I'll be making a number of posts prompted by a note from Dave in a different area. It'll be a number of posts because I'd like to take some care on each of the points.
Let's start with:
This topic of global warming has alot of problems... First of all you have a complicated science. It's not likely alot of people will truly understand the science well enough to be able to argue the points.
Climate certainly is a messy business. One of the things that makes it interesting to those of us who work on it is precisely that. Wherever you look, you find something that affects climate, regardless of whether you look at permafrost, sea ice, forests, farms, rivers, factories, sunspots, volcanoes, dust, glaciers, ...
So certainly we have a complicated science and certainly few people are going to understand enough of it to argue the finer points. This is true within the science as well, as few who study volcanoes and their climate effects are going to be able to argue the finer points about the role of sea ice in climate, or vice versa.
What does an honest and interested person do then? Two things as I see it. First, not all the science involved is difficult. For those parts of the science, learn the science. Anybody who can get through normal life, cook a recipe, balance a checkbook, etc., can understand the basics. One source is Jan Schloerer's summary at http://www.radix.net/~bobg/faqs/scq.basics.html Jan was not a climate scientist, but, as I said, you don't need to be one to understand the basics. One thing he did do (see his acknowledgements, for instance) is check with people who were to ensure that he'd gotten the science right (or at least correct given the limits of writing a general audience description). I'll come back to basics in a minute.
Second, for things that aren't elementary, start looking to expert opinion. No different than if your car is acting up and you can't figure out why, or you've got something like a cold but it isn't going away like one should. You go find an auto mechanic or doctor and use their expertise. If your concern is, instead, about climate, then find some climate scientists. While there aren't that many (even counting worldwide) they do exist. And it's not that hard to find their professional understanding. You'll see it more directly in journals like Science and Nature than Scientific American or Discover. But both can be gotten fairly easily, and both include summaries of the science which are written for laymen.
You can also look to the IPCC reports, the fourth having been issued recently. The first was the best, I think, in terms of explaining the science to non-professionals. As the basics haven't changed since then, you might want to look for the first edition. The summary for policymakers, in each edition, is the most readable and aimed for non-professionals. The drawback is that it necessarily includes fewer details about the science. Nevertheless, it (the IPCC report) does represent as good a summary of the state of the science as you'll find.