Whether or not the debate is over is a red herring that is irrelevant to any debate on any scientific issue. The debate is never over in any scientific area, scientists still pick away at the edges of all scientific theories but that doesn't change the fact that if I sit under a tree I might get hit by a falling apple. Still there seem to have been many debates on the edges of the theory of gravity but so what?
Did you read The Times piece linked to above? There are serious questions regarding the underlying data, as articulated by the former head of the IPCC, data which go to the very heart of the issue.
Also, the interview of professor Jones on BBC (also linked to above) indicates that there is a serious and legitimate debate about whether any current warming is truly "unprecedented" or if a similar warming happened only 500 to 700 years ago.
To distill this debate down to being equivalent to your elementary "apple example" really says something.
Politically, in the worst way, many on the Left really hope that the warming trend is real and that the only solution is a massive movement away from (evil) capitalism. As George Victor noted above, people see in science exactly what they want to see (and that goes for the Left, too).