A benefit of increased Carbon Dioxide: increased efficiency in tree growth, no “Mike’s Nature trick” needed

Gosh, whouda thunk it? There goes Mann’s hockey stick. No wonder he had to truncate all the data after 1960 and splice on the instrumental record. Of course, as I’ve said before, Mann ignored Liebigs Law to make the “big lies” called “Mikes Nature trick” and “hide the decline“. Trees simply can’t be just a proxy for temperature, they are also a proxy for water, CO2, sunlight, nutrients, etc. The total growth response of a tree is the product of all environmental factors, not just temperature, something that any unbiased scientist should know and consider. Commercial greenhouse operators already know this.

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Image courtesy Jo Nova, click image for her article

From the University of Exeter: Increased atmospheric carbon dioxide makes trees use water more efficiently

The increase in atmospheric CO2 concentration has allowed trees across Europe to use their available water resources more efficiently, new research has shown.

Over the course of the 20th century, the so-called water use efficiency has risen nearly 20% from the increase in atmospheric CO2 concentrations.

These results, produced by an international research team, including experts from the University of Exeter, are reported in leading scientific journal Nature Climate Change.

Trees take up carbon dioxide from the air through tiny pores on their leaves called stomata and they lose water through these same pores.

When the CO2 concentration in the air increases, the size of the stomatal opening reduces to regulate the amount of carbon acquired which minimises the water lost. As a result the so-called water use efficiency increases.

In this study the researchers used measurements of carbon from tree-rings and computer models to quantify tree and forest responses to both climate variation and increased atmospheric CO2 concentrations.

“Tree-ring data provide one of the unique opportunities to obtain long-term records of ecosystem responses to climate change”, said David Frank, a Dendroclimatologist at the Swiss Federal Research Institute WSL and collaborator at the Oeschger Centre for Climate Change Research, University of Bern.

The researchers used data from 23 tree ring sites spanning Morocco to Norway to quantify variation in water use efficiency – the amount of water required to produce a given amount of carbon – and a basic measure of plant and ecosystem economy.

Professor Pierre Friedlingstein, Chair of Mathematical Modelling of Climate Systems at the University of Exeter and one of the authors of the report, said: “The observed water use efficiency increase, in response to atmospheric CO2 increase, is something we are able to reproduce with global vegetation models giving us more confidence in the whole ecosystem response to CO2.

“However, our models simulation also indicate that globally, other drivers, such as climate change and land use change, also impact on the plant hydrological cycle.”

“By measuring the ratios of heavy to light carbon isotopes of tree-ring cellulose we are able to reconstruct various physiological metrics such as water use efficiency and their environmental drivers”, said Kerstin Treydte co-author of this study and a specialist in tree-ring isotopes at the WSL.

On average, 100 kilograms of water released by a tree through the stomata equates to one kilogram of tree biomass created. The study showed that reduced stomatal opening increased water use efficiency by 14% in broadleaf species and by 22% in needleleaf species.

Despite the CO2 induced stomatal closure, the models showed that the consequences of a warming climate – lengthened growing seasons, increased leaf area and increased evaporation – resulted in a 5% increase in forest transpiration – the cycle of water through trees. This increase cancels out any savings in water from improved efficiency. Plants are therefore unlikely to reduce levels of atmospheric water vapour – an important greenhouse gas. It is also unlikely that plant responses to increased CO2 will substantially increase soil moisture or river run-off.

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91 thoughts on “A benefit of increased Carbon Dioxide: increased efficiency in tree growth, no “Mike’s Nature trick” needed

  1. So lots more CO2, a lot less early morning mist produced by plants (water vapour). Great. Definitely no warming then . . . . thank you.

  2. Mann’s HS was a new low in science history, since it had such dire consequences for humanity and furthered the corruption of the scientific endeavor, whereas the Piltdown Man hoax affected only paleontology and anthropology.

    • Another reason there should be some severe consequences for Mann and his enablers. I blame the academia and the climate community for not speaking up. They had to know the science and conclusions were shite. Disgraceful. GK

  3. Trees, trees, trees. I planted four generic pine trees (all the same size and variety) in a line approx. 2 metres apart somewhere around thirty years ago along an open ground facing property boundary line although there was considerable scrubby growth behind on the north side of the boundary. The boundary faced near enough due south. Recently I had them cut down, all left as an approx. 1 metre stump. One, the eastern-most, measured 54 cm across the base, the next measured 30, then 41 and the last one 34. If environmental temperature was truly a main driver of growth surely there would not have been so great a discrepancy?

    • Your result doesn’t surprise me. Morning sun is more important for growth of most plants. There might be a water factor as well, with the easternmost tree perhaps shaded somewhat from peak PM warmth.

      • It could also be random. One line of four trees is hardly a large enough sample to draw any conclusions at all.
        Tree farms, foresters, and lumber concerns plants rows of thousand of trees, stretching for miles in some cases. Generally they all grow at the same rate, but over time there will be large ones and smaller ones, and some will die.
        The edges do not grow faster, nor does the middle, per se.
        Soil depth and quality, moisture availability, sunlight and nutrients all have an effect, and these interact in various ways, some random, some not. Also, the genetic variability of the seeds can be more or less of a factor.
        As for morning sun as opposed to max sun during other times, this may be true for a plant such as a rose bush or certain types of vegetable plants in a garden, but this may have more to do with drying dew from foliage to minimize fungal pathogens from damaging the plant that anything else.

      • I didn’t mean to imply that there are not plants which do better with a western exposure and blasted by full sunlight all day. But a lot of trees and shrubs, not just low plants, are, as you know, quite shade tolerant or even shade needy.

        Not just sunshine of course affects the effect of aspect.

      • @Menicholas
        There is also inherent and substantial biological variability – people are great examples though not best analogy for a row of trees.
        Best

      • Yes Bubba Cow, I did mention genetic variability in there somewhere.
        Many commercially grown plants and trees have low genetic variability, but there is always some, except in the cases where vegetative clones (cuttings) or, more recently, tissue culture starter plants are used.

      • Mr. Hooper,
        Indeed sir, this is true.
        Not so many important food crops, but many commercially important ornamentals are adapted to and require low light (relatively speaking) conditions.
        Many of these have as a native habitat the forest understory, and are ill suited for direct sunshine except for short periods and low sun angles.
        Other examples includes the seedlings of certain species, in which the newly sprouted plant would have a hard time surviving in direct sun, but the mature form does grow out to dominate the canopy.
        Such necessity and variation is part of the reason for the ecological succession of species which occurs prior to the establishment of the mature climax forest ecosystem.

    • What was the soil nutrient regime? What about root and leaf damage at various times? Many things contribute to plant growth and can produce different phenotypic responses in genetically identical individuals.

      • Your mention of “soil nutrient” lead me to wonder if increased CO2 could reduce the quantity of fertilizer used, and consequently, the runoff that is blamed for alge growth in waterways?

      • More C available from the air might actually make addition of more other nutrients useful, since natural and synthetic chemical fertilizers generally enhance elements other than C, such as N, P or K.

      • Increasing CO2 will not reduce macro- or micronutrient requirements of plants.
        It will increase the required flux of these, as the [plants] will be trying to grow faster.
        Growing plants under nursery conditions in which growth rates are being maximized, is often called “forcing” by those in the trade, as opposed to more casual methods in which less attention is paid to maximizing each factor.
        Greenhouse plants which are being forced by the use of supplemental CO2 must have additional nutrients available or such undesirable results as internodal stretching, chlorosis, leaf spotting, premature flowering, delayed flowering, or increased susceptibility to disease due to nutrient deficiencies may occur.
        Many growers will use growth regulating hormone treatments to counteract some of these tendencies.

    • The main feeding roots are at the edge of the canopy where there is most moisture. There would be so much completion between them. Dose your spring rains come from the east?

    • You have answered your own question ..

      “If environmental temperature was truly a main driver of growth surely there would not have been so great a discrepancy?”

      Temperature is a significant driver of growth but obviously not the only one.
      Tree rings are a poor proxy for temperature.
      Everything else being equal works in a laboratory but does not apply in fields or hills.
      A first year botany student should be able to work that out.

  4. Friedlingstein is looking for real world data to support his models. His quote shows that he is one of those who think the “simulation” is reality. That within his model, the “simulated” climate change also causes changes in real world water use efficiency. His CV claims that he is a IPCC lead author.
    His understanding of forest biology resembles something from a 1970s high school science report.

    • When these guys look for real world data to support their models, they tend to get very selective. They are fussy. Although, I don’t think he will shrink the search down to the only tree in the forest that supports his work like famous Yama tree. I still laugh at Anthony’s headline from several years ago. IIRC it was “Once you’ve seen one, you’ve seen Yamal”

    • He wasn’t all wrong:

      “‘Trees cause more pollution than automobiles do,’ he opined. A little later, environmental scientists ruefully confirmed he was partially right. In hot weather, trees release volatile organic hydrocarbons including terpenes and isoprenes – two molecules linked to photochemical smog. In very hot weather, the production of these begins to accelerate.”

      http://www.theguardian.com/science/2004/may/13/thisweekssciencequestions3

    • Reagan lived in Southern California where plants like the “Creosote” and “Chamise” shrubs grow. Both fill the air with aromatic oils on hot days to the point where the fragrance can be nearly overpowering, albeit wonderful when at the lower concentrations in the atmosphere of the mountains and deep ravines.

      When fire sweeps through the area the bushes are said to explode with flames. The high concentration of oil vapor in the air also helps to create flash-overs as one can imagine when the INTENSE radiant heat of an approaching fire (especially when burning up-hill) accelerates the rate at which the oils from these plants evaporate.

      So yes the air can indeed get lots of natural oils in it in California and other desert locations.

      • Not only in deserts. Anywhere there are plants and trees. Not sure about “lots”.
        Enough to cause haze under conditions of stagnant air and summer heat.

  5. Is this an actual paper or just a statement of the obvious? This is 20-25 year old research that was being done in Finland (that I know of personally) as well as other places. I guess Nature Climate Change have to fill their pages to justify the subscription fees (I subscribe to Nature Biotech and boy do they send me a lot of adverts for NCC!).

  6. It is also unlikely that plant responses to increased CO2 will substantially increase soil moisture or river run-off.

    The exact opposite of most model assuptions.

  7. Friedlingstein is looking for real world data to support his models. His quote shows that he is one of those who think the “simulation” is reality.

    All scientific equations/formulas are in fact models of reality. By attacking the use of models, you are attacking science itself. Any complex system of interrelated components will require a system of equations, which require a computer to analyze.

    • By attacking the use of models, you are attacking science itself

      Gross conceptual error regarding what the process of science is.

      • Gross conceptual error? I don’t think you understand what models are.

        F = mA is a model of reality. (We don’t even really know what matter or mass is. We thought we did a 100 years ago. As the decades roll by, we’re less and less sure.)

        Models are not the root of all evil. Attacking models is a sign of intellectual laziness.

      • VikingExplorer May 11, 2015 at 2:17 pm says

        Attacking models is a sign of intellectual laziness.

        Accepting models as evidence is a sign of intellectual laziness. Fixed it for you.

    • Yes but climate models have not matched reality. Einstein’s and Newton’s models ( or equations ) have been tested and verified against reality. The media and ipcc are trusting models without any verification. They are accepting them at face value and this is scary and immoral.

      • “Have not matched reality” is a very Boolean expression. Science is all about floating point numbers. There has been a significant buzz during the last decade challenging Newton’s law of gravity. A recent experiment showed a 2% deviation from Newton’s Law/Model of gravity.

        A 2% error in earth’s temperature is about 6 degrees C. I would also speculate that climate models are not exactly built on first principles, or enough first principles. However, one can hardly say with a straight face that models that are off by .2 or .3 C (.06%) are immoral.

        Are they predictive? I would say not. Do I respect them? Absolutely not. Is restricting freedom based on speculative pseudo-science immoral? Yes, absolutely.

        However, what the climate modelers are trying to do is somewhere between extremely difficult and impossible.

        I stand up in defense of models per se as integral to scientific analysis.

      • Certainly impossible when based upon false assumptions and ignoring large swaths of physical reality. Before models can have any hope of reflecting reality to a statistically significant extent, science will have to acquire more and better, valid observations of the climate system over at least multidecadal periods.

      • I believe the statement was that accepting the models “at face value” is what is questionable.

      • Just another pov: Models like F=MA are models that conform to the data. Those who engage in climate models are now engaged in seeking data that conform to their models.

      • ” A recent experiment showed a 2% deviation from Newton’s Law/Model of gravity. ”

        That is absurd. An error that large would have a huge effect on the orbits of planets, and indeed on practically everything. Definitely not happening.

    • It’s the NOT TESTING of models that is attacked. Testing against reality that is, not against other models. F=ma is a model but it has been and is tested daily. A model that doesn’t match observation is supposed to be changed until it can predict accurately or it gets junked. Changing the past measurements to match the models doesn’t count as scientific testing.

      • >> Accepting models as evidence is a sign of intellectual laziness. Fixed it for you.

        Every scientific prediction is based on models. If scientists predicted that an asteroid would hit earth, it would be based on a “simulation” of reality using various “models”. The difference is presumably the nature of the models in the two scenarios. You should be criticizing the details of the specific GCM models, rather than the general use of models and simulation.

        Models like F=MA are models that conform to the data. Those who engage in climate models are now engaged in seeking data that conform to their models.

        What you’re saying here is really a distinction without a difference. Perhaps you are making the valid point that manipulating (discarding data that doesn’t fit) or adjusting data to conform to a hypothesis are both examples of scientific fraud. However, it’s unlikely that the people doing that are climate modelers themselves. There is no indication that Friedlingstein has done so.

        It’s the NOT TESTING of models that is attacked. Testing against reality that is, not against other models. F=ma is a model but it has been and is tested daily.

        It’s actually no so clear cut. It’s very difficult to measure anything directly. There is no “reality” measurement. For example, temperature is not measured directly. It’s typically measured using a “model” of how mercury expands and contracts, or the very indirect measurement of IR, which uses many models to determine the result. The satellite measurements are calibrated using surface mercury measurements.

        F = ma is not testing directly against reality. How can we measure Mass? Well, we typically put an object in a gravity field and measure the Force. That uses the Gravity “model”, which as I’ve said, we only know G to 4 decimal places (least accurate constant), which some very controlled experiments can’t verify (2% error). It also not easy to measure “force”. For example, compressing springs requires the use of models.

        Note that we used F = ma to measure Mass. Is it any wonder then that F = ma? We’ve defined it that.

        Bottom line: verifying any hypothesis requires empirical data, but all empirical data relies on the use of “models”. I strongly suspect that many GCMs are missing various scientific first principles. However, I don’t have first hand knowledge, so I can’t really say. Criticizing ALL GCMs would be irrational. I hope to create a climate model one day, and it would be irrational to criticize all climate models without any first hand knowledge of the specifics. Even worse is criticizing the use of models in general, because that’s how science works.

      • VikingExplorer May 12, 2015 at 7:33 am

        Uhm, who are you talking to? You quote me, but post a reply to Jon Lonergan.

    • Good grief, if you think my post was an “attack on the use of models” then you are projecting. Global climate models are tools like any other. If you think GCM simulations are representations of Earth’s various climates, then you must think that the disney film Snow White is a useful simulation of young females.

      • I agree with your comparison. The models are akin to a cartoon version of reality.

      • if you think my post was an “attack on the use of models” then you are projecting.

        Projecting? Me thinks thou dost protest too much. Friedlingstein didn’t say anything to indicate that he thinks simulations are reality (“who think the “simulation” is reality”). Therefore, any reasonable reading of your post indicates that you think there is something wrong with the use of models in general.

        I wholeheartedly agree that various members of the “hockey team” have been acting in bad faith. I agree with the speculation that GCMs are missing several key scientific first principles. However, other than the conclusions drawn from them, and judging from the results alone, they aren’t obviously inaccurate.

        Are you saying that a Disney simulation of young females is only about .06% inaccurate?

  8. The Robinsons and Soon authored the petition project paper indicating this back in 2007.

  9. “Despite the CO2 induced stomatal closure, the models showed that the consequences of a warming climate – lengthened growing seasons, increased leaf area and increased evaporation – resulted in a 5% increase in forest transpiration – the cycle of water through trees. This increase cancels out any savings in water from improved efficiency. Plants are therefore unlikely to reduce levels of atmospheric water vapour – an important greenhouse gas. It is also unlikely that plant responses to increased CO2 will substantially increase soil moisture or river run-off.”

    Once again, we have scientists that are specialists in one area, using models and projecting in other areas they don’t understand.

    Their assumptions are missing the evapotranspiration aspect and effects on the water cycle and weather.
    https://www2.ucar.edu/atmosnews/perspective/4997/corn-and-climate-sweaty-topic

    There is alot going on here that we really have no good handle on.

    1. Increasing CO2 is causing explosive growth in plants world wide

    2. This is increasing evapotranspiration(during the growing seasons in mid/higher latitudes)

    3. This is increasing moisture in the lower levels. This means higher dew points, lower lifting condensation levels, more precipitable water, more low clouds(cumulus) and earlier in the day, more rain. There is a positive feedback going on. More rain to the plants/soils means more to evapotranpiration later. Also, warmer nights and cooler days……..to name a few.

    Overall, this could be a negative feedback from increasing H2O(less SW radiation from more daytime low clouds and higher soil moisture as well as the albedo change from more dense vegetation)

    I wouldn’t expect them to cover all this but then, they speculate about soil moisture and river run-off without having a clue about these key elements.

    • Increased plant growth is a negative feedback on atmospheric CO2 concentration.

      And increased forest cover should be a negative temperature feedback in most places.

      As for the temperature impact of water vapor, you’d have to characterize both when (seasonally and time of day) and where the increased transpiration occurs.

      It’s worth noting that not all water vapor is the same. Trees emit VOCs – some of which function as clouds seeds. Presumably, they emit more VOCs when they grow more:

      https://earthdata.nasa.gov/featured-stories/featured-research/volatile-trees

    • Thanks Mike, I was hoping someone would spare me making a similar point, and you said it better then I could have!

  10. From the article: . . . “By measuring the ratios of heavy to light carbon isotopes of tree-ring cellulose we are able to reconstruct various physiological metrics such as water use efficiency and their environmental drivers”, said Kerstin Treydte co-author of this study and a specialist in tree-ring isotopes at the WSL.

    On average, 100 kilograms of water released by a tree through the stomata equates to one kilogram of tree biomass created. The study showed that reduced stomatal opening increased water use efficiency by 14% in broadleaf species and by 22% in needleleaf species . . .

    Very Interesting. Could tree samples from the medieval warm period (if they exist . .) be evaluated, in effort to estimate what ppm of CO2 was in the atmosphere at that time?. Would sure like to know what that would show . . . !

  11. Reblogged this on the WeatherAction News Blog and commented:
    Plants and people in cold climes <3 CO2, Environmentalists and bankers* hate CO2 (for us plebs and plants).

    I'm with nature on this one ;)

    * Amber Rudd used to work for JP Morgan. Former BBC Environment 'churnalist' Richard Black approves of her appointment –

    “The appointment of Amber Rudd as Energy and Climate Change Secretary is significant in that it shows that the Conservative Party leadership retains its commitment to policies based on sound climate science,” said Richard Black, director of the Energy and Climate Intelligence Unit.

    http://www.telegraph.co.uk/finance/newsbysector/energy/11597112/Greens-welcome-Amber-Rudd-as-new-Energy-Secretary.html

  12. The problem with physicists doing climate science is they are unaware of or deliberately ignore the biological aspects. It works in the other directions too, so research ought to be a collaborative effort that takes advantage of the expertise in multiple disciplines.

  13. “On average, 100 kilograms of water released by a tree through the stomata equates to one kilogram of tree biomass created.” Can someone tell me is that moist (living) or dry biomass. I am presuming the latter.

  14. “Trees simply can’t be just a proxy for temperature, they are also a proxy for water, CO2, sunlight, nutrients, etc. The total growth response of a tree is the product of all environmental factors, not just temperature, something that any unbiased scientist should know and consider”

    Very very true.

    Tree rings can tell us how good or bad the conditions for growing were in particular years.

    If it was good, then we can assume that all individual elements which might have contributed to adversity, were minimized. If it was bad, there are numerous possibilities. Could have been from one extreme one year and the opposite extreme the next year.

  15. increased water use efficiency by 14%“.
    a 5% increase in forest transpiration – the cycle of water through trees“.
    So they use 14% less water per tree, but 5% more in total? There must be ~19% more trees?

  16. What really worries me is that rising atmospheric CO2 will make water melons bigger and more numerous.

  17. Commercial growers and farmers are all aware of the “least limiting factor” principle.
    Whatever there is the least of, will limit growth. Adding more of one thing that plants need will not result in faster growth, unless lack of a sufficient quantity that one things was previously holding them back.
    Hold back on any of the things that a plant (or tree of course) needs to grow, and it will grow more slowly, or die, depending on how bad the deficiency is.

  18. I’m curious about the legal ramifications of the EPA designating CO2 as a harmful toxin. Specifically, does that designation allow legal action taken on that basis? What I mean is, can legal action be taken against companies which produce or use CO2 in the production of food?

    I have in mind the following tactic to force the EPA to rescind their CO2 designation. The way is, file legal action against all greenhouses, on the basis that they use extra CO2 in their air. According to the EPA, the extra CO2 should be toxic to the greenhouse workers and must, ipso facto, cause high toxic content in grown vegetables. Of course it’s a nonsense, but consistent with the EPA’s CO2 designation — if it has force of law.

    In this way, industry and rational men would rise up to quash the EPA designation. But I suppose the Obama administration would stonewall as usual, right? Just thinking about effective tactics against stoooopid government rules — take them to their logical conclusion to quash them.

    • What about those poor submariners, exposed to levels of the poison gas CO2 higher than during the Cambian Period, ie several thousand of more ppm?

    • Lawyers on behalf of the leftist CAGW agenda made the case that CO2 was a potentially hazardous gas; not a toxic gas.

      Lawyers, with the help of pro-CAGW “scientists” as “expert” witnesses, argued that doubling CO2 could increase global temperatures by as much as 6C by 2100, with devasting consequence: 10’~50′ sea levels rise, desertification, droughts, floods, acidic oceans, famine, ad nauseam.

      The court bought the “expert” testimony and upheld EPA’s assertion that CO2 is a hazardous gas, thus allowing the EPA to regulate CO2 emissions.

      Unfortunately for the pro-CAGW advocates and the EPA, there hasn’t been a global warming trend for 18+ years, despite 30% of all man made CO2 since 1750 being made over just the last 18 years….

      Eventually, some organization will sue the EPA to remove its authority to regulate CO2 and get the previous ruling overturned.

  19. Eureka – I’ve found the “missing heat”! Its hidden in the wood of trees ( with some radiated back into space courtesy of evaporo-transpiration of water. Quick, let Dana Nutticello know! He will be so excited!

  20. This is basic vegetation biology (which climate science goes out of their way to ignore except when they are trying to prove CO2 global warming).

    Almost ALL C3 pathway vegetation (trees, bushes, wheat, rice and 95% of all plants) are CO2-starved except in extremely high rainfall environments like tropical rain-forests. They need to keep their CO2-absorbing stomata more open to get the CO2 they need but this also leads to more loss of water through evapotranspiration.

    As rainfall gets lower and lower, the 95% of plants that are C3 suffer more and more until they cannot even grow anymore. In low rainfall and low CO2, these plants are done, and the C4 pathway grasses take over. The C4 grasses are more efficient at absorbing CO2 so do not require as much rainfall. Even 10 inches per year is enough.

    But take anywhere on the planet where grasses are dominant, it is because rainfall is too low for trees and bushes, combined with CO2 being too low.

    Now ramp-up CO2 and the trees do better in these regions. In fact, they do better absolutely everywhere. Now ramp-up precipitation as well, as should happen in a warmer world, and we have forests everywhere and they grow better everywhere.

    Go back to the little ice age, when temperatures were lower and precipitation was lower and CO2 was lower, all plants grew at a lower rate and C3 crops like vegetables, wheat and rice probably failed regularly and people died of starvation.

    In the ice ages, when all these numbers were even far lower, our ancestors lived off the grassland herbivores because there was no trees or bushes and no fruit, nuts, wheat, or berries to be found. But these lots of grass-eating herbivores like the Auroch which was the ancestor of today’s cattle. Our ice age ancestors eat steak for every meal. Not that there is 7 billion of us, that is simply not practical.

    • Well stated, as usual.

      It’s not widely known that corn (maize) and other C4 plants open their stomata at night to take in CO2 without losing as much H2O, then use the photons incoming by day to power the chemical reactions with the stored “toxic” gas leading to the production of glucose.

      • “The C4 pathway bears resemblance to CAM; both act to concentrate CO2 around RuBisCO, thereby increasing its efficiency. CAM concentrates it in time, providing CO2 during the day, and not at night, when respiration is the dominant reaction. C4 plants, in contrast, concentrate CO2 spatially, with a RuBisCO reaction centre in a “bundle sheath cell” being inundated with CO2. Due to the inactivity required by the CAM mechanism, C4 carbon fixation has a greater efficiency in terms of PGA synthesis”

        http://en.wikipedia.org/wiki/Crassulacean_acid_metabolism

    • Mr. Ellis,
      Good post.
      As you may know, there are of course other pathways.
      One of the most important such pathway, which does bear some similarity to the C4 metabolic pathway, is called the crassulacean acid metabolism (CAM for short).
      Most plants in arid regions, (succulents and cacti, agaves, and others) and many commercially important plants, such as pineapples, use this pathway, in which the stomata remain closed during the day, and open at night. CO2 is stored by the plant as malate in vesicles until needed to allow photosynthesis during the day.

    • One of the most significant effects of increasing atmospheric CO2 maybe the encroachment of the juniper species into all sorts of new habitat in the Great Plains and Western states. A study (Paul Knapp, 2001, Global Change Biology) comparing growth of Oregon’s Western Juniper in low CO2 years 1896 -1949 and Juniper growth in high CO2 years 1950 – 1998 found a 63% growth increase in drought years and a 37% growth increase in wet years when the two periods of low CO2 and High CO2 were compared.

      Juniper removal from pastures and even woodlands is a big headache in the Midwest. They are growing and thriving in habitats where they previously were very sparse. We have to preserve the pastures so the beef can thrive. We will probably still want steak once and a while.

  21. Trees simply can’t be just a proxy for temperature,
    true but they get used because they are ‘better than nothing ‘ although the way Mann uses them using nothing instead would still give the same results .

  22. There conclusions at the end are wrong, the 5% increase in water vapour, was because of an increase in vegetation, this surely has to improve soil moisture and prevent run off.

    • We are nowhere near a 5% increase in water vapour.

      The most one can get to from the data is 2.0% and then the data indicates the overall global level is controlled by the ENSO which has no trend over time. El Ninos are balanced off by La Ninas so cherry picking a timeline based on the ENSO can give you any number you want but the long-term trend in water vapour is a very small increase less than 50% of that predicted in the theory.

      • Rats, scratching for some feeling of significance here, and even the twice as much water as Carbon dioxide we produce with our fires is lunch money?

    • No surprise to those who frequent WUWT. Type “Tree rings” into the search window on the home page.

  23. Studies reported on in CO2 science from back in 1965 show lower stomatal conductance. higher yields for c3 plants are an added bonus-these are the vegetable type plants which humans are supposed to eat, not wheat (C4.) Wheat is a survival food- it has some big negatives, but at least you do not starve to death.

    Optimum CO2 is around 1600ppm, so humans have a long way to go to fulfil our role on earth-recycle carbon. Pretty well all WUWT readers would be well aware that below 150-200ppm, plant life stalls. Pre industrial era CO2 was around 280ppm, which is not that far from the life-stall figure. As I say, perhaps the ecological niche of our species is carbon recycling as well as asteroid deflection. Alas, with the “boy who cried wolf” , humanity could well not rise to thechallenge of deflectingan earth shattering asteroid because they have put all their energy in to reducing CO2 levels.

    Gaia would not be happy. You listening, Tim Flannery. Gaia wants the carbon available for plants. gaia wants that asteroid nuked or deflected.

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