Clarification – This post is an attempt to say two things – but badly.
First, a simplistic verification of a global temperature reconstruction is to cross-check against local temperature reconstructions from around the world. These, on average, strongly contradict the hockey stick.
Second, Tamino’s claim is essentially McIntyre has just been taking pot-shots at sound science. Instead McIntyre has looked at all the steps in making a reconstruction, and found all wanting.
So what of a neutral lay-person trying to compare the Montford’s Hockey Stick Illusion and Tamino’s debunking? From my accountancy experience, it is normal to try to get a sense-check. What is the expected result? If the actual is different from the expected, then difference needs to be reconciled. The MBH98, MBH99, and the subsequent reconstructions in the book, completely overturned perceived thinking, so there needs to be a sense-check to make sure the results are valid.
The sense-check for the global temperature reconstructions can be from localized reconstructions from around the world, to see if the global reconstruction replicates the typical pattern. A website, CO2science.org, documents peer-reviewed articles estimating temperatures in the medieval warm period. For those that have a temperature estimate, those that agree with the hockey stick – that temperatures were lower than today – are out-numbered 5 to 1 by those that say temperatures were higher in the MWP. The raw median, median, and mode values are that temperatures were about 0.75oC warmer than today. The weaker, qualitative, studies have a similar picture. Those that suggest that temperatures in the MWP were similar to or lower than today are outnumbered more than 4 to 1 by those that suggest temperatures were higher. So when the more scientific, global, reconstructions come up with a novel, contrary, result, there needs to a full reconciliation to explain why. Without such an explanation, we just have McIntyre’s multi-layered* findings that the global reconstructions are critically flawed stands.
*McIntyre’s findings are multi-layered, including.
a) Hockey Stick shapes were given undue weighting by the short-centering of the PC analysis. For instance, McIntyre calculated that Sheep Mountain had 390 times the weighting of Mayberry Slough (p113-114). Of the 112 original proxies in MBH9, just 13 had a hockey stick shape. Tamino does not counter this, only looking at the 22 longer hockey stick series, made up of individual series, such as Gaspe, along with regional combinations such as NOAMERPC1.
b) Dodgy data and infilling. Looking across the columns of data, McIntyre noticed identical data in adjacent columns, as though infilling had taken place. (p78-81)
c) Many of these series were based on old data. If Mann had used the most recent data available in 1998, could the final Hockey Stick have been less pronounced? (p83-84)
d) Some of the most important original proxies were flawed.
- Gaspé has better data, but was unpublished. (p174) It also had an alternative proxy with better data in Alaska. (More here)
- Sheep mountain had updated proxies that fails to show an HS (p 357-361)
- The Graybill bristlecone series had a number of flaws (e.g. p121-125 & p353-357)
e) The failure of alternative reconstructions. (Chapter 10).
f) There was considerable evidence of biases in the data selection in the proxies (along with small sample sizes); the selection of the proxies in the reconstruction; and the short-centring which gave rise to hockey sticks on random data 99% of the time. Given this, any measure of correlation statistic was rendered largely meaningless. McIntyre did not explore this. However, Montford provides evidence that the verification statistic used was highly irregular in the disciplines outside of climate science. (e.g. p156-164) Latest – McIntyre shows the evidence that to suggest verification statistic was cherry-picked.
That is, the selection of data in the proxies, the proxy selection, the bias by short-centering, and the selection of verification statistic are all different levels in establishing a reconstruction, and all shown by McIntyre to have failed.
For a different take – which side pursues scientific understanding, see the follow-up http://manicbeancounter.wordpress.com/2010/07/27/the-hockey-stick-and-climate-science/