In addtion to borehole data concerns, there are concerns with how air temp./proxy data from radiosondes, satellites, surface thermometers, oxygen isotope, element ratios from tests, etc. are manipulated. And not to mention, GCMs and how they seemingly over use CO2 as a general predictor of near-future air temps and either don’t include clouds and aerosols, etc., etc.

I understand that CO2 actually absorbs energy over a fairly limited range of the electomagnetic spectrum. If that’s truely the case then its seems to me that there should be more focus on just how much can we expect air temps. to increase given a certain increase in CO2.

Nevertheless, I think the starting point is to look for the basic analysis of sample numbers required for a certain accuracy. What has been published on that? I would think that in analogy to papers on tree rings that say how many times you need to core an individual tree or a stand to get a particular accuracy. Those exist right? Seems basic, no?)

From the near proximity twin and multiple hole graphs Willis E has presented here, I would think that, as he has indicated, one needs more information to explain these differences before doing more statistics on their collective. Perhaps an expert can explain the differences and a prior have accounted for them, but I doubt that a good statistician or scientist would proceed beyond this point without it.

The Alaskan borehole data is located at http://esp.cr.usgs.gov/data/bht/alaska/“.

Mann’s borehole data is in the Mann2003 folder at http://www1.ncdc.noaa.gov/pub/data/paleo/borehole/.

The Utah boreholes are found in the “North America” section of the main borehole site, at http://www.ncdc.noaa.gov/paleo/borehole/nam.html

And the !@#$%^&* link button isn’t working for me …

re #72, Hans, you say:

Borehole temperature is strongly dependent on geology and geohydrology. Are you sure the wells you are comparing are comparable?

I would assume that would be considered, and these variations removed, during the analysis of the data. However, these graphs I’ve been showing you are the analysed, 100 year averages of the results …

Finally, TCO, thanks for your contribution. You say:

Willis, I think the basic question comes down to something like inherent variability and how uncertainty is affected by that. If you are really interested in a specific site (and the variability is just noise), then you need to average a lot of holes. Maybe on a larger scale, some of this averaging takes care of itself. (Not sure that you need to subaverage for locations). The more troubling thing is: does the large variation indicate some form of non-random noise such as experimental method or water or something like that which throws the whole method in doubt.

Nevertheless, I think the starting point is to look for the basic analysis of sample numbers required for a certain accuracy. What has been published on that? I would think that in analogy to papers on tree rings that say how many times you need to core an individual tree or a stand to get a particular accuracy. Those exist right? Seems basic, no?)

Unfortunately, for most specific sites, there is only one borehole record in a 5° x 5° gridcell, so it’s not possible to “average a lot of holes”.

I have not yet found the paper you described that sets out the accuracy of the record. Dr. Beltrami found good results in Canada, for example … but what we need is not that, but an analysis of bad results to let us know the uncertainties. I haven’t seen that yet.

My thanks to all,

w.

Nevertheless, I think the starting point is to look for the basic analysis of sample numbers required for a certain accuracy. What has been published on that? I would think that in analogy to papers on tree rings that say how many times you need to core an individual tree or a stand to get a particular accuracy. Those exist right? Seems basic, no?)

Thanks Eduardo,

You answer goes directly to my questions about the sensitivity of the method, given the small changes which modellers and reconstructionists are attempting to capture.

No silver bullet, then.

Borehole temperature is strongly dependent on geology and geohydrology. Are you sure the wells you are comparing are comparable?