate would not normally be above zero.
The Sami had watched the treeline expand, opening up larger tracts of tundra. When reindeer tried to dig through the winter snow to reach lichen, the ground was blocked by hard layers of ice formed by melting in warm spells.
"It struck me that people who live close to the environment are as good as long term temperature records at detecting climatic trends, and they are all saying the same thing."
In Antarctica, Dr Lamb witnessed the vulnerability of the great ice sheets to future global warming.
Deep drilling into the rocks beneath McMurdo Sound revealed that only a few million years ago, when global carbon dioxide levels were only slightly higher than today, West Antarctica's ice completely vanished, pushing up sea levels by 5m. This posed a warning of what might happen if global carbon emissions - projected to lift the world's average climate by around 4C by the end of the century - continued at their present rate.
Closer to home, he chronicled the work of Kiwi scientists and found them to be playing a "remarkably important" role in international climate science.
At Baring Head, south of Wainuiomata, just outside Wellington, he found the most crucial clean air monitoring station in the Southern Hemisphere, monitoring changes in the level of carbon dioxide and other greenhouse gases in the atmosphere.
Dr Lamb said his film did not aim to tell the world what it should do to curb climate change, nor did it seek to hit back at climate sceptics.
Rather, he said, it strived to help people better understand what was one of the most researched areas of science in the world.
"In fact, the film is almost entirely in the words of the scientists, and I am really only the glue that holds what they say together," he said. "By watching the film, you not only find out what the scientists think, you also see for yourself the research being carried out, whether it be on the polar plateau in Antarctica, at -40C, or in a storm on the southern ocean, or back in the laboratory."