Northern Sierra Trees Falsify Claim of 'Unprecedented' Global Warming

Guest post by Larry Fields

The last Ice Age razed all of the coniferous forests in Finland. After the ice sheet retreated, trees from elsewhere–like the Scots Pine–gradually colonized the vacant niches. On a smaller scale, the same thing happened in many high mountains of the Earth’s temperate regions, including the Sierra Nevada Range of California. We can learn a thing or two about climate history from Alpine dendrology.

Round Top Lake, at 9340 feet elevation in the Northern Sierra near Carson Pass, is my favorite place for informal climate history research. Whitebark Pine trees grow in tight clumps around the North half of the lake.

Other high altitude conifers–like Lodgepole Pine, Mountain Hemlock, and Red Fir–also grow in the Carson Pass area. But Whitebark Pines can grow at slightly high elevations than these other trees.

At Round Top Lake, the Whitebark Pines in any given group are nearly identical genetically, since they reproduce asexually. New tree trunks grow outward from an existing root system. This is called suckering. The seeds that do sprout can’t endure the harsh Winters at that altitude. Walking 100  yards downhill from the lake on the main trail, one can see Whitebark Pines that have grown in a more normal way.

Naturalist Jeffrey P. Schaffer mentioned Round Top Lake in the 1989 edition of his book, The Tahoe Sierra: A Natural History Guide to the 106 Hikes in the Northern Sierra. Here’s a link to a review of a more recent book by Schaffer.

http://www.amazon.com/Tahoe-Sierra-Natural-History-Northern/dp/0899972209

Question: After the last Ice Age, how did the Whitebark Pines reach the lake in the first place?

My answer: At some time after the last Ice Age, the Northern Hemisphere was warmer than it is these days. The Whitebark Pines sprouted from seeds at that time, with a little avian assistance.

The Clark nutcracker helps to spread seeds from the conifers in the Carson Pass area. The bird caches seeds that it gathers in anticipation of the Winter food shortage, but often stores more than it needs. Some of the forgotten seeds sprout a fair distance–and even uphill–from the parent trees.

Several years ago, I was surprised to see a knee-high Whitebark Pine seedling outside the half-circle of clone clusters hugging Round Top Lake. However it did not survive.

If the Northern Sierra climate heats up in a big way, I’d expect individual seed-sprouted Whitebark Pines at Round Top Lake to eventually supplant the clumps of small trees. Over the last 1000 or more years, the clones have been gradually accumulating random mutations, which should put them at a slight competitive disadvantage with any future surviving seed-sprouted progeny. When I see a lot of isolated Whitebark Pine seedlings that grow to 6 feet in height at Round Top Lake, then I’ll believe that the Northern Sierra climate is the warmest that it’s been since before the last Ice Age.

Jennifer Marohasy kindly allowed me to guest-post a guest article about this preliminary investigation on her blog.  That report is similar to this one, but with less detail. On 29 August 2009, co-investigator James Mayeau and I visited Round Top Lake for more detailed study. Here’s a link to James’ account of our exploits on that day, in a second guest-posting at Jennifer’s blog.

http://jennifermarohasy.com/blog/2009/09/white-bark-pine-trees-part-2-a-note-from-james-mayeau/

This blog post includes a link to more of James’ photos from Round Top Lake.

Although the overwhelming majority of Whitebark Pines at Round Top Lake were clones growing in clumps, we did manage to find a few medium-sized individual trees near the sunnier West end.  I’m guessing that their growth rates were pretty slow, given the marginal nature of the habitat. They probably predate the latest global warming that started in the late 1970s. If any of the West-end trees date from the 1930s, that would be additional evidence that the last round of’ global warming in the 80s and 90s was not a big deal, even by 20th Century standards.

A good follow-up project would be to count the growth rings in these few West-end trees, in order to determine their ages. Alas, my academic background is in analytical chemistry; I’m not qualified to drill for core samples in living trees.

Studies that emphasize tree ring analysis tell parts of several different stories that Nature has woven together into the fabric of climate history. These stories are about precipitation (in the case of Bristlecone Pines in the semi-arid Basin and Range Region of the Western US), insolation, wind, and yes temperature. Modern dendroclimatology often requires sophisticated  techniques to tease out the temperature parts of tree-ring stories. One lesson from the recent Keith Briffa controversy: In modern-dendroclimatology-based climate history studies, the methodological uncertainties stemming from sampling error, inter alia, are huge.

On the other hand, Seat-of-the-Pants Dendroclimatology (SPDC) emphasizes straightforward early 20th Century technology: shoeleather, cameras, maps, field guides, and optional hand-operated tree-boring devices. The key insight of SPDC: For a given topography, temperature is the single unambiguous control variable that governs tree reproduction mode just below Alpine timberline. When clumps of clone trees dominate the landscape there, one can be certain that the climate was appreciably warmer at some time in the past.

Side note. At timberline in the Northern Sierra, it is difficult to find Whitebark Pines in the form of trees; instead they typically grow as Alpine shrubs–known as krummholz. This is the subject of ongoing climate-related investigation by other researchers.

http://www.fs.fed.us/psw/programs/snrc/climate_landscape/high_elevation_sub1/genetic_variability.shtml

Summary. In the Northern Sierra, Seat-of-the-Pants Dendroclimatology can give a more accurate indication of pivotal warming events in Earth’s geologically recent climate history than can modern dendroclimatology. In terms of the debate surrounding the ‘unprecedented’ global warming of the late 20th Century, Round Top Lake is ‘the elephant in the room’.

Cluster of Whitebark Pines at Round Top L. Photo by James Mayeau.

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31 thoughts on “Northern Sierra Trees Falsify Claim of 'Unprecedented' Global Warming

  1. Simple observation. Clear conclusion. You can’t argue with that!
    Lake Tahoe is the nearest USHCN station, although it is some 3000ft lower. You can find it here on the CA map:
    http://cdiac.ornl.gov/epubs/ndp/ushcn/ushcn_map_interface.html
    Taking a look at the data from the station (by clicking on the marker) is interesting (I hope these links work).
    Mean temperature:
    http://cdiac.ornl.gov/cgi-bin/broker?id=048758&_PROGRAM=prog.gplot_meanclim_mon_yr2008.sas&_SERVICE=default&param=TAVE&minyear=1895&maxyear=2008
    Undulating – peaks in 1934 and 2001
    But Tmin has consistently risen since 1910
    http://cdiac.ornl.gov/cgi-bin/broker?id=048758&_PROGRAM=prog.gplot_meanclim_mon_yr2008.sas&_SERVICE=default&param=TMIN&minyear=1895&maxyear=2008
    And Tmax has fallen and stayed low since the 1920s/30s
    http://cdiac.ornl.gov/cgi-bin/broker?id=048758&_PROGRAM=prog.gplot_meanclim_mon_yr2008.sas&_SERVICE=default&param=TMAX&minyear=1895&maxyear=2008
    That is an ~8 degF drop in daily range.
    Question is, is this a locational thing due to human influence or would it be repeated proportionally at altitude?

  2. Is it possible to date the clone-groups of Whitebark Pines at Round Top Lake – when each one began? Perhaps carbon dating?

  3. The obvious question is, which part of a suckered tree mass to you core? The different suckers have time-variable interactions with each other, with ones now dead, whith new ones just sprouting. It’s like a big family of children dividing up the breakfast porridge. Some will end up with more tree ring than others, in a manner unpredictable, that has a good chance to interfere with the temperature record.

  4. Very very interesting. I really appreciate that this was written up. Makes me hungry for more.
    Treelines treelines treelines! Who is studying treelines?
    I had noted in a paper that was not about treelines that there was mention of trees over a thousand years old above the treeline in the sierras– in passing–climatological significance not even hinted at.
    Unfortunately it was in the beginning of my info quest. Just a ‘hey, look at this’ moment that I didn’t memorialize in my notes.

  5. re:vjones 14:12:16
    Are you sure that is raw data and not “adjusted”.
    Most of what you get these days has been “adjusted” and you have to dig a bit to get what the thermometer actually said. Miraculously, the “adjustment” cools the 30s off a bit.

  6. One more puzzle piece.
    Perhaps, we need more backpackers with GPS and cameras…
    I used to be very active in the back country and often wondered how some trees were able to grow above ‘treeline’, I always kept some distance away from those hardy survivor’s.
    Great piece and great evidence.

  7. DJ Meredith (14:20:59) wrote:
    “Ever thought about doing some dendroclimatology of the trees submerged in Lake Tahoe??”
    That’s interesting. I didn’t know that there were submerged trees in Lake Tahoe. There definitely are partially submerged trees in Aloha Lake, in Desolation Wilderness, just to the West of Lake Tahoe. My understanding is that Aloha and some other small lakes in the area were dammed, as part of a water project for the Central Valley.
    Depending on which part of Aloha you hike in to, the drowned trees can be a bit of an eyesore. If you’re doing a day-hike from the trailhead at Echo Lakes, I recommend Lake of the Woods instead. It’s every bit as scenic, and the walk in is a tad shorter than the better-known Aloha hike.

  8. Larry —
    I spend time each summer on Fallen Leaf Lake, just off the south end of Lake Tahoe, and hike into Desolation Wilderness every summer. Virtually all of these lakes have submerged forests in them, and it has nothing to do with 20th century damming. I don’t believe Aloha Lake has been dammed at all.
    About 10 years ago, a tree that had lived for 200 years was pulled up from 120 feet below the surface of Fallen Leaf Lake. The tree was dated to have lived from about 1000AD to 1200AD, so we know the surface of the lake had to be at least that low for at least that long. During the Depression, the Civilian Conservation Corps built a small dam at the outlet of the lake, but that only raised the level of the lake by about 3 feet.
    During the same period, a forest was growing in what is now the bed of the Truckee River, the outlet for Lake Tahoe, so we know that Tahoe did not drain at all during this period.

  9. At timberline in the Northern Sierra, it is difficult to find Whitebark Pines in the form of trees; instead they typically grow as Alpine shrubs–known as krummholz.

    Who’da knowed it? Nature adapts!
    DaveE.

  10. Jon Adams (17:21:24) wrote:
    “One more puzzle piece.
    Perhaps, we need more backpackers with GPS and cameras… ”
    Great idea! And a preliminary part of the High Altitude Lake Survey that you’re suggesting would be to scan hiking guidebooks for any mention of clumps of conifer clones, and to scan topo maps for lakes–just below Alpine timberline–that are partially sheltered from the sun on 2 or 3 sides.

  11. Curt (18:34:46) :

    There is an article over at Climate Audit on that topic and I have posted the link here a few times. But the Sierra Nevada has apparently experienced what we would call a “mega drought” many times in the past and it seems like the past several centuries may be one of the wettest times of the past couple thousand years in the California Sierra. Now if weather patters were to return to a more “normal” condition and those lake levels were to drop back to where they were a thousand years ago, this state will be in a world of hurt.
    People capable of recording history on paper have only lived here for a few centuries. Mission San Jose was founded only a little more than 300 years ago. One problem is that people get this sense that the conditions under which they are living are “normal” and that any change is “abnormal” when over a span of a couple of thousand years, maybe we are living in a quite abnormal period.
    I really would like to ask my state legislators what they plan to do if we suddenly enter a period where we get only half of “normal” rainfall for five hundred years or so. That is a major problem. People are “spring loaded” to believe there is something someone can “do” about it if only enough dollars are shot in the general direction of the problem. Well this is going to be a problem that no amount of dollars is going to fix.
    And sending all that water South to Los Angeles from Tahoe is probably a huge mistake, too. That runoff from Tahoe would otherwise be going to Pyramid Lake where it would be increasing the lake level and the humidity levels and thereby winter snowfall on basin and range mountains across Nevada. Shipping that moisture South to LA and diverting Tahoe runoff to irrigation might be altering a lot of ecosystem across the basin and range.
    If you want to build a city next to the sea in the middle of a desert, fine, build a nuclear plant and use desalinized water from the ocean. Then you get all the water you need without messing up the natural progression of things.

  12. Nice simple logic. I think the alarmists will counter the title though. They contend when pushed that it is the rate of warming which is unprecedented. Mind you, they have been claiming this for a long time, and the flatlining of global temperature increase since early 1997 further undermines it.
    This ties in well with scaninavian studies on tree line heights.

  13. My wife and I went walking in the Swedish mountains back in 1993 for our honeymoon and came to the lake Pietsaure, next to Saltaluokta. You will find Pietsaure on Google Earth.
    In Sami, or Lappish if you wish, Pietsaure means the “Pine lake”. There are no pines there now, there haven’t been any for maybe 3000 years, but the name remains.
    Here is a link that discusses some of this. In Nordic languages though:
    http://www.arkeologiforum.se/forum/index.php?topic=1679.140

  14. crosspatch (23:38:31) :
    Hints of that occured in the 1840’s and 1870’s in California.
    The Indian legends of rivers going dry in N. Calif in 1840’s are recently found to tie into the Columbia River record lows, and in 1870’s the Stanislaus and Mokelumne Rivers went dry.
    In the Younger Dryas period, the State is modelled as being Semi-Arid.

  15. Geoff Sherrington (14:27:31) :
    The obvious question is, which part of a suckered tree mass to you core? The different suckers have time-variable interactions with each other, with ones now dead, whith new ones just sprouting. It’s like a big family of children dividing up the breakfast porridge. Some will end up with more tree ring than others, in a manner unpredictable, that has a good chance to interfere with the temperature record.
    It would still be in the realm of SPDC to core them all. It’s a relatively small cluster. Taking two cores at 90 degree angles from each tree (assuming permission could be obtained) would still be in the SPDC realm. How these then should be averaged would be a whole different ball game, requiring some statistical and dendro skills. This averaging of the cluster might show believable growth curves.
    Regardless of the warming record shown by rings, Mr. Fields says that one objective is to get a record of the elder tree’s absolute age, to see whether it started at a warmer period. This an SPD-expedition could accomplish with relative ease.

  16. @fred (16:21:15) :
    Good point. I believe USHCN does some adjustment, but this is data before it has been though the GIStemp homogenisation process. The Giss site has been down so I couldn’t check last night.
    Tahoe City – GIStemp pre-homogenisation:
    http://data.giss.nasa.gov/cgi-bin/gistemp/gistemp_station.py?id=425724880010&data_set=1&num_neighbors=1
    Tahoe City – GIStemp post-homogenisation:
    http://data.giss.nasa.gov/cgi-bin/gistemp/gistemp_station.py?id=425724880010&data_set=2&num_neighbors=1
    Not one of the worst adjustments – for a “Hall of Shame” (IMHO) see:
    http://diggingintheclay.blogspot.com/2009/11/how-would-you-like-your-climate-trends.html

  17. Richard Heg,
    Thanks for posting that [unintentionally] funny link. Some choice quotes:
    ***
    “In the sense of reducing atmospheric CO2 concentrations, it is actually a good thing that these old trees are kicking into life again,” says Jinbao Li of the Tree Ring Lab at Columbia University in Pallisades, New York.
    ***
    “This is a cautionary tale,” says Michael Mann, who uses tree rings to gain insights into past climates at Pennsylvania State University’s Earth System Science Center, most famously to create the ‘hockey stick’ graph showing an increase in temperature. “Only the human impact of increasing greenhouse gas concentrations can explain that warming.”
    [But they don’t mention that Mann’s hokey stick graph has been repeatedly debunked.]
    ***
    Christof Bigler… says that if the ancient trees grow more rapidly they may simply die younger.
    ***
    “Temperature only explains about a quarter of the variance in ring-widths, so CO2 fertilisation could still play a minor role.”
    Huh? Then what explains the rest of the growth? They don’t say.

  18. Well Larry, It looks like we gave Michael Mann and NewScientist a pepto bismalt moment.
    Big Al has the same ulcer acting up from CCI and PETA.
    I like to think, as he reachs for the antacid, that some few of those calcium tablets he pops, are popped on our account.

  19. Well familiar with the area in question and concur. More generally, everywhere I’ve been in the Sierra around tree line it’s pretty obvious that things are not all that warm, geologically speaking. If the Sierra is teetering at some sort of inflection point, if any, it’s an inflection point that would lead in the direction of much more extensive glaciation than now seen.

  20. To filk an old saying:
    Six months, ago I couldn’t even spell dendroclimatologist. Now I are one.
    That said, I’d like to respond to phlogiston (14:20:28):
    “Is it possible to date the clone-groups of Whitebark Pines at Round Top Lake – when each one began? Perhaps carbon dating?”
    Dating an individual clone-group is not a trivial exercise. If expense was not a consideration, we could go with DNA. Scientists are already doing that in the Mitochondrial Eve (ME) research. It’s a 4-step process:
    1. Quantitate the differences in mitochondrial DNA from living humans from all over the world.
    2. Assume that there was a single ME for all living humans.
    3. Measure the current mutation rate for human mitochondrial DNA (mDNA), and assume that it’s essentially constant.
    4. Use the above plus random-walk theory to arrive at a rough estimate for a hypothetical ME.
    As is the case with all measurement-based quantities, there are uncertainties and nuances. For openers, ME is not unique.
    If we include the 40-thousand-year-old remains of Mungo Man from New South Wales (in which some mDNA has been preserved) in our sample, then that ME is considerably older than the one that’s commonly reported in the popular press.
    In the case of the clone-groups at Round Top Lake, we could take DNA samples from trees at opposite ends of the clump, and attempt to use a similar methodology. However at best, we’d only get a ballpark figure for the age of the clone-group.

  21. Jon Adams (17:21:24) :
    One more puzzle piece.
    Perhaps, we need more backpackers with GPS and cameras…

    I bet a systematic search of the web for back packer pictures of popular destination lakes would yield at least 20 years worth of record. Those destination lakes are very frequently photographed to document trips, and in all the “hiking guides” on the web an enterprising graduate student could dig though google searches for peoples hiking documentary blogs and pull up lots of old pictures of the same or very similar view.
    It is not uncommon for folks to include pictures of “the last time we were here” shots showing children at a young age etc.
    Larry

  22. –In terms of the debate surrounding the ‘unprecedented’ global warming of the late 20th Century, Round Top Lake is ‘the elephant in the room’–
    Is that a bad pun, relating to The Elephants Back, a broad mountain just down the trail from Round Top Lake?

  23. In response to my elephant-in-the-room metaphor, Brian B (15:37:58) wrote:
    “Is that a bad pun, relating to The Elephants Back, a broad mountain just down the trail from Round Top Lake?”
    I am fond of puns, but that connection had not occurred to me. Usually I label the obscure puns. 🙂

  24. Here’s another warmer:
    “Increasing temperatures at high altitudes are fueling the post-1950 growth spurt seen in bristlecone pines, the world’s oldest trees, according to new research.”
    […]
    “There is increasingly rapid warming in western North America,” said Hughes, a UA Regents’ Professor of dendrochronology. “The higher you go, the faster it’s warming. We think our finding may be part of that whole phenomenon.”
    http://www.sciencedaily.com/releases/2009/11/091116163206.htm
    http://www.pnas.org/content/early/2009/11/13/0903029106

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