[WOSG]

I don't need to say "implies" se previous reply ... U.S. Assessment took Mann's work and on that basis (incorrectly) stated directly:

"New studies indicate that temperatures in recent decades are higher than at any time in at least the past 1,000 years. (Overview p.11)" See
http://www.greeningearthsociety.org/Articles/2000/hockey.htm

I leave it to you to decide if this was unwarranted inference or not based on Mann's work. The graph seems stark, but then the U.S. assessment took out the wide 'error bars' in Mann's original report...

Mann's "Myth #3":
MYTH #3: The "Hockey Stick" studies claim that the 20th century on the whole is the warmest period of the past 1000 years.
http://www.realclimate.org/index.php?p=11

"Abstract: The data set of proxies of past climate used in Mann, Bradley and Hughes (1998, “MBH98” hereafter) for the estimation of temperaturefrom 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 chape 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 artefact of poor data handling, obsolete data and incorrect calculation of principal components. "
http://www.uoguelph.ca/~rmckitri/research/trc.html

Thus the M+M critique is not simply the PCA, but the underlying data... which is what others (eg Daly) were questioning too ... There are better proxies than tree rings, apparently.

And Mann and M+M are IN AGREEMENT THAT LATE 20TH CENTURY IS NOT WARMEST PERIOD IN LAST 1000 YEARS, both contradicting the 'assessment' reports.

We may have the horrible conclusion that global warming, even if real, is simply bumping the world up slightly to a temperature that the world enjoyed in 1100AD, when the Vikings colonized Greenland.

[Yelling]

I am not following you here. The Myth 3 you reference (by Mann) says the following:

" On the other hand, in the context of the long-term reconstructions, the early 20th century appears to have been a relatively cold period while the mid 20th century was comparable in warmth, by most estimates, to peak Medieval warmth (i.e., the so-called "Medieval Warm Period"). It is not the average 20th century warmth, but the magnitude of warming during the 20th century, and the level of warmth observed during the past few decades, which appear to be anomalous in a long-term context"

So he is saying that the latter decades are where we see warming that is greater than other times during the last 1,000 years. This appears to be what your quote from the US Assessment says.

In regards to McKitrick's work, what you quote is from his early paper on it. After Mann published to correct some errors in his references, M&M have looked mostly at the PC analysis. After according to McKitrick's analysis, the start of the Little Ice Age is warmer than current times.

Oh, and by-the-way, as per my comments above, Mann and McKitrick do not agree "THAT LATE 20TH CENTURY IS NOT WARMEST PERIOD IN LAST 1000 YEARS"

Anyway, that was fun. I look forward to your next post addressing the points I raised.

Regards,
Yelling