This might be slightly off-topic, but I’ve always wondered:

One of the more common allegations by deniers is that the scientists have been inconsistent, etc. Why has no one called them on the inconsistencies in their own arguments?

Is the world heating up? Yes or no? And if yes, are humans causing it?

You can’t nail deniers down on either of these. Sarah Palin, for example, has flip-flopped on that first question many times over the past several years. The deniers hedge their bets with “well okay the world is getting warmer, but it might not be humans’ fault” whenever evidence presents itself to that effect. They take the point of the concerned, intelligent skeptic who believes the scientific data about increasing global mean temperatures, but just doesn’t quite agree with that last point. More research needed. Perhaps not anthropogenic. Economic impact. Might be the sun. Need more evidence. Etc.

Then they gleefully fall back to “Hahaha, see? It’s not warming at all!” whenever we have a snow storm.

Why does no one ever call them on that?