Ah yes, climate change deniers. These accidental comedians continue to insist that the planet isn’t warming. As amusing as their denials are, the comedy stops when you realize their humor is of the severely tragic kind. Case in point: “Chasing Ice,” the fact-filled documentary cataloging the effects of climate change in the Arctic, which drives home that our inaction to address the issue will lead to humanity’s eventual demise. Is this a movie most people want to see? Hell no — it’s an unmitigated bummer, but it’s a movie everyone should see. Because if you value being alive on this big blue ball we call Earth, this is the most important issue of our time. A free screening of “Chasing Ice” plays Thursday at 6 p.m. at the Camel, 1621 W. Broad St. chasingice.com.