This instantly ‘famous’ 2013 Science hockey stick paper derived from Marcott’s 2011 Ph.D thesis at Oregon State University, available here. His thesis doesn’t show a hockey stick ‘blade’ projecting above its anomaly baseline NCDC 1961-1990. H/T to Jean S, posted at Climate Audit. Something changed after the thesis was published to produce the new ‘blade’ in Science. That something was significant, since the Science paper’s Supplementary Information discussion said it did not enable discriminating such a temperature variation (i.e. a ‘blade’) on such a short a time scale.
See my previous post here, Lets Play Hockey Again, which was right about the Medieval Warm Period (MWP) but wrong about the ‘blade origins. Mea Culpa. Here we deduce whence the ‘blade’ came using ‘crowd-sourced’ science.
First, SI table S1 and thesis figure C1 confirm both use exactly the same 73 proxy records. The only difference is that thesis series MD98-2181 was renamed KY07-04-01 in the SI.
Second, thesis figure C7 graphed each proxy series individually using the mean and 2 sigma error band from its Monte Carlo statistical error estimation technique. A visual check confirms that there is no near T0 (1950) ‘blade’ visible in any of 73 dithered proxies, although five have distinct upticks near ‘present’ (the past 100-200 years or so visually). These include Dome C (Antarctic ice core δD with ±30% uncertainty), MD98-2165 (equatorial Mg/Ca), TN057.17 (temperate diatom mat with ±0.75°C uncertainty), Agassiz Renland (Arctic borehole δ18O with ±30% uncertainty), and GeoB3910, an equatorial alkenone. The thesis itself shows (below) that these are insufficient to uptick the ensemble.
Importantly for what follows, figure C7 also shows start and end dates for each proxy series as given by their references, along with their proxy age/date [radioisotope] controls. 20 unequivocally carried through about 1850, and 9 extended beyond T0 (1950). All the other proxies ended earlier in time. For example, proxy MD95-2043 (Cacho 2001, alkenone, Western Mediterranean) ended about 942 AD per its reference, with a notable ending uptick from the Medieval Warm Period. Remember this proxy for a couple of pages more.
Third, the outstanding Ph.D thesis on which this Science paper was based does not contain a hockey stick ‘blade’ anywhere. We can compare five important correlated pieces of information from its chapter 4 and supplemental data to deduce where and how the Science ‘blade’ originated. To start, both 2000-year reconstructions were compared to Mann 2008. The purple lines are the ‘standard’ simple area weighted mean 5×5 grid reconstructions.
The Science ‘blade’ is obvious. It does not exist in the thesis. Something changed.
The ‘blade’ (above anomaly baseline) is visibly present in all Sciencereconstruction methods, yet in none in the thesis. It is therefore not an artifact of the various reconstruction methodologies. Something changed in either the data or in the data processing algorithms to produce the blade in Science.
The blade is obvious in the mean of all 1000 dithered Monte Carlo proxy simulations in Science, yet is non-existent in the equivalent 10000-simulation thesis mean. The thesis error band widens symmetrically and significantly as T0 is approached. It must, given that Science reported the mean proxy resolution is 180 years, and the median is 120 years. This validates the thesis’ basic statistical algorithm as directionally correct and obviously useful.
The schematic algorithms used to generate the above error information are identical. Without comparing the underlying code, it is impossible to ascertain with complete certainty that there was no algorithm change in Science. But beyond any reasonable doubt, the ‘blade’ arose from some data change rather than from some algorithm change
The ‘blade’ is only present in data for figure S12a’s 20-year sampled reconstruction after 1900. It is not present in the 100-year version that goes to 1900, and which closely tracks the 20-year version to that time. Although lower frequency sampling will mask any earlier changes, significant data changes obviously occurred in the years after 1900 where the blade arose.
The latitude coverage in Science and the thesis is identical (horizontal grey bars). It has to be, since using the same proxies. The number of Mann2008 proxy records increases identically as the present is approached (vertical tan bars). They have to, since the same study. In both Science and the thesis, the number of Holocene proxies available at ‘2000’ is identically about 70. It should be. (And actually is exactly 70 based on scrutiny of thesis figure C7). These figures appear to be accurate visual representations of the underlying analytical facts.
But the number of Holocene proxies is not the same after about 1550 (500 before T0). Oddly, Science includes more proxies until after 1900. Even more oddly, in the thesis 9 ‘survived’ 1950, yet in Science none did.
Zero. And that is the proverbial smoking gun. The data were changed by re-dating, and Science figure 1G proves it without digging into proxy details buried deep within the SI proxy data spreadsheets.