Search Results for: marcott

Marcott’s Dimple: A Centering Artifact

One of the longstanding CA criticisms of paleoclimate articles is that scientists with little-to-negligible statistical expertise too frequently use ad hoc and homemade methods in important applied articles, rather than proving their methodology in applied statistical literature using examples other than the one that they’re trying to prove. Marcott’s uncertainty calculation is merely the most […]

Marcott Monte Carlo

So far, the focus of the discussion of the Marcott et al paper has been on the manipulation of core dates and their effect on the uptick at the recent end of the reconstruction. Apologists such as “Racehorse” Nick have been treating the earlier portion as a given. The reconstruction shows that mean global temperature […]

April Fools’ Day for Marcott et al

Q. Why did realclimate publish the Marcott FAQ on Easter Sunday? A. Because if they’d waited until Monday, everyone would have thought it was an April Fools’ joke.

The Marcott Filibuster

Marcott et al have posted their long-promised FAQ at realclimate here. Without providing any links to or citation of Climate Audit, they now concede: 20th century portion of our paleotemperature stack is not statistically robust, cannot be considered representative of global temperature changes, and therefore is not the basis of any of our conclusions. Otherwise, […]

The Marcott-Shakun Dating Service

Marcott, Shakun, Clark and Mix did not use the published dates for ocean cores, instead substituting their own dates. The validity of Marcott-Shakun re-dating will be discussed below, but first, to show that the re-dating “matters” (TM-climate science), here is a graph showing reconstructions using alkenones (31 of 73 proxies) in Marcott style, comparing the […]

How Marcottian Upticks Arise

I’m working towards a post on the effect of Marcott re-dating, but first I want to document some points on the methodology of Marcott et al 2013 and to remove some speculation on the Marcott upticks, which do not arise from any of the main speculations. In the graphic below, I’ve plotted Marcott’s NHX reconstruction […]

Marcott’s Zonal Reconstructions

I’m going to do a detailed post on my diagnosis of the Marcott uptick, but before I do so, I want to comment on the reconstructions for NH and SH extratropics, neither of which have attracted sufficient notice though both are very remarkable. In a substantive sense, because orbital changes have different effects on NH […]

No Uptick in Marcott Thesis

Reader ^ drew our attention to Marcott’s thesis (see chapter 4 here. Marcott’s thesis has a series of diagrams in an identical style as the Science article. The proxy datasets are identical. However, as Jean S alertly observed, the diagrams in the thesis lack the closing uptick of the Science. Other aspects of the modern […]

Marcott Mystery #1

Marcott et al 2013 has received lots of publicity, mainly because of its supposed vindication of the Stick. A number of commenters have observed that they are unable to figure out how Marcott got the Stick portion of his graph from his data set. Add me to that group. The uptick occurs in the final […]

SH Proxies: Peru d18O

One of the hidden assumptions of proxy reconstructions, as carried out by IPCC authors, is that each “proxy” has a linear relationship to temperature plus relatively low-order red noise. Under such circumstances, the noise will cancel out in a linear combination of proxies (reconstruction) and a “signal” will emerge. However, I’ve never seen any author […]

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