I remember reading something a few years back where the scientists found that weather definitely is different around cities. The warm mass of the city - all the buildings, concrete, asphalt, etc. affects the weather patterns - at least locally. Whether it affects weather globally or not probably can't be proven ( at least not yet) but from everything I can understand about climate everything affects everything else in some way or another.
The whole global warming/global cooling debate seems to me a little bit like the arguments we hear about all the bad things that affect our health. Smoking for instance - it seems to be pretty much universally agreed (in this country at least) that smoking is bad - yet we still hear the stories about "my 90 year old grandmother" who smoked a pack a day and is doing just fine. When I hear those stories I tend to think - yeah, she is doing ok but she would be doing even better if she wasn't smoking. I think the weather is complicated enough that it can't be proven 100% that the climate is entirely being affected by what we do - but I think that it is also probably also 100% certain that human activity has at least some effect on the climate.
So why is it that the stereotypical "liberal" position is that we are killing the planet with all of our pollution - while the stereotypical "conservative" position is that it is not a big problem? I would think that when it comes to air we breathe and planet we live on it would be more prudent to say better safe than sorry - which seem a very conservative way to think of the problem. While claiming that pollution and global warming are no big deal is more of a liberal approach to the issue. Just another one of those things that confuse me. /forums/images/graemlins/tongue.gif