"A blockbuster Chinese study of Tibetan Tree rings by Lui et al 2011 shows, with detail, that the modern era is a dog-standard normal climate when compared to the last 2500 years. The temperature, the rate of change: it’s all been seen before. Nothing about the current period is 'abnormal,' indeed the current warming period in Tibet can be produced through calculation of cycles. Lui et al do a fourier analysis on the underlying cycles and do a brave predictions as well."
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- There have been much hotter and much colder ages than the one we live in now. Something that global warming believers don't want discussed. After all, how could climate change when no humans were around to "cause" it????May 10, 2012
- It is interesting how the iknowandyoudont.com people like to draw conclusions from studies that the authors of the study do not. Did you even read their conclusion?
Tree-ring studies in north-central China [9−14,16−18] have
shed some light on local climate variations over the past
several hundred years. Studies have also suggested that tree
growth in arid to semiarid northern China is generally limited by a period of water deficit [9,10,24]. This relationship
can frequently be reflected in the directly positive correlation between tree-ring width and rainfall over a given period.
Temperature has been shown to have a less important negative influence on tree growth. In north-central China, for
example, in the Huanglong Mountain in Shaanxi Province
, the Lüliang Mountains (this study), Kongtong Mountain in Gansu Province , and Nanwutai, on the north
slope of the Qinling Mountians , studies have disclosed
tree-growth responses to precipitation and temperature
similar to those found elsewhere in northern China. At these
sites, however, temperature replace precipitation as the
predominant limiting factor on tree growth, by accelerating
soil moisture evaporation and tree transpiration; at these
sites, low temperatures are favorable for the formation of
wider rings, while high temperatures limit tree growth and
produces narrow or even missing rings. A possible cause is
that precipitation in the southern region of northern China is
higher than that in the north, and in mountain areas, precipitation also increases with altitude, making precipitation
less important to tree growth than temperature. However,
when the latitude of the sampling site is lower, especially
across the Qinling Mountains——an important climatic and
geographical boundary between northern and southern
China, tree growth response to climatic factors is the reverse
of that in northern China. For example, in the watershed 
and southern slopes of Qinling Mountains [11,26], tree-ring
width is positively correlated with temperature, but negatively correlated with precipitation. This is an interesting
phenomenon and worth further study. The results of the
present paper verify the way trees respond to climate in
north-central China, but further research is needed to prove
This study has revealed that the tree-ring width index in
BWD reflects the May−July mean temperatures, not only in
the central region of the Lüliang Mountains, but also over a
larger region in north-central China. A number of statistical
tests validated our reconstruction model, and the reconstructed warmer and colder periods were comparable with
those that have been inferred from reconstructions in
neighboring areas. The temperature since the 1950s has
shown a slow warming trend, with temperatures of 1994−2002
being the highest since 1836.
So they see the hockey stick from 1994-2002. They also say that there is an inverse correlation between rainfall and tree ring growth. Do you think it's possible on the Tibet plateau that a rise in heat might correlate with a decrease in rain?May 10, 2012
- Nothing you quoted even disputes, let alone disproves, the conclusions drawn by Joanne Nova (as quoted by Anthony Watts.) And reading the paper falsifies your assertion that the study "sees the hockey stick." It simply does not. Why not? *Because the "hockey stick" is not the same thing as a warming trend from 1994 to 2002. The presence of a warming trend since the late 1970s to roughly 2000 (give or take a few years due to regional variations) is not disputed, nor would its alleged absence have anything to do with the now well-documented and generally-accepted falsification of Mann's "Hockey Stick" graph.
The error in Mann's "Hockey Stick" graph concerns the temperature history prior to 1980, especially regarding the Little Ice Age and the 300-400 year temperature rise since then.
The fundamental and irrefutable mathematical error in Mann's computation of the "Hockey Stick" is explained here: http://www.informath.org/apprise/a3010.htm To argue against that refutation has the same effect as arguing that 2 + 2 = 89.
The effect that error has on the "Hockey Stick" graph is not that it creates the "blade," but rather that it creates the "shaft," as explained here: http://www.ncpa.org/pub/ba478May 10, 2012
- Alan, try this link instead and then tell me that Mann et al. is wrong: http://en.wikipedia.org/wiki/Hockey_stick_graphMay 10, 2012
- That Wikipedia article is an embarrassment of political advocacy, blatant failure to follow the scientific method, and mathematical falsehood.
It is the skeptics of CAGW who are following the scientific method, and the advocates who are in denial of what is required for a discipline to qualify as science. Scientists who show methodologically-correct, scientifically-required skepticism of any unproven hypothesis (and even of ones considered 'proven,' for that matter,) are not "political opponents of climate science," as the Wikipedia article alleges. Even to make such a statement reveals a bias that disqualifies that article as anything other than a political hit piece.
There are many other falsifying criticisms of the data used to produce Mann's Hockey Stick. One is simply that the sample size is to small: YAD06 – the Most Influential Tree in the World: http://climateaudit.org/2009/09/30/yamal-the-forest-and-the-trees/
Another is that Briffa's sampling methodology is strongly affected by sampling bias:
Detecting evidence for CO2 fertilization from tree ring studies: The potential role of sampling biases: http://www.agu.org/pubs/crossref/2012/2011GB004143.shtml
Note: wider tree ring width correlates with higher implied air temperature
Tree ring analysis allows reconstructing historical growth rates over long periods. Several studies have reported an increasing trend in ring widths, often attributed to growth stimulation by increasing atmospheric CO2 concentration. However, these trends may also have been caused by sampling biases. Here we describe two biases and evaluate their magnitude. (1) The slow-grower survivorship bias is caused by differences in tree longevity of fast- and slow-growing trees within a population. If fast-growing trees live shorter, they are underrepresented in the ancient portion of the tree ring data set. As a result, reconstructed growth rates in the distant past are biased toward slower growth. (2) The big-tree selection bias is caused by sampling only the biggest trees in a population. As a result, slow-growing small trees are underrepresented in recent times as they did not reach the minimum sample diameter. We constructed stochastic models to simulate growth trajectories based on a hypothetical species with lifetime constant growth rates and on observed tree ring data from the tropical tree Cedrela odorata. Tree growth rates used as input in our models were kept constant over time. By mimicking a standard tree ring sampling approach and selecting only big living trees, we show that both biases lead to apparent increases in historical growth rates. Increases for the slow-grower survivorship bias were relatively small and depended strongly on assumptions about tree mortality. The big-tree selection bias resulted in strong historical increases, with a doubling in growth rates over recent decades. A literature review suggests that historical growth increases reported in many tree ring studies may have been partially due to the big-tree sampling bias. We call for great caution in the interpretation of historical growth trends from tree ring analyses and recommend that such studies include individuals of all sizes.
As for the math errors in the code that always produces a hockey-stick shape, the facts are simply beyond any possibility of rational dispute. We know for a fact that the math errors in the hockey stick formula were well and widely known in the paleoclimatology field. How? Because it's admitted in their publicly-released e-mails with each other: http://wattsupwiththat.com/2011/12/05/tim-barnett-on-the-hockey-stick-statistics-were-suspectthe-rest-of-the-team-knew-of-problems-with-manns-reconstruction/
Try denying that.
The full fraud has been comprehensively and irrefutably documented in The Hockey Stick Illusion, by Montford: http://www.quadrant.org.au/magazine/issue/2010/7-8/the-tree-ring-circus
"McIntyre’s discoveries were numerous, and startling, and damning. When he started posting them on the web, the Hockey Team scathingly dismissed them as ignorant nonsense that would never get past a peer review; but as soon as McIntyre and fellow Canadian Ross McKitrick had their first peer reviewed paper (MM03) published in Environment and Energy the debate escalated into a Hockey Stick war. Mann furiously orchestrated a campaign of denunciation and sabotage. His “friends over at Nature”, as he called them, treated McIntyre and McKitrick particularly badly, accepting their paper, delaying it, then rejecting it and publishing Mann’s exculpatory corrigendum instead.
While their paper was languishing at Nature the Canadians were constrained from responding to attacks by the team. Mann declared that a paper by Scott Rutherford “completely discredited” MM03. But in 2005 McIntyre and McKitrick had their second paper published in Energy and Environment (MM05EE) and another one in Geophysical Research Letters (MM05GRL) and another one in a Dutch magazine. Mann’s response was to claim that Energy and Environment was not a legitimate scientific journal and that MM05GRL had “managed to slip through the imperfect peer review filter at [GRL]”. He didn’t explain how he knew this about the allegedly confidential peer review process, but thanks to Climategate we know the sort of influence he could wield over that process, and what sort of filter he had in mind.
The war that raged between McIntyre and the hydra, in the journals, on the net, and in the media, came to a head, to one of them at least, when Mann once again refused to disclose his computational codes. As long as McIntyre had to rely solely on the codes he had broken, Mann could claim that he hadn’t got them right, so McIntyre asked Mann to provide the right ones—and was again refused. Hence Mann’s stance amounted to: no one can understand my methods and reproduce my results without my codes, and I am not going to allow anyone else to examine or use them."
Until Mann releases the computer code used to construct the Hockey Stick graph, it is scientifically, legally and morally required that it be assumed to be guilty as charged. In science, claims are assumed to be false until proven true.May 10, 2012
- "In science, claims are assumed to be false until proven true."
Proving them true requires that the claimants provide the means for others to independently verify, validate, confirm, OR falsify and refute the claims!!!
Mann has failed to provide the means to have others replicate his results thus he has failed the basic requirements of the scientific method and as such has failed as a scientist... given the number of chances he's had to provide what others need to reproduce it... one can easily conclude that Mann is being intentionally dishonest and disrespectful of the scientific method for nefarious purposes. Prove otherwise Mann!May 10, 2012