A new paper has been published in the journal Nature entitled: ‘Subtropical to boreal convergence of tree-leaf temperatures’ by Brent R. Helliker & Suzanna L. Richter, which has implications for climate reconstructions using tree ring data.
The Abstract states:
The oxygen isotope ratio (18O) of cellulose is thought to provide a record of ambient temperature and relative humidity during periods of carbon assimilation. Here we introduce a method to resolve tree-canopy leaf temperature with the use of 18O of cellulose in 39 tree species. We show a remarkably constant leaf temperature of 21.4 2.2 °C across 50° of latitude, from subtropical to boreal biomes. This means that when carbon assimilation is maximal, the physiological and morphological properties of tree branches serve to raise leaf temperature above air temperature to a much greater extent in more northern latitudes. A main assumption underlying the use of 18O to reconstruct climate history is that the temperature and relative humidity of an actively photosynthesizing leaf are the same as those of the surrounding air. Our data are contrary to that assumption and show that plant physiological ecology must be considered when reconstructing climate through isotope analysis. Furthermore, our results may explain why climate has only a modest effect on leaf economic traits in general.
There is a summary of the paper in Nature News here.
The authors state in the text of the article:
“Our analysis shows that reconstructing ambient humidity by using tree-ring d18O becomes increasingly dubious as MAT [mean annual temperature] decreases. Caution is therefore advised when interpreting treering d18O data from high latitudes for both contemporary samples and samples of relictual wood from high-latitude forests of the past.”
and:
“The discovery of relatively invariant leaf temperatures has two important ramifications that transcend stable-isotope studies. First, elevated canopy temperature and depressed leaf relative humidity should have a large effect on real and modelled water loss from boreal ecosystems. Second, if the architectural controls of branches on leaf temperature are as widespread as our data suggest, then direct climatic selection on the evolution of leaf traits would be relaxed, whereas the selective force of climate on other plant organs (for example stems and roots) would remain. Our results therefore offer a possible explanation for the unexpected finding that climate is a minor correlate with global leaf economic traits.”
Roger Pileke Sr’s take on this is:
This study has major implications with respect to the use of tree ring data to reconstruct long term air temperature trends, as the authors indicate in their text.
This study also illustrates the dynamic response of vegetation to their environment so as to maximize the ability to grow and compete within their ecological environment. This biological effect must be incorporated within climate models that seek to accurately simulate the response of the climate to human and natural effects, including the increase of the atmospheric concentration of CO2.
Jennifer Marohasy BSc PhD is a critical thinker with expertise in the scientific method.
Another story along the lines of “We don’t know anything perfectly, so we know nothing”.
If we took that attitude with every line of science, we’d still be living in the middle ages. Newton was wrong, Einstein was wrong, the current scientists are all wrong. They don’t know anything perfectly.
Yes we do SJT – “the science is settled!” No need for more inconvenient climate research.
If I was Dana Royer, I would be very depressed right now.
For quite some years now Dana has been a leading figure in the ‘consensual’ group of paleoclimatologists who claim the paleoclimatic record shows CO2 has generally been the major determinant of paleoclimates. Dana obtained extra kudos by publishing a number of papers with the ‘grand old man’ of paleogeochemistry Bob Berner.
https://wesfiles.wesleyan.edu/home/droyer/web/publications.htm
Dana’s whole career as a paleoclimatologist was built on the widespread use of leaf species and stomatal indices as proxies for past temperature and CO2 concentrations and rolled on like a stream train despite the odd cracks in the edifice of his body of work popping up at regular intervals e.g.:
Do extant nearest relatives of thermophile European Cenozoic plant elements reliably reflect climatic signal?
Palaeogeography, Palaeoclimatology, Palaeoecology, Volume 253, Issues 1-2, 14 September 2007, Pages 32-40
Zlatko Kvaček
So far it has not been seen in the scientific careers of pillars of the AGW establishment that one single paper comes along to destroy more or less the whole basis of that career (yet) but I’d say this is once such occasion.
SJT, Newton and Einstein weren’t as wrong as “the consensual ones”.
It’s better to be like Christy and admit it than like Hansen and wing it.
As Einstein once remarked about 400 scientists who disagreed with his theory of relativity, “you don’t need so many, only one is needed to refute it”.
There is one troubling implication with this paper, how many past geological CO2 estimates were made on leaf stomata? I sense a paradigm shift over the horizon.
This fetid AGW charade is a charade! It is a travesty that gore got a nobel and McIntyre is still out there plugging away; Mann is still being feted over at dingbat sites like tamino’s and for what? Mann based his hockey stick on Graybill’s 1993 Bristlecone study; McIntyre has exposed this and, in 2006, Ababneh published her more extensive study from the same Bristlecone source as Graybill’s and it was completly different, showing that the MWP was warmer than today.
Oh what utter bollocks Cohenite. 0.00001% of the literature. Do go on. And 1000 denialist blogs are sprouting shit every day – why not get upset about that too?
So how do we get from O18 to stomatal indices?
And what AGW papers are using O18 in plants?
Luke,
now we discover your physical ignorance.
Louis,
how does water act as a GHG?
SJT
Water isn’t a gas, it is a liquid.
Water vapour Louis, you clever little fox you.
Water vapour behaves like a gas.
There is evidence for both a cooler and a warmer MWP, but the UN IPCC TAR and AR4 were biased towards a cooler WMP.
SJT,
Reading what you have posted here, and the replies, only leaves one conclusion.
I am from a culture which avoids impolitness.
Paul
Not according to physics – liquids and gases have separate propeties. Missing from discussions about liquids and gases is the electrical input.
Sceptical observers have pointed to the effect of charged particles on the earth’s atmosphere on clouds.
“Not according to physics – liquids and gases have separate propeties.”
If you want to model their dynamics, liquids and gases are pretty much the same. It’s the water vapour that’s a GHG. You have said many times, Louis, that water vapour is the most powerful GHG. How does it do that?
SJT,
dumb is dumb pal.
Perhaps I should have said water vapour behaves like a greenhouse gas:
http://physicsworld.com/cws/article/print/17402/3/pwten5_05-03
Bollocks? What is this, a Monty Python blog?
Parrot, what? it’s not dead.
Look at it! It’s AGW, Mummufied.
C’or blimey, talk about thrashing a dead parrot,
fx,
rendition of Life of Brian final scene……
“If you want to model their dynamics, liquids and gases are pretty much the same.”
Just what sort of education and/or training and/or elective surgery is required for expert modelling of climate dynamics?
The (18)O isotope measurements are dependent on a lot of things, and not just temperature. These measurements must be latitude dependent, for example; as the length of a day varies, so do the length of cycles of plant photosynthesis and respiration during the night – and the fate of the water oxygen is certainly not the same for both cases
It strikes me as odd that every tree is quipped with an inherited coping mechanism for a global warming which is supposedly unique/umprecedented.
Yes that’s why trees hundreds of years old die in unprecedented drought. Get real.
“SJT,
dumb is dumb pal.”
Simple question, Louis. How does water vapour work as a greenhouse gas? You do think it is a GHG?
SJT
It does not work as a greenhouse gas, it works as a liquid phase to block the convection of heat in air to space. Same reason a greenhouse works – a physical barrier to stop the hot air inside mixing with the cooler outside.
No I do not think it is a gas – since when have clouds been described as a gas?
Hundred year old trees die of many reasons, old age, root disturbence, insect attack, chainsaw.
As long as they send out seed there will be a next generation to suck up that carbon.
I believe a chap by the name of Darwin had some thoughts on the selection of species that match the environment they are growing/living in.
allan
good comment – Luke and his loonies probably realise that changing environments mean the eradication of them, hence the extraordinary efforts to preserve the existing environment.
And they, pejoratively, describe us as conservatives.
Touche!
Bit of a strange series of posts about water in liquid and gas forms. They do behave quite differently, clouds are water and reflect incoming and outgoung radiation but in general the greater reflection of the incoming causes a negative forcing. The vapour or gas has resonant frequencies in the 4 to 5 micrometer band so it absorbs outgoing but has little effect on the incoming. CO2 has resonant frequencies in the 2.5 and 15 micrometer band and since the peak of the stefan boltzman spectrum curve at 20 deg C is at about 9.3 micrometers the CO2 is only effected by the tail end of the outgoing radiation frequencies whereas the water vapour collects much more from the area closer to the peak thus water vapour is a much more powerful greenhouse gas ( which is a very misleading term because glass is opaque to all IR frequencies and the gasses are highly selective)
Luke cried:
“Yes that’s why trees hundreds of years old die in unprecedented drought.”
That’s your survival of the fittest at work. Without it you would still be a one cell organism according to Darwin and some of the brightest CFL’s of evolutionary theory!!
“Water isn’t a gas, it is a liquid.”
At or near standard temperature and pressure (1 ATM, 0 deg. C) plus or minus 50 deg. C (i.e., the range of temperature extremes on earth), water can act as BOTH a gas and a liquid. Equilibrium vapor pressure is the pressure of a gas exerted by a system at equilibrium. It is a function of temperature. In temperate climates, the water vapor (H2O in the gas phase) comprises about 2% of the atmosphere.