I don't really know how to respond to your post, simply because I have yet to meet anyone who considers the idea of global warming to be a concocted conspiracy of some kind. In all humility, I ask you to indulge me for a minute, if you would be so kind, and let me offer my view of things.
Fact: The vast majority of scientists working on the question view global warming as something that is real, happening now, and caused by humans. A small minority do not agree with this theory, and believe that something else is to blame for what is going on, or indeed that nothing is going on. Could the majority view be wrong? Certainly. It has not been proven, beyond the shadow of a doubt, that global warming is happening or that people are causing it.
The other thing that we don't have much knowledge about is the speed at which the planet will continue to warm, if that is indeed happening. But there seems to be indications that it is happening very quickly. Do we know what the consequeces will be? Mostly not, we can only make educated guesses. But I ask you, should we simply be planning for the best case scenario? Given the limited knowledge that we have, it only seems to make sense, I think, to try to work towards improving the state of things as much as is within our power.
The fluctuating temperature extremes that you make reference to are a normal part of things when climate change is iminent. And yes, geological changes will account for climatic changes, but it is thought that these kinds of changes do not occur so rapidly.
With all due respect, I don't understand this idea that global warming is somehow a kind of political ploy. What are countries that support the Kyoto accord to gain from supporting the accord? It just seems to me like they have to put a lot of BST into changing over to different ways of garnering energy. On the other hand, I could see how it might be very appealing to big multinationals like Exxon and Mobil to debunk the theory of global warming as much as possible, as they would be looking out for their own interests.