Watts Up With That?

WUWT readers may remember when Bishop Hill wrote Caspar and the Jesus paper. It was a wonderful narrative of the complex subject of tree rings and Steve McIntyre’s quest with debunking the Mann MBH98 paper, which created the original hockey stick. Now Bishop Hill has done it again with another great narrative. – Anthony

The Yamal implosion

September 29, 2009 Climate

There is a great deal of excitement among climate sceptics over Steve McIntyre’s recent posting on Yamal. Several people have asked me to do a layman’s guide to the story in the manner of Caspar and the Jesus paper. Here it is.

The story of Michael Mann’s Hockey Stick reconstruction, its statistical bias and the influence of the bristlecone pines is well known. McIntyre’s research into the other reconstructions has received less publicity, however. The story of the Yamal chronology may change that. Read the rest of this entry »

For those that don’t read a lot of the WUWT comments closely, there has been a scholarly argument going on between  Tom P of the UK and several WUWT commentators over the methodology Steve McIntyre used to illustrate the “breathtaking difference” between the plot of  the hand picked set of 12 Yamal trees and the larger Schweingruber tree ring data set also from Yamal. Tom P. reworked Steve’s R-code script (which he posted on WUWT) to include both the 12 excluded and the Schweingruber and  thought he found “insensitivity to additional data”, saying “There is no broken hockeystick”.

Jeff Id audited the auditor of an auditor and found that Steve’s work still holds up “robustly”. – Anthony

Just a short post tonight I hope. Tom P, an apparent believer in the hockey stick methods posted an entertaining reply to Steve McIntyre’s recent discoveries on Yamal. He used R code to demonstrate a flaw in SteveM’s method. His post was on WUWT, brought to my attention by Charles the moderator and is copied here where he declares victory over Steve.

Steve McIntyre published an update tonight showing the last 200 years of the Yamal tree ring data versus the archived CRU tree ring data used to make the famous hockey stick. For those just joining us, see the story here.

First here’s the before an after at millennial scale.

Steve McIntyre writes:

The next graphic compares the RCS chronologies from the two slightly different data sets: red – the RCS chronology calculated from the CRU archive (with the 12 picked cores); black – the RCS chronology calculated using the Schweingruber Yamal sample of living trees instead of the 12 picked trees used in the CRU archive. The difference is breathtaking.

Figure 2. A comparison of Yamal RCS chronologies. red – as archived with 12 picked cores; black – including Schweingruber’s Khadyta River, Yamal (russ035w) archive and excluding 12 picked cores. Both smoothed with 21-year gaussian smooth. y-axis is in dimensionless chronology units centered on 1 (as are subsequent graphs (but represent age-adjusted ring width).

Now lets have a look at the data for the last 200 years where that hockey stick lives (and dies):

Read the rest of this entry »

Since there has been a huge amount of interest in Steve McIntyre’s recent discovery of what happens to the “hockey stick” when all of the Yamal tree ring data is used rather than a special subset of 10, I thought it might be a good time to talk about how tree rings are grown.

Several readers have correctly pointed out that trees don’t respond just to temperature. The also respond to available water, available nutrients in soil, and available sunlight. For example, the only time in modern history where some trees did not produce summer growth rings occurred in the year 1816, also known as the Year Without a Summer:

Many consider the Year Without a Summer to have been caused by a combination of a historic low in solar activity (The Dalton Minimum) and a volcanic winter event; such as the powerful Mount Tambora eruption in 1815 which had four times the power of the famous Krakatoa eruption and hurled huge amounts of aerosols into the atmosphere.

Obviously, sunlight was a limiting factor for tree growth then, reduced temperature also figured in.

I touched on the idea of trees used for dendroclimatology being rain gauges before: Bristlecone Pines: Treemometers or rain gauges ? There has obviously been years of drought when trees also did not grow as much, so how do we separate temperature and moisture in the growth analysis?

But, right now what I really want to introduce readers to is Leibig’s Barrel. Read the rest of this entry »