mP, it's clear you've not taken (OR if you have, you'd remember much of) statistical analysis, since you clearly don't know that there are commonly-accepted CONVENTIONS (rules) in play for HOW data is interpreted, just to avoid such arguments from developing. I'm not going to embarrass you by ASKING how far you got into stats (I can't recall exactly how many courses I took, since it was so long ago, but it was at LEAST 3 courses on stats required for my undergrad science degree), but if you're offering your unedumcated (sic) opinion on graphical analysis without having taken any course, you're talking outside your backside orifice.
The other point to remember is that the full title of the fallacy is actually "appeal to QUESTIONABLE authority", not just "appeal to authority". The point is that if someone refers to some "expert's" opinion in the field of study in question, then the next step SHOULD be to VERIFY if the cited expert actually IS respected by their colleagues to support their opinion; like it or not, science is a group endeavor. The point is not to discount the opinions of ALL experts (as if appeal to authority are BAD things: that's what we MUST do, trust the experts!), but that the consensus wins out, since the cited expert might be a crackpot who's operating at the very fringe; the rule is the majority opinion wins. Not that the minority of scientists MUST just give up their hypotheses, and go with the group and abandon their opinion; instead, the onus is on THEM to conduct valid studies that PROVE their opinion and show WHY the majority opinion is wrong to convince them.
Fact is, sometimes the minority opinion IS correct, it's just that they need to demonstrate it to the group to advance science forward. That's exactly WHY the scientific method works: it doesn't squelch the minority opinion, but also doesn't just accept it without good reason.
That stated, there IS a consensus amongst climatology experts (97% is the figure I saw cited) that GCC IS occurring and man plays a role in the etiology. Point being, science doesn't wait around for 100% agreement to begin addressing problems, since the ice cap could be the size of an ice cube before many would be convinced, and even then some deniers would only say, "Well, that's no proof, and it'll come back!"
Adam