Thread Rating:
  • 0 Vote(s) - 0 Average
  • 1
  • 2
  • 3
  • 4
  • 5
A possible 'divergence' problem at CRU
#1
I'm sure everyone is aware of the "divergence" phenomenon and "hide the decline" and how it is apparently a non-problem to many 'climate scientists'. So when I stumbled upon this text on the CRU website I thought it would initiate some discussion, especially in light of the CRU inquiry (http://www.uea.ac.uk/mac/comm/media/pres...ment+Panel) which references Briffa here:
http://www.cru.uea.ac.uk/cru/people/briffa/yamal2009/


Quote:The Dendroclimatic Divergence Phenomenon: reassessment of causes and implications for climate reconstruction.

Palaeoclimate reconstructions extend our knowledge of how climate varied in times before expansive networks of measuring instruments became available. These reconstructions are founded on an understanding of theoretical and statistically-derived associations acquired by comparing the parallel behaviour of palaeoclimate proxies and measurements of varying climate. Inferences about variations in past climate, based on this understanding, necessarily assume that the associations we observe now hold true throughout the period for which reconstructions are made. This is the essence of the uniformitarian principle. In some northern areas of the world, recent observations of tree growth and measured temperature trends appear to have diverged in recent decades, the so called "divergence" phenomenon. There has been much speculation, and numerous theories proposed, to explain why the previous temperature sensitivity of tree growth in these areas is apparently breaking down. The existence of divergence casts doubt on the uniformitarian assumption that underpins a number of important tree-ring based (dendroclimatic) reconstructions. It suggests that the degree of warmth in certain periods in the past, particularly in medieval times, may be underestimated or at least subject to greater uncertainty than is currently accepted. The lack of a clear overview of this phenomenon and the lack of a generally accepted cause had led some to challenge the current scientific consensus, represented in the 2007 report of the IPCC on the likely unprecedented nature of late 20th century average hemispheric warmth when viewed in the context of proxy evidence (mostly from trees) for the last 1300 years. This project will seek to systematically reassess and quantify the evidence for divergence in many tree-ring data sets around the Northern Hemisphere. It will establish a much clearer understanding of the nature of the divergence phenomenon, characterising the spatial patterns and temporal evolution. Based on recent published and unpublished work by the proposers, it has become apparent that foremost amongst the possible explanations is the need to account for systematic bias potentially inherent in the methods used to build many tree-ring chronologies including many that are believed to exhibit this phenomenon.

http://www.cru.uea.ac.uk/cru/research/

And who is Principal Investigator? Yes, you guessed it, Briffa. The project start and end dates are 12/09 – 05/12. Great timing!
"Correlation is NOT Causation"
Reply
#2
Over at tAV Jeff Id posted this a few days ago.
I think it might be relevant regarding the maths used by Briffa.

http://noconsensus.wordpress.com/2010/04...ing-board/
The whole aim of practical politics is to keep the populace alarmed
(and hence clamorous to be led to safety)
by menacing it with an endless series of hobgoblins, all of them imaginary.

H. L. Mencken.

The hobgoblins have to be imaginary so that
"they" can offer their solutions, not THE solutions.
Reply
#3
Since the surface instrumental temperature data is not valid to start with, isn't all this discussion about using tree rings (or anything else) to somehow correlate with it, irrelevant? In fact I read a recent paper that states it is impossible to determine the mean temperature at the surface of the Earth using existing instrumentation. Or am I missing something here?

Link to the article

http://nzclimatescience.net/index.php?op...6&Itemid=1
Reply
#4
(04-15-2010, 07:03 PM)ajmplanner Wrote: isn't all this discussion about using tree rings (or anything else) to somehow correlate with it, irrelevant?

YES, but "it" has to be shown to the general public, and how, and why.
"it" in this context is the use of surface temperature to justify / show the effects of AGW.
In such a way as "they" can not defend "it".
Or rather when "they" do defend "it" because "they" HAVE to defend "it",
we know "they" are lying, just like politicians "sometimes" do............
to protect, maintain, and / or increse their own personnal money, job security, reputation, and power.

"they" HAVE to defend "it" because,
1) "it" will NEVER be admitted as deliberately false, and that "they" knew "they" defended the indefencible.

2) "it" is wrong, because "it" has NO PREDICTIVE VALUE whatsoever.

we all here KNOW "they" are lying,
by "their" own data, maths, and unproven (but already falsified) AGW hypothesis.
The whole aim of practical politics is to keep the populace alarmed
(and hence clamorous to be led to safety)
by menacing it with an endless series of hobgoblins, all of them imaginary.

H. L. Mencken.

The hobgoblins have to be imaginary so that
"they" can offer their solutions, not THE solutions.
Reply
#5
There´s now an interesting open thread about proxy methods on The Air Vent. Craig Loehle actively participating:


http://noconsensus.wordpress.com/2010/05...y-methods/
Ni cien conejos hacen un caballo, ni cien conjeturas una evidencia (F. Dostoyevski)
Reply


Possibly Related Threads...
Thread Author Replies Views Last Post
  A Non-Problem Spun up into a Global Crisis Sunsettommy 6 4,146 12-16-2009, 06:31 PM
Last Post: Sunsettommy



Users browsing this thread: 1 Guest(s)