As of tomorrow, humanity is operating in the red for 2012.
See, today is the day that the Global Footprint Network estimates that we've exhausted a year's worth of global resources. If you think of how much energy and resources the planet can replenish in a year, we've used up that amount since Jan. 1. Everything from now until New Year's Eve, then, is us putting it on our credit cards. Or, more accurately, using next year's resources. Even more accurately, some year in the 2030s' resources.
Since 1970, we've been using more resources than can be replenished, meaning we keep going deeper and deeper into the hole. Each year, "Earth Overshoot Day" (which isn't really that great a name) comes sooner.