Arctic and Antarctic have two c‘s. No matter how the words are pronounced, Artic and Antartic are misspellings. Both are surprisingly common even though spell check rightly marks them as wrong. Some of the online occurrence of artic can be attributed to that spelling’s use in a few product names, and it’s also an abbreviation of several things (the Art Institute of Chicago, for one).
As most people are aware, the Arctic is the polar region on the northern side of the earth, and the Antarctic is the polar region on the southern side. Arctic is commonly used to describe tundralike conditions regardless of whether what it describes is in the north or south. This might be stretching the word a little, but it is an accepted use, listed in most major dictionaries.