Personally, I think GW is certainly an alarming prospect, but... If we really plan to double the amount of CO2 in the atmosphere, in the next 100 or 200 years, GW may end up being the least of our worries. That's a huge difference to make in our atmosphere and nobody knows the ramifications.
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The % of CO2 is so low that doubling it does not make the atmosphere all that different. It IS primarily the climatalogical effect. Remember that past Earths have had lots MORE methane & CO2. The concern we have is that we do not know enough to say precisely what the effects will be. Maybe some non-linear effect. Even a coupla foot rise in sea level would be economically devastating to many.

Me, I have NO FAITH in climate models. Not even future, "better" ones. They tend to confirm the bias (even unconsciously) of the researcher. Remember all those solar system formation models pre-1995 that always constructed variations of OUR solar system? Not ONE Hot Jupiter in the bunch. Totally bogus and a affirmation of the beliefs of the "researchers".

-p