Medieval Climate Not So Hot

University Of Arizona ^ | 10-20-2003 | U of Arizona

[AFPhys]

Solar variability has NOT been factored in ---- sorry, bud

The only way to measure long-term solar variability is through exactly the methodologies which are being used to argue about temperature changes. These changes are the one and only evidence of solar variability. I could envision some others which MIGHT come about from having a true laboratory on the moon or asteroids or other planets, but that seems unlikely to occur in my lifetime.

Tell you what, let me know about all the references you have pertaining to sunspots and corona temperatures prior to the last 300 years... you _may_ be able to find a couple rudimentary "sunspot number" papers during the last century, but these in themselves do NOT measure solar output and variations.

The historical temperature data ARE the measure of solar variance. The hope is that we can interpret those measures in a truly scientific fashion, not a politically correct one. That is not easily done, this article's "study" is not the first and appears to me to come to anamolous conclusions which have been refuted by earlier studies.

It _may_ give us more data, but whatever data it provides will not definitively answer the question.

For THIS scientist, who cares more about bending a theory to the data (instead of vice-versa) than about political correctness and who has spent a huge amount of effort studying the data, any "global warming is caused by man" statements STRONGLY appear to be pure and unadulterated tripe designed to fund certain political movements and to line unscrupulous pockets (some of them being well meaning.)

[sistergoldenhair]

Certified Clap-Trap

Absolutely.
Thanks for the ping.

[aruanan]

Note above they said that "some areas warmed while others cooled"? Duh. People have known that for a long time. The Medieval Climate Optimum didn't occur over the entire earth at exactly the same time. I read about this years ago.

Did you see this over at www.sepp.org today? It's always fun to see something like this:

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2. Hockeystick demolished

Corrections to the Mann et. al. (1998) Proxy Data Base and Northern Hemispheric Average Temperature Series.
McIntyre, Steven and Ross McKitrick,. Energy & Environment Vol. 14, No 6, pp. 751-771, October 26, 2003

Freely downloadable from < <http://www.multi-science.co.uk/mcintyre_02.pdf>
See also www.climate2003.com/index.html and www.climate2003.com/audit.html

ABSTRACT

The data set of proxies of past climate used in Mann, Bradley and Hughes (1998, "MBH98" hereafter) for the estimation of temperatures from 1400 to 1980 contains collation errors, unjustifiable truncation or extrapolation of source data, obsolete data, geographical location errors, incorrect calculation of principal components and other quality control defects. We detail these errors and defects. We then apply MBH98 methodology to the construction of a Northern Hemisphere average temperature index for the 1400-1980 period, using corrected and updated source data.

The major finding is that the values in the early 15th century exceed any values in the 20th century. The particular "hockey stick" shape derived in the MBH98 proxy construction - a temperature index that decreases slightly between the early 15th century and early 20th century and then increases dramatically up to 1980 - is primarily an artifact of poor data handling, obsolete data and incorrect calculation of principal components.

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Comment by David Wojick: We all suspected that the Mann et al hockey stick was hiding the Medieval Warm Period and Little Ice Age. Now these two Canadians have proven it. It may have been warmer just 500 years ago. A fine piece of work.

Comment by Fred Singer on the initial response by Mann, Bradley, Hughes to McIntyre, McKitrick:

First, it is entirely appropriate for MBH to express their views about MM. They do so without invective or rancor, and without ad hominem attacks on MM, the journal and its editor , etc. In that sense, it is in the best scientific tradition.

Having said this, I notice that MBH do not reply to the specific criticisms discussed by MM regarding the data quality in the MBH data-set (as listed in MM's Audit Issues) but instead develop criticisms of their own against the reconstruction of MM.

The response of MBH also seems to indicate that their conclusions are highly sensitive to subtle points in "principal-component" analysis of tree rings. In itself, elucidation of this sensitivity will be an interesting result of this discussion.

I think we should hear what MM have to say before we jump to any conclusions. Even if MBH are successful in their critique of the MM reconstruction, but do not at the same time respond to the data-integrity issues, we may be left with the situation where both parties are wrong.

Accordingly, the first concern should be to resolve the data problems: let's get an agreed data-set representing the most up-to-date versions of the proxies used by MBH: no truncations, no obsolete data, etc.

It would also be helpful in resolving this controversy if there was full disclosure by MBH of their procedures in far more detail than done in MBH98. Until that is done, it is very difficult to express further opinions on any of the technical aspects of the analyses by MM and MBH.

After taking these steps, if the parties can resolve their differences in some way -- fine. If, as I suspect, they cannot, then one needs an independent body of experts in the analysis of time series, possibly economists and statisticians, who are uninvolved with climate issues.

I will therefore express no further opinion on any of the technical aspects of the analyses by MM and MBH.
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[blam]

"Did you see this over at www.sepp.org today? It's always fun to see something like this:"

Thanks, no. That's a little more detail than I prefer. I already spend about eight hours a day on the web, any more detail and I'll have to stop sleeping. LOL

[aruanan]

Thanks, no. That's a little more detail than I prefer.

Well, anything that kicks the crap out of Hughes and Bradley can't be bad.

[SunkenCiv]

Blast from the Past (2003).

Just adding this to the GGG catalog, not sending a general distribution.

To all -- please ping me to other topics which are appropriate for the GGG list. Thanks.

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[Kozak]

How about the archives that include the facts that people lived and grew crops in Iceland? Or is that too subjective?

People have been doing that for a long time, you mean Greenland. And you fell for the first great advertising ploy of all time....

[SunkenCiv]

Note: this topic is from 2003.

The Little Ice Age: How Climate Made History 1300-1850 by Brian M. Fagan Paperback

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[SunkenCiv]

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