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"The hockey stick is alive and well"

BBC NEWS | Science/Nature | Climate 'hockey stick' is revived

A new study by climate scientists behind the controversial 1998 "hockey stick" graph suggests their earlier analysis was broadly correct.

Michael Mann's team analysed data for the last 2,000 years, and concluded that Northern Hemisphere temperatures now are "anomalously warm".

Different analytical methods give the same result, they report in Proceedings of the National Academy of Sciences.

UPDATE : Study is now online here http://www.pnas.org/content/early/2008/09/02/0805721105.full.pdf+html


The 1998 hockey stick was a totem of debates over man-made global warming. ...But some academics questioned its methodology and conclusions, and increasingly strident condemnations reverberated around the blogosphere....

Michael Mann's conclusion is that far from being broken, "the hockey stick is alive and well".

I'll be keeping an eye on the obituary writer..

Update - More details at Mongabay which unlike the BBC gives the citation:

Mann et al. (2008). Proxy-based reconstructions of hemispheric and global surface temperature variations over the past two millennia. PNAS September 9, 2008 vol. 105 no. 36

0901pnas.jpg

Composite "composite plus scale" (CPS) methodology and "error-in-variables" (EIV) regression method ("total least squares") North Hemisphere (NH) land and land plus ocean temperature reconstructions and estimated 95% confidence intervals. Shown for comparison are published NH reconstructions, centered to have the same mean as the overlapping segment of the CRU instrumental NH land surface temperature record 1850 - 2006 that, with the exception of the borehole-based reconstructions, have been scaled to have the same decadal variance as the University of East Anglia (Norwich, UK) Climatic Research Unit instrumental surface-air temperature data (CRU) series during the overlap interval. Image courtesy of National Academy of Sciences, PNAS (© 2008).

Comments

... this feels like the start of an old Hammer Dracula movie ... the bloody thing is rising from its grave again ...

This is hardly a confirmation that the conclusions / results of their earlier work was "broadly correct."

I've never heard anybody dispute that it's warmer now than it was in the Little Ice Age; the authors made much bolder claims than that it's "anomolously warm" today. The grand claims of "warmest decade in 2000 years" which were used to garner support for Kyoto are not supported by their new EIV or EIV / CPS composite.

Look at the green and dark grey lines [and claimed error bars...] around 960 A.D.

According to Mann's new EIV and EIV / CPS composite methods, the proxy record indicates it was WARMER in 960 A.D. than the proxy record shows today. They have retained the scary 'blade' of the hockey stick, but notice that it's still comprised entirely of the INSTRUMENTAL record [red and light grey]. They still put it ON TOP of the proxy reconstructions, so as to hide the fact that the proxies don't agree with the recent instrumental record. When comparing apples to apples [or proxies to proxies] their data now ADMIT it was warmer during the Medieval Warm Period.

The current Instrumental Temp record is 'hotter' than the current proxy record [the divergence problem], how do we know the Medieval Temp record was not also 'hotter' than the historical proxy record ? We have no old oranges [temperature readings] to compare to the new oranges. "Anomolously warm", perhaps. "Warmest in 2000 years", not according to the data.

They have made many assertions that the Medieval Warming Period was not a widespread event, which was why the 'shaft' of their stick was so flat. They have ridiculed people who claimed it was pretty warm 1000 years ago. Now they show the elevated Medieval Warming Period that they have been fighting for so long, but hide it in a 'spaghetti graph' of older reconstructions.

It is absurd for them to claim this is some sort of confirmation of their earlier work.


Science by press release, yet again.

The current issue of the PNAS is Aug 28th so we will have a while to wait unless anyone can find a source.

Thanks Mr. E.

No sooner do I ask than you come up with the goods!

Will take some reading. At least they supply the supplementary information this time which is how it should be.

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