I've planted around 10,000 trees, and installed around 10KW of solar panels. The solar panels are on a 4-5 year schedule to pay back the money spent on them, after which it's pure profit. AND, all the CO2 emissions that have been avoided by having them producing energy. I changed jobs to reduce my drive by an hour a day. We even gave tree seedlings to our wedding reception guests. Maybe I don't have a magnet on the back of my car, but, to me, actually doing something about it is more important than "raising awareness".
Solar is a great way to do something, and, have a great investment. Where else can you put your money and get a ~5 year ROI?