Last night, Nova tackled an interesting, less-discussed danger from pollution: global dimming. It hasn’t gotten that much attention (outside of Grist, of course) but Nova presented a very compelling and rather harrowing picture.

Basically, while the earth has been getting warmer due to greenhouse gases, it has simultaneously been getting cooler due to a layer SP50 sunblock made up of smog particles in the air. As a result, the globe is like a guy who drinks fifty cups of coffee a day and then pops five Valium and proudly declares he’s “in the zone.”

It’s easy to imagine how the distraction faction would use this to cast doubt on the whole idea of global warming. “What’s with these egghead scientists? Is the globe getting warmer or colder? Make up your mind!” Well, we know it’s getting warmer. So here’s the scary part: the dimming of the sun has been masking the full effect of global warming, which may be much further along than we previously realized. We’ve been reducing the particulate smog that causes dimming for the past few years, and we’re starting to see an accelerated shift. Once this guy gets off the Valium, he’s going to be on one hellish caffeine kick.

Grist thanks its sponsors. Become one.