"They are essentially admitting that tree rings aren't good proxies for temperature. "
No, they aren't. You are reading what you want in to that. They are saying they are good proxies until something changes and they aren't, at which point they aren't used.
Would you have been happier if they only looked at half the trees for twice as long? Nope. You would only be happy if all 37 hockey sticks disappeared.
To examine earlier periods, one study split a network of tree sites into northern and southern groups ( Cook 2004). While the northern group showed significant divergence after the 1960s, the southern group was consistent with recent warming trends.
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"The burden of proof should be on the parties using tree rings as temperature proxies that they ARE good proxies."
You are about 100 years behind the time. Face it; you just can't handle the truth. At this point, the burden of prove is on anybody saying they aren't reliable, either in general, or in this case. That doesn't mean lies on a crazy blogger's website. It means something like a paper at the AGU.
en.wikipedia.org
Dendrochronology
is the science that deals with the dating and studying of annual growth layers in wood.
The Value of Dendrochronology
It is the most accurate dating technique that we use today. It provides annual and even seasonal resolution throughout the entire record. Other records such as varved lake sediments, some ice cores, and coral records can provide annual resolution but it is not as consistently reliable as dendrochronology. Another factor that makes dendrochronology a useful tool is that trees are ubiquitous on the landscape. Most terrestrial-temperate regions of the globe have trees present that can be useful to the techniques of dendrochronology.
Time Frame of Dendrochronology
The time frame of dendrochronology covers anywhere from the present back 10,000 years. But most chronologies are only a few hundred years long. There are some 1,000 year long chronologies scattered around the globe, but they are rare.
Short History and Scope of Dendrochronology
Dendrochronology was developed by A.E. Douglass, founder of the first laboratory entirely devoted to tree-ring research. Douglass' initial interest was the impact of solar cycles on the Earth’s climate. While working in Flagstaff, Arizona in A.D. 1904, he noticed a distinct annual ring pattern in the stems of many ponderosa pine trees, a repeated signature of narrow and wide rings. This now famous pattern, which Douglass subsequently found in trees throughout the region, became known as the Flagstaff signature. Ring-width patterns enable dendrochronologists to precisely and accurately date every individual tree ring in a chronology.
When all trees on a site are limited by a common factor, such as inter-annual variability in climate, the size of their annual growth rings is affected in a similar manner, and a common ring-width pattern emerges across the site or region. Crossdating, i.e., matching the ring patterns in tree-ring samples across a site, can provide an accurate chronological record of the natural history of the stand.
Among other applications, dendrochronology has been used to date:
- Archeological ruins
- Climate change
- Fire history
- Insect outbreaks
- Volcanic eruptions
- Glacier movement
dendrolab.indstate.edu |
