Esper et al. [2002]: Quebec

Esper uses 14 sites in his reconstructions. My objective is to see which ones are "active ingredients" in yielding a high 20th century relative to MWP. Today, I’ll look at the "Quebec" site on the east side of Hudson Bay, which does not solve the problem. In fact, the acknowledged authors report of a site on the east coast of Hudson Bay where no trees are presently growing that:

"The northernmost postfire regeneration during the 20th century occurred about 130 km south of the study area [Payette et al 1989b]. This suggests, on the basis of the difference of the current annual temperature between the two locations, that the Medieval Warm Period was ~1 degree C warmer than the 20th century."

So this site – whichever it is- doesn’t look it’s an "active ingredient" in showing an exceptionally warm 20th century.

I have not been able to track down the exact "Quebec" site. Tracking down the site is complicated by the fact that, as noted before, Esper does not archive and so we don’t know exactly what series he used. Clues sometimes provided by the Hockey Team, e.g. even a print citation, are not provided here. There are only the following 3 clues in the article itself as to the site, which are insufficient to identify it based on my present research:
1) the location of the site is shown on the east shore of Hudson Bay; see
2) he "gratefully acknowledges" S.Payette and L. Filion;
3) the graph in the SI showing the number of cores extends from ~1400 to ~1900 here

I contact Dr Payette, who was very pleasant, but was at as much of a loss as I was in trying to identify the data used by Esper. He had no recollection of any direct contact with Esper concerning their northern Quebec tree ring series and expressed surprise that his name had been included in the list of acknowledgements, without precluding the possibility of his coauthor having been in contact with one of Esper’s coauthors. I asked him for his best guess at a paper describing the series in question – he sent me Payette et al. [1985], which had a chronology going from 1398 to 1982, which had the following chronology (I’ll try to get a better pdf from the university library tomorrow). Note that this chronology is in mm, not standardized units. It’s possible that this is the series, but this chronology goes to 1982 – which is much later than indicated on the Esper graphic – suggesting that maybe a different series is involved (although the starts match pretty well.)

The site in this article is Bush Lake on the east side of Hudson Bay, where there was a severe LIA, with only a recent recovery. Payette et al. reported:

The transition from the Little Ice Age to the present regime was characterized by mass mortality in old-aged spruces that were not able to take advantage of the new favourable climates and by the replacement of these spruces by seedlings that later formed normal trees…. Tree growth climaxed in the 1930s and early 1940s, during maximum growth. A reversal in the growth trend occurred afterwards and corresponds to the post-1940s cooler conditions registered in the NH except for a brief interval between 1950 and 1960.


Figure 1. From Payette et al [1985]. Mean ring width chronology

I also consulted Arsenault and Payette [1997], which had some interesting observations about another site in the same general area (riviàƒ⧲e Boniface). This is also a spruce chronology. It ends in 1591 when the site burned. It has not regenerated since then. The chronology goes back (with a couple of floating sections) to ~1274 BC. They report:

it is likely that sustained sexual reproduction ceased during the climatic deterioration that ended the Medieval Warm Period… The northernmost post-fire regeneration during the 20th century occurred about 130 km south of the study area [Payette et al 1989b, Ecology 70]. This suggests, on the basis of the difference of the current annual temperature between the two locations, that the Medieval Warm Period was ~1 degree C warmer than the 20th century. This is in contrast with the published data from the Urals [Briffa et al. 1995] and Tasmania [Cook et al 1991].

Elsewhere they say:

Our reconstruction (especially the cold 9th century, the Medieval Warmth, the sharp climatic reversal centered on AD1150, the cold 13th and 14th centuries and the warmer 15th and 16th centuries) also agrees with the pattern of summer temperature deduced from tree ring data in Fennoscandia [Briffa et al 1992] and the temperature reconstruction from oxygen isotopes in the Greenland ice sheet [Dansgaard et al 1975]. This suggests similar climatic trends over the North Atlantic region. However our data contrast with tree ring records from western North America [Lamarche 1974, Graumlich 1993] and the Urals [Briffa et a; 1995], suggesting prolonged warmth and associated drought between AD1000 and 1400. These results are additional evidence questioning the existence of a globally synchronous Medieval Warm Period.

Needless to say, my antennae go up when I see that the counter-examples are bristlecone pine (Lamarche), foxtail (Graumlich) and Polar Urals. Here’s their ring-width chronology from the Boniface site (done with RCS in second panel).

They conclude their study by saying:

Our study cautions against any reconstruction of past climate and vegetation using only proxy indicators (like dendroclimatic reconstruction from tree ring series) in a poorly documented ecological context.

This would pretty much rule out any Hockey Team study, where there is virtually never any ecological information.

References:
S. Payette, L. Filion, L. Gauthier and Y. Boutin, 1985. Secular climate change in old-growth tree-line vegetation of northern Quebec, Nature 315, 135-138.
D. Arsenault and S. Payette, 1997. Reconstruction of millennial forest dynamics from tree remains in a subarctic tree line peatland, Ecology 78(6), 1873-1883.

3 Comments

  1. TCO
    Posted Sep 17, 2005 at 10:44 PM | Permalink

    Is the Quebec study part of MBH? Surely a very important part of the MBH work is related to what substudies to include and this effort was detailed in depth in the paper?

  2. Steve McIntyre
    Posted Sep 17, 2005 at 10:57 PM | Permalink

    Not looking closely, I misread your comment as saying “subsidies” to Quebec – this is a Canadianism. Quebec is not in MBH. None of these studies say how they choose their proxies – this is a big issue in evidence-based medicine. I asked Nature to require a statement of how the proxies were chosen, but they didn’t bother. NOAA has Mann et al [2000] on their website, saying that they used “clear a priori” criteria to select their proxies. Why don’t you write them and ask what the criteria are? Seriously.

  3. TCO
    Posted Sep 17, 2005 at 11:05 PM | Permalink

    To me, it’s not even an issue of the auditability of the meta-analyses but just a simple concept that a big part of the value of the work depends on selection and even that adroit selection or weighting or whatever should be explained as it is a lot of the work and is something that others may want to emulate. This is very different from asking fo skcode or data or whatever. this is a big picture concept that peer reviewers and editors should ask for. REally surprised that more detail on subordinate study selection is not included. What is the standard for that sort of thing in sociology?

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