There is so much material on this subject, that I'm not sure more is needed. I've done a fair amount of research and have concluded that every lunatic on the planet is involved in this controversy and it's not entirely clear which side is crazier. Nonetheless, I have pretty much come to a conclusion.
Catastrophic Anthropogenic Global Warming ((C)AGW) is a theory that projects devastating planetary warming due to human release of the green house gas Carbon Dioxide (CO2) which accumulates in the atmosphere. AGW projects rising sea levels, changes in weather patterns, loss of glacial and polar ice, loss of agricultural land, and increased tropical storm activity.
Substantial increases in CO2 concentrations have been observed as have some overall reductions in glacial and North polar ice. Modest temperature increases have been observed (1.1C-1.7C) per century. No meaningful acceleration in sea level rise or tropical storm activity has been observed. Predictions of serious future problems are based largely on speculation and complex computer models that are claimed to somehow produce high confidence outputs from low confidence inputs.
The debate over global warming has become highly politicized. Preposterous claims are routinely made by both sides. A few facts stand out. AGW proponents make few verifiable claims. Verifiable claims except continued increases in CO2 have proven to be incorrect or substantially overstated. AGW theory appears not to be easily reconcilable with polar ice core data that clearly shows that planetary temperature increases in the past half million years weren't primarily caused by CO2.
In my opinion there is reasonable evidence to support modest and hopefully harmless current and future global warming due to CO2 emissions. There appears to be little credible evidence for dramatic/catastrophic increases later in the century.
It is hard not to sum up CAGW with Richard Feynman's 1980s assessment of 'Nuclear Winter' theory as it stood in the 1980s.* "I don't think these people know what they are talking about."
*We haven't heard much about Nuclear Winter since Carl Sagan confidently but incorrectly predicted dire consequences for SouthEast Asians from the Kuwaiti oil well fires. I suspect, but don't know for sure, that the oil well fire fiasco and the data from eruption of Mt Pinatubo in 1991 have probably resulted in Nuclear Winter theorists knowing a lot more today than they did in the 1980s.
More briefly. Do I think the planet is warming because of from CO2 emissions? Yes. Is the extent of future warming substantially overstated? Most likely. Are we all gonna die? Not, I think, from climate change.
A point rarely made: The world appears to be running out of cheap hydrocarbons but not out of people who want first world standards of living. I believe that CO2 generating energy sources will become more expensive on average -- probably by a series of "energy shocks". That will produce pretty much the same results as green energy subsidies, Carbon taxes, Cap and Trade. Greenhouse gas emissions in the developed world are not likely ever to increase much from 2000 levels. They will eventually fall some. Folks in the developing world will produce more CO2 for a while. But they were never going to comply with Kyoto anyway (Strictly speaking, being developing countries, Kyoto doesn't require anything of them anyway, but you get the idea). Eventually -- probably sooner than most people think -- they will run out of stuff to burn and/or switch to non-hydrocarbon based energy. It's not like they have a choice.
We all won. Or maybe we all lost. Anyway, IMO the war's pretty much over. Eventually, the screwballs on both sides will move on to being vocally mistaken about some other issue
Caveat1 One largely ignored aspect of AGW could be a problem -- water. There are a great many people on the planet (too damn many if you ask me) and it is predicted that there will be more -- 10,000,000,000 by the end of the century. They will need to be fed. That requires a lot of fresh water. It is virtually certain that warming will alter precipitation patterns. What's not so clear is how the patterns will be altered. We think we know that a glaciated planet is cold and dry. A warmed planet may be warmer and wetter -- which would probably be good. But it might not. Unfortunately the global climate models currently are -- and there is agreement on this -- unable to make reasonable predictions of rainfall patterns in a warmer world.
Caveat2 It's reasonably sure that sea levels have been rising worldwide for at least a century. Rates of apparent sea level are different at different locations and in different regions, but on average, they seem to be about 30cm (a foot) a century. There's no reason to believe that rate of increase will slow. With rational management 30 cm a century is not likely to be devastating, but past experience indicates that rational management is not very probable. In fact, it seems that far too much infrastructure is being built far too close to sea level. That, not sea level rise or a warming planet, is why large storms cause devastating flooding, infrastructure damage, and loss of life. Geologic forces (tectonics) cause some places to rise and others to sink. In some cases, sea level rise is exacerbated by pumping fluids (fresh water, petroleum) out from under sea shore regions. And a few metropolitan areas (Alexandria, Egypt; New Orleans) built on unconsolidated sediment are sinking as the underlying sediment compacts. By the way, low coral islands are perhaps at less risk from sea level rise than temperate zone cities since coral islands have a well established mechanism, first identified by Charles Darwin in 1842, for staying near sea level.
Addendum The transition to non-hydrocarbon based energy is likely to be a bumpy one. All the current technologies for generating vast amounts of non-carbon based power except nuclear fission are either limited (hydro-electric, geothermal, maybe bio-diesel), seriously flawed(wind, ethanol), or immature (solar). Nuclear power is controversial. Many well meaning, but foolish, souls think the problems are trivial and that solving them is just a matter of will and of stomping on the evil oil companies. No doubt their hearts are in the right place, but engineers they are not. If they built airplanes, sensible people wouldn't fly in them.
And a final point. In my opinion, the entire global warming debate has become a festival of bad science, worse logic, stupidity, atrocious behavior, and outright lunacy. Both sides are guilty of all those things. But on the whole, the skeptics seem to have the data -- such as it is -- on their side.
Here's a link to a somewhat similar opinion -- perhaps better written and more thoughtful than mine