Wednesday, August 23, 2017

Marohasy Mess Up

Among the things that bother Eli, and there are myriad, is not understanding that because proxy reconstructions are calibrated by using instrumental records they by necessity ASSUME Mike's trick, extending the proxy by use of instrumental data.  In fact, the instrumental data is more accurate in the period where they overlap, because the proxys are scaled to it.  Thus, the instrumental record used for the calibration should always be shown.  Moreover, IEHO, the usable instrumental records (properly homogenized of course) in the area where the proxy is sampled should be the ones used to scale each proxy individually.  Something that either does not appear to be much done or at least not much noted.  No matter.

Anyhow, Jeniffer Marohasy and accomplice John Abbot have published a paper in a soon to be former Journal, GeoResJ, of which it could be said that it is Elsevier and it is history

GeoResJ will be discontinued from January 2018 and is closed to new submissions. We would like to express our sincere thanks to the authors, referees, editors and editorial board members who have contributed to the journal over the past few years.
As to Jen and John, well Eli guesses that they have observed the profit that Judy Curry and Peter Webster are making, well they have set up their own long range weather forcasting service, one that Eli assumes will compete with the Farmer's Almanac and Piers Corbyn for James Annan's betting attention.  They even have their own journal.  Isn't the Internet wonderful.  Frankly Eli is of the opinion that Curry and Webster are ahead in that game even tho the Bunny's opinion of the later two, is, well, limited.

ATTP has published a comment on the Abbott Marohasy paper.  Go there for details, but Eli wants to pick up on the Twitting.  One of the fits from the AM paper were featured on Breitbart (friends don't link friends to Breitbart :(.  It turns out that that was from Moberg 05 and various claims were undressed by the usual skeptics.

Zeke was the first to notice, and he twitted the
which he later ammended to
Now Eli went and looked at Moberg 05 to find
To calibrate the reconstruction, its mean value and variance were adjusted to agree with the instrumental record of Northern Hemisphere annual mean temperatures [19] in the overlapping period AD 1856–1979 (Fig. 2b).
Ref 19 is Hemispheric and Large-Scale Surface Air Temperature Variations: An Extensive Revision and an Update to 2001 by P. D. Jones and A. Moberg the first two sentences of which are
This study is an extensive revision of the Climatic Research Unit (CRU) land station temperature database that is used to produce a gridbox dataset of 5° latitude × 5° longitude temperature anomalies.
but also included a land+ocean data merge and it looks like that is the one Moberg used.  Gavin got an ear in pointing out that Abbott and Marohasy's time axis was off by ~ 35 years.  That meant that their 20th century was really 1845-1965. As all know there has been a steep rise in global temperature since then. 

and fetched J. Marohasy out of the brian patch
which is amusing in light of Fig. 2B from Moberg 05


Unknown said...

Marohasy should stick with accusing the Australian BOM of professional misconduct and other such Conspiracy Theories.

J. Zimmermann said...

I believe, that an error is made here. According to the text in table 1 the so called northern hemisphere composite actually is an Islandic reconstruction given as reference 33. Unfortunately the article is in the Journal of Paleolimnology, which my institution doesn't have, so it would take a few days to get a look into the paper. But the reconstruction shows a few differences to Moberg et al 2005. Since Abbot&Marohasy didn't use original data, but scanned the curves, I rather doubt, that they used Moberg et al 2005 for this. It is perfectly plausible, that the islandic reconstruction resembles the northern hemispheric reconstruction, but with a higher amplitude. And since the islandic reconstruction goes from 50 - 1980, this explains perhaps the perception of a shift, when they are interpreted as the Moberg et al 2005 reconstruction. From the method it doesn't make sense to use Moberg et al 2005 - they use 6 perhaps well selected single sites, which give a desired result. Or which were just the most convenient to get and put into a scanner. Moberg et al 2005 (reference 66) is used only in one place - to show, that the temperature curve is bumpier than the hockey stick according to Mann et al. 1998, which is a never ending complaint of deniers.

On the other hand, quite some possibility for critic was left out, when it comes to the allegation that the ECS is 0.6. This is taken from the assumption, that the residual temperature increase in the data from 1880 to the end after subtracting the temperature prediction from the neuronal network is 0.2 degrees C. But what they actually calculated was the mean deviation. If one looks at the table 12, the only relevant data are from Switzerland and from New Zealand. If you look at the Swiss data, the match between prediction and reconstruction is very poor. Now what difference does one want to take here? By coincidence the curves meet each other at the end (which is in 1950). Difference zero. If you calculate the trends (I didn't do that, because I don't have the data; they are not provided), I guess the projection has a trend twice as high as the reconstruction. That means, the anthropogenic signal would be negative - a ridiculous result. For the New Zealand data it is worse. They don't show a trend difference between projection and reconstruction. But in the end, the projected temperature is higher. Again, the anthropogenic signal is negative. Greenhouse gases lower the temperature. It is complete nonsense. The trouble is, the average deviation has no meaning at all for the question about the amount of residual temperature rise in the data. Considered, the trend in the prediction is zero and in the reconstruction is x, the mean deviation is x/2. On the other hand, if both curves are trendless, but are noisy, they could easily have a mean deviation of x (whatever x is), but no real residual temperature rise. Therefore they can't calculate ECS this way - they have used a random number, which by coincidence had the desired value.

J. Zimmermann said...

One correction: the data from Island are from 50 to 2000, not 50 to 1980, according to table 1.


Maharosy's paper has led Breitbart to declare:


Its publisher not so much- Elsevier has pulled the plug on GeoResJ, which
"will be discontinued from January 2018 and is closed to new submissions..."

Kevin O'Neill said...

Jörg Zimmermann -- you are correct that the reference given by Abbot and Marohasy for the Northern Hemisphere reconstruction [33] is Á. Geirsdóttir, G.H. Miller, T. Thordarson, K.B. Ólafsdóttir; A 2000 year record of climate variations 747 reconstructed from Haukadalsvatn, West Iceland; J Paleolimnol, 41 (2009).

But if you eventually find that paper you'll see that it is NOT a multi-proxy reconstruction. It is a lake sediment measure of Total Organic Content (TOC) and Biogenic Silica (BSi). No attempt is made to reconstruct temperatures from these measurements.

Figure 13 shows 5 panels: BSi/TOC, TOC, BSi, Mann & Jones (2003) and Moberg et al (2005). The only one of these panels that has the appropriate date range (50 - 2000 AD) is Moberg et al (2005).

Perhaps Marohasy and Abbot just completely screwed up the proxy description; it's not northern Hemisphere, it's not a temperature reconstruction, has nothing to do with stalagmites or boreholes, and isn't from 50-2000 AD - all of which they claim.

Or they could have used Moberg et al; (2005) which I believe meets all those criteria and is cited by Geirsdóttir et al.

J. Zimmermann said...

Ok, it looks like I have got it wrong here. I will order the paper by Geirsdóttir et al and find out about it.

EliRabett said...

Not a problem Jörg. You are always welcome at Rabett Run, but that Icelandic proxy raises an interesting question about how many proxys one needs for a reliable record.