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.
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.
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.)
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.