There is a pretty sobering doumentary here about a phenomenon called global dimming. It’s caused by the pollution particles sent into the air lessening the amount of the sun’s energy that is reaching us. Basically it has slowed down the effects of global warming. While this may sound like a good thing it naturally isn’t, in the sense that it has caused a great deal of problems (such as the drought in Africa) and perhaps has made us feel as if global warming’s effects are further into the future then they really are.
You can watch the documentary here.

Beware of two things, one is that it is 50 minutes long so you need some spare time. The second warning is that there is a rather gruesome scene within the first two minutes so listen to the documentary with your eyes closed for the first few minutes if you don’t want to see it.