The Supra-Long Finnish Chronology #2

This post is going to be a bit more interesting than my last one, where I was getting some preliminary information out of the way. The post here draws heavily on Mauri Timonen’s 2009 PPT, which explains how their 7500-year long chronology is obtained. I’m also going to get to some results which will intrigue many readers.

In small lakes in Finnish Lapland, there are hundreds of submerged Scots pine logs that can be thousands of years old. (BTW the countryside and topography of these photographs looks very familiar to a Canadian). On the left below is a picture of an underwater logs (later determined to be from about 2000 BC); on the right is a montage of pictures showing the recovery of the logs and the taking of sample disks: these obviously give better data than pencil thin drill holes where perpendicularity is hard to maintain and where the pith is not known for certain.

   

Fnland has been surprisingly successful in high-tech for a small country. Here is an example of high-tech :) methods being applied to the recovery of ancient logs. What I actually want readers to notice is that the trees are all scrub birch trees; there isn’t a pine tree in sight. The pine treeline is some tens of km to the south.

Figure 2. Lohikoste, Utsjoki (compare to Eronen et al 2002 Figure 1).

Timonen shows pictures of present-day alpine meadows and invites his audience to imagine a Holocene pine forest. For example, here is a picture from Enontekio, where the legend explains that there are submerged logs about 1 m below the surface of the small lake, with the stumps still in situ.

The tree zones are nicely shown in the map below (from Rudner and Seppala), which distinguishes between alpine heath (white), scruffy birch (yellow), with a mixed pine/birch zone shown in orange. The various sites shown in the Metla pictures (Lohikoste, Vallijarvi) are to the north of the pine treeline, well into the yellow zone.

Kultti et al (Holocene 2006) (picture below is from Kultii et al 2003 poster) shows their estimates of past treeline locations from these extensive surveys. The treeline denominated +0.57 deg C corresponds to the MWP, while the treeline denominated +2.4 deg C corresponds to the Holocene Optimum.

Here is the corresponding figure (Figure 5) from Kultti et al 2006, discussed briefly at CA in 2006 here, clearly showing their estimates of MWP temperature (+0.55 deg C), 3000 BP (+0.96 deg C) and 6000 BP (2.55 deg C.) They reported:

Between c. 8000 and 4000 cal. yr BP pines were growing at 350/400 m higher altitudes than at present and the shift in mean July temperatures compared with 1961/1990 climate normals was ~2.5/2.6 deg C. … During the ‘Mediaeval 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.

These estimates are based on treelines – a method that I find intuitively appealing. I’ll discuss temperature estimates based on ring-width chronologies in another post. In an email to me, Timonen clearly distinguished between using ring width chronologies to establish dates (their original purpose) and using ring width chronologies for temperature reconstructions (which he regards as considerably more speculative).

I’ll also discuss IPCC AR4 handling of treeline issues; while the issue is not discussed in AR4 itself (nor are the Finnish studies), this point was raised by one reviewer and IPCC reasoning for excluding such results will interest some readers.

REFERENCeS:
Timonen, M. 2009-Jan-05. An updated version of “Studies on past and present climate change in Finnish Lapland, based on the 7642-yr supra-long pine chronology for Finnish Lapland;
Pdf (14 MB). This presentation was originally held 23-Oct-2007 in the “Forest Science Day” seminar.http://lustiag.pp.fi/MTP_231007.pdf
Timonen, M. 2007. Past, Present and Future Climate from Tree-Rings. Studies on past and present climate change in Finnish Lapland, based on the 7641-yr supra-long pine chronology for Finnish Lapland. Pdf (13 MB). Forest Science Day 23-Oct-2007, arranged by The Finnish Society of Forest Science and Taksaattoriklubi, themed as “Adaptation to climate change and Finnish Forests”. The House of Sciences (Tieteiden talo), Kirkkokatu 6, Helsinki, Finland.
Kultti, S., Mikkola, K., Virtanen, T., Timonen, M. & Eronen, M. 2006. Past 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): 381-391. Pdf
Kultti, S., Mikkola, K., Virtanen, T., Timonen, M. & Eronen, M. 2003. Past changes in the Scots pine treeline and climate in Finnish Lapland – evidence from pine megafossils and lake sediments. Pdf. Eurodendro 2003 10-14 September 2003. University of Innsbruck, Institute of High Mountain Research, Innsbruck, Austria.
Rudner, Seppala http://www.helsinki.fi/geography/research/RZEposterKilpisj.pdf


124 Comments

  1. tty
    Posted Jan 6, 2009 at 1:12 PM | Permalink

    A minor terminological quibble, you should speak of “alpine heath” rather than “alpine tundra”. There is no real tundra in Scandinavia. You only find proper tundra with permafrost east of the White Sea (the Bolshezemelsk Tundra). You may have been misled by the term “barren ground” which however in this context however does not have the same meaning as in Canada.

  2. jae
    Posted Jan 6, 2009 at 1:57 PM | Permalink

    That is some fascinating work by the Finns. It’s hard to argue with actual tree-line data. But we will all probably be told again that the MWP was a “localized phenomenon.” I anxiously await your discussion of the relation of temperature and tree ring widths.

    tty: In the USA, tundra is anything above tree-line.

  3. Jeff Alberts
    Posted Jan 6, 2009 at 1:58 PM | Permalink

    Good thing today’s temps are “unprecedented”…

  4. bmcburney
    Posted Jan 6, 2009 at 1:59 PM | Permalink

    I still say “supra” is wrong. “Supra” essentially means “above.” It refers to the direction and should not be used as a superlative.

  5. jae
    Posted Jan 6, 2009 at 2:00 PM | Permalink

    OOps, Maybe I should have said tundra is the area above tree-line that supports plant life.

  6. Ron
    Posted Jan 6, 2009 at 2:28 PM | Permalink

    bmcburney,
    Re: “Supra”.
    Considering that the word’s conceptual field also includes “…over, beyond, or before” (WNW, 3rd College Ed), then it seems to me OK to use it in the context of the relationship of this Finsh work and the IPCC cannon.
    Ron.

  7. Ron
    Posted Jan 6, 2009 at 2:29 PM | Permalink

    Sorry, “Finnish”.

  8. MC
    Posted Jan 6, 2009 at 3:19 PM | Permalink

    Do the Finns know what tectonic activity i.e. gravity recovery, is going on and if there is any plate rebound in Finland from the last ice-age? That would make treelines appear to move up the mountain, so to speak, as water levels would remain relatively constant. Parts of Canada show this as seen by the geoid mapping of the GRACE mission some years ago. Gravity mapping is a bit close to my heart as I helped design the propulsion systems for the upcoming GOCE mission which will do the same mapping but in finer resolution (if it gets launched!)
    I wonder if geological comparisons have been made with tree line estimates and then factored into the temperatures? Otherwise there might not have been as dramatic a change in temperature 6000 years ago. Not sure if the MWP would be incorrect though as 1000 years may be too recent, though that said parts of Greece show an alarming rate of land height reduction over the last 2000 years i.e. whole buildings disappearing into the sea.

    • Craig Loehle
      Posted Jan 6, 2009 at 3:45 PM | Permalink

      Re: MC (#9), I would think that Finland would be rising, not sinking since all of scandinavia is rising due to rebound after ice melted. If it is rising, the a past tree line north of where it is now is even more dramatic.

      An important thing about treeline is that it takes a long time for it to move–trees have to sprout and grow and then send seed to the next step of the migration (though faster for a retreat when it gets cold because then the trees living where it is too cold either die or simply fail to reproduce). This means that decadal and shorter fluctuations are NOT captured, really only several hundred years of warmer period will show.

  9. Ron Cram
    Posted Jan 6, 2009 at 3:48 PM | Permalink

    Steve,

    This is great stuff. I cannot wait to hear the reason the IPCC gave for excluding treeline and Finnish results.

    • thefordprefect
      Posted Jan 6, 2009 at 6:54 PM | Permalink

      Re: Ron Cram (#11),

      This is great stuff. I cannot wait to hear the reason the IPCC gave for excluding treeline and Finnish results

      Data availability may have been a problem.
      An early version of same data – not peer reviewed.
      Monday, 12 June 2006
      Concurrent Session (Room 2 of Building 7)
      Session 15: Climate reconstruction from tree rings
      Chair: Paul Sheppard
      Mauri Timonen, Finnish Forest Research Institute, Finland:
      Climate from the 7520-year unbroken Scots pine tree-ring chronology for Finnish Lapland
      ————-
      1st Peer reviewed article
      Finnish supra-long tree-ring chronology extended to 5634 BC
      Authors: Helama, Samuli; Mielikainen, Kari; Timonen, Mauri; Eronen, Matti
      Source: Norwegian Journal of Geography, Volume 62, Number 4, December 2008 , pp. 271-277(7)
      Publisher: Routledge, part of the Taylor & Francis Group
      —————-
      Mann
      Proxy-based reconstructions of hemispheric and global surface temperature variations over the past two millennia
      Michael E. Mann*,†, Zhihua Zhang*, Malcolm K. Hughes‡, Raymond S. Bradley§, Sonya K. Miller*, Scott Rutherford¶, and Fenbiao Ni‡
      Communicated by Lonnie G. Thompson, Ohio State University, Columbus, OH, June 26, 2008 (received for review November 20, 2007)
      —————–
      IPCC latest:
      IPCC Fourth Assessment Report (AR4)
      “Climate Change 2007”, has been completed.
      —————–
      So IPCC and Mann are dated 2007
      They would therefore have to use non-peer reviewed data.
      Mike

      • Ron Cram
        Posted Jan 6, 2009 at 8:36 PM | Permalink

        Re: thefordprefect (#23),

        Perhaps you do not know about the extensive criticism of the IPCC and the bias shown in the papers they chose to include and those they chose to ignore. Roger Pielke, one of the critics and an ISI highly cited climatologist, wrote about IPCC bias on several occasions here, here and here.

        I look forward to Steve’s comment because I think it may add additional evidence about IPCC bias.

  10. bmcburney
    Posted Jan 6, 2009 at 3:57 PM | Permalink

    Ron,

    Yes, “over, beyond, or before” but only as to a comparative location (e.g., a prior reference in an article). This does not rule out a reference to tree canopy or even Finland being “above” Germany (despite Germany being “uber allis”) but should rule out a superlative dendrocronology.

  11. anonymous
    Posted Jan 6, 2009 at 4:07 PM | Permalink

    Ron,
    Try not to get hung up on this treeline business. The treeline methodology is only one way of looking at it. The IPCC prefer another, equally logical, methodology; namely teleconnection. Using the teleconnection methodology, since the tree ring widths of this Finnish chronology do not correspond well with the “training” portion of the Northern hemisphere temperature record, we can clearly see it is OF NO USE as a proxy record and weight it accordingly in our studies (should we choose to incorporate it at all – and remember, you do have to pick the cherries to make a decent cherry pie!).

  12. Hasse
    Posted Jan 6, 2009 at 4:13 PM | Permalink

    #10 Here you can see how Scandinavia is rising and sinking: http://www.oso.chalmers.se/oso/geo/gps/bifrost/html-sv/raise.html
    The text is in swedish, but the graf is clear.

    • MC
      Posted Jan 6, 2009 at 6:03 PM | Permalink

      Re: Hasse (#14), Looking at the uplift the figures of a 40/80 m higher altitude tree line does suggest a strong case for hotter surface temperatures even with a surface uncertainty + 1 m (uplift) which leads to a suitable growth temperature to create the tree line at higher altitudes. Also the tree line is a natural threshold which should reduce in altitude with surface temperature with some correspondence (precipitation and available sunlight notwithstanding) so it does appear that there was an MWP in Finland. Even with the degree of error/uncertainty it is a fairly clear result. Certainly one that a person can’t ignore.
      So kiitos to Mauri and co for some good work.

  13. Steve McIntyre
    Posted Jan 6, 2009 at 4:27 PM | Permalink

    Some of the Kultti authors are geologists and would be familiar with isostatic issues. At a very quick sizeup, the reported changes in treeline are much greater than isostatic changes in any event.

  14. insurgent
    Posted Jan 6, 2009 at 5:26 PM | Permalink

    #14 Let me get this straight: Part of Scandinavia is falling into the ocean at .5 centimeters per year (.5 meters per century) and nobody seems to care. The ocean rises 2mm per year (.2 meters per century) and the world goes apesh*t. Irreconcilable disconnect in my book.

  15. Allen63
    Posted Jan 6, 2009 at 5:27 PM | Permalink

    Having read a book on dendrochronology (because of this site’s referral to dendro “this and that” got me interested), I am extremely skeptical of tree rings for temperature reconstructions (even if they agree with my bias).

    On the other hand, tree lines as an indication of past temperatures make good sense, as a first approximation.

    As others note, one has to factor in “spring back” after the ice sheet melted (and other issues). So, I guess treeline data is only interesting (not conclusive) — unless it is accompanied by data indicating geological stability or movement of the region. As the rates may have changed over the years (e.g. a faster rate initially), current rates may not tell the whole story. In the subject case, unconsidered “spring back” (or upward land movement from any cause) could lead to an erroneous judgment that past temperatures were higher, I suppose.

    Nonetheless, I hope its true that geological movements have not muddied the data — because the world needs some un-muddied ancient climate data. And, in any case, properly analyzed treeline data is stronger than tree rings regarding temperature, I think.

  16. jim west
    Posted Jan 6, 2009 at 6:00 PM | Permalink

    Isostatic re-adjustment is potentially a fairly major confounding issue here. Allen63 is right to point out “…as the rates may have changed over time”. Not only might they have changed, you can be reasonably certain that they have, and further more, that the rate was faster further back in time, closer to the initial unloading. I suspect that rebound is not an issue for the higher treeline during the MWP, as the max. rebound in that time is probably only of the order of 10m (the rate should have been roughly the same as now, perhaps touch faster). For the 350/400m higher treeline back around 8000BP mentioned, I would be not be dismissive of rebound.

  17. Ron
    Posted Jan 6, 2009 at 6:11 PM | Permalink

    bmcburney,
    Okay, it’s agreed then. You say “Supra” and I’ll say “Supra”.

    annonymous,
    Good point. I’ll try not to forget to remember it.

    Ron

  18. Colin Aldridge
    Posted Jan 6, 2009 at 6:14 PM | Permalink

    Rebound is obviously a significant factor since .5cm rise pa which is happening now in parts of scandanavia is 5m /16ft per millenium which makes a significant difference but doesn’t account for the whole delta. To get to 400 metres over 4000/8000 years we need a rise of 5 to 10cm per year average to cancel out the apparent rising of the tree line. Sounds like a lot of recovery from the melt of the ice sheet to me … Are there any general figures on this?

  19. Joachim
    Posted Jan 6, 2009 at 6:37 PM | Permalink

    During the viking age, or MWP, oceanlevels in southern Norway were about 9 m higher due to tectonic movement. Tectonic movement was in the order of 200-250 meters after the ice age i think, though the areas in northern finnland might have changed more.

    This is a flash animation that shows ice and land movement after the last ice age in sentral areas in Norway. It’s in norwegian, but the graphic shows that the shoreline was moving before the ice had retreated completely.

    http://geografi.cappelen.no/autoimages/kart_3c619589ff7c3311b44b9744ed1dc34d.swf

    The animation is for use in norwegian version of high school. Thin blue lines are coaslines at the time, thin red lines are coastlines today.

  20. Robert Wood
    Posted Jan 6, 2009 at 6:57 PM | Permalink

    Here is a google translation of the web page pointed to by Hasse:

    By using the approximate GPS stations operating and Interpolate the increase between the stations, a picture of land uplift is developed. The colors on the map changes depending on the size of increase that has taken place for each station. While there is no GPS station near the great uncertainty and map colors are less intense for the eventual transition in white.

    It looks like that area is around about 3-4 cm/year. Over 1,000 years, this would be around 30-40 meters.

  21. Robert Wood
    Posted Jan 6, 2009 at 7:02 PM | Permalink

    Dang, thumbs. Sorry, that should be 0.3-0.4 cm/year. And around 3-4 meters over the past 1000.

  22. Steve McIntyre
    Posted Jan 6, 2009 at 7:34 PM | Permalink

    #23. Nope. You’re wrong.

    Helama et al 2002 was a prior version of the 2008 article and was available in plenty of time. Even Kultti et al 2006 was published long before Wahl and Ammann 2007.

    We can discuss IPCC in a separate post that I’m planning – as I mentioned, one (and only one) reviewer drew their attention to this literature and the disposition is intriguing.

  23. Tim Ball
    Posted Jan 6, 2009 at 9:20 PM | Permalink

    What does the palynological record show for the area? With all those lakes good palynology cores should be available. There are also likely varve records for the region, which provide another source of dating in addition to the climate change sequence.

  24. Posted Jan 7, 2009 at 12:23 AM | Permalink

    Ron, #7
    I didn’t realize the IPCC was so heavily armed. :)

  25. tty
    Posted Jan 7, 2009 at 4:16 AM | Permalink

    There exists a vast quantity of data on isostatic rebound in Scandinavia, since this has been an active field of research since the eighteenth century.

    That it is matter of the land rising, rather than the sea sinking was actually first suggested by a surveyor from Finland (then a part of Sweden) in 1765. That the shorelines recede have of course been known since time immemorial.

    Note that the rebound is largest at the former center of the Scandinavian icecap and declines towards the former edges and that the study area in Northern Finland is fairly marginal as you can see here:

    http://www.lantmateriet.se/templates/LMV_Page.aspx?id=10588

    or here, a map of the current rise in Finland, in millimetres per year:

    The maximum rise since deglaciation is 285 meters in Ångermaland, Central Sweden (there is no way to determine the rebound before deglaciation).

    Here is a nice visualisation of the process from the Swedish Geological Survey:

    http://www.sgu.se/sgu/sv/geologi/geologi_sverige/jord/strand_intro.htm

    Here is some details on the rebound at the northern end of the Bothnian gulf (where the rise is largest, nearly 1 cm/year) and a sea-level curve for the area.

    http://www.geol.lu.se/fo-info/mli-hk.pdf

    The sea-level curve is based on dating of coast-lines and isolation of lakes and gives an idea how the rise slows down over time.
    Here are two more such sea-level curves for southern and northern Finland, from another METLA research projects:

    http://www.metla.fi/hanke/3194/alue-sve.htm

    And if you really want to get into the subject, this report will probably tell you more than you want to know:

    http://www.skb.se/upload/publications/pdf/R-01-41webb.pdf

    It was prepared as part of a large geological research project about storage of nuclear waste in Sweden. It contains references to most of the more important research on this subject.

    As for the total isostatic rebound in the part of northern Finland we are talking about, I would say that it is less than 10 meters since the MWP, and about 100 meters since 7600 BP, though it decreases towards the north.

    • Craig Loehle
      Posted Jan 7, 2009 at 7:56 AM | Permalink

      Re: tty (#30), Thanks for the details. A rise of between 10 and 100 meters would cause tree lines to retreat over time (past times would appear warmer), all else equal, though 10 meters not much of a difference. This would need to be subtracted from the treeline data to see what the climate was over time.

      • tty
        Posted Jan 7, 2009 at 9:09 AM | Permalink

        Re: Craig Loehle (#31),

        10 meters since the MWP is an absolute maximum, I would say about 5 meters is the most likely figure.
        By the way if the chronology is extended beyond 8000 BP things will get more complicated. Isostatic rebound seems to have been much faster the first 2000 years or so after deglaciation, but simultaneously the sea-level was still rising fast as the Laurentide ice-sheet melted. One of the references I gave (http://www.geol.lu.se/fo-info/mli-hk.pdf) tries to show the “true” rebound, corrected for sea-level changes, as well as the apparent.

        • Dave Dardinger
          Posted Jan 7, 2009 at 12:14 PM | Permalink

          Re: tty (#35),

          I wonder if someone familiar with the climate models could say if the rebound is considered in modeling for ice ages? Since areas which rebound will be cooler, this would make cool episodes eventually more likely to accumulate ice and click the climate over into an ice age. Contrawise, coming out of an ice age, land denuded of an ice cap will be lower and thus warmer than at equilibrium and thus accelerate melting.

    • Reference
      Posted Jan 7, 2009 at 5:03 PM | Permalink

      Re: tty (#30),

      Hi tty, Useful links thanks.
      Here is a posting of the SGU link, that appears to lack an English option, wrapped in Google Translate:-
      Visualisering av strandlinjeförskjutning

      • tty
        Posted Jan 8, 2009 at 1:31 AM | Permalink

        Re: Reference (#39),

        If anybody wonders what “sjöstjälpningsförlopp” means, it translates as “lake tipping-over process”, this happens when rebound is larger at one end of a large lake and the lake is therefore “tipped over” towards the end with the smaller rebound. This is actually very noticeable for a lake like e. g. Vättern (90 miles N-S) with lake level going down in the north and up in the south. By the way I don’t blame Google Translate for giving up on it.

  26. Posted Jan 7, 2009 at 8:26 AM | Permalink

    It’s important to look at other papers on treeline, to get around the excuses of a localised effect or land rising.

    Mediaeval climatic warming recorded by radiocarbon dated alpine tree-line shift on the Kola Peninsula, Russia, by A. Hiller et al, The Holocene, Vol. 11, No. 4, 491-497 (2001) found
    “a distinct maximum betweenc. 800 and 1000 yr BP”. But this is near Finland.

    Climate change and the northern Russian treeline zone, Macdonald et al, Phil Trans Roy Soc B 363, 2285-2299, (2008) say “conifers have not yet recolonized many areas where trees were present during the Medieval Warm period (ca AD 800–1300) or the Holocene Thermal Maximum (HTM; ca 10000–3000 years ago). ”

    How has climatic variation influenced treeline dynamics in the past? Andrea H. Lloyd, http://www.yosemite.org/naturenotes/FoxtailTreeline.htm finds that “Treeline elevation was higher than at present throughout most of the last 3500 years.”

    Perhaps Steve will review some of these or other such work in his next post, since the IPCC chose to ignore it except for one paper by MacDonald et al (of course there are several earlier CA threads).

  27. Steve McIntyre
    Posted Jan 7, 2009 at 8:33 AM | Permalink

    #32. I’m familiar with those citations and will discuss them. If you search CA, I think that there is prior discussion – there’s definitely a picture of a high medieval foxtail.

  28. Steve McIntyre
    Posted Jan 7, 2009 at 8:34 AM | Permalink

    The discussion of uplift reminds me of some interesting articles by Peter Molnar about mountain uplift and climate change, see refs at: http://cires.colorado.edu/science/groups/molnar/projects/erosion/ starting with Molnar and England 1990.

  29. Tim Ball
    Posted Jan 7, 2009 at 11:27 AM | Permalink

    The father of tree line studies is Finlander I. Hustich. I became familiar with his work when working on movement of the tree line in Central Canada. His 1983 work provides many answers debated here. Morisset and Payette held a conference in Quebec to recognize his contributions. (Tree-Line Ecology. Proceedings of the Northern Quebec Tree-Line Conference.) There is also this work on the topic in that region.

    http://herkules.oulu.fi/isbn9514280075/isbn9514280075.pdf

  30. Posted Jan 7, 2009 at 2:34 PM | Permalink

    PaulM (#32)

    Second, the period from AD 1050 to 1450 illustrates the extent to which water balance can reverse treeline response to temperature. Whereas climate appears to have been warm when treeline forests expanded, warmth does not necessarily lead to subalpine forest expansion. The observational record of the relatively wet 20th century leads to the prediction that treeline will rise if temperatures rise. The paleoecological record, however, indicates that future warming is unlikely to cause an expansion of subalpine forests if it is accompanied by a reduction in water supply.

    This part is interesting in that the strip bark pines used on the next mountain range over (the white mountains) figure prominently in our friends attempts to diminish the MWP.

  31. pjm
    Posted Jan 7, 2009 at 5:56 PM | Permalink

    How fast can a tree line advance? Could the modern tree lines be so far behind the MWP line because the line can’t move fast enough.

    Also, can a forest survive where young trees cannot? ie Do conditions need to be more favorable for a tree line to advance to a position than they do for it to remain there?

    • tty
      Posted Jan 8, 2009 at 1:51 AM | Permalink

      Re: pjm (#40),

      Question one. Reaction is fast in terms of new tree seedlings establishing. It only takes several warm summers in a row. This process can actually be seen going on on Scandinavian mountains today due to the recent warm years. Remember that in terms of distance a tree-line change of say 100 meters is fairly trivial. Studies of forest establishment after the last glaciation suggest that the maximum speed of advance for forest trees is on the order of a few kilometers per year. However a full-grown forest takes several centuries to grow at the tree-line.

      Question two. Yes indeed. As a matter of fact forests at the treeline are normally more or less unable to rejuvenate, and this is often the factor that determines the treeline. New seedlings will only survive if there are several unusually warm summers in a row. This is a well-known problem for forestry in Scandinavia. Replanting of trees will usually fail close to the treeline. As a matter of fact I think a more reliable method of identifying warm periods than tree-ring measurement would probably be to tabulate the years when trees close to the tree-line germinated.

  32. Trogluddite
    Posted Jan 7, 2009 at 9:10 PM | Permalink

    Sir,

    Could you possibly have one of your underpaid, overworked lackeys – sorry, grad students – attach a concise translation from Canadianish to English – oops, sorry again – from intensively technological scientific/statisticalese to lay English. I consider myself reasonably well-educated and, given time, I could work my way through this and develop a bottom line to put up front that concisely and fairly summarizes what your saying, where it fits in any ongoing debates on climatology and our unstoppable slide into a manmade sauna, but I’m not sure that many laymen could do. And while I realize that your website may not have a primary purpose of educating laymen or influencing the (nonsensical) debate about how we’ll all clearly and unequivocally be swimming in the Hudson River in December twenty from now, it may benefit from doing so. Regards, Trogluddite

  33. Steve McIntyre
    Posted Jan 7, 2009 at 9:15 PM | Permalink

    41. “grad students” – are you confusing me with someone else? This is just me and my keyboard.

    • Mark T
      Posted Jan 8, 2009 at 2:34 AM | Permalink

      Re: Steve McIntyre (#42), Well, you are apparently Dr. McIntyre, why not enlist a hoarde of graduate students? Or at least, virtual ones. :)

      Mark

  34. Basil
    Posted Jan 8, 2009 at 9:39 AM | Permalink

    Is this 7500 year time series archived for public access anywhere? I did a reasonable amount of searching, and came up empty. I’m intrigued by what they’ve already done in the way of spectral analysis, but would like to apply a couple of other techniques to see what kind of natural climate variability this series reveals.

  35. Posted Jan 9, 2009 at 3:51 AM | Permalink

    Paludification is the process of bog expansion resulting from rising water tables as a consequence of peat growth over permafrost. Forests are replaced by muskeg. The process is complex and organic. It may not be entirely due to climate change, but a natural progression over time from early Holocene mineral soils to Late Holocene peat soils. There is considerable debate as to whether paludification is a feature of neoglaciation or not. I am not familiar with Finnish soils, but rising water tables in Canadian boreal forests are not necessarily climate-change related.

    • tty
      Posted Jan 9, 2009 at 3:25 PM | Permalink

      Re: Mike D. (#48),

      Paludification does not by any means occur only over permafrost. It is common in Scandinavia where there is no permafrost, and the “blanket-bogs” of Scotland and Ireland is a prime example, though in these particular cases deforestation has probably played a part in the process.

  36. Urederra
    Posted Jan 9, 2009 at 1:35 PM | Permalink

    A couple of questions. how a doubling of CO2 concentration would affect the treeline?
    And how the increment of CO2 concentrations that we are having since industrial ages affects the 8000 years temperature reconstructions?

    Re: Trogluddite (#41),

    Oh, come on troglu. This article must be one of the easiest to understand Steve has written lately.

  37. Mike Lorrey
    Posted Jan 9, 2009 at 4:47 PM | Permalink

    Steve, at risk of annoying a relative of mine, have you taken a gander at Andrew Lorrey, et als Kauri tree ring records of the last 3750 years? He seems to be verifying the LIA with similar data, although he also shows warming over the 20th century. His team also has subfossil data from bog-submerged kauri dating as far back as 50kyr.

    http://www.niwa.cri.nz/pubs/wa/ma/16-1/climate

    http://apt.allenpress.com/perlserv/?request=get-abstract&doi=10.1043%2F1536-1098(2005)061%5B0003%3AGCOK%5D2.3.CO%3B2&ct=1

    http://www.niwa.co.nz/__data/assets/pdf_file/0005/67523/climate.pdf

    http://www3.interscience.wiley.com/journal/113374841/abstract

  38. peter_ga
    Posted Jan 9, 2009 at 9:22 PM | Permalink

    Looking at the spectral analysis in the power point presentation, I was struck by the drop-off in spectral power at periods greater than 100 years. Could it be that dendrochronology is merely a high-pass filter, and not to be trusted over periods of time greatly in excess of the life-time of a tree?

  39. Posted Jan 9, 2009 at 10:11 PM | Permalink

    tty #50 — you are quite correct. The point remains that treelines are not necessarily indicative of temperature. That is not to say that the MWP or the Climatic Optimum did not occur. It is merely to point out that treelines are poor indicators of such. For that matter, tree rings are also poor indicators of climate, because they are so confounded by competition and disturbances not related to climate or weather.

    • tty
      Posted Jan 10, 2009 at 3:55 AM | Permalink

      Re: Mike D. (#53),

      I would say that in Scandinavia treelines *are* indicative of temperature and not much else. It isn’t wet enough for blanket-bog to develop here, paludification occurs almost exclusively in lowlands and on flat ground. Also (scrubby) birch is still growing in the areas where pine forest once stood, proving that it isn’t edaphic factors that prevents tree growth.

      • Urederra
        Posted Jan 10, 2009 at 6:02 AM | Permalink

        Re: tty (#54),

        I would say that in Scandinavia treelines *are* indicative of temperature and not much else.

        I have to insist, sorry. I would be surprised if an increment of CO2 levels like the ones we are having during the last 150 years didn’t have any effect on treelines.

  40. curious
    Posted Jan 10, 2009 at 10:34 AM | Permalink

    Urederra, tty, peter_ga
    Re: Treelines – One thing that crossed my mind reading Steve’s post and skimming the presentation was how much do species adapt over these time frames? If tree life is (say) 100-200 years it would seem odd that, given the slow and relatively minor average temp. changes, species could not respond in some way? Better low temp. resistance could allow higher treelines? Although I guess if climate changed to have an altered pattern (more abrupt seasonal change etc.) that could prevent/inhibit response?

    Interested to hear any thoughts – apologies if this is mentioned and I haven’t spotted it, it’s a bit OTTOMH but a v.quick Google didn’t throw any light. Thanks.

  41. Posted Jan 10, 2009 at 1:50 PM | Permalink

    tty #54 — It is hard to imagine what factors other than edaphic would shift boreal treelines. The temperatures, including extreme cold snaps, are not all that different on one side or the other of boreal treelines. It’s the below ground portion of those trees that is most impacted. Water tables can rise, and be perched, even on upland slopes.

    I don’t discredit neoglaciation, but I think there is probably a combination of factors at play. A more thorough analysis of the soils and water tables would go a long ways towards adding credibility to the report. Before we accept one factor or another as the dominant one, all possible factors should be examined.

    Scrub birch and pine have different tolerances to edaphic conditions. The comparative presence/absence is not necessarily due to above ground temperatures.

  42. Posted Jan 10, 2009 at 2:12 PM | Permalink

    I mean, it’s pretty obvious that water tables have risen. The trees are submerged. They didn’t grow under water. The hydrologic changes are significant. They merit explication.

    • Jeff Alberts
      Posted Jan 10, 2009 at 9:03 PM | Permalink

      Re: Mike D. (#58),

      I think you’d be hard-pressed to find any place that hasn’t changed appreciably over several hundred years.

  43. Posted Jan 14, 2009 at 1:09 PM | Permalink

    Good point. I’ll try not to forget to remember it.

  44. Posted Jan 24, 2009 at 9:53 AM | Permalink

    so very inresting plan!1

  45. Posted Feb 3, 2009 at 12:42 PM | Permalink

    Interesting discussion on the Finnish dendrochronological data. Mauri has done excellent wotk with his colleagues and as he has pointed out, it was done mainly for chronological reasons. I have asked him to comment to this thread.

    Using the tree ring data for climatological purposes is very tricky. In fact, a former director, Elias Pohtila of METLA, the Finnish Forest Research Institute, doing research in the mid 1900’s came to the conclusion that tree growth correlates rather well with solar activity.

    Anyhow, for temperature evaluation the tree rings are not reliable. Firstly the growth season is limited to “summer” and secondly precipitation is a major factor to consider and thirdly pests can influence growth considerable.

    More information (partly in English) can be found at: http://lustiag.pp.fi/whatsnew.htm

  46. Posted Feb 3, 2009 at 1:24 PM | Permalink

    Scrub birch and pine have different tolerances to edaphic conditions. The comparative presence/absence is not necessarily due to above ground temperatures.

    Proxy studies in other parts of the world as have been specifically referenced here help as well.

  47. Posted Feb 3, 2009 at 6:25 PM | Permalink

    Sorry in 63 the link did not post. Here it is. An interesting paper on how changes in temperature effect the level of the treeline and tree density in the southern Sierra Nevada. Good stuff in here.

  48. Erasmus de Frigid
    Posted Nov 4, 2009 at 11:04 PM | Permalink

    Steve writes: Polar Urals and the Divergence Problem in West Siberia
    On the minus side, Briffa totally avoided two critical reconciliations.

    The online article made no mention whatever of Polar Urals and did not present any rationale for why the Polar Urals update has never been reported in “the peer reviewed literature” despite a shortage of millennial proxies. Nor did it present a rationale for using Yamal rather than Polar Urals (or a combination.) These questions remain even if they “move on” to a new Yamal data set.

    In addition, the online article failed to reconcile the Yamal Stick (either old or new) with regional West Siberian results from the Schweingruber network (or Esper et al Glob Chg Biol 2009 discussed recently here [link]) showing a second-half 20th century decline in ring widths across a large population of sites. On numerous occasions, I’ve pointed to regional reconciliations as (IMO) critical in trying to advance paleoclimate beyond cherrypicking and data snooping and argued that a serious effort to investigate, analyze and reconcile this sort of regional reconciliation is what’s really required here.

    EDF:
    I have read Hantemirov 2002 concerning a study of both larch tree line movement and tree ring widths and although
    they show 20th century warming after a really cold 19th century, there have been periods over the last 8,000 years
    of both warming and cooling. Neither show a spike up in the later 20th century for this part of the world, the
    southern Yamal peninsula. We see the same thing in Finland and the Polar Urals. Tree line at present is well south
    of its maximum extent (67 deg N vs 70 deg N) showing that climate today is cooler than in the past, even accounting
    for the time lag of Larch reseeding. Tree line doesn’t seem to have the same resolution as tree ring or density,
    but provides a sort of gross ballpark estimate of climate. Still puzzled why Polar Urals aren’t in multi-proxy studies.
    Silence.

    • bender
      Posted Nov 5, 2009 at 6:46 AM | Permalink

      Re: Erasmus de Frigid (#17),

      Tree line at present is well south of its maximum extent (67 deg N vs 70 deg N) showing that climate today is cooler than in the past, even accounting for the time lag of Larch reseeding.

      I like the word “accounting”. Can you explain how the lag in seeding was accounted for? I am skeptical of your claim.

      • Craig Loehle
        Posted Nov 5, 2009 at 8:10 AM | Permalink

        Re: bender (#23), I believe what is meant is that the difference in tree line (and it is latitude, not elevation here) can not be accounted for simply by how long it takes trees to migrate north. Various studies give figures for this. Jim Clark at Duke U. has a whole series on this. As well there are data on migrations following the end of the last ice age. Something on the order of a km to 10km per century migration rates have been observed (when unaided by man and not a windblown disperser like aspen whose seeds travel many miles).

        • bender
          Posted Nov 5, 2009 at 8:54 AM | Permalink

          Re: Craig Loehle (#29),
          If rates of migration are limited to 10km/100y latitudinally then the treeline may not move fast enough to track rapid changes in climate. I would like to see EdF’s demonstration that this limitation on the rate of migration is either small (Cram’s argument) or has been “accounted for”. Show the accounting. Cram attempting to place the burden of proof on me is a dodge. EdF made the assertion. Let’s see the evidence. I have no horse in the race. I want to see evidence.

        • Ron Cram
          Posted Nov 5, 2009 at 9:07 AM | Permalink

          Re: bender (#29),

          I was not attempting to put any burden of proof on you. It seemed to me you had an answer to the question that differed from EdF. I was interested to hear it. That’s all.

        • Ron Cram
          Posted Nov 5, 2009 at 9:05 AM | Permalink

          Re: Craig Loehle (#30),

          Okay, this is helpful. So we have a difference of 3 degrees or roughly 300 km and the tree line may advance north at the rate of 10 km per century. If nothing else, it seems to me, this indicates that in the past it was warmer for a longer period of time. Isn’t that significant info in the discussion? Isn’t it possible recent warming may be largely nature getting us back to our former and warmer state of equilibrium?

        • bender
          Posted Nov 5, 2009 at 9:14 AM | Permalink

          Re: Ron Cram (#30),
          The 3 degrees is assumed. Rather than presume the consequence, you have to ask how to interpret treeline when you have a treeline migration rate that may or may not track the rate of warming. When the rate of warming is very fast, the lag between climatic threshold and observed treeline will be large. When warming is slow the treeline may keep pace. Proceed from there …

        • bender
          Posted Nov 5, 2009 at 9:41 AM | Permalink

          Re: Craig Loehle (#28),
          Are you suggesting that treeline migration rates under post-glacial warming are equivalent to modern treeline migration rates?

        • Craig Loehle
          Posted Nov 5, 2009 at 9:56 AM | Permalink

          Re: bender (#33), No, treeline migration following deglaciation were probably slower because the soils were sterile. Some trees don’t mind this, but many do. It causes delays of at least a few centuries to go the long distances, plus the near-ice climate was not yet so good. However, treeline migration rates have also been estimated from the mid-holocene warming and cooling.

        • bender
          Posted Nov 5, 2009 at 10:23 AM | Permalink

          Re: Craig Loehle (#78),
          The rate limiting process of soil conditioning that you refer to would be accounted for in past treelines. What I’m pointing to is a rate limiting process that might not have been limiting under a slow-warming climate, but might be limiting under a fast-warming climate. One-liners will not answer the question. You have two moving processes, one limiting the other, with the second being co-limited by other ancillary processes. The opportunity for migratory lags to play a role in interepreting past treelines vis a vis temperature is not as trivial as one might think.

    • Ron Cram
      Posted Nov 5, 2009 at 7:30 AM | Permalink

      Re: Erasmus de Frigid (#17),

      Tree line at present is well south of its maximum extent (67 deg N vs 70 deg N) showing that climate today is cooler than in the past, even accounting for the time lag of Larch reseeding. Tree line doesn’t seem to have the same resolution as tree ring or density, but provides a sort of gross ballpark estimate of climate.

      I believe you are correct that treeline is a gross estimate of past climate. While treeline may not measure global temp anomalies to a tenth of a degree like treemometers do, I consider treeline to be a much more reliable indicator. However, I do not understand the phrase bender is skeptical of. I googled “larch reseeding” and got exactly four hits, one of them yours and one a translation from a book passage. I skimmed through the paper by Arthur Roe on regeneration studies in Montana which talked about larch reseeding but did not learn anything helpful.

      To be honest, the phrase seems wholly unnecessary to me. With a 3 degree difference in treeline, how could any time lag make up for such a large difference? Has anyone published an explanation of how larch reseeding could make a 3 degree difference and how long the time lag would have to be?

      • bender
        Posted Nov 5, 2009 at 7:42 AM | Permalink

        Re: Ron Cram (#24),
        The tree line lags behind the shift in climate because it takes a while for a newly warmed area to seed in and grow trees. EdF is asserting that that lag time is “accounted for”. I want to know how it was “accounted for”. I want to know what lag he estimates and how he got that number.

        • Ron Cram
          Posted Nov 5, 2009 at 8:07 AM | Permalink

          Re: bender (#25),

          I’m not sure EdF is using the term “accounted for” in a technical sense (3 degrees!), but perhaps he is. You say it takes a while for a newly warmed area to seed in and grow trees. Okay, fair enough. I will wait for him to answer and then I want to hear your answer.

      • bender
        Posted Nov 5, 2009 at 7:47 AM | Permalink

        Re: Ron Cram (#24),

        With a 3 degree difference in treeline, how could any time lag make up for such a large difference? Has anyone published an explanation of how larch reseeding could make a 3 degree difference and how long the time lag would have to be?

        These are questions that EdF asserts have been answered in his “accounting”. Moving seed upslope is not as fast a process as you might think. If EdF has done the analysis, let’s not guess. Let’s see it.

  49. bender
    Posted Nov 5, 2009 at 9:48 AM | Permalink

    -#34 is badly OT

    -The whole treeline discussion, starting with Erasmus de Frigid, should also be moved

  50. bender
    Posted Nov 5, 2009 at 10:22 AM | Permalink

    Nice surgical work!

  51. Erasmus de Frigid
    Posted Nov 5, 2009 at 10:23 AM | Permalink

    Bender et al.

    Didn’t mean to get off track with tree line discussion, Bender is
    correct, “accounting for” is not good terminology, I was only
    commenting that the tree line is a good indicator of gross climate
    but that it has a fairly large lag. If there is a very rapid
    upswing in recent temperatures, it will likely take awhile for the
    treeline to show it. I was more interested in
    Hantimorov’s assertion in his paper that Polar Urals and Yamal
    can be lumped together since they are only 100 km apart. If he
    considers them to be similar, then the added trees from Polar Urals
    could be combined with Yamal to up the tree count and improve
    the confidence in the data.

  52. Tim Ball
    Posted Nov 5, 2009 at 10:27 AM | Permalink

    I addressed these issues in my 1986 paper, “Historical evidence and climatic implications of a shift in the boreal forest tundra transition in central Canada”. Climatic Change, Vol. 8 Number 2 April 121-134.

    The tree line approximates the 10°C summer isotherm. My research showed the line moved in some areas up to 200 km in approximately 200 years. This equates to 1 km per year, which even if 50 percent wrong is a remarkable rate of adaptation in such a harsh environment. Part of the problem is the false assumption that climate changes slowly and therefore adaptation abilities are slow. Both are false and products of the continued influence of uniformitarianism. The different amount of movement along the tree line was determined by the general circulation pattern.

    It is important to understand that most species move by reseeding, but the success rate varies as the conditions vary in the first few years after seeding. Some species are more successful in moving because they spread by root growth. Once they establish they create microclimate conditions to allow other species to survive. Incidentally, there are trees poleward of what we define as the tree line, which is trees that grow vertically. Arctic willow grow horizontally so they are protected by the snow in the winter.

    An argument can be made that the tree line is determined by the isotherm or conversely the isotherm partly reflects the tree line. A critical issue is the ability to trap snow which protects the trees in the winter and provides adequate moisture for spring growth. The interesting aspect of the tree line not studied to my knowledge is the existence of open areas within the forest area and outlying clumps of forest beyond the general tree line. wind is important in its ability to deflate snow in an area or not remove snow because of the protective ability of the trees. One aspect of the trees at the snow line is their dramatically offset concentric pattern of growth due to the desiccating effect of the excessively dry wind. Some researchers, such as Peter Scott at the University of Toronto, tried to determine the effects by coring on four sides and by sampling every few centimeters over the height of the tree. If nothing else these remarks should clarify how complex the factors are that determine the growth of a tree and the movement of the tree line. One sobering comment relates to the observations of Samuel Hearne included in my paper, who in the 18th century had a much better grasp of climate trends than most people today. He could see the forest for the trees.

    • Joe Crawford
      Posted Nov 5, 2009 at 1:54 PM | Permalink

      Re: Tim Ball (#32),
      Thank you, that’s a very interesting post. Has Peter Scott published his results or the data yet? With my some what rudimentary knowledge off dendrochronology, I have still been a bit suspicious of relying on data from a single core to tell you much about the tree, much less it’s environment.

  53. bender
    Posted Nov 5, 2009 at 10:37 AM | Permalink

    Referring to the OP, treelines during “MWP” and “HTO” can be assumed to be at climatic thermal equilibrium because the time frame in each case is so fuzzy, with thousands of years of imprecision on “HTO” and hundreds of years of imprecision on “MWP”. So I accept those historical maps as is. Now, contrast with today, where there is zero imprecision on the date. Are treelines today in a state of thermal equilibrium? No way. In any short time interval trees can not keep pace with weather and climatic variations; their time-scales of integration are much longer than a year or a decade or two. Tree lines today represent the climatic conditions of some decades in the past. How many? That is a good question that I expect Erasmus de Frigid to answer. I have my guesses, and my abilities to estimate with precision, but the ball is in his court.
    .
    A simple linear extrapolation of EdF’s number will provide a useful approximation to where treeline would be today were treeline in a continuous state of climatic thermal equilibrium. That will give us the apples-to-apples level playing field we need when comparing data from the imprecise the past to those of the precise present.
    .
    Please proceed now, EdF, with your accounting that you said has already been done.

  54. bender
    Posted Nov 5, 2009 at 10:41 AM | Permalink

    Erasmus de Frigid:
    November 5th, 2009
    Bender et al.

    Didn’t mean to get off track with tree line discussion, Bender is correct, “accounting for” is not good terminology, I was only commenting that the tree line is a good indicator of gross climate but that it has a fairly large lag. If there is a very rapid upswing in recent temperatures, it will likely take awhile for the treeline to show it. I was more interested in Hantimorov’s assertion in his paper that Polar Urals and Yamal can be lumped together since they are only 100 km apart. If he considers them to be similar, then the added trees from Polar Urals could be combined with Yamal to up the tree count and improve the confidence in the data.

    Yes, it will take “awhile” for treelines to reflect climate change. To argue that treelines of today are directly comparable to historical treelines requires you take some things into consideration that you have not taken into consideration. Once we’ve done that, then let’s make the comparison. After. Not before.

  55. bender
    Posted Nov 5, 2009 at 10:45 AM | Permalink

    Tim Ball:
    November 5th, 2009
    I addressed these issues in my 1986 paper, “Historical evidence and climatic implications of a shift in the boreal forest tundra transition in central Canada”. Climatic Change, Vol. 8 Number 2 April 121-134.

    The tree line approximates the 10°C summer isotherm. My research showed the line moved in some areas up to 200 km in approximately 200 years. This equates to 1 km per year, which even if 50 percent wrong is a remarkable rate of adaptation in such a harsh environment. Part of the problem is the false assumption that climate changes slowly and therefore adaptation abilities are slow. Both are false and products of the continued influence of uniformitarianism. The different amount of movement along the tree line was determined by the general circulation pattern.

    It is important to understand that most species move by reseeding, but the success rate varies as the conditions vary in the first few years after seeding. Some species are more successful in moving because they spread by root growth. Once they establish they create microclimate conditions to allow other species to survive. Incidentally, there are trees poleward of what we define as the tree line, which is trees that grow vertically. Arctic willow grow horizontally so they are protected by the snow in the winter.

    An argument can be made that the tree line is determined by the isotherm or conversely the isotherm partly reflects the tree line. A critical issue is the ability to trap snow which protects the trees in the winter and provides adequate moisture for spring growth. The interesting aspect of the tree line not studied to my knowledge is the existence of open areas within the forest area and outlying clumps of forest beyond the general tree line. wind is important in its ability to deflate snow in an area or not remove snow because of the protective ability of the trees. One aspect of the trees at the snow line is their dramatically offset concentric pattern of growth due to the desiccating effect of the excessively dry wind. Some researchers, such as Peter Scott at the University of Toronto, tried to determine the effects by coring on four sides and by sampling every few centimeters over the height of the tree. If nothing else these remarks should clarify how complex the factors are that determine the growth of a tree and the movement of the tree line. One sobering comment relates to the observations of Samuel Hearne included in my paper, who in the 18th century had a much better grasp of climate trends than most people today. He could see the forest for the trees.

    • bender
      Posted Nov 5, 2009 at 10:52 AM | Permalink

      Re: bender (#83),
      A migration rate of 1km/y is, as you admit, cherry-picked, and is 10-100 times faster than the rate reported by Loehle from Jim Clark’s work. This number is very important because it determines how comparable today’s treelines are with those of the past, especially if climate is warming faster in the last (and next) few decades than it did during those centuries and millenia.

  56. Tim Ball
    Posted Nov 5, 2009 at 2:44 PM | Permalink

    #88

    “Large -Scale Changes in Atmospheric Circulation Interpreted from Patterns of Tree Growth at Churchill, Manitoba Canada.”
    Scott et al., Arctic and Alpine Research Vol. 20, No. 2, 1988, pp. 199-211.

  57. Cold Lynx
    Posted Nov 5, 2009 at 3:01 PM | Permalink

    Last great warm period as this Finnish chronolgy, or this Swedish one and this one about Sahara Mega lakes show one thing which is very intresting
    A warmer world is a greener world.
    At its maximum extent Lake Megachad was larger than any lake that exists on Earth today. At around 7500-6950 BP
    it was 361 0009+/-13 000 km2; and just one of several big Saharan lakes.

    Finnish opimum was about 7500 year BP and the Swedish optimum with 1.5-2 degrees C warmer than precent was about 4500- 8300 BP.

  58. Posted Nov 5, 2009 at 4:25 PM | Permalink

    Bristlecone pines come in all manner of character, fat or thin, straight or twirly. This seems to be part of their extremophile survival kit. So what is the equivalent in Yamal? Siberian larches I’ve seen seem to be either straight and tall (in “nice” growing conditions) or almost as stumpy and shrunken as heather. But they all seem to have plenty of light. So, would the dwarf trees precede the tall ones, to start to provide a “nice” environment and speed up treeline migration? Other thought: would Yamal soil on reappearing from ice cover really be that barren? could it not be a re-exposure (think preserved mammoths)? Last thought: what seed propagation methods are found for the Siberian larch? Animals? Wind?

  59. bender
    Posted Nov 5, 2009 at 6:54 PM | Permalink

    dougie:
    November 5th, 2009
    Re: bender (#27),

    i agree/think that tree line studies (+ current list of) need a thread (at some time) on c/a, any chance Steve/anybody ?

    to a layman, treeline moves would seem a strong/obvious indicator of climate in that region past/present, but is it that simple (species etc…).

    iv’e been reading the blog/net for papers on this & am still unsure.

    Temperature determines the rate of treeline movement, not the treeline position. It’s amazing to me that people do not understand something so basic. It’s like morainal deposition from glacial melting: temperature determines the rate of melting, not the position of the glacier’s edge. The position of ice or trees is the integral of the rate of melting over some period of time. Finally, these rates are determined by more than one process, not just temperature.

    • Ron Cram
      Posted Nov 5, 2009 at 8:35 PM | Permalink

      Re: bender (#92),

      Finally, these rates are determined by more than one process, not just temperature.

      This is true of treerings as well. When looking at an old treeline 3 degrees north of the present, that deserves some serious consideration. If anything, it seems to show the Little Ice Age was much out of character for Earth’s climate. So then it is possible that a large percentage of 20th century warming resulted from natural causes moving us back to the planet’s default temperature (if such a concept has any value). Based on the data Craig provided, the Earth must have been warmer than the Little Ice Age for thousands of years. Of course, if Tim Ball’s data is correct, then …

      • bender
        Posted Nov 5, 2009 at 9:29 PM | Permalink

        Re: Ron Cram (#95),

        This is true of treerings as well.

        Sure it is.

        When looking at an old treeline 3 degrees north of the present, that deserves some serious consideration.

        Who is not being serious?

        If anything, it seems to show the Little Ice Age was much out of character for Earth’s climate.

        (1) I don’t follow your logic. (2) I don’t know what this means: “much out of character”.

        So then it is possible that a large percentage of 20th century warming resulted from natural causes moving us back to the planet’s default temperature (if such a concept has any value).

        The leap in logic, I don’t get it. We know the HTO was very warm. We know the MWP was warm. We know the LIA was cold. We know it’s warm now. The question is whether it’s unusually warm now (and if so, why). Have we exceeded MWP? How much more to get to the HTO? If you want to talk about HTO and MWP treelines as evidence of past temperature you better get serious about the fact that temperature determines rates of change in ice and treelines, not their positions. Just as it determines rates of tree increment or lake sedimentation. [You understand this. You better tell Tim.]

        Based on the data Craig provided, the Earth must have been warmer than the Little Ice Age for thousands of years.

        Yes, but so what?

        Of course, if Tim Ball’s data is correct, then …

        His data may well be “correct”. No one questioned that. I pointed out that (1) his rates of treeline advance were cherry picked for a specific time and place (one piece of one 1986 study vs all those done since), (2) his treeline advance rates don’t match those of Jim Clark, and (3) treeline tracking of an isotherm is meaningful only in the context of the time frame when the process was studied, and only if the method of inferring the isotherm is is specified and only if the measure of “coincidence” is robust.

        • Ron Cram
          Posted Nov 6, 2009 at 12:54 PM | Permalink

          Re: bender (#96),

          You say you do not know what I mean when I write “the Little Ice Age was much out of character for Earth’s climate.” Perhaps I should have said “from the recent climate seen from a geologic perspective.” The point is, and you evidently agree, the Earth was warmer than the LIA for thousands of years while the LIA only lasted a few hundred. In my view, this makes the LIA quite the anomaly. It is not, evidently, a few hundred year cycle of warming and cooling as I might have expected. This view is reinforced by the fact treeline retreat is faster than the rate of advance.

          I hold to the view no one knows how much of 20th century warming was natural and how much was anthropogenic. The information we are discussing here, admittedly new info for me, leads me to conclude a large percentage of the warming may be natural as the planet looks to be still recovering from the LIA. It seems to me the alarmists are neglecting/ignoring this information.

          As you can tell from my question to Craig in comment #100, I am also intrigued by the cooling period from 1945-1975. Based on ecological evidence, I think the 1930s and 1940s may have been warmer than the 1990s and 2000s. I have no confidence in the temp records produced by GISS or CRU. Just looking at the ecological evidence, the Northwest Passage opened up in 1944 just like in 2007, only it was much harder on the polar bear population then than now. By the 1940s, the polar bear population had dropped to 5,000. It currently stands at 20,000 and the ice is returning to the Arctic. Many people want to know if the MWP was warmer than now. I am also interested to know if the 1930s and 40s were warmer than now. In addition to the other questions, I am wondering what may be learned from treeline advance and retreat in the 20th century.

        • Craig Loehle
          Posted Nov 6, 2009 at 3:12 PM | Permalink

          Re: Ron Cram (#101), oops: forgot your question–I have seen no evidence of tree line retreat from such a small cooling as happened in the 1940-1980 period. Further, mountain treeline advance in e.g. switzerland since 1970 can be better attributed to reduction in sheep grazing and in firewood cutting due to reduction in pastoral activities than due to any climate effects.

        • Ron Cram
          Posted Nov 6, 2009 at 8:09 PM | Permalink

          Re: Craig Loehle (#103),

          Your answer is quite reasonable. My question arose because Tim Ball was citing a 200km/200yr advance in one location. Based on this info my thought process was: “If retreat happens faster than advance, then a 30 year cooling may cause a small but measurable retreat. I wonder if anyone has ever looked into that question?”

        • bender
          Posted Nov 6, 2009 at 8:52 PM | Permalink

          Re: Ron Cram (#106),
          Even a ten-year cooling may cause a huge retreat:

          Serge Payette (2007) CONTRASTED DYNAMICS OF NORTHERN LABRADOR TREE LINES CAUSED BY CLIMATE CHANGE AND MIGRATIONAL LAG. Ecology: Vol. 88, No. 3, pp. 770-780.

          The northern Québec–Labrador tree lines are the most climatically stressed tree ecosystems of eastern North America. In particular, white spruce (Picea glauca) tree line populations distributed between 56° N and 58° N and 61° W and 66° W show contrasted responses to recent changes in climate according to their geographic position relative to the Labrador Sea. Along the coast, the northernmost latitudinal and altitudinal tree lines responded positively to warming over the last 50 years with invading spruce several tens of meters above the current tree line. In contrast, white spruce tree lines across the wind-exposed Labrador plateau are located much higher in altitude and have receded a few tens of meters beginning around AD 1740–1750 and have not yet recovered. Whereas no field evidence of recent fire and insect damage was found, all inland tree line stands were progressively damaged likely due to mechanical defoliation of wind-exposed trees. Massive tree death in the 19th century caused a reduction in the number of seed-bearing trees, and declining tree lines were not replenished by seedlings. Recent warming reported for northern latitudes has not been strong enough to change the regressive tree line trajectory in interior Labrador. However, white spruce expansion above coastal tree line in the northernmost forest site in Labrador is in line with current climatic trends. It is hypothesized that the species is still advancing toward its potential tree line higher in altitude due to delayed postglacial migration. The slow advance of white spruce in northernmost coastal Labrador is likely caused by the rugged topography of the Torngat-Kaumajet-Kiglapait mountains.

      • bender
        Posted Nov 8, 2009 at 9:18 PM | Permalink

        Re: Ron Cram (#95),

        the Little Ice Age was much out of character for Earth’s climate

        Please provide some evidence. It seems to me you are making the same sort of specious claim made by Mann et al. when they say that the Medieval Warm period (MWP) was out of character – just a Medieval Climate Anomaly (MCA). Was the LIA an “out-of-character” “anomaly”? Or are the MWP and LIA linked – as suggested by Broecker (2001), through a 1500-year cycle mediated by the Atlantic Thermo Haline Circulation (THC)?

        Broecker, W. S., Was the Medieval Warm Period global? Science, 291, 1497, 2001.
        .
        The exchange between Broecker and The Team circa 2001 is illuminating. Read Mann’s reply to Broecker (2001). Then read this later article, 2002, which counters the Mann argument that the MWP was just an MCA restricted to the NH:
        Evidence for a ‘Medieval Warm Period’ in a 1,100 year tree-ring reconstruction of past austral summer temperatures in New Zealand
        .
        I would be careful before I went around asserting such and such an event of the past is “out of character”. I don’t think we know what’s in character.

        • bent-out-of-shape
          Posted Nov 9, 2009 at 12:10 PM | Permalink

          Re: bender (#109),

          global: yes. Same response in the northern and southern hemispheres: jury is still out… I didn’t see a MWP in the New Zealand tree record. Not even squinting.

          The MWP was most likely a warming in the northern hemisphere relative to southern hemisphere. As a result the monsoon north of the equator strengthened/ITCZ moved northward. That would reduce the strength of the monsoon in the southern hemisphere. In that respect, the effect would be “global”. LIA was somewhat the opposite of the MWP.

        • bender
          Posted Nov 9, 2009 at 9:30 PM | Permalink

          Re: bent-out-of-shape (#111),
          If you want to bait me on the SH MWP you’ll have to say something concrete and provocative, and say it in an appropriate thread. Are you saying the article’s title is a fraud? Prove to me you even bothered to look at the graphs. As for the rest of what you say, all I see are some baseless assertions. You might want to back some of that up. Clearly you’re an authority. So go ahead and wow us with your knowledge of the SH. Don’t back down like you did last time.

        • steven mosher
          Posted Nov 10, 2009 at 2:05 AM | Permalink

          Re: bender (#113), Wow bender, I like the way they commented on the number of cores. And how they went back to resample. I could actually understand what they are saying.

        • bender
          Posted Nov 10, 2009 at 2:31 AM | Permalink

          Re: steven mosher (#114),
          Fig 3:
          ca AD1150, AD1240 = ~15.4°C
          -error bars bracket current warm period
          -no squinting necessary
          -up to bent to tell us why the title of the paper is misleading

        • steven mosher
          Posted Nov 10, 2009 at 3:03 AM | Permalink

          Re: bender (#116), I appreciated the clear presentation they gave. That’s not an audit of course.

        • bender
          Posted Nov 10, 2009 at 3:31 AM | Permalink

          Re: steven mosher (#119),
          It is up to “bent” to initiate audit, and to do so on an appropriate thread. I mention the article in response to various assertions that LIA and/or MWP “anomalies” are unique. Ron Cram appears to be playing with The Team on that one. I don’t know that we know for certain what’s unique versus what’s normal.

        • steven mosher
          Posted Nov 10, 2009 at 4:07 PM | Permalink

          Re: bender (#120), agreed. I’m just precluding the stupid argument that bender and mosher agree with this article without auditing it.

        • bender
          Posted Nov 10, 2009 at 2:40 AM | Permalink

          Re: bent-out-of-shape (#111),

          I didn’t see a MWP in the New Zealand tree record. Not even squinting.

          Eyes open?

  60. Tim Ball
    Posted Nov 5, 2009 at 7:28 PM | Permalink

    #92
    Movement of the snout of a glacier can also be affected by precipitation variation in the accumulation above the firn line. It can also move with increased basal slip which may be due to geothermal or other increase in water under the glacier.

    Temperature does determine the position of the tree line because it is coincident with the 10°C summer isotherm. The tree line also moves as that mean position moves. The rate of movement can be affected by a variety of factors as noted in my last post.

    • bender
      Posted Nov 5, 2009 at 8:25 PM | Permalink

      Re: Tim Ball (#93),
      Over what time frame was treeline movement “coincident” with the 10°C isotherm, and what is your measure of “coincidence”?

  61. Tim Ball
    Posted Nov 6, 2009 at 8:35 AM | Permalink

    It was hardly cherry picked. It is only 23 years since 1986. It covered the difference between the position in 1772 and 1972 over the entire length of the tree line from the Coppermine River, NWT to Churchill MB. I also considered it with regard to the position based on the palynological work done in the region. This is for the northern tree line where the controlling factors are temperature and precipitation, but here in the form of snow.

    There is also work available on the movement of the southern limit, which has also moved considerable distances in short time spans. Here the movement is slightly more difficult to assess because reduction in bison as a grazing agent and control of grass and forest fires has altered the regime. In addition the southern limit is controlled by precipitation as you transition from the boreal forest through the aspen parkland to the tall grass prairie and then to the short grass prairie. I interviewed one farmer who said the edge of the forest was not even visible when he was a young man, now 70 years later it was within a mile. Koeppen recognized with his climate classification system the different influences of temperature and precipitation on vegetation.

    • bender
      Posted Nov 6, 2009 at 9:14 AM | Permalink

      Re: Tim Ball (#97),

      It was hardly cherry picked.

      Yet you say:

      My research showed the line moved in some areas up to 200 km in approximately 200 years.

      So my statement stands. A treeline advance rate of 200km/200y is not broadly representative.

      It is only 23 years since 1986.

      And how many papers have been published on treeline shift in that time?

      http://scholar.google.ca/scholar?hl=en&q=treeline&as_ylo=1990&as_vis=0

      And what is the consensus rate of advance? 1 km/y?

      difference between the [treeline] position in 1772 and 1972

      Right. Just 200 years out of 10000.
      (1) A rate of advance measured over that 200-year time frame is directly comparable to rate of advance measured during a relatively imprecisely defined HTO? I would disagree.
      (2) Treeline seeming to track an isotherm over a short 200 year period is not too surprising. Over a longer time frame, however, that “coincidence” (which you still haven’t explained) breaks down as temperatures vary more widely. Over these longer time scales it becomes clear that it is the rate of treeline shift that is determined by temperature (amongst other rate-limiting processes), not position.
      (3) If this is so easy to accept for glacial advance & retreat, why is it so hard to accept for treeline advance & retreat?
      .
      Finally, you didn’t say yet how the 10°C isotherm was determined. Over what time-scale is it integrated? (Surely you are not suggesting the treeline moves in annual lockstep with annual fluctuations in this isotherm?)

      • Craig Loehle
        Posted Nov 6, 2009 at 9:51 AM | Permalink

        Re: bender (#98), An important consideration when studying tree line is something Tim Ball mentioned–that tree line is NOT the northernmost limit of trees, but is rather the limit of more or less continuous forest of upright trees. Small, damaged, isolated, and dwarf trees can extend for hundreds of km north of “tree line”. If it warms up, these trees can quickly assume upright stature and spread seed that otherwise could not possibly reach the area otherwise. This would explain the more rapid rate than observed and modeled by Jim Clark for true invasions (trees or a particular species not present at all). It will depend greatly on this situation of scattered trees or not north of treeline. In the following paper we showed very slow invasion of forest into adjacent grassland where trees were truly absent:
        58. Loehle, C., B.-L. Li, and R. Sundell. 1996. Forest Spread and Phase Transitions at Forest-Prairie Ecotones in Kansas. Landscape Ecology 11:225-235.
        In the following paper I also discuss historical data on boreal treeline movement and that treeline retreat is faster with cooling than is advance with warming:
        Loehle, C. and D. C. LeBlanc. 1996. Model-Based Assessments of Climate Change Effects on Forests: A Critical Review. Ecological Modelling 90:1-31.

        • Ron Cram
          Posted Nov 6, 2009 at 11:53 AM | Permalink

          Re: Craig Loehle (#99),

          Your post answered a question I had but had not yet asked regarding the rate of retreat compared to rate of advance. I thought it was possible the rate of retreat may be faster, but I have no idea how fast retreat happens. Can you tell me if treeline retreated significantly from 1945 to 1975? I know it is only a 30 year period but it would be interesting to know if anyone has looked at the question.

        • Craig Loehle
          Posted Nov 6, 2009 at 3:09 PM | Permalink

          Re: Ron Cram (#100), Trees are pretty tough because they must survive many hundreds of years of weather (or a thousand in a few cases). What generally happens to cause retreat is that it gets too cold for successful seedling growth, so trees that die are not replaced (and perhaps some frost damage to existing trees). I would estimate for a given distance that takes 1000 years for advance it will only take 400 years for retreat, or less.

      • Tim Ball
        Posted Nov 8, 2009 at 2:24 PM | Permalink

        Re: bender (#98),

        “So my statement stands. A treeline advance rate of 200km/200y is not broadly representative.”

        It only appears your statement stands. I never presented it as representative but as an example of the maximum I had determined. Notice I said “in some areas”. This was a reference to the nature of the tree line in this region which runs from near Churchill west to just north of Yellowknife and then north to the Coppermine River. The movement was greatest in the east west section and least in the north south section. This pattern is predetermined by the general flow of the planetary waves and the influence of the Rocky Mountains and other geophysical situations. The least amount of movement was in the north south section, but even here it was at least 50 km. This is coincident with the mean position of the summer isotherm defined as the average temperature for the three summer months. I was not determining a consensus rate of movement but simply saying that in those areas where a temperature shift was greatest the tree line shift was greatest. So it is a combination of temperature shift and position modified by local effects.

        As I noted in the original paper coincidence between the summer isotherm and the tree line in this region is not fully replicated on the east side of Hudson Bay. The presence of that body of water seems critical to this disruption – it is why I was concerned years ago about the situation regarding the Cri Lake dendro records in northern Quebec (an outlier). On the west side the tree line is a surprisingly distinct narrow zone between the boreal forest and the tundra. (I have flown over it many times).

        No I am not saying the tree line moves in annual lockstep with the isotherm. There is always going to be a delay modified partly by the ability of the trees to trap snow. As Hearne observed there were ‘outlier’ clumps of trees well north of the tree line he was following and the Indians told him their oral tradition said the tree line was much further north. Hearne astutely noted this was evidence the world was cooling, which was correct as he was traveling after the nadir but in the heart of the LIA. The question of a different rate of advance or retreat is intriguing, but the existence of outliers suggest the rate of retreat is slower.

        • dougie
          Posted Nov 8, 2009 at 3:43 PM | Permalink

          Re: Tim Ball (#107),
          uncanny, just watched ‘Ray Mears – northern wildness (CANADA) 3 off 6′ prog on BBC2 & treelines & scrub tree’s are mentioned.

        • bender
          Posted Nov 9, 2009 at 9:14 AM | Permalink

          Re: Tim Ball (#107),
          Seems we are in agreement, then, that the treeline lags behind the isotherm because it is the rate of treeline shift that is determined by temperature (rate of seeding & vertical growth & dieback), not the position of treeline. And only when the isotherm is moving slowly and consistently in one direction for a long period of time do the two appear to coincide and shift without a lag.
          .
          Thus one must be extremely careful in making modern-historical comparisons vis a vis treeline position. First, there is imprecision on the historical timeline that does not exist in the present. Second, treeline position is the integral of treeline movement rate over time, and a slow and steady, long-term, 3°C advance in isotherm will result in far more treeline shift than a sudden and rapid 3°C shift. Failure to account for these two facts could lead to major errors of inference through an unfair apples-to-oranges comparison.
          .
          (Anyone writing this up for the literature, please be sure to credit CA.)

        • Craig Loehle
          Posted Nov 9, 2009 at 3:44 PM | Permalink

          Re: bender (#110), Remember also that boreal “treeline” is difficult to pin down. It is not a “line” it is fuzzy. Even for present day one could argue about the position + or minus tens of km. A big fire (and they can be big in the boreal zone) could wipe out the treeline zone with a 200 year recovery time–same in the past. So not only is there a lag, but it is a fuzzy concept, thus giving only vague answers about past position.

        • bender
          Posted Nov 10, 2009 at 2:22 AM | Permalink

          Re: Craig Loehle (#112),
          Of course. It’s a zone, not a line. It’s fuzzy, hard to define, hard to estimate. Still, the point remains: it is the rate of shift, and not its position, that is determined by temperature. Point to me just one article that takes that perspective.

  62. MrPete
    Posted Nov 7, 2009 at 6:51 AM | Permalink

    An alt download for the Devi08 paper. Thanks, Google!

    [Hint: you can “view image” on any page, then modify the “size=” number at the end to see the paper at any resolution. That’s how I grabbed high quality images of the figure. :-) ]

  63. bender
    Posted Nov 10, 2009 at 2:36 AM | Permalink

    The rapid warming since 1950 is certainly unusual, but is not statistically unprecedented when compared to the previous 1000 years of reconstructed temperatures (Figure 3), especially the warm interval indicated in the first half of the 13th century. This early warm period, and another in the 12th century, fall within the generally accepted interval of the MWP based on evidence from the NH [Lamb, 1965; Hughes and Diaz, 1994; Crowley and Lowery, 2000; Bradley, 2001]. Similar to the NH, this SH expression of the MWP is not homogeneous in time. Rather, it is composed of two periods of generally above-average warmth, A.D. 1137–1177 and 1210–1260, that are punctuated by years of below-average temperatures and a middle period that is near average. Overall, this translates to a MWP that was probably 0.3–0.5°C warmer than the overall 20th century average at Hokitika and, for the A.D. 1210–1260 period, comparable to the warming that has occurred since 1950.

  64. bent-out-of-shape
    Posted Nov 12, 2009 at 11:52 AM | Permalink

    hey bender, you are too funny! I found a good thread the other day that I wanted to comment on. That should address your eloquent request. Unfortunately, I will have to find it again. …there are so many posts it’s hard to keep up.

    But that comment will be delayed a bit. Modern Warfare 2 just came out – so fun time on the web will decrease! ;)

  65. PhilipM
    Posted Nov 12, 2009 at 5:26 PM | Permalink

    This seems to be the best thread to park this pdf slide compilation (Finnish text only).

    Climate Change and Forests in Finland

    Forest Fair 7/11/2008
    Kari Mielikäinen
    Forest Research Institute

    Slide 8: Position of tree line 5000 years ago.
    Slide 23: 250 year old pine tree at modern tree line.

    • bender
      Posted Nov 12, 2009 at 5:50 PM | Permalink

      Re: PhilipM (#123),
      Anyone want to translate slide #13 for me?
      Jean S?

  66. jeez
    Posted Nov 12, 2009 at 8:16 PM | Permalink

    Via Google translate

    Fungi and insects

    • Warm winters, and damage to the tree
    favor the basal rot

    • Southern pests and
    kesässä {inessive case of summer or during the summer?) two generations?

  67. Ron Cram
    Posted Nov 5, 2009 at 11:51 AM | Permalink

    Re: bender (#27),

    I’m disappointed. I had to be in a meeting and so missed several comments made before the zamboni showed up.

    Steve, can we have a thread that discusses treelines and the possibility they may impact (verify, falsify or constrain) treering thermometry? It seems Craig Loehle has a good background. Perhaps he would be willing to write the head post?

One Trackback

  1. […] am posting a followup to yesterdays post “The Excluded Data”. As usual Steve McIntyre ( Climate Audit LINK ) is keeping us current regarding his work and projects. This is an except from his latest update […]

Follow

Get every new post delivered to your Inbox.

Join 3,379 other followers

%d bloggers like this: