The newspaper comic strip “Arctic Circle,” by the environmentally minded cartoonist Alex Hallatt, is about talking penguins and their fellow creatures living in the north. Starting Monday, under a caption that says “An Inconvenient Truth,” the menagerie will find their world shrinking and their conversations will be about global warming. Readers will see the drawings diminish to nothing by Friday as a snow bunny muses, “Climate change will lead to habitat loss and the extinction of many species.”