Back when we didn't have any electricity in CA back in 2000-01, businesses were adding on "energy surcharges" all the time--even in Vegas, I got a room with a $5/night energy surcharge. There was, believe it or not, a story on the news back then about TACO BELL, of all places, adding .25 onto each order.
Oh, and if you go to Carnival's website, they've got a fuel surcharge (supplement) of $9/day based on double occupancy. That's one more reason I didn't book a cruise with them this year...2 people X 7 days X $9 = $126 on top of the $2K they wanted already. No thanks.