Let me try to separate two different sources of argument related to global warming. The first and most basic is the assertion that global warming *is* happening and *is* due in a significant part to human activity.
The second aspect of global warming is the *rate* at which this is happening, precisely at what points in time various bad things start happening and even precisely how bad these bad things will actually be.
If some folks want to claim that there is a segment of the population that are global warming alarmists then I cannot deny that claim. If they also want to legitimately argue about how soon various dire consequences will start to occur then I would also have to admit that there is plenty of room for legitimate discussion.
However the folks that deny that global warming is even happening or that if it is happening is not due in a significant part to human activity simply have their head in the sand or more likely have a political agenda that is in some way philosophically opposed to the idea of global warming.
The problem is that most any evidence that anyone can point to is anecdotal, however in my mind there has been such an overwhelming preponderance of "anecdotal evidence" that I believe any reasonable person (i.e. anyone without some contrary political agenda) would accept global warming as an established fact and any application of Russell's Teapot (two l's not one, BTW) applies to the opponents of global warming, *not* to the proponents of global warming.
As yet another piece of anecdotal evidence take a look at this report of the 1st commercial ship to navigate the Northwest passage as recently as two months ago, http://www.cbc.ca/canada/north/story/2008/11/28/nwest-vessel.html.
Again, anyone is free to disagree with me but do try and keep the curse words and personal abuse to a minimum.