I've been told that carbon dioxide and other gases from cars and other things trap the sun's heat and warm up the planet. I find this easy to believe, and as we are cuttin down LOADS of trees, amd making TONNES of carbon dioxide, I find it very easy to believe that humans are heating up the planet, and in general, the polar caps seem to be melting, and weather seems to be a bit more unstable (although the weather proably has not changed much yet, although several people believe its getting warmer.)
And if we make more CFC gases, ok, the hole in the ozone layer may have been there before or it may not have, but people can make it worse, and hope that by not using CFC gases, it will not worsen. It doesnt matter if it was ther or not before, it matters if we make it worse when we dont have to.
Not sure what will happen, but if we carry on as we are without trying to save our environment, I find it easy to believe that humans will have some sort of effect on the planet, like heating it up.
A lot of action is being taken, but its hard to get everyone to help and research more eco firendly things, when it doesnt seem to matter yet, and when people just want money. When we run out of coal and oil, then maybe people will be mor serious about other ways to power cars, like hydrogen.