There is a tremendous amount of opinion floating around here, much of it seemingly based on ideology and not science, and that is disheartening on a science forum, because the only real tools that we have for detecting and measuring and mapping changes in climate are scientific.
Climate change is real. We are losing polar ice, glaciers, and mountain snow-caps. This is not just "weather". Losing such masses of fresh water long-term is indicative of something more than that.
The question before us is a 3-parter, IMO:
1)Is climate change driven by the activities of man?
2)If so, to what extent?
3)If not, are we humans just "along for the ride" in a natural cycle?
I don't believe that the AGW folks have nailed down their argument #1, though the preponderance of evidence seems to rest with them at this time.
Given the complexity of climate and the diffuse nature of pollutants, etc, the answer to #2 may be out of our reach.
It is for certain that the anti-AGW have not made a rational scientific argument for #3, which is interesting. Instead, they have relied on political appeals, nay-saying, and some level of skullduggery to make their case.
Given the stakes involved, you would expect OPEC, refiners, power companies, gas and oil companies to fund climate research on a scale at least equivalent to that at CRU and other research centers to scientifically advance their case that carbon emissions are not causing climate change. Why have they not done so, or have they failed to disprove the IPCC reports and are silent about that failure? Using the model of the tobacco industry, we can see how big businesses can fund "research" -real or not- to publicly refute real science that threatens their bottom line.
It's OK to be skeptical, and try to evaluate the research products as well as we can, with the information available to us. It's not OK to accuse groups of people of collusion, fraud, etc, just because you disagree with their findings.