From Baylor University, a suggestion that leaves are a better paleo-proxy than tree-rings:
New Baylor Research Shows Using Leaves’ Characteristics Improves Accuracy Measuring Past Climates
NSF-funded study shows high promise for new method to estimate temperature, precipitation for ancient ecosystems
A study led by Baylor University and Wesleyan University geologists shows that a new method that uses different size and shape traits of leaves to reconstruct past climates over the last 120 million years is more accurate than other current methods.
The study appeared in the April issue of the journal New Phytologist and was funded by the National Science Foundation.
“Paleobotanists have long used models based on leaf size and shape to reconstruct ancient climates,” said Dr. Daniel Peppe, assistant professor of geology at Baylor, College of Arts and Sciences, who is an expert in paleomagnetism, paleobotany and paleoclimatology. “However most of these models use just a single variable or variables that are not directly linked to climate, which obviously limits the models’ predictive power. For that reason, they models often underestimate ancient temperatures.”
Baylor geology researchers, along with 26 other co-authors from universities around the world, collected thousands of leaves from many different species of plants from 92 climatically-different and plant-diverse locations on every continent except Africa and Antarctica. Multiple linear regression models for mean annual temperature and mean annual precipitation were developed and then applied to nine well-studied fossil floras.
The results showed:
• Leaves in cold climates typically have larger, more numerous teeth, and are more dissected. Leaves in wet climates are larger and have fewer, smaller teeth.
• Leaf habit (deciduous vs. evergreen), local water availability and phylogenetic history all affect the relationships between climate and leaf size and shape.
• The researchers’ multivariate mean annual temperature and mean annual precipitation models offer strong improvements in accuracy and precision over single variable approaches. For example, the mean annual temperature estimates for most of North American fossil floras were considerably warmer and wetter and in better agreement with independent paleoclimate evidence. This suggests that these new models offer the potential to provide climate estimates that will help scientists better understand ancient climates.
“Our study demonstrates that the inclusion of additional leaf traits that are functionally linked to climate improves paleoclimate reconstructions,” Peppe said. “This will help us to better reconstruct past climates and ecosystems, which will allow us to study how ecosystems respond to climate change and variations in climate on local, regional and global scales.”
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Since they have not included the actual paper with the Baylor press release, and didn’t even give a title for the paper, I have not been able to figure out which paper it is in the April edition of New Phytology here. Maybe some readers with more time than I can figure it out and leave a comment.
Three things make me just as skeptical of this claim as of tree rings being a good proxy for past temperature:
- Liebigs Law, which I cover in detail here: A look at treemometers and tree ring growth
- The revelation that leaves seem to maintain a constant temperature: Surprise: Leaves Maintain Temperature, new findings may put dendroclimatology as metric of past temperature into question
- How do you calibrate such a thing? If using modern leaf response as a baseline, how do they know the response millions of years ago was the same?
I’m sure we’ll learn more in discussion.
I am disappointed with many of the immature attacks here thrown at the cited paper. Most attackers probably didn’t read the paper and are not qualified to judge it. It appears that we have pre-conceived notions and ideological biases, exactly what some warmists are guilty of. Lets stick to the science and cool the insults. I will be reading the link to Dana Royer’s work given by Leif as it sounds quite interesting. Are some of you afraid that this research will support Mann? I personally just want the truth.
Major civiliazation collapse and barbarian invasions as one region’s climate tanked and neighboring regions soared are anchoring events.
A strange phenomenon is that Climate Change often preceeds economic and agricultural collapses, as nature rubs salt in self-inflicted wounds.
A lot of research has been done on leaf stomata which totally invalidates the ice core data, a good place to start is the work by Dr. Friederike Wagner of Utrecht University I could post a whole string of references, there are also some very good papers analyzing the shortcommings of ice core results which are well worth looking up.
As many others have pointed out, the simple fact that trees vary on the same tree and between individual trees makes this as ‘scientific’ as reading tea leaves.
In the wonderful world of over-simplification:
“Leaves in cold climates typically have larger, more numerous teeth, and are more dissected. Leaves in wet climates are larger and have fewer, smaller teeth.”
How about the huge leaves of devil’s club in a cold wet climate?
There is clearly way too much money and way too many researchers if this kind of garbage is supposed to be a worthwhile project.
And if we cut all this funding, the world would be a much better place.
OT: the return of the polar bear on his Smol ice float…
http://www.vancouversun.com/Arctic+coastline+shrinking+faster+than+predicted+Study/4637395/story.html
Worse than we thought…
Well-said, and an important corrective. Anthony often posts articles about papers that offer interesting, even important, contributions to science and have no necessary or obvious connection to the Realist (‘Skeptic’) versus Alarmist climate wars.
Understandably, readers here have their antennae out for any hint of Warmist BS, but as Duster says, just using the terms ‘model’ or ‘climate’ should not trigger an alert. Little did I know that leaf morphology is an accepted area of study in paleo- studies, and an important tool in understanding ancient environments. It’s great to learn new things. That’s why this is an award-winning science blog, not just an anti-CAGW blog, though it does of course play an important role in disinfecting that canker.
/Mr Lynn
I am, so far, scratching my head… You could draw some broad based general conclusions about the micro climate around the tree (or trees), but you have to make so many assumptions its hard for me to understand there could be any “accuracy”; no more than tree rings anyway
If you happen to study an area that humans occupied you might decide the climate is temperate and warm, when in reality the humans occupied the most comfortable (temperate and warm) micro-climate available to them (near the coast, in a valley, by a lake). That doesn’t mean most of the area further away isn’t colder, or dryer… So how do you draw a conclusion on the climate? Other than the tree grew nearby and that tree likes this type of climate?
Well, its interesting, but I really would like to find a more direct physical proxy for temperature and a separate one for “wetness” – like a chemical reaction, then use a biological proxy like leaf shape.
I had heard about at least one study similar to this some time back. It seemed in that particular study of leaves, at that time yet to be reviewed, “solved” the problem of the (alleged) disconnect between the temperature during parts of the Miocene and the carbon dioxide levels.
Just don’t anybody bring up the ‘reindeer crap’ thing, ok?
This is an interesting approach, though still very much in the early stages of development. It won’t develop chronologies, but could reasonably characterize local and regional climate regimes. It needs a much larger database of samples since Europe, Africa, and most of Asia are unsampled. I’m a little concerned how they related leaf characteristics to modern temperatures (a model with 1km gridding) and I’d want to know more about phenotypic plasticity among the dozens of species they examine.
reconstruct past climates over the last 120 million years is more accurate than other current methods.
Ummm perhaps going back 10,000 might make sense but going back further millions of yeas back into history i think the problem that the trees evolve and we have no idea of the evolutionary paths that modern trees took.
There is no reason to think that leave shapes and sizes followed the same climate patterns as modern trees do now.
For all we know a 10 million year old fossilized leaf pattern is the shape and size it is because it had adopted to a peristaltic moss that long ago went extinct…and we end up with a climate 10 million years ago that is several degrees off because of it.
I’m certainly skeptical and withholding judgment at this point, but it is very interesting that they say: (i) current methods (read existing tree-ring reconstructions, among others) don’t cut it, and (ii) analysis of tree leaves shows a warmer past, consistent with other evidence (and inconsistent with the hockey stick).
It sounds like these researchers are open to the possibility that the past was warmer and that the hockey stick is unreliable. Are the tree leave proxies going to hold up under additional scrutiny? I don’t know. But it is good to see a different line of research, in the peer reviewed literature, using a different proxy, that comes to a different result than the Team got. Before completely trashing this study, let’s at least recognize it as, at a minimum, one more welcome stake in the hockey stick coffin.
Zeke the Sneak says: April 18, 2011 at 3:39 pm
“Any tea leaves in this new improved highly promising model, by chance?”
Nope, Coca leaves maybe, or perhaps Khat leaves. Coca does seem more likely though, sort of matches the timing of the start of the big lie and the mindset of the believers.
http://northernwoodlands.org/discoveries/tree_leaves_regulate_their_own_temperature/
Tree Leaves Regulate Their Own Temperature
“Seventy degrees? Well that’s just about the perfect temperature, isn’t it?
It turns out we’re not alone in our admiration of the 70-degree mark. According to scientists at the University of Pennsylvania, trees around the world strive to maintain a near-constant temperature of 70 degrees in their leaves. This finding contradicts conventional wisdom that assumed leaf temperature mirrored that of the ambient air around it.”
Turns out that 70 F is also the most common average temperature for the earth for the past 600 million years. As compared to 55 F today.
http://www.geocraft.com/WVFossils/Carboniferous_climate.html
So if the earth has been 15F warmer on average for most of its history, and both trees and humans like it warmer, who is to say that most of the other life on earth won’t like it warmer as well? It seems a stretch for the IPCC and others to forecast global disaster at a 2C temperature rise. Heck, it goes up and down at least 10C where I live every day.
““solved” the problem of the (alleged) disconnect between the temperature during parts of the Miocene and the carbon dioxide levels.”
Temperature has been at 22C for most of the past 600 million years, regardless of CO2 levels. The disconnect is between reality and the followers of the church of algore.
http://www.geocraft.com/WVFossils/CO2_Temp_O2.html
the question for humans going forward is do we really want to see the northern hemisphere under a couple of miles of ice, which is the most likely future based on historical records. Or would we instead like to return to the 22C that is more normal for the planet? If CO2 does indeed affect warm the planet, then rather than destroy the future, we could well be saving it. We should make sure before spending our future tilting at windmills.
Andrew30 says: Nope, Coca leaves maybe, or perhaps Khat leaves.
Well, what’s a little stimulant/dopamine reuptake blocker when you are a hardworking “researcher,” “collecting leaves” from almost every continent? It is a big job, after all.
“Are some of you afraid that this research will support Mann? I personally just want the truth.”
The case is worse than i thought…so the leaves will say it is Co2 plus will show the last 100 years of temperature up to 0.1 degree precision?
This seems like a long shot to me, and if more accurate than other paleo-proxies, than that just shows how poor the others really are!
One example that springs to mind is the tree Totara (Podocarpus totara), this is a tree unique to NZ and evolved in a much warmer climate, hence it grows faster than current when grown in an artificial climate. However, it also seems well enough adapted to grow as far south as Christchurch and further south, only it grows very slowly. To me this would suggest that it either changes it grow rate to suit the climate (as per tree ring studies) or it has not yet adapted, as the adaption process is very slow and as the climate in NZ has only been cooler for the last few thousand years, it has not yet had time to catch up – and there is the issue – do leaves adapt immediately to the climate on a annual timescale, or do the leaves change on an evolutionary basis over hundreds or thousands of years, and if so, than it will be an adaption to an average climate over time, or will only occur if stable for prolonged enough periods – hence I would seriously question the validity of such a tax payer funded jolly
Mike Bromley says:
April 18, 2011 at 3:05 pm
crosspatch says:
April 18, 2011 at 2:10 pm
Oh for crying out loud. As they get more desperate, they start grasping for ever more subjective ways to validate their hypothesis.
Exactly. It’s all boiling down to model validation. Model this, model that, if the model says so, etc., etc. Oops!!! The MODEL was wrong, have to recalibrate! Let’s see: While we do that, let’s just add another decade to the predfiction date to buy us some time, and watch the cash roll in, because in our grant application, we mentioned “temperature”.
How collossally transparent and tiresome, all at the same time.
Why stop at leaf morphology and tree rings?
Why not stop all scientific research. One can never be sure of anything.
Scientists have no idea about what they are doing and are constantly wasting our money. Let us invest in a sure thing – the ignorance of the general public.
Tree rings and leaves are both organic and suffer the same inputs so neither is more reliable than the other.
Anthony Says:
Three things make me just as skeptical of this claim as of tree rings being a good proxy for past temperature:
1. Liebigs Law, which I cover in detail here: A look at treemometers and tree ring growth
2. The revelation that leaves seem to maintain a constant temperature: Surprise: Leaves Maintain Temperature, new findings may put dendroclimatology as metric of past temperature into question
3. How do you calibrate such a thing? If using modern leaf response as a baseline, how do they know the response millions of years ago was the same?
I’m sure we’ll learn more in discussion.
All three of third points seem wrong to me.
Liebig’s law doesn’t apply here, because the researchers are looking at multiple variable morphological analysis. All morphological variables do not respond in the same way to environmental variables that determine leaf morphology. In that way the impact of different combinations of environmental variables can be determined.
The variables in tree rings are latewood density and ring width. These are combined with position in the range of the trees in an attempt to tease out the role of different environmental variables.
Since we know that all climates don’t have a constant temperature, in order to keep a constant temperature during growth, the morphology of leaves has to change. The same may be said of humidity. Since the interior of leaves has to have liquid water, the morphology of leaves in a dry climate has to be different from the morphology of leaves in a wet climate.
The third point is similarly misguided. Photosynthesis is based on physics and chemistry which is unchanging, and evolution optimizes the formation of plants over time to grow in different environments. The paper itself answers the question of how plant evolution has worked to optimize the features of plants to survive in different environments and provides the calibration.
It seems to me that your skepticism is driven more by a desire to have the science shown to be wrong, than by an understanding of the underlying science, but I could be biased as well. At any rate, the experts in paleobotany, who study this stuff 24/365 are the ones who will sort it out over time. The number of experts, and the number of graphs, and the number of cititations make the paper quite impressive.
One great proxy of climate past are the leaf fossiles in the Spitsbergen… Aren’t we lucky the ahmosphere did not boil into the space and turn earth into venus2 😉
Having read the abstract only (am getting tired of having to register at every publication online …), perhaps those who have read the article can say something about the methods used, e.g. where did these leaves come from, stratigraphically.
I’m asking this because of two concepts which must play a role in their methods, but which weren’t mentioned in the abstract.
One is ‘taphonomy’ – which addresses why stuff found in the ground ended up there, and from where it originally came. It is very important in environmental archaeology.
The other is something botanists must know and address: ‘environmental plasticity’.
It isn’t just weather/climate which has an influence on leaf size …
Oh – and perhaps it’s worth mentioning that very young trees (up to about 5/6 years old) tend to have leaves much larger in size than old trees of the same species …
Next up, palm reading as a form of climate prognostication!
🙂
“We applied our multivariate models to 10, well-studied, latest Cretaceous to Eocene fossil floras (Table 1). We emphasize that the climate estimates presented here are provi-sional until the potential confounding effects already discussed (especially phylogeny and leaf habit) are more fully accounted for. Nonetheless, we feel an initial application of this new approach is warranted and demonstrates its promise.”
Sites and their age in My:
Fox Hills 66.5
Williston Basin I 65.5–64.0
Williston Basin II 64.0–63.0
Williston Basin III 61.0–58.5
Palacio de los Loros 61.7
Cerrejon 58
Hubble Bubble 55.8
Laguna del Hunco 51.9
Republic 49.4
Bonanza 47.3
And about the recent leaves analyzed:
All leaf images used in this study are available from Dryad (http://dx.
doi.org/10.5061/dryad.8101) and the personal websites of DJP and DLR.