Steve McIntyre has made what I can only describe as a stunning discovery as to why there is a sharp uptick in the main Marcott et al graph being touted by the media from its publication in Science.
![marcott-A-1000[1]](http://wattsupwiththat.files.wordpress.com/2013/03/marcott-a-10001.jpg?quality=83)
It seems the uptick in the 20th century is not real, being nothing more than an artifact of shoddy procedures where the dates on the proxy samples were changed for some strange reason.
McIntyre writes:
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 results with published dates (red) to results with Marcott-Shakun dates (black). As you see, there is a persistent decline in the alkenone reconstruction in the 20th century using published dates, but a 20th century increase using Marcott-Shakun dates. (It is taking all my will power not to make an obvious comment at this point.)
Figure 1. Reconstructions from alkenone proxies in Marcott style. Red- using published dates; black- using Marcott-Shakun dates.
…
In a follow-up post, I’ll examine the validity of Marcott-Shakun redating. If the relevant specialists had been aware of or consulted on the Marcott-Shakun redating, I’m sure that they would have contested it.
Read his entire post here.
This is going to get very interesting very fast.
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Jon says:
March 18, 2013 at 12:21 pm
The only question is what caused it?
========
what caused the minoan warming, roman warming, medieval warming? what caused the cooling in the dark ages and the LIA? no one knows. all we can say for sure is that real climate change has happened in the past and no amount of human sacrifices at the time, carried out by the high priests of the day, did anything to prevent climate change – but it sure did cause a lot of extra suffering for the common people. until the temples were torn down and the priests put to the sword, and then conditions generally improved. the climate didn’t – but at least the human sacrifices stopped for awhile. the french revolution was most likely a product of climate change (let them eat cake) as the LIA caused widespread famine and eventually revolt.
SkepticGoneWild says:
March 18, 2013 at 5:18 pm
Paul Dennis, scientist at the University of East Anglia, published the following blog comment today at Bishop Hill (“OMG” thread) regarding <Marcott et al 2013:
Thanks for the repost SkepticGoneWild, it is truly a remarkable statement, balanced, well thought through and sad summary of the (not only but most)-climate science nowadays. A very short and concise summary of the paper:
“We have to move away from such a stance and try to re-establish the scientific method. Developing hypotheses and experiments or measurements of nature that attempt to refute these hypotheses. We mustn’t torture data to fit an apparent paradigm. One can only guess at what Marcott et al were attempting to do when they made gross adjustments to core top dates. It is one thing to run a new, for example 14-C calibration, that will make small adjustments to age models but a completely different issue to redetermine core top dates by such gross margins.“
ferd berple says:
March 20, 2013 at 12:45 am
Jon says:
March 18, 2013 at 12:21 pm
The only question is what caused it?
========
what caused the minoan warming, roman warming, medieval warming? what caused the cooling in the dark ages and the LIA?
ferd I am many times shocked at the ignorance of the warmista, they imagine the temperature has been stable for milenia and have no understanding at all of the past climate and keep on posting their “but we are all doomed” post
http://bishophill.squarespace.com/blog/2010/3/19/josh-13.html