Category Archives: Medieval

New Millennial Warm Pool Foraminifera Study

Hot off the press this week is a study on foraminera over the last millennium in the Indo-Pacific Warm Pool – something that you’d think would be relevant to Hansen’s attempts to splice modern instrumental records to core tops ending in the Holocene Optimum. Newton et al 2006 have the following abstract:

Allen and the "Cool" Medieval Pacific

A press release for Allen (Current Anthropology 2006) has been referred to as showing that there was a “cool” medieval Pacific – thus supporting the view of the Team that the MWP was an incoherent dog’s breakfast. I was wondering if an anthropology professor had actually generated new paleoclimate records – it seemed unlikely, but […]

What is the evidence against warmer MWP?

Lee has criticized me for not fully canvassing the supposedly manifold lines of evidence marshalled by the NAS panel against a warmer MWP. So I’ve done a little exercise to summarize the evidence AGAINST the MWP being warmer than mid-20th century, disaggregating what I believe to be the salient information from the spaghetti studies. The […]

Medieval Treeline in Finland

Kultti et al. [Holocene 2006] has just been published in Holocene, showing higher medieval treeelines in northern Finland (27 deg E). This is consistent with the more northerly distribution of oak in medieval Finland reported in Hulden [2001] discussed here and adds to the growing inventory of articles both demonstrating higher medieval treelines and using […]

Millar et al: The Sierra Nevada MWP

Otto-Bliesner asked me how I would do a reconstruction. As I’ve said on other occasions, I said that I didn’t know. I’m really reluctant to just apple-pick some series but it’s prbably worthwhile showing that you can pick apples as well as cherries. More constructively, I think that there are some approaches that look better […]

Archaeological Finds in Retreating Swiss Glacier

I will write up some notes on the U.S. Climate Change Science Workshop, but I’d like to post up some information on a couple of interesting reports in the past few days on archaeological discoveries in a receding glacier on a high Swiss pass towards Italy, sent in by a reader. Glacier retreat in the […]


Naurzbaev et al [2004] is a terrific article by Naurzbaev, Hughes (yes, that Hughes) and Vaganov about deducing climate information from tree-ring growth curves in Siberia. (I find Naurzbaev’s work consistently interesting.) They studied 34 larch sites in a meridional transect from 55 to 72 N (at a longitude of about 90-100E) and 23 larch […]

Updated Polar Urals Data

I have obviously been very critical of the 11th century portion of the Polar Urals dataset used in Briffa et al. [1995], without which Jones et al [1998] does not have a cold 11th century (and which is a staple of other studies). It turns out that Schweingruber collected new subfossil samples for this site […]

Lamarche on Treelines #2

Here is Lamarche’s diagram of altitudes at the key bristlecone sites of Sheep Mountain and Campito Mountain (as noted below, when wood erosion is allosed for, the post-MWP decline is placed after 1500.)

Lamarche [1973] on Treelines #1

Valmore Lamarche was perhaps the first person to suggest that temperature information could be extracted from bristlecone pine information and his early publications are often referenced. Lamarche et al. [1984] (with Fritts, Graybill and Rose) first postulated CO2 fertilization. As you know, I’m increasingly interested in changes in treeline elevation as a "low-frequency proxy". It […]