Why is there more carbon Monixide in the Southern Hemisphere?

I was looking on the application Earth Now, to view a bunch of vital signs our earth has, and noticed the carbon monoxide levels were very weird. If you want to see a picture here's the link:
http://www.treehugger.com/gadgets/visualize-climate-change-data-free-iphone-app-nasa.html
Just scroll through until you see the picture of the globes, its the one on the left.
I'm just wondering. Thanks!

Added (1). I know that it is not because it is warmer in the Southern Hemisphere. It is only warmer near the equator. The poles are cold. So saying the Southern Hemisphere is warmer doesn't make sense. (And the blue in the picture goes all the way down the the South Pole.)

Its warmer in the southern hemisphere

You may be reading the scales incorrectly. The blue actually indicates that there's less carbon monoxide in the southern hemisphere than the north (in reds and orange). This makes more sense since China, the US and Europe are all in the northern hemisphere and definitely are the more industrialized countries.