You can track the clock online here, at the Deutsche Bank's website. As I write this, another 1,000 tons are being added into the atmosphere every second. The billboard doesn't say so, but the survival of civilization and most life on earth relies on stopping this clock and beginning to turn it backwards in the next ten to twenty years.
Anyhow, as I've said before, one of the biggest hazards of climate change is the fact that it's hard to perceive: unlike other pollutants we've dealt with, CO2 is invisible and odorless, and you can't feel the effects of a multi-trillion-ton blanket in the atmosphere until a category four hurricane is at your doorstep.
The carbon counter helps with that problem. I'm also encouraged by the fact that the billboard's being paid for by a major global bank: as Mindy Lubber wrote today in the Huffington Post, the costs of greenhouse gas emissions aren't on anyone's balance sheet, which makes them a huge financial loophole in the global economy. Tallying greenhouse gases on a huge billboard in the world's financial capital is a step in the right direction (and it gives Deutsche Bank a measure of credence in the carbon accounting and trading businesses that are expected to emerge once the United States passes a climate bill).
This is just a couple of blocks away from the well-known "debt clock," which hasn't been successful enough to forestall the addition of another digit when the debt went over $10 trillion last fall. This counter will never need another digit: if our atmosphere accumulates that much carbon, there won't be anyone around to keep the lights on.