It's easy to talk about carbon dioxide (CO2) emissions and their effect on our planet, but visualizing them? That's hard. Thankfully, NASA has stepped up to the plate with a computer model that shows how CO2 travels across Earth's atmosphere in the space of a year. As you'll see in the clip below, a lot of gas in the northern hemisphere originates in major pollution centers across Asia, Europe and North America before it drifts across the globe. The abundance of plant life in the spring and summer quickly cuts down on CO2 levels, but the chemical comes roaring back once fall arrives -- and the concentrations are higher than NASA would like to see.