Tag Archives: O18

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 […]

A New Alaskan d18O Series

PAGES2K Arctic introduced a lake sediment d18O series from Kepler Lake, Alaska that hadn’t been used in previous studies. Although O18 data is a workhorse of paleoclimate, O18 data from Alaska (or, for that matter, anywhere in the Arctic hemisphere between 90E and 90W – going east) is very scarce. Thus, the appearance of a […]

New Light on Svalbard

In 1997, the 121 m Lomonosovfonna ice core was drilled in Svalbard. As of mid-2009, when Hu McCulloch and I wrote CA posts on this core, nothing had been published on O18 values prior to AD1400 nor had any Lomonosovfonna data been archived, even for the post-1400 period. Both Hu McCulloch and I, in separate […]

Kinnard Arctic O18 Series

Kinnard et al 2011 report a highly hockey-stick shaped reconstruction of sea ice. (For a different perspective based on Holocene ocean sediments under the Ellesmere Island ice shelf, see the recent Antoniades et al (PNAS 2011). Kinnard et al use a regression-based statistical methodology that looks at first blush to be a sort of inverse […]

Sargasso Sea dO18

Recently Keigwin’s Sargasso Sea dO18 temperature reconstructions have been mentioned in the climate public eye. Keigwin’s reconstruction famously has a warm MWP as shown below. This reconstruction uses modern dO18 measurements at Station S to calibrate two cores (with modern Station S values specifically shown in the graphic below): I observed last year that the […]