[quote name='willardhaven']There was a great Youtube video on the whole subject so that people could stop arguing.
It summed up the whole debate with a fun chart:
Do nothing + climate change is affected by man =

Do nothing + climate change is not affected by man =
Act now + climate change is affected by man =

Act now + climate change is not affected by man =

s
Obviously you want to avoid the burning smiley. It's oversimplified but acting without all the facts is better than arguing until something happens.[/QUOTE]
I remember that video. The biggest problem with it is that it underestimated the costs of reducing carbon dioxide emissions. Treasury estimates $100-400 billion a year.
http://www.cbsnews.com/blogs/2009/09/15/taking_liberties/entry5314040.shtml
http://www.cbsnews.com/blogs/2009/09/18/taking_liberties/entry5322108.shtml
This is not a small price to pay, especially given the fact that (1) the cost far outstrips any benefit, even if the models are correct (all 40 used by the IPCC have been completely wrong for the last 10 years); (2) our federal budget crisis is the biggest problem facing our country, and this would make things far, far worse; and (3) the estimates linked to above don't even take into account certain costs like rising prices that are sure to result from anything close to Waxman-Markey.
So basically the flaming smiley should be by "doing something and finding out it was not necessary" as well.
[quote name='willardhaven']We stand to gain in terms of air quality, food supply and other areas by acting as if humans are catastrophically affecting climate so we might as well change things. There's nothing religious or impractical about that.[/QUOTE]
1. Carbon dioxide at the levels we're talking about does not adversely affect air quality. In fact, due to rising CO2 levels, plants are more productive and yields have improved. It's really a fascinating story that nobody seems to know, but read here:
http://agron.scijournals.org/cgi/content/abstract/75/5/779
2. 0.6 degrees C of temperature change, even if induced by humans, is not "catastrophic." And as I argued above, the proposed costs of reducing carbon dioxide emissions far outstrip any benefit even assuming predictions for what the climate will be in 100 years turn out to be correct. Here is an excellent article written just yesterday on this subject:
http://www.forbes.com/2009/09/20/cl...nsus-opinions-contributors-bjorn-lomborg.html