Tag Archives: alkenone

Important New North American East Coast Proxy Data

One of my long-standing interests is the location of ocean sediment series that enable apples-to-apples comparison of the 20th century to the mid-Holocene.   These are not nearly as common as one would think.   Ocean sediment series covering the Holocene typically stop prior to the 20th century due to core recovery problems and, on […]

Ground-truthing Marcott

The MD99-2275 core offshore Iceland is a very high-resolution ocean sediment core, results of which over the past millennium have been discussed here from time to time. Alkenone and diatom results for the last millennium have been available for about 10 years. MD99-2275 results were used in PAGES2K Arctic and Hanhijarvi 2013, also Trouet et […]

New Data and Upside-Down Moberg

I’ve been re-examining SH proxies for some time now, both in connection with PAGES2K and out of intrinsic relevance.  In today’s post, I’ll report on a new (relatively) high-resolution series from  the Arabian Sea offshore Pakistan (Boll et al 2014, Late Holocene primary productivity and sea surface temperature variations in the northeastern Arabian Sea: implications […]

Alkenone Divergence offshore Iceland

The longest very high-resolution alkenone core that I’m aware of is Sicre et al’s MD99-2275 (plus splices) from offshore Iceland (67N 18W). It is 4550 years long, its most recent value is 2001AD and its resolution is 4 years. Marcott used nearby core JR51GC-35 (also at 67N 18W), also an alkenone record, which had a […]

Alkenone Divergence in Peru

Gutierrez et al (GRL 2011) pdf here; data here is another very high resolution alkenone series that is well-dated in the 20th century. It was taken in an upwelling zone offshore Peru at a similar latitude to Quelccaya. Like the high-resolution series offshore Morocco and Namibia, it shows a sharp decline in alkenone-estimated SST in […]

Alkenone Divergence

While there are disappointingly few high-resolution alkenone ocean cores with 20th century resolution, there are a few. Given the importance of this class of proxy in Marcott et al, one would have thought the performance of high-resolution alkenones in the 20th century would have been of interest to Marcott et al, but they were silent […]

Bent Their Core Tops In

In today’s post, I’m going to show Marcott-Shakun redating in several relevant cases. The problem, as I’ve said on numerous occasions, has nothing to do with the very slight recalibration of radiocarbon dates from CALIB 6.0.1 (essentially negligible in the modern period in discussion here), but with Marcott-Shakun core top redating.

Hiding the Decline: MD01-2421

As noted in my previous post, Marcott, Shakun, Clark and Mix disappeared two alkenone cores from the 1940 population, both of which were highly negative. In addition, they made some surprising additions to the 1940 population, including three cores whose coretops were dated by competent specialists 500-1000 years earlier. While the article says that ages […]

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 […]

“More and more concerned about our statement”

In a previous post, I reported that Coordinating Lead Author Overpeck wanted to “deal a mortal blow to the misuse of supposed warm period terms and myths in the literature”. The MWP was one such target; the Holocene Optimum was another. Overpeck said that there was “no need to go into details on any but […]


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