New paleo study "leaves" me skeptical of the claim

There’s also the variation in stomata in leaves to consider, but that relates directly to CO2 availability. More CO2 = smaller/fewer stomata, and hence reduced water transpiration/loss/use = higher productivity.

and they are calibrating these leaf temperatures against what………………

As everyone know, the leaves at the bottom of a tree are usually different in size and thickness that those from the top of the tree. How do they know they have a bottom or top leaf fossil?

So how do you acount for changes in trace gas levels (including CO2) light levels (yes, oddly enough plants depend on sunlight, a bit like ourselves) and other variables, such as rainfall, air pollution (or didn’t they have volcanoes and forest fires back then?) mineral changes, animal and insect population changes (yep, they eat leaves) and deseases.
But hey, lets use these ever so accurate measurements to base the spending of countless trillions of dollars on, after all that’s what we are doing with tree rings. Not that using that money to acutally clothe, feed, medically care for and educate folk might actually be a better idea (duh!).
As interesting as these studies are, should public money really be funding them? Haven’t we got more serious things to do with our limited academic funds?

I read the summary of Peppe’s paper and when I came to this … “This work also illustrates the need for better understanding of the impact of phylogeny and leaf habit on leaf–climate relationships.” … I became aware of what was at the root of the initial study.
They want more money to continue looking at the remnants of old vegetation.
If I was the financier, I’d just say “Endex!”
(Those with a background in any disciplined service will understand that!)

Have the paleo-community considered constructing a temperature history from fossilized straw?
(Though, I am sure that even the least clairvoyant among us can guess the shape that such a temperature chronology would possess.)

The word model is frightening me . A climate model based on past paleo-records of leaves ? It is sounding to me like indian hocus-pocus . Do these researchers , who are most probably paid by governmental donations , make their basic materials available for other scientists or will they also block FOI – requests as usual with alarmists ?

Leif Svalgaard says:
April 18, 2011 at 1:41 pm
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?
Dana Royer has some good research on this:
http://droyer.web.wesleyan.edu/research.htm
Personally, I think the method is sound and has a lot of promise.

I thought you might, sir. What’s in a name, eh? 😉

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.

Lonnie E. Schubert says: April 18, 2011 at 1:42 pm
I’m skeptical how one dates leaves?
Like a panda … who Eats, shoots and leaves!

In perusing some of the more panicky, skeptical responses here, it seems pretty clear that some of us need to learn to read and watch that old knee-jerk response. It is also evident that a primer on alternative means of dating geological evidence would help some of us. Then there are “skeptical” responses that are strictly political when the persiflage is peeled away. While politics can insert itself into science, and scientists are often encouraged to be more “active” these days, there is simply no reason to presume that science, “paleoclimate” and politics are chained together at the ankles.
For example, only in “climate science” will you see “paleoclimate” attached to studies for time periods in which there are historical records available. Geologists would laugh at the idea, while archaeologists (prehistorians anyway) would tend to smirk. “Paleo-” simply isn’t applied to periods with written records. The article, and leaf geometry studies in general, looki at much longer periods than “the team” is interested in. In fact, even 8,000 years ago the word “unprecedented,” as employed by the team, loses any significance. When you are stomping around 120 mya, the present looks like what it is – an Ice Age. So, please, leave off the hysteria; “model” and “climate” are not necessarily bad words. Leave it for warmists. We are in a cold climate period and have been for a (geologically) long time.

What is needed as with all these claims is validation.
So give the researchers some leaves from trees where the temperature (and all other weather variables are known. Ensure that some leaves are from the top of the tree others from the bottom, some are from a tree at the top edge of the forest and others are from trees in the middle of the forest by a river etc etc. In other words standard validation testing technique. Then have them use their clever model to tell you what the weather conditions were in which the leaf grew. No ‘clever tricks’ just straightforward validation testing. Perhaps enhance the impact of the testing to include the loss of tenure for any results less than 50% correct – it would concentrate their minds before making claims that they have not tested themselves.
This is relatively basic undergraduate level experiment design – perhaps these people have forgotten what that is?

Another suggestion for Baylor researchers:-
Would you recommend using tree leaf size, and number of points as a Temperature proxy to control the operation of a Nuclear reactor; if not; Why not ??

@jorge
Paleospeleochiropterocoproclimatology.
What a magnificent word!
Maybe a shorter version could find popular usage:
Coproclimatology.
Reminds me of a UN panel for some reason…

Quite some time ago in the “Tips and Notes” section, I left this link:
http://www.pbs.org/wgbh/nova/nature/arctic-dinosaurs.html
Robert Spicer
Paleobotanist, Open University, UK
cepsar.open.ac.uk/pers/r.a.spicer/p5.shtml
Dr. Spicer has done quite a bit of work on this

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.

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.

Duster says:
April 18, 2011 at 3:57 pm
In perusing some of the more panicky, skeptical responses here, it seems pretty clear that some of us need to learn to read and watch that old knee-jerk response. It is also evident that a primer on alternative means of dating geological evidence would help some of us. Then there are “skeptical” responses that are strictly political when the persiflage is peeled away. . .
The article, and leaf geometry studies in general, look at much longer periods than “the team” is interested in. In fact, even 8,000 years ago the word “unprecedented,” as employed by the team, loses any significance. When you are stomping around 120 mya, the present looks like what it is – an Ice Age. So, please, leave off the hysteria; “model” and “climate” are not necessarily bad words. Leave it for warmists. We are in a cold climate period and have been for a (geologically) long time.

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 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.

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.

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.

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

Tree rings and leaves are both organic and suffer the same inputs so neither is more reliable than the other.

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 😉

Next up, palm reading as a form of climate prognostication!
🙂

Leif Svalgaard says:
April 18, 2011 at 4:38 pm
Ian W says:
April 18, 2011 at 4:21 pm
What is needed as with all these claims is validation.
So give the researchers some leaves from trees where the temperature (and all other weather variables are known. […]
This is relatively basic undergraduate level experiment design – perhaps these people have forgotten what that is?
What makes you think that the claim is not validated? See their Figure 2. Did you even read the paper?
Show me where they can show that summers are 35 deg C and dry while winters were wetter and as low as minus 3 deg C – the kind of temperatures and differences that are being argued that made the MWP more or less warm than today. I am sure (as Dana Royer’s research makes plain) that the size and shape of leaves found as fossils in certain geographic localities varies after a period of time dependent on temperature and water availability and possibly also on CO2 availability. but showing that the climate at a particular position geographically tends to favor certain sub-species with a particular leaf shape is a not the same as being able to say what the actual atmospheric temperatures were.

Well I don’t have any problem with Botanists looking at tree leaf fossils, and looking for apparent patterns of variation.
But when it comes to global climate we are making critical decisions based on changes of hundredths of a deg C; and that out of a data range, the extends from about -90 deg C to about +60 deg C total range possible on any northern summer day. And due to a clever argument by Galileo Galilei (Italian Physicist), we can say with certainty, that on any continuous path between the two points having the two extremes of Temperature, can be found some point(s) having any and every possible Temperature value between those extremes. And there are an infinite number of such possible continuous paths, and points.
So no, I really don’t care how interesting this Botany paper is; I’m just not into leaves (but I’m glad some others are). But it’s a far cry from some leafy patterns, and major global economic disruption based on how many points are on the fossilized leaf of some ancient tree. I like reliable Thermometers please, if we are going to talk about Temperatures; and if we want to know hundredths of a degree C, then I want good thermometers; not some flimsy non-linear resistor, and certainly not an old leaf.
I’m sure that there are a lot of other variables that determine how many points there are on some tree leaf, or the fossil of a tree leaf. I’d like to see a breakdown of say just the top ten tree leaf point count adjusting variables, including Temperature (where/when), which properly apportions the number of points etc, to the various and sundry variable that determine that.
Is Temperature 37% of the count; of maybe 75%; perhaps rainfall, is only 12% of the count. Well give us a breakdown of all the leading variables (well only the top ten.)
We laugh about the Yamal, hockey tree; how often do you run across a fossil leaf ?

Perhaps some clarification is in order here. There is no doubt that this method is sound in principle. If you know a bit about botany it is easy enough to predict the climate in any area approximately based on leaf shape and size. However temperature is not the only significant variable, moisture and wind also have an influence.
Also, this is not a year-to-year or even century-to-century technique. Leaf shapes are actually remarkarkably conservative from an evolutionary point of view.
If you compare for example leaves grown in Washington DC today and, say, 15,000 years ago you would certainly notice a large difference and could probably estimate the respective climates fairly well, but not because the trees have changed the shape of their leaves, rather it is the trees that move north and south with climate, so 15,000 years ago it would have been a very different set of tree species in the Washington area.
However there is something slightly ominous about that press release:
“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”
It has always been a problem that climates in the past apparently weren’t nearly as hot as they should have been according to the amount of CO2 and the orthodox climate sensitivity, so there has been a marked tendency in recent years to try and find proxies that can be made to yield higher temperatures than the traditional ones. This may be the latest try.

Anthony Watts said,
REPLY: Mr. Adler. The TONE was set by the non-inclusion of the paper in the press release. Something that I’ve griped about for a long time. If the academics want to put our PR without providing the paper, then they will have to accept the TONE that follows.
Take your comments elsewhere if you want to complain about the TONE without the paper. Or argue to these universities to include the paper, but don’t you dare blame me for not having read the paper when they don’t include it in the first place. I’d go broke having to subscribe to journals. – Anthony
The paper could actually be found easily on the Internet by Googling some of the authors and the title. You chose not to look for it and commented anyway.
REPLY: And that still doesn’t excuse the sloppy amateurish press release where they
1. Didn’t even bother to mention the name of the paper (almost unheard of in science PR)
2. Got the month it was published in the journal wrong (and yes I DID look, and it is noted in my post where I said: I have not been able to figure out which paper it is in the April edition of New Phytology here.)
3. Didn’t bother to provide the paper that was apparently free access
But you’ll defend such sloppiness by the Authors/PR office/University since it suits your points, and you then make it “my problem”, instead of placing the blame where it correctly lies, with the University.
You have no scruples Mr. Adler. As I said, take your comments elsewhere. That’s a permanent invitation to leave.
– Anthony

Surely it’s a good point and worthy of discussion. How can someone comment on a paper without reading it?