If you don't believe humans are responsible for global warming, you are treated as someone as stupid as those who deny the holocaust happened. 

I'm not dumb, but I can't understand why, if the climate as far as we can tell, has never remained perfectly the same from year to year and era to era, we expect it to stay that way now.  There was ice in the Delaware river when Gorge Washington crossed it in December 1776.  I bet there hasn't been ice there at any time during the winter for generations.  In 1705 Colchester, Connecticut delayed Thanksgiving for three weeks because ice prevented the molasses delivery ship from arriving.

We had the Medieval Warm Period from about 800 to 1300, followed by the Little Ice Age from about 1300 to 1850.  1816 is known as the year without a summer because volcanic activity caused snow in June and hard frost in early September here in New England.  Crops failed, Yankees stayed, Pioneers moved.  American culture was transformed.

Since 1850, the planet has been warming.  A lot of folks blame people making CO2.  But the most abundant greenhouse gas in the atmosphere is?  H2O.  The most potent greenhouse gas is? CH4 (Methane or Natural Gas).  Nature makes a heck of a lot more carbon dioxide, water vapor and methane than we can ever imagine.

But the interesting thing, is as I said, everything in nature fluctuates, and 2008 is cooler than normal.