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 this to estimate MWP temperatures locally higher than at present, some of which I’ve posted about from time to time Medieval Category. These “local” results from treelines are not limited to the north Atlantic and Greenland, but extend to the Sierra Nevadas (117 W), Sweden, Finland, Polar Urals (65 E) and a Siberian transect (90-100E). I’ll add a comment on Chinese proxies of this type. Kultti et al. also consider information from other proxies and report similar results for all proxies EXCEPT the tree ring width chronology of Helama et al [2002]. Here are some extended quotes.
Kultti et al. report that treeline is a proxy for July temperature, They state that:
During the “ÅMediaeval Warm Period’ the distribution area of pine was 7200 km2 more extensive than at present, and pines were growing at 40-/80 m higher altitudes. For this period, the mean July temperature reconstruction shows /0.55 deg C shift compared with the present….
Their survey of similar results mention:
At the same time, presence of pine has been detected c. 100 m above the current pine limit in Sweden (Kullman, 1998) and 100/140 m above in the Kola Peninsula (Hiller et al., 2001). The same pattern at the upper larch (Larix sibirica) timberline on the Eastern side of the Ural Mountains has also been found; from c. 1000 cal. yr BP to c. 600 cal. yr BP numerous megafossils have been found from above the present tree limit (Shiyatov, 1993). Assuming a lapse rate 0.6 deg C per 100 m, these finds correspond with a shift of/0.6-0.8 deg C in temperatures.The conifer limit during the “ÅMediaeval Warm Period’ appears to have been well above the present conifer limit in extensive areas in Fennoscandia and Russia. This suggests that the climate during the “ÅMediaeval Warm Period’ was even warmer than during the twentieth century in northern Fennoscandia. Most of the quantitative reconstructions from Finnish Lapland (Figure 4) show warmer than at present at c. 1000 years ago (Korhola et al., 2000, 2002; Seppa and Birks, 2001, 2002, Seppa et al., 2002). Only reconstruction made from tree-ring widths suggests colder than at present mean July temperature (Helama et al., 2002)
Their Figure 4 shows the following other reconstructions. The Korhola proxy is used in Moberg et al 2005, where it contributes to the warmish MWP in Moberg. However, this proxy in Moberg is swamped by two non-normal series – the offshore Oman coldwater diatoms and Agassiz melt, discussed elsewhere.
Original Caption. Figure 4 The mean July temperature anomalies from present in the reconstructions from Finnish Lapland. Reconstruction a shows minimum shift in mean July temperatures between 8300 cal. yr BP and present based on this study. Reconstructions from lake sediments (b, c, d, e and f) show deviations from the mean of three uppermost samples. In reconstruction g non-overlapping 100-yr mean deviations from the twentieth century are shown. Reconstructions b and c are from Tsuolbmajavri and d, e and f from Toskaljavri. Reconstructions a, b, c, d, e and f are elevation adjusted for land uplift. Numbers in parentheses in reconstruction a refer to the site number in Table 2
Kultti et al [2006] was submitted on 2 February 2004; the revised manuscript was accepted 19 October 2005. Thus, its submission long preceded the May 2005 data for consideration in the IPCC First Draft and the acceptance long preceded the December 2005 cut-off data, in marked contrast to (say) Wahl and Ammann 2006 or Osborn and Briffa 2006, which met neither date. I wonder if Kultti et al will be incorporated in IPCC 4AR.
References:
Kultti, Seija, Kari Mikkola, Tarmo Virtanen, Mauri Timonen and Matti Eronen, 2006.1Past changes in the Scots pine forest line and climate in Finnish Lapland: a study based on megafossils, lake sediments, and GIS-based vegetation and climate data, The Holocene 16,3 (2006) 381-/391.
Huldén, Lena, 2001. Terra 113, 171-8. Oak barrels and the medieval warm period in Satakunta [Finland] (Finnish) .
Climate Audit 
38 Comments
Fig4 image doesn’t show.
I seem to remember Larry Hulden asking Phil Jones about these medieval tree lines, with Jones earnestly lecturing Larry that 11th Century Finnish farmers were deliberately planting oaks further north….
The Korhola Chironomids differ considerably from Seppa and Birks Chironomids & from most of the others (but it does show a MWP).
From these 10000-yr records, the magnitudes of the MWP, LIA, & current warmth are all unremarkable. How remarkable.
Is it possible that there is a significant time lag between warming and higher tree lines? If that were the case, then it could be argued that in fifty or more years, say, the tree lines will be higher than they were during the MWP as a result of today’s “unprecedented” warmth.
#4, presumably so. However for there to be trees in 50 years, there ought to be sprouts now. After all, we’ve had an unprecedented temperture rise at least since 1975. They’ve had 30 years of increasingly luxuriant growth conditions. So, has anyone noticed a higher sapling-line limit?
#2 It was my wife (Lena) who had this dispute with Phil Jones!
Insects or diatomes in lake sediments are definitely not reliable as indicators of (summer) temperatures. 55 years (1945-2000) statistics from Finland from 16 different waters show that 10 years mean temperature of water surface (1 meter) may suddenly (“chaotically”) jump up or down 1-2 centigrades in relation to air temperatures. This depends on longterm shifts in dominating wind direction causing shifts in wind stress on lakes. As a consequence you can never estimate the air temperature deviation from water temperatures in the past. This must be the cause of difference in the presented results.
I had a presentation of this in a climate meeting in Italy in 2001 and tried to publish it in The Holocene. Some referee said that he had the impression that the diatoms and insects living in water correlate better with air temperature than with water temperature !!!! After that I realized that I could never get it published.
I published an article in Climatic Change Vol 8 (1986) titled “Historical evidence and climatic implications of a shift in the boreal forest tundra transition in central Canada.” It showed a shift of approximately 200 km in 200 years in one of the harshest growing environments in the world. This was a shift in latitude and like a shift in altitude appears to be mostly temperature related. Generally it is shown that the treeline coincides with the 10°C summer isotherm. There are some who argue that the isotherm is a response to the treeline not as generally assumed. The movement of 200 km in 200 years underscores the rate of natural change in response to climate change. Even if 50% wrong we still have a 100 km shift in 200 years. There is no evidence of anyone planting trees in this area and during this period.
If one had to pick a proxy to show low-frequency changes, it’s hard to argue against treelines.
#7 I presume the shift was toward higher latitudes. #8. I can’t see much argument against the use of treelines, either.
#9 Yes, the shift was to higher latitudes, although from Artillery Lake to the Coppermine River the treeline runs more north and south becuase of the influence of the Rocky Mountains on the standing planetary wave of the circumpolar vortex. In this rgion the expansion was less, but still an ‘expansion’ indicating warmer. Samuel Hearne who made the map with the treeline of 1772 noted “wind blasted” clumps of dead trees well north of the treeline of his time. He asked his Indian (Chipewyan) guides about this and they said their ancestors said the treeline used to be further north. Hearne noted this was clear evidence that the world had become colder – a very accurate observation reflecting the conditons of the lowering of temperatures from the Little Ice Age following the Medieval Warm Period. Hearne was well qualified to make these observations. He was a first class biologist (naturalist) whose observations and reports on Arctic Fox are still considered definitive and among the best. He knew all the Latin names for the plants and clearly delineates “the wood’s edge” on his map that is in the Hudson’s Bay Company Archives in Winnipeg.
lag?
hard to measure?
RE: #5. In terms of the Alpine tree lines, the only saplings I see are the ones underneath existing well established trees. I see no saplings at any higher elevations. This is based on an observation made at 2000 Z yesterday, at the tree line, near 39N, ~ 119W. Also of note, given the extreme snow pack (only just now receding at such elevations) this year, saplings have been severely stressed.
13:
Generally there is a successional order, as trees are dependent upon multiple factors for survival, and understory vegetation gives a better chance at survivorship, thus trees go last. That is: saplings absent expected understory vegetation have a lower chance of survival (fungal communities, bacteria, organic matter in soil). That said, there is no reason to believe an entire community will increase in elevation intact, as current evidence may indicate.
Best,
D
RE: #14. Some nice tap dancing in that paper, I must say. A real piece of work.
15:
Thanks for sharing the specifics. Let us know whether your comment gets accepted.
Best,
D
Re 16, Dano, now that you’re on the other side of the fence, perhaps you’re actually starting to get it. Steve Sadlov makes a comment like you have often made, with no specifics at all … I can understand your frustration.
However, you said much the same to Steve on another thread, your comment was “Let me know, willya, when your groundbreaking paper gets accepted? Thanks!”
Perhaps the experience of having someone do the same to you will make you stick to specifics … I hope so.
w.
Re 14, Dano, thanks for an interesting post. However, I’m not sure I understand it. You say:
The part I didn’t understand is this. If the saplings likely won’t survive without the understory, and there is no reason to believe the “entire community will increase in elevation intact” (I assume this means trees and understory), then …
… how does the treeline ever increase in elevation?
Like I said, I’m not sure I understand your post.
w.
19:
Hi willis:
often the treeline increases in concert with understory vegetation, but it doesn’t always have to be that way. Survivorship increases with understory veg., as mychorrizal fungae are more likely to be present, beneficial insects have cover, temps are moderated, organic matter adds nutrients, etc.
The point above was that one data point is not enough to make an assertion, due to the complexity and interconnectedness of interactions. Certainly if there is sufficient organic matter and nutrients in the soil seeds can germinate and grow without companions. In that area that Steve mentions, the Italians of the late 1800s drove their sheep over the Sierra to escape drought and brought grasses and other exotics with them, so the dynamics of sites in that area have changed considerably.
BTW, I’ve snowshoed over Carson Pass on Mem. Day weekend before – there’s often lots of snow in that area.
Best,
D
Carson Pass is a bit higher than the site I was at. I was nearby Donner Pass.
It would seem that treelines are like just about any other proxy, subject to many confounding factors. It is also worth noting that there has been a generally acknowledged increase in temperatures since the LIA (regional or otherwise, being neutral here) and that this has been underway for a reasonable period, there should be one would think at least some evidence for an increase in treeline altitudes.
Now this may be (pace Dano) not necessarily the trees themselves in all (or even many) situations but at least in a broadly defined “treeline” including understory and possibly soil composition. And (nod to Dano again) at least some sites will have been modified since the LIA times leading to further confounding factors, but at least in theory studies could be made to see if such movements are occurring. After all, assuming that there was a MWP (and I think everyone acknowledges such a thing at least on a regional basis) and that treelines were higher in some places at that time, these treelines had to expand to those altitudes in a relatively short period as well.
Admittedly this is a crude bit of logic and please correct it if wrong, but would not one expect to see signs of a recovery in the treelines to MWP like levels starting to occur ? These signs may be subtle so maybe studies such as those cited above may not have noticed (or looked for) such evidence.
I noted these references in a paper on simulated changes:
So such work is being done, and maybe results are out there. It would useful to follow up these references and others. An informed discussion is always helpful. Thanks to those who have contributed so far on this thread.
#21. Ed, there’s lots of evidence of rising tree lines. Some authors argue that the response of tree lines is highly lagged and present tree lines do not reflect present temperatures – presumably the saplings at higher elevations when grown will. The treelines are not a real sensitive measure on decadal scales. But for “low frequency” which is the current buzzword, if they haven’t reached medieval treelines yet, then there must have been some medieval interval which was warm.
(#2,#6) Not exactly related, but Larry’s famous wife Lena is now even more famous. Her new research on malaria in the 18th century Finland (Finnish archipelago to be exact, I think) was covered today by the main newspaper in Finland, Helsingin sanomat (article here $$$). Nice job!
For those who haven’t seen it, Roger Pielke’s site has an interesting paper from Harvey Nichols on Arctic treelines here.
He also tentatively identifies potential correlation between treelines and sunspots.
Regards;
24, Ken: Very interesting paper, indeed. I was especially interested in this statement:
(don’t know why it copied so poorly, though)
Another interesting statement in the comments section:
Could this be yet another scientist who does not reflect the “consensus” on AGW?
More from this interesting quote:
The intro to Nichols paper ends with an extremely telling observation
Who’d imagine that the sun could have anything to do with the earth warming? Just because solar activity is the highest it’s been in a thousand years couldn’t possibly mean a thing.
http://www.news.uiuc.edu/news/06/0801glacial.html
TCO,
What can I offer you to be a dear and use the link function for those long urls in the first line?
Ok.
Where treeline is rising fastest in the northern Rockies it is, ironically, DESPITE warming. In these areas it is fire frequency that is the slow-changing variable modulating treeline. When lightning caused fires are frequent and burn large, mountain-tops stay tree-free longer (colonization rates are slower at harsher elevations). In the 20th century, however, human-caused fire suppression is allowing these natural tree-free grassy meadows to fill in with trees. Not knowing any better, one might ignore the intermediate controlling process (fire occurrence) and conclude that the treeline is creeping up because of the direct effect of temperature rise. But of course, human populations are rising at the same time, and these humans don’t like fires, so fire frequency and size have dropped tremendously in alpine areas. If fire suppression were suspended, the tree line might actually drop under a climate warming scenario!
This may have no relevance for pre 20th century changes in treeline. But it does show (1) how treeline is controlled by more than one variable, and (2) how spurious correlations can arise very easily with low-frequency processes where you don’t have all the facts about what the rate-limiting processes are.
Is there a good study describing the extent of this confounding factor?
I’m just hoping this message will push that long web link OFF the sidebar so my search results stop getting truncated.
Re #33 I doubt it, because that would require a set of spatially replicated studies. The process I’m referring to would be relevant only in the northern Rockies where the sub-polar storm track generates alot of lightning caused fires. I will dig for an authoritative reference for you on that – however this alone will not answer the “extent” question.
A specific case study would be a good start. Trying to understand your point about “the fastest moving tree lines” do so from this effect.
This has been posted before, bender — still worth repeating regarding arctic treelines. Nichols is a real biologist, seemingly in the Lamb fashion.
Interesting. Did you hear they found a hybrid polar/grizzly this spring? Story here
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