The reason bristlecones have been selected as temperature proxies is (aside from longevity) because in many sites growing season temperature and/or length are assumed to be the limiting factors to growth. The high elevation sites used have very short growing seasons and the warmth arrives long before the snow entirely dissapears.
The more I think about this, however, the more skeptical I am. Many of the places I have observed long-lived bristlecone pines one can find nearby mixed spruce/fir/bristlecone stands at nearly the same elevation. The only difference is aspect (and thus soil depth, snow loading and snowmelt). In these sites moisture is LESS limiting than the “classic bristlecone” sites nearby; but the trees are not useful as temperature proxies because they have crown and root competition – and because they don’t live all that long. The longevity of the oldest stands is because of avoidance of mortality agents – not because the trees are particurally resistant to disease, insects, or fire. Because the sites are harsh densities are too low for dwarf mistletoe to spread, sparse fuels (and a short fire window)remove the threat of wildfire, low temps. aand low densities both discourage beetle outbreaks, and the well-drained soils and narrow ring widths along with the open spacings make root disease uncommon. Other factors besides moisture limitations (notably wind and avalanche) help to maintain the wide spacings, but given the associated vegetation, aspect and topography of old bristlecone sites drought seems like it must be a factor.
Now there are a lot of bristlecone (and limber and whitebark) stands I have not seen, but I have looked at a lot of them, and often found individuals growing on better nearby sites, but they are not particurally old trees. This is just anecdotal evidence of course, but I believe it squares with the observations of foresters and biologists from the pre- anthropogenic global warming theory era.

The thing is – all this can be tested. You don’t have to simply guess which sites have a precipitation signal and which have a temperature signal. You could do controlled experiments (imagine that) and look at root/shoot ratios on different sites, stomatal density, cuticle thickness, or ideally by measuring water potential during the growing season. Some of these methods require destructive sampling so one might have to plant trees and wait a few years before beginning. All this would take time and $(plus some trained undergrads)but it seems better than just assuming given the stakes.

Likewise, I’ve lived for 30 years in mountain forest and high desert and think so far that using tree rings as a proxy for temperatures is very dubious. Just anecdotally, I’ve noticed that older dead Lodgepole Pine trees I’ve cut down for firewood have much narrower rings towards the later part and end of their lives. The last one another guy cut down for me this year was a 2 foot diameter tree which died about 5 years ago. It turned out to be about 100 years old, but I really couldn’t accurately count the last ~ 10 rings by eyeballing them, and the previous x number or them were shrinking. It hasn’t been getting that cold around here.

I have a hard time imagining that Bristlecones wouldn’t do the same kind of thing – as they “age”? But I don’t know anything about them from personal experience.

Anyway, I maintain that each individual tree is different according to how it can compete with everything in its immediate locale in order to survive, given also its own genetics, perhaps making the selection of individual trees as proxies for anything other than general conditions within small areas difficult. Water availability is obviously a big factor among general conditions necessary for tree growth, but maybe rings don’t necessarily reflect it either in a direct way compared to all other factors.

A place where there was more than enough rainfall but short gowing seasons, for example, would be my preference if I wanted a temperature guage.

The problem with a short growing season then, is what exactly are you measuring w.r.t. temperature? I.e.,
the proxy is then only indicative of the growing season temps, not the whole year. This is another point
never mentioned when using proxies. A year could easily have a warm summer followed by an unusually cold
winter, but the ring-growth would, presumably, only indicate the growing season, which is in the summer.

Mark

Some animals stand to gain from warming climates, say researchers who have looked at the effect of changing rainfall on mating and sexual selection in grey seals in Scotland.

The Idsos used extensive direct quotations denoted by actual quotation marks. Many civilians would think that this would make it almost impossible for distortion to occur, but this is simplistic.

I agree, but I still have not seen an example of them mischaracterizing a study. Of course, they do add interpretations, which are not in the study (Lee’s problem). But they certainly have the right to do that.