[greenbean36191]

Like, how do we reach such grand conclusions about natural events on this planet when the planet is over 4 billion years old and our ability to record observations is less than 200 years?

We have proxy data that overlaps with our 200 years of direct observations. Proxy data is basically an indirect measure of something else. Ice cores are one of the most publicized sources of proxy data. You can look the thickness and structure of snow layers and tell how wet, cold, or windy a year is. You can also look at the amount and composition of dust or ash in the snow and tell how dry or windy it is where the dust came from. The ice also traps microscopic bubbles of air that allow for direct measurement of ancient air. You can also look at the ratios of different oxygen isotopes and tell how much sun was hitting the upper atmosphere. You can do similar things with cores from coral reefs, ocean and lake sediments, and tree rings (from live and dead trees). The 200 years of direct observations plus occasional observations before that give us a check on the calibration of the proxies. Obviously I'm oversimplifying a lot, but Richard Alley has a great book called The Two Mile Time Machine that does a really good job of explaining how we know what we know in easy to understand terms.

Is it not true that there is evidence to suggest the earth cycles, i.e., moves from warm to cold to warm to cold, etc.... and that this cycle has been ongoing well prior to man even finding the value of carbon?

There is no doubt. Dr. Alley's book does a great job of putting past and recent trends into perspective too.

If that is the case, then how can we so dramatically reach these almost religious like conclusions about how man is responsible for what is otherwise thought by some experts to be a totally normal and natural event, i.e. warming (like where did the great lakes come from).

I know of no experts on the subject that believe that the current trend is a totally normal and natural event. They certainly aren't publishing anything in the scientific journals to that effect. Even John Christy has acknowledged that humans are having an impact, though he disagrees with most scientists on the extent of our impact.

I think this question is a great example of the false dichotomy that's been set up by skeptics. They would have you think that the only options are that either humans are causing the current warming (and that that's what scientists are claiming) or that it's caused by natural variations. Given that we have good records of huge changes that predate humans, the second of the two seems like the obvious choice. In reality there is also the option that the current trend is the result of natural fluctuations being amplified by the impact of humans. That's the option supported by science. There is currently no scientific debate over whether or not we're a factor. The only debate it how much.

So how do we know that we're partly to blame? We know what greenhouse gases like CO2, water, and methane do in the atmosphere. We know that we produce a lot of them- more than the planet can sink. There is no way we know of that the excess can not have an impact so the question becomes how much. To figure out that impact we have to know how much of those gases we've produced vs how much is produced naturally and how much is sunk as well as feedbacks like changes in the reflectivity of ocean water vs. ice or clouds vs. clear skies. When you combine all of that you can make a model. If you only include natural things like volcanoes, orbital changes, changes in the sun's output, etc. The model matches the real world data up until about the time of the industrial revolution, where it starts to underestimate the trend. If you add in the human impacts suddenly the model starts matching the real world data the whole way. No, it's not perfect, but the fact that we can get the model to fall that closely to what actually happened shows that we have a pretty good understanding of what caused the changes- at least well enough to predict the trends.