Note: this was written sort-of on request, so it isn't quite pointless navel gazing.
In 2010 I was asked about this and wrote "As it says on that last page: I was invited, I think by Sheldon Rampton, and think it was to sort out [[global cooling]], which is a subject I've had a long interest in, dating from usenet days: http://www.wmconnolley.org.uk/sci/iceage/ In those days, things were free-n-easy, and there were lots of terrible climate pages in bad need of updating: not just because of bias, though there was some of that, but just because many pages hadn't had more than a cursory glance from anyone competent."
In fact the very first version of GC dates from August 2003, and was extracted from the now dearly-departed Global Warming Skepticism article, and is vaguely sane; though you'll notice the extracted and inserted text doesn't quite match.
But back to the mainstream of GW. My very first edit was uninspiring. The state of the page at that point was poor, and it wasn't clear what to do about it, so I just quibbled The factor which correlates most closely with observed temperature increases and decreases in the earth's atmosphere is solar activity with but correlation-is-not-causation, when I should just have ripped it out; but Damon and Laut came out later. This is characteristic of the early days. A little later in the day I did better, demoting the text and wrapping it in weasel words. Not long later I made my first unexciting edit as me and then created my userpage. A few days later I created Instrumental temperature record with mostly new text and information. Over at Urban heat Island I was again just reacting to what was there, quibbling the silly SEPP view with This argument conveniently ignores the fact that the marine temperature record is essentially in agreement with the land-based one. Touching up the Ozone Hole article was less controversial, but again we see how poor the state was, and the "informality" shall we say of my additions. I put up the first meaningful version of the Satellite Temperature Record page, based on the discussions I was familiar with from sci.env. Over at Attribution of recent climate change I edited to Remove anti-IPCC bias (sigh). Add fuller text of IPCC role. You get the idea I hope: lots of things were wrong, I was feeling my way.
This is all going rather slowly. I'm going to call this "Introduction" as an excuse to break off here.
Update: the thrilling saga continues at The dim and distant history of Global Warming on Wiki: the GW wars.