By Paul Jay, CBCNews.ca. A few weeks ago I had a chance to talk to Francis Zwiers about the complex and evolving process of developing climate models for an upcoming feature. Zwiers, the director of the climate research division at Environment Canada, was preparing for a visit to Alert in Nunavut territory, his first visit to the remote town.

Naturally, given his work, it wasn't a sight-seeing trip. Alert, as it turns out, remains a key location in Canada's assessment of atmospheric greenhouse gas concentrations.

Alert is one of three locations where Canadian scientists measure carbon concentrations in the atmosphere, with the others being Sable Island off the coast of Nova Scotia and Estevan Point on Vancouver Island. Chosen because it is far removed from local emissions from cars, buildings and industry, scientists at Alert began measuring carbon dioxide in glass flasks on a weekly basis and on a continuous basis in 1988.

It's also the only one of the three locations in Canada that monitors carbon concentrations on a continuous basis.

The flask program is interesting, if only because it manages to combine the seemingly simple idea of grabbing air and sticking it in a bottle with rigorous testing. Flasks of air from Alert are sent to Environment Canada scientists in Toronto where they are analyzed and compared against each other, says Zwiers. But to ensure our results are accurate, Canada routinely swaps these flasks with other countries so each nation can compare and see if they produce the same results.

For some reason all of these bottle exchanges calls to mind images of hundreds of bottles travelling through some sort of Rube Goldberg machine - to the same tune Warner Bros. cartoons played whenever they showed a machine at work - before being spit out on the desk of a climate scientist's lab.

So when climate scientists talk about carbon concentrations in the atmosphere, you can thank the air up in the little town on the northeastern tip of Ellesmere Island. It is as close as we may get to know what is happening to the air we breathe.