Off on an email list we’ve been discussing wildfires and their connection to global warming. I’ve always been somewhat cynical about the connection, which appears in the popular press  to amount to “fires are hot, global warming is, err, warm, so they must be connected”. However, I really do know well enough to ignore the popular press.
This kind of thing: There are many reasons for any particular fire, but basically the (wildfire) pattern is reflection of two things related to higher temperatures – earlier spring snow melt and also higher spring and summer temperatures,” he added.  isn’t the popular press though. Or The increase in outdoor fires in England andWales between 1965 and 1998 may be attributable to a trend towards warmer and drier summer conditions (Cannell et al., 1999).  (thanks Eli).
I’m entirely happy with dryness causing fire, and I’m entirely happy with warmer temperatures causing earlier snowmelt causing summer dryness causing fires. What I’m dubious about is fire risk from pure higher temperatures unmediated by drying. Maybe this is a strawman. Maybe no-one believes it; though the quote above suggests not.
JF says that Westerling and Swetnam  is a key paper; and that says what the quote above said, so is probably the source for the above. However it is hard to disentangle the effects of temperature and dryness, since dryness often leads to heat (since evaporative cooling is then lost, as in the Great European Summer of 2003). Indeed, W&S say “Temperature affects summer drought” though it seems odd to make it so one-way, when the system is clearly coupled, and I would have thought that the influence was more largely in the other direction. W&S make no effort that I can see to disentangle the two effects.
But does anyone actually believe that warmer temperatures, without and change in dryness, causes wildfires? Is a fire really (significantly, measureably) more likely to start and / or spread at 32 oC than 30 oC? It seems rather unlikely to me, though I suppose possible.
[Very late update: http://bbickmore.wordpress.com/2012/07/31/deseret-news-hotter-climate-equals-more-wildfires/ -W]