But as for your general point. I don't believe there is any scientific basis behind the idea that that doubling or tripling of current levels of CO2 will cause significant global warming.
Nor does it seem likely that global CO2 levels will double within a century. Nor does it even make much sense to be very worried about something occurring beyond 100 years particularly when at the same time we can't predict what energy we will be using in, say in 50-60 years from now.

I think that in 1998, it may have been somewhat reasonable to be concerned about Global Warming, ten years later it's almost foolish to still believe in this nonsense. Ten years from now, no one will be interested in it. But no doubt people will be very concerned about something- and it will probably be as foolishness or even more idiotic than global warming.

This doesn't mean, I know what the weather/climate will be in next year or next decade. Maybe 2008 will be the warmest year on record, in other words maybe 2008 will be warmer than 1998. Maybe the polar ice will melt to such an extent in 2008 that instead of 5 weeks of being able to go through the northwest passage, you will have claims of there being 7 weeks, or perhaps this record will have to wait until 2012 or 2050 or never.

But even if all the polar sea ice were to completely melt this year [nobody thinks this has a chance of happening] Greenland's massive icecaps are not going melt any faster than any other glacier in temperate or subarctic regions has ever melted- meaning even if we had global temperature increases higher and faster than any nutjob is predicting, Greenland's icecaps won't melt in 100 years. If you changed the earth axis so that Greenland was at the equator, it wouldn't melt half of it's mass in 100 years. The only way the Greenland ice cap could completely melt in 500 years is if a large asteroid impacted it or the Sun explodes [and at this scale of an event at least half the people in world would be dead with 20' sea level rise being the least of anyone's concern].