I find data that chooses 1880 to be extremely counter productive. This [1] is an image of longterm temperature estimations from NASA. When somebody sees this they're inclined to ask themselves why exactly do these sort of data start at 1880? It misses the critical cyclical pattern of temperature changes and starts at the lowest low possible to present a misleading picture indicating complete clarity of a linear pattern. To be clear I think we're almost certainly playing a significant role in the current rate of temperature changes, but presenting misleading data completely removed from context is a really great way to completely undermine faith in everything you say.
[1] - http://upload.wikimedia.org/wikipedia/commons/7/7e/Global_te...