“CO2 fertilisation will not be a factor prior to 1850? After that we have reasonable instrument records. So why is everyone so interested in the proxies after 1850?”

To which Michael Jankowski in #20 wrote:

“If you’re going to compare the instrumental records to pre-1850 proxies, you must be able to calibrate the pre-1850 proxies using the instrumental record. Therefore, you need a sufficient calibration period post-1850 where the instrumental record and proxies overlap.”

So the issue is calibrating the proxies and MBH9x do it by calibrating during the 20th century when the problematic growth occurs. One way around this issue would be to make a reconstruction back to say, 1600, for which there are far more proxies than earlier and then use this reconstruction to calibrate the earlier proxies over say, 1600 to 1800, thus avoiding calibrating the proxies that are affected during the 20th century. This approach can easily be done using a REGEM reconstruction and illustrates an important benefit about REGEM that is not directly available in MBH9x, i.e. information from later-beginning proxies is used to calibrate earlier-beginning proxies. In MBH9x, the information from later-beginning proxies is completely ignored in calibrating earlier-beginning proxies.

I don’t think they’ve applied the approach I described above in Rutherford et al 2005, (i.e. leave out the Bristlecone proxies after 1800), but the reconstruction before 1500 (for example) does depend on how the Bristlecone proxies correlate with all other proxies after 1500 and the instrument record, and not just on the instrument record in the 20th century.

I’ve made this argument in other posts in previous weeks.

However, they did sample same trees as earlier study, which certainly should be the standard. I guess all these trees should be tagged really. Except the ones that are cut down for sectioning. Need to do that sometimes. I guess if someone wants to really understand these arguments about places where the biomass is added, we might need to cut whole trees down and pull out the roots and weigh it all.

Also (of course) the same issue applies to your auditing/examination of people’s papers. If you find errors the minimze(!) stickishness, you need to share those as well. I won’t go so far as to say you need to look for them with the same ardor. But definitely if you get wind of something or get a reasonable impression that such an error in the numbers exists, you ought to finish that little subanalysis and bring it forward. Forensic accounting finding errors either way….

The cedars like cool moist climate and do not have a linear response to temperature. More like an upside down quadratic. I think that the upside down quadratic is abig problem for the tree ring jockeys. Briffa has complained like a stuck pig that tree rings haven’t been getting wider in the 2nd half of the 20th century. They chop off the graphs after 1960. Briffa blames an “unknown anthropogenic” factor and drives on. I think that it’s equally likely that there’s an upside down U relationship and the proxies are really in trouble in the 1990s – which is why we don’t hear about them.

As I’ve said before, if the tree rings in the 1990s were off the charts, we’d be hearing about it from the tree ring jockeys. Their silence is deafening. That’s why they’re talking about glaciers now.

The other trick that’s in the works is SO&P. They seem to have focused on tree rings after 1500 and will probably have hysterical articles timed for IPCC 4AR. But no ones’ arguing about the post-1500 proxies.

Outstanding. Always better to get data closer to home, and you don’t have to cross our border. You should be able to see a long record of the AO in the record as well. The Pinus l./a. are marginally (if at all) affected by the AO, so you may have issues there making direct comparisons. In addition, you may want to consider these plants may experience some maritime influence, whereas the Pinus have solely a continental influence, further complicating matters. Lastly, I seem to recall an article about that area when I was studying adaptive management and it seemed quite interesting, so that’s reason enough to give it a go.

IIRC, the strip-bark feature in slow-growing tree spp affects metabolism and apportionment, but shouldn’t be a reason for preferential selection when coring (e.g. it is something to account for, but won’t tell you something that a tree completely encircled by bark would).

Anyway, it will be interesting to see whether these trees indicate, in this place, the MWP was warmer than present. And an acknowledgement of the utility (sure, TCO, in the economic sense) of TCO’s well-written comments WRT to points made at ends of paras as an important purpose.

Gotta go,

D