I know why the hockey stick diagram showed 1998 to be the hottest year ever, it has nothing to do with CO2 or anything like that.. The reason is simply numbers. The year 1998 had 3(!) Friday the 13th (bad luck baaaad luck) and if you divide 1998 by 3 you start to understand why it was the hottest year ever.
Seriously though, here are some links about said hockey stick diagram:
http://news.bbc.co.uk/1/hi/sci/tech/3569604.stm
http://news.bbc.co.uk/2/hi/science/nature/5109188.stm
http://www.realclimate.org/index.php?p=11
Some other links of interest:
http://en.wikipedia.org/wiki/Tempera...ast_1000_years
http://en.wikipedia.org/wiki/Temperature_record
http://en.wikipedia.org/wiki/Image:F...ate_Change.png
As it is now I'm not convinced either way, on one hand I see the ones claiming that humans are responsible are pretty arrogant in assuming that we can affect that much and on the other hand, it is getting hotter where I live and less snow in the winters.
But as it is now
blahblah454 said it best. Why bother why we want to clean up the air, it's a good thing no matter what reason.