Negative water vapor feedback in plant evapotranspiration found

Rising CO2 is causing plants to release less water to the atmosphere, researchers say

Stomata are structures that allow plants to exchange gases with the air. Contemporary plants in Florida have fewer stomata than their ancestors did a few decades ago.

BLOOMINGTON, Ind. — As carbon dioxide levels have risen during the last 150 years, the density of pores that allow plants to breathe has dwindled by 34 percent, restricting the amount of water vapor the plants release to the atmosphere, report scientists from Indiana University Bloomington and Utrecht University in the Netherlands in an upcoming issue of the Proceedings of the National Academy of Sciences (now online).

In a separate paper, also to be published by PNAS, many of the same scientists describe a model they devised that predicts doubling today’s carbon dioxide levels will dramatically reduce the amount of water released by plants.

The scientists gathered their data from a diversity of plant species in Florida, including living individuals as well as samples extracted from herbarium collections and peat formations 100 to 150 years old.

“The increase in carbon dioxide by about 100 parts per million has had a profound effect on the number of stomata and, to a lesser extent, the size of the stomata,” said Research Scientist in Biology and Professor Emeritus in Geology David Dilcher, the two papers’ sole American coauthor. “Our analysis of that structural change shows there’s been a huge reduction in the release of water to the atmosphere.”

Most plants use a pore-like structure called stomata (singular: stoma) on the undersides of leaves to absorb carbon dioxide from the air. The carbon dioxide is used to build sugars, which can be used by the plant as energy or for incorporation into the plants’ fibrous cell walls. Stomata also allow plants to “transpire” water, or release water to the atmosphere. Transpiration helps drive the absorption of water at the roots, and also cools the plants in the same way sweating cools mammals.

If there are fewer stomata, or the stomata are closed more of the day, gas exchange will be limited — transpiration included.

“The carbon cycle is important, but so is the water cycle,” Dilcher said. “If transpiration decreases, there may be more moisture in the ground at first, but if there’s less rainfall that may mean there’s less moisture in ground eventually. This is part of the hyrdrogeologic cycle. Land plants are a crucially important part of it.”

Dilcher also said less transpiration may mean the shade of an old oak tree may not be as cool of a respite as it used to be.

IMAGE: Researchers extract stomata-bearing leaves from a peat formation in Florida. At some sites, the peat was estimated to be as much as 150 years old.

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“When plants transpire they cool,” he said. “So the air around the plants that are transpirating less could be a bit warmer than they have been. But the hydrogeologic cycle is complex. It’s hard to predict how changing one thing will affect other aspects. We would have to see how these things play out.”

While it is well known that long-lived plants can adjust their number of stomata each season depending on growing conditions, little is known about the long-term structural changes in stomata number or size over periods of decades or centuries.

“Our first paper shows connection between temperature, transpiration, and stomata density,” Dilcher said. “The second paper really is about applying what we know to the future.”

That model suggests that a doubling of today’s carbon dioxide levels — from 390 parts per million to 800 ppm — will halve the amount of water lost to the air, concluding in the second paper that “plant adaptation to rising CO2 is currently altering the hydrological cycle and climate and will continue to do so throughout this century.”

Dilcher and his Dutch colleagues say that a drier atmosphere could mean less rainfall and therefore less movement of water through Florida’s watersheds.

The Florida Everglades depend heavily on the slow, steady flow of groundwater from upstate. The siphoning of that water to development has raised questions about the future of the Everglades as a national resource.

###

Dilcher’s Dutch coauthors for the two papers were Emmy Lammertsma, Hugo de Boer, Stefan Dekker, Andre Lotter, Friederike Wagner-Cremer, and Martin Wassen, all of Utrecht University in Utrecht, Netherlands. The project received support from Utrecht University’s High Potential research program.

To speak with Dilcher, please contact David Bricker, University Communications, at 812-856-9035 or brickerd@indiana.edu. To speak with any of the Dutch coauthors, please contact Emmy Lammertsma, Utrecht University, at 31 (0) 64 137 6175 or e.i.lammertsma@uu.nl.

“Global CO2 rise leads to reduced maximum stomatal conductance in Florida vegetation” Proceedings of the National Academy of Sciences (online), vol./iss. TBD

“Climate forcing due to optimization of maximal leaf conductance in subtropical vegetation under rising CO2Proceedings of the National Academy of Sciences (online), vol./iss. TBD

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115 thoughts on “Negative water vapor feedback in plant evapotranspiration found

  1. Wouldn’t less water vapor also mean much less greenhouse impact and might this just be a way to link CO2 to colder temperatures now that they realize Earth isn’t warming?

    I mean, we have just gone through 20 years of “we are going to cook because of CO2″ and now that temperatures are cooling we have this. The logical conclusion, if you buy the study, is “we are going to freeze-dry because of CO2″.

    They can’t have it both ways.

  2. Isn’t this proof of a negative feedback system – so why don’t they say so!? Less water vapour as a GHG balances out more CO2? Surely now all the other bad effects of CO2 like heating and flooding will be negated?

    By the way it takes peat 10 years to form 1cm so they could have gone down more than 15cm to get older evidence surely?

    And another thing, how do plants grow bigger with more CO2 if they reduce the gas exchange so they can’t use it?

  3. Selective information output: I need to read the article I grant you, but:

    what was the total leaf area compared to number of stomata ?
    is low CO2 a selective agent for decreased stomatal function ?
    did the epidermal cells change in size ?
    is CO2 a selective agent for decreased stomatal function ?
    did the researchers try to estimate/compare plant dry weight ?

    Previous papers on the same subject do not agree on this.

  4. So? Obviously CO2 has been so short in the atmosphere that plants have had to risk dehydration in order to get enough. As the level rises, the plants need fewer stomata to get enough CO2 for respiration and so can cut down the risk of excessive water loss. Sounds good to me.

  5. It truly sounds as if the involved researchers are trying to find a cesspool instead of a silver lining.

  6. Nutrients could have changed two. BTW I didn’t know 390×2 = 800? I thought it was 780?

  7. I guess this will make the Amazon even more resilient to water concerns then it already is.

    This could presumably be corroborated with an empirical investigation conducted in glasshouses, raising or lowering CO2 levels and seeing how the plants respond.

  8. This doesn’t make sense to me. The C02 in the atmosphere contributed by man is said to be so small compared to other sources of CO2 in the environment. If the doubling of a gnats whisker amount ofMMCO2 can cause such changes in plants, then it must cause us to rethink the imnpact on the climate generally. It can’t go both ways, either the MMCO2 is significant or it isn’t. I doubt that the MMCO2 can be the cause of the changes noted by the research, but I don’t see why, if it is true, that it is anything negative against AGW.

  9. This is not news as anyone who reads the co2science web site will tell you. Indreased CO2 reduces a plant’s requirement for water. Can only be good for the planet!!!!!!!!!!!!!

  10. Was it not in the Cambrian Expolosion that most plant/animal/plankton diversity existed, & CO2 was 20 times higher than it is today? Oh, we mustn’t be here then because life all died out because of the CO2, or maybe not?

    Anyway, this is only a “puter”model, based on what they think they believe they ought to know they are right about! Still using non-comttal words like “could” & “may”. Just as easily these words can read “could not” & “may not”!

    Slightly OT: Recent BBC tv appearance (Tuesday) by maths guru Johnny Ball stated on tv that manmade CO2 content was only 4% of total. My understanding was that this figure was from the IPCC sources & sinks section of their report, can anybody confirm that at all? Namely the 770 Gt or so natrual outgassing as opposed to the 25 Gt or so of manmade outgassing. It is used in the video clip at Climaterealist site presented by a school teacher (very eloquently I must say)!

  11. It’s well known that if you increase CO2 levels plants are more able to withstand drought and the probable reason is that they transpire less so this is hardly a surprise.

    Also their statement:” That model suggests that a doubling of today’s carbon dioxide levels — from 390 parts per million to 800 ppm” is suspect because most data is showing that the Oceans are cooling so more CO2 will be taken up by the Oceans, and the atmospheric levels will not reach 800ppm.

  12. “The carbon cycle is important, but so is the water cycle,” Dilcher said. “If transpiration decreases, there may be more moisture in the ground at first, but if there’s less rainfall that may mean there’s less moisture in ground eventually.

    Let’s continue shall we. Less water vapour in the air means less of the most powerfull greenhouse gas called water vapour. I recall that plants also become more drought resistant. These people are tying themselves in knots. Gaia at work?

  13. That’s very interesting, as it would be yet another negative feedback, and considering how much more important water vapor is than CO2, it could even mean the effect of CO2 is cooling.

    The paper’s argument about air temperatures is probably not significant, and even if the temperatures are slightly warmer, the air will be drier, and since we are also evaporatively cooled, we’ll probably feel more comfortable.

    However, mammals will also be losing water faster, since we don’t have stomata that adapt to CO2 levels. To verify how this will effect animal life I’ve input horse DNA into a multi-billion dollar computer simulation that extrapolates horse behavior from chemical interactions, protein transport, electrical charges, Van der Waals forces, and Brownian motion. My model horse quickly dehydrated, because even though there is increased surface water because of the reduced plant draw from the soil, he simply refuses to drink. I’ve had my underpaid lab assistant double check the code, and he says there’s no way it’s a glitch in a subroutine.

    So, taking the average of 350 model runs, I predict a 35% species loss by 2050 and the devastation of agricultural production, causing widespread famine on top of the human deaths due directly to dehydration/drowning caused by lower humidity and increased surface water. I’m sure Science or Nature will publish my results with all possible haste.

    [ah yes the old sayings are often the best]

  14. Interesting… I wonder if anyone will try correlating past desertification cycles with CO2 levels? Lowering CO2, if the stomata theory is correct, could increase water needs, and in a borderline environment that could cause desertification.

    I know there are other factors at play, but ice ages tend to have low CO2 levels, and desertification on a global scale. If the climate was getting drier while plants were needing more and more water due to CO2 declines, that would contribute to desertification.

  15. As a plant physiologist I find this “new” discovery all profoundly depressing.

    The effect of incresed CO2 on stomatal density and evapotranspiration has been known for more than 50 years.
    In fact stomatal density has been used as a proxy for past atmospheric CO2 concentrations
    (Stomatal density and stomatal index as indicators of paleoatmospheric CO2 concentration)
    See http://droyer.web.wesleyan.edu/RPP.pdf

    Why do I not find it surprising that if vegetation covers some 50% of the Earth’s dry land a reduction in evapotranspiration is likely to have a global effect?

    I bet this is not factored in GCMs

    Why is so much of Climate “Science” reinvention of the wheel?

  16. Do we know that CO2 is the cause of fewer stomata, or could it be something else? People long acclimated to high altitude environments have a different lung morphology than those who live at sea level. Does that mean that either group of people breathe less?

  17. Nicely confirming, yet again, that today’s CO2 levels are sub-optimal for plant life. Yikes, I’ve just realised what that means for my gardening chores!

  18. How the hell did they separate out the CO² signal from everything else? I can’t see it in the article. Someone help me please.

  19. heck, I am struggling to recall my Biology from 30+ years ago but a check reveals the following:
    In most plants, transpiration is a passive process largely controlled by the humidity of the atmosphere and the moisture content of the soil. Of the transpired water passing through a plant only 1% is used in the growth process. Transpiration also transports nutrients from the soil into the roots and carries them to the various cells of the plant and is used to keep tissues from becoming overheated. Some dry environment plants do have the ability to open and close their stomata. This adaptation is necessary to limit the loss of water from plant tissues. Without this adaptation these plants would not be able to survive under conditions of severe drought.

    I would guess that the purpose of reduced stomata is an environmental response by the plants because they have either increased CO2 and therefore need less water to photosynthesize (?), or increased ambient moisture, or reduced soil moisture (i.e. unavailable/reduced precipitation) and possibly increased temperature which means increased evaporative rates – and, of course, a possible random mixture of these and many other reasons?
    All in all, it seems like a difficult thing to explain?

  20. My old botany text-book (printed in the 1950s) has a whole chapter on plant transpiration and describes how stomata density and water loss decrease with increased CO2 concentration. It’s written for children and lay-people but even has a graphs showing the realtionships.
    Makes me wonder about the value of interdisciplinary science when I now find out Professor Emeritus in Geology David Dilcher has just rediscovered what botanists have known since at least the turn of the last centruty.

  21. “The scientists gathered their data from a diversity of plant species in Florida, including living individuals”,

    The leaves of different plants and the sections of leaves will have different number of stomata, just pointing out the obvious here, but they really only have to study the stomata of one plant species over a longer period of time to get an estimate of what the ecology is like for that plant and it’s surrounding area,
    Was it mentioned anywhere that when one variety of plant species loses water vapor through Transpiration, another variety of plant species takes advantage of this or compensates and vice versa?.

    I know… lets use this speculative research on a variety of plant species in Florida to speculate on the future of the entire earths climate./sarc

  22. If extra CO2 is used by the plant then extra water is required as well. The photosynthesis combines CO2 and water to make sugars.

  23. So this is a new negative feedack. Why can’t these people just be honest. Every paper is dressed in global doom.

  24. David Schofield March 4, 2011 at 12:45 am: how do plants grow bigger with more CO2 if they reduce the gas exchange so they can’t use it?
    If you double the amount of CO2 and if all other factors are the same, then you can halve the number of pores (think of them as “open ports”) and still get the same amount. If only a 40% decrease you’d still get a large percent uptake of CO2. Obviously, with water vapor the reverse would be true.

    Regardless, what is really interesting is the way plants regulate themselves. If the only control they have is the number of stomata they make. Which, in turn implies the plant has little control or no control over the volume of gasses going in or going out. But they can control their water uptake from the soils. If Darwin were a plant, he’d be able to describe why plants evolved this way. Shame Darwin isn’t a warming believer.

  25. Good news, surely more CO2 means arid places can support plant life? has to be good news , with the cooling perhaps parts of the Sahara will become arable?

  26. “As carbon dioxide levels have risen during the last 150 years, the density of pores that allow plants to breathe has dwindled by 34 percent, restricting the amount of water vapor the plants release to the atmosphere,”

    What they didn’t mention:

    “At the same time, because of the increased plant food available, total leaf surface area has risen by X percent, (partially/completely/more than) offsetting the reduction of water vapour released per unit area.”

  27. So what percent of global evaporation occurs from our 70% ocean surface?
    The plants of the NH above 40 degrees N are not transpiring much water this winter so we should expect less snowfall.

  28. Maybe the next climate-related Nobel Prize can go to Wagner-Cremer, Dilcher, Kurscher, Kouwenberg, van Hoof and the rest of the Utrecht stomata people.

  29. What I find intriguing is that the number of stomata decreases at higher CO2-levels. That means imho that CO2 is not the bottleneck for plantgrowth, but cold and waterloss. So this research is another proof that moist and warm are the best conditions for plantlife and therefore for animals and humans too. That’s of course why you want to use a greenhouse to grow crops (moist and warm) and that’s why in the tropics plants can get huge quickly (moist and warm).

    Based on this, together with the knowledge that rising CO2-levels have little or no effect on global temperatures, one can conclude that:
    - warm is good, warmer is better;
    - CO2 is good, more CO2 is better.

    CAGW has now definitely been falsified, period.

  30. Hang on a minute. Finding 34% less stomata density in living samples than in samples taken from 150-year-old peat certainly does not show that “The increase in carbon dioxide by about 100 parts per million has had a profound effect on the number of stomata and, to a lesser extent, the size of the stomata.” That’s correlation, not causation.

    And then they have the chutzpah to create a climate model predicting that the amount of water released too the air by plants will be halved, resulting in a drier atmosphere and lower rainfall.

    Climate models produced by climatologists themselves are woefully inadequate and plain wrong. A climate model produced by a biologist has no chance of accuracy. Sadly, it has every chance of being cited as yet more “scientific evidence” of climate change forced by anthropogenic CO2.

  31. I wonder if the study took into consideration the fact that plants grow more quickly with higher levels of atmospheric CO2. If levels double, there will be more plants and larger ones, so while each leaf might release less water, since there will be more leaves, the total water released might be the same or higher.

  32. Metryq says:
    March 4, 2011 at 2:35 am

    Do we know that CO2 is the cause of fewer stomata, or could it be something else?

    Plants create less stomata as an adaptation to conserve energy.
    No need for an excessive amount of stomata when less can do the same work.

    The research fails to show if the plants’ dry weight changes with lower number of stomata.

    Keep your eyes on the pea.
    What the researchers in this paper is trying to prove/show is that CO2 concentrations in the atmosphere is rising, hence the low stomata count.

    So, nothing new there…

  33. Here’s the money shot:

    “But the hydrogeologic cycle is complex. It’s hard to predict how changing one thing will affect other aspects. We would have to see how these things play out.”

    THAT’s the plain truth: The climate is complex. It IS very hard to predict how changing one thing, i.e. CO2 concentration, will affect other aspects.

    Thank you, and good night!

    (You gotta love unintended honesty)

  34. Schrodinger’s Cat says:
    March 4, 2011 at 3:23 am
    …If extra CO2 is used by the plant then extra water is required as well. The photosynthesis combines CO2 and water to make sugars….

    I would have said it might be a yes and no answer. More CO2 may make the process more efficient? and then of course, it depends on whether the plant is in its growing season? do plants show stomata cell changes through a season? we know growth rates increase with CO2 and temperature (up to a point, obviously) – but how much of the water demand is required for cooling and photosynthesis, I don’t know.

  35. It’s quite well known (for a long time) that:

    1) increasing CO2 up to as much as 2000ppm substantially increases plant growth rate so long as there are no other limiting factors (sunlight, water, nutrients, temperature)

    2) optimum growth temperature rises with increasing CO2

    3) water use per unit of growth decreases with increasing CO2

    This makes sense in light of evolutionary adaptation and history of the earth’s climate. The earth is usually NOT in an ice age as it is today. Ice ages are characterized by low temperatures and low levels of CO2. The vast majority of the earth’s history is characterized by no polar ice caps, global average temperature 6-8C higher than today, and CO2 concentration as much as 20 times higher. These latter conditions persisted for tens and hundreds of millions of years at a stretch. Green plants evolved under these conditions and these conditions are hence what they are best adapted for. There is absolutely nothing mysterious going on in why plants prefer higher atmospheric CO2 and warmer temperatures for optimum growth.

    Stomata can open and close as required to accomplish and regulate gas exchange. The anatomical structure that opens and closes the stomata is called “the closest thing to a muscle that plants have”. So plants have no great need to change the number or density of stomata in response to gas concentration. It would appear to be a metabolic adaptation so that energy isn’t wasted by building more stomata than are needed. The density and number of stomata vary on the same plant during the same growing season. If I recall correctly the regulatory mechanism has been recently identified. A signalling protein is produced by mature leaves that informs newly forming leaves what stomata density is optimal for the current environmental conditions.

    The water savings under higher CO2 conditions is straightforward. The stomata regulate gas exchange i.e. excreting oxygen and taking in CO2 when photosynthesis is happening. When there is a higher concentration of CO2 in the air the stomata remain open for a shorter period of time because the exchange goes faster. Water is lost through evaporation when the stomata are open so less time spend open means less water loss during gas exchange. No mystery there either.

    This is one reason why climatologists are the last people you should ask about the consequences of so-called anthropogenic global warming. Evidently few if any of them know jack diddly squat about botany and if they do know something they dishonestly disregard (called a lie of omission) the benefits of anthropogenic CO2 and global warming. It’s disgusting. And the talking dimwitsoobs on the Weather Channel wonder why CAGW boffins get no respect. There’s a simple answer for that too – CAGW boffins deserve no respect.

  36. Water-use efficiency of plants goes up with increased atmospheric CO2. The plants become more drought resistant. My neighbor, an old farmer, now dead, told me in 2002 during a severe drought, “It’s just a miracle. This is worse than ’36 and in ’36 we had nothing. All the crops died, all the weeds died, and were left with dust.” In 2002 we harvested 25-30 bushels an acre of soybeans and 50+ bushels of corn, dryland. My neighbor’s “miracle” has a complex, not a simple explanation; new crop genetics are part of the answer. But I thought back in 2002, and I still think, increased atmospheric CO2 is responsible for big gains in water-use efficiency in plants.

  37. Nothing particularly new here, although it is interesting to note that the Miskolczi effect can be catalyzed by vegetation (rather than being a passive equilibration).

    Anyone know if this effect is linear based on CO2 levels ?? A logarithmic CO2 effect meets an opposing linear water vapor feedback effect ?? Just wondering.

  38. Don’t think the NH and the SH are singing from the same hymn sheet.We in Australia are being told that due to la nino we can expect more rain from global warming but then again 6 months ago we were being told we would never see heavy rain again.It is hard to keep up.

  39. As others have pointed out here… they are assuming total biomass stays the same. I’m not a scientist, but my bet is that nature balances the water cycle just fine all by itself.

  40. Wait a minute. At the end of the article they say:

    “The Florida Everglades depend heavily on the slow, steady flow of groundwater from upstate. The siphoning of that water to development has raised questions about the future of the Everglades as a national resource.”

    Isn’t it possible that the plants are reducing stomata in response to the reduction of water due to development and not in response to CO2 levels?

  41. geoff says:
    March 4, 2011 at 4:22 am

    “I wonder if the study took into consideration the fact that plants grow more quickly with higher levels of atmospheric CO2. If levels double, there will be more plants and larger ones, so while each leaf might release less water, since there will be more leaves, the total water released might be the same or higher.”

    Exactly. Adding insult to injury 71% of the earth’s surface is ocean. Nothing will change there. The entire continent of Antarctica has no terrestrial plant life so add that to the 71% that won’t change. Then during a substantial portion of the year high northern and southern latitudes over land are too cold for any plant growth so that won’t change either.

    The notion that CO2 will have any substantial effect on total atmospheric water vapor through changes in plant transpiration is not at all credible. More wasted research funds. It just never ends does it? We need a lot fewer unaccountable scientists wasting time and money in academia and a lot more engineers getting practical things done and being held accountable when they fail.

  42. ****
    Article says:
    “The carbon cycle is important, but so is the water cycle,” Dilcher said. “If transpiration decreases, there may be more moisture in the ground at first, but if there’s less rainfall that may mean there’s less moisture in ground eventually. This is part of the hyrdrogeologic cycle. Land plants are a crucially important part of it.”
    ****

    Bit of a simplification. Stomata aren’t static, they open & close on a daily basis (completely closed at nite). CO2 increases cause relatively less opening during the day. If one assumes that local rainfall is related to transpiration-rate, rainfall may decrease when water is plentiful. But when plants are water-stressed, the stomata additionally close during the day somewhat (independent of CO2 level) to prevent loss of turgidity. If there is more moisture remaining in the soil from lower transpiration, during extended dry periods the stomata may actually be more open than they would be otherwise, and rainfall may increase during the dry periods.

    Some guesswork on my part, but their simple statement above is a stretch without some explanation.

  43. cedarhill says:
    March 4, 2011 at 3:31 am:

    Just curious; are you from Cedar Hill, Texas? I graduated from CHHS in 1984.

  44. So these grant seekers extrapolated an apparent change in stomata density to global climate change ha?

    I got news for them. I know of plants that completely lose their stomata within weeks. They’re called DECIDUOUS plants. You see, plants have adapted in many ways to all sorts of changing conditions. Some actually change hourly, observe flower petals closing or leaves turning down during heavy rain. Heck, remember why the SUNFLOWER is called a SUN flower?

    An earlier commentor said these AGW guys are tying themselves in knots. Could it be because their much vaunted climate models are just digital forms of the old TWISTER game? Gunna be hot, gunna be cold, wet, dry, windy, calm, dang their heads are up their ar$e$ now.

  45. Maybe these folks should explore what fields of science already exist before they make their ‘discoveries’. Sounds like finding the existence of a navel would be a novel discovery. It would be interesting if someone extended this related area of study:
    From Canada to the Caribbean: Tree leaves control their own temperature June 11th, 2008
    The temperature inside a healthy, photosynthesizing tree leaf is affected less by outside environmental temperature than originally believed, according to new research from biologists at the University of Pennsylvania.
    Surveying 39 tree species ranging in location from subtropical to boreal climates, researchers found a nearly constant temperature in tree leaves. These findings provide new understanding of how tree branches and leaves maintain a homeostatic temperature considered ideal for photosynthesis and suggests that plant physiology and ecology are important factors to consider as biologists tap trees to investigate climate change.
    Tree photosynthesis, according to the study, most likely occurs when leaf temperatures are about 21°C, with latitude or average growing-season temperature playing little, if any, role.

    the rest of the abstract is here:

    http://www.sciencecentric.com/news/article.php?q=08061131

    Doesn’t say much for tree rings as a proxy for temperature.

  46. Patrick M. says:
    March 4, 2011 at 5:28 am

    Wait a minute. At the end of the article they say:

    “The Florida Everglades depend heavily on the slow, steady flow of groundwater from upstate. The siphoning of that water to development has raised questions about the future of the Everglades as a national resource.”

    Isn’t it possible that the plants are reducing stomata in response to the reduction of water due to development and not in response to CO2 levels?

    No. The stomatal index (SI) in these particular plant taxa is unresponsive to water and light conditions. Stomatal density (SD) is responsive to CO2, water and light.

    The SI is generally calculated by dividing the SD by the density of epidermal cells (or needle length in conifers).

    This research is basically a continuation of Wagner et al., 2004; which thoroughly demonstrated that the CO2 increase from 310-370ppmv (ca. 1940-2000) could be reconstructed from stomatal frequency.

  47. Plant contribution to atmospheric moisture content is different than open water’s contribution. They involve different mechanisms of atmospheric injection.

    Open water uses evaporation, as its mechanism, which means its injection rate is entirely dependent on temperature, relative humidity, air circulation speed, body surface area.

    Plants however, push water molecules, one at a time, directly into the atmosphere. It has its own internal drivers governing this atmos injection processes. This pumping action cannot be compared to the normal evaporation process. When environmental evaporation is low, plant water vapor injection could be conversely high.

    Plants do modify their own micro-climate. Collectively, uncountable numbers of them, affect and modify our global climate.

    If we could poll plants they would respond to increased temperatures, available moisture, and enhanced CO2, with a deafening “YES PLEASE!”

    When our food source flourishes… So do WE! GK

  48. So when you point out to them that this leads to a lower greenhouse effect due to water vapour, how will they respond? Maybe they’ll say ‘ah, but most water vapour comes from the oceans.’

    When you point out that if most of the water vapour comes from the oceans, then how can reduced transpiration from vegetation in Florida lead to drying up of its swamps (Florida is a peninsula, after all), how will they respond this time?

  49. Good gawd, what spin!

    Could they be more negative about how they report neutral facts?

    “As carbon dioxide levels have risen during the last 150 years, the density of pores that allow plants to breathe has dwindled by 34 percent, …”

    ‘That allow plants to breath’ – makes it sound like its a bad thing that plants develop fewer stomata in response to higher CO2. Nothing is further from the truth.

    The reality is that stomata cause plants to waste water. They dont ‘allow the plants to breath’, they allow the plants to eat. Their food is CO2. When there is more CO2 in the air, it makes it easier for plants to get the food they need. They can get the same amount of food using fewer stomata. Since having more stomata than necessary causes plants to waste water, and thus be less resistant to drought, they grow fewer when they can get away with it. This is a good thing.

    The whole article is written with the doom and gloom filter turned to “high”.

  50. @JJ…

    The negative spin is in the text of the press release from Indiana University… Not from the authors of the papers.

    If you read any of the papers by David Dilcher, Lennie Kouwenberg, Tom van Hoof, Wolfram Kürschner, Friederike Wagner-Cremer and the other stomata experts, you’ll find their approach amazingly non-alarmist. They also don’t strike me as fellow skeptics/deniers. They are doing very solid, basic science. They call it as they see it – And this often ruffles the feathers of the so-called scientific consensus – particularly the ice core people.

    Over the last 10-15 years, they have clearly demonstrated that pre-industrial Holocene atmospheric CO2 levels were higher and much more variable than indicated by Antarctic ice cores… For this, they have been vilified by the Warmistas.

  51. I have used CO2 enhancement to promote plant growth. I did not see any reduction in the water requirements. I did, on the other hand note a greater need for nutrients.

  52. David Middleton,
    Never had botany, so I need a little help here. You differentiate stomatal index and stomatal density. Then in your last paragraph you refer to stomatal frequency. Is this a third parameter, or one (which one?) of the first two?

  53. Dave Springer and Geoff,
    I agree with your assumptions that the release of vapour from plants may very well remain nearly the same, given that CO2 will lead to an increase in biomass. But, would not an increase in biomass bind more atmospheric CO2, thus serve to reduce or stabilize the amount of atmospheric CO2?

  54. David Middleton says:
    March 4, 2011 at 8:37 am

    Over the last 10-15 years, they have clearly demonstrated that pre-industrial Holocene atmospheric CO2 levels were higher and much more variable than indicated by Antarctic ice cores… For this, they have been vilified by the Warmistas.

    Although I agree that stomata (index) data do have some value, one need to be a little cautious with claims of absolute height and variability of the CO2 levels found. Stomata data suffer from the same problems as many of the historical data had: they reflect CO2 levels over land, which are by definition more variable and show a positive bias.
    The bias in the past century can be compensated for by calibrating the SI data to direct measurements and… ice cores. Which BTW reject the 1942 peak found by the late Ernst Beck. But we have little idea how the CO2 levels in the neighbourhood of the SI samples changed over time in the previous centuries. In The Netherlands there was a tremendous change in landscape (sea and marshes – forests – agriculture – industry, traffic) over the past few thousands of years in the main wind direction of one of the main SI finding places. Even the main wind direction may have changed over the centuries (MWP – LIA), all with a hardly correctable impact on local CO2 levels…

  55. juanslayton says:
    March 4, 2011 at 9:24 am
    David Middleton,
    Never had botany, so I need a little help here. You differentiate stomatal index and stomatal density. Then in your last paragraph you refer to stomatal frequency. Is this a third parameter, or one (which one?) of the first two?

    Stomatal index (SI) and stomatal density (SD) are measures of stomatal frequency. Both express inverse relationships to atmospheric CO2. SI is far less likely to be affected by other environmental stresses than SD.

  56. G. Karst says: “If we could poll plants they would respond to increased temperatures, available moisture, and enhanced CO2, with a deafening “YES PLEASE!

    Or a deafening “Feed me! Feed me!”

  57. @Ferdinand Engelbeen

    I agree that one has to be careful in relying on the absolute values in the stomata reconstructions. The data are “noisy” and many reconstructions are based on Quercus (oak) leaves; which are unresponsive above ~350ppmv. Most stomata reconstructions employ a 3-pt running average to smooth the data out a bit. But the relative change and variability is solid.

    The funny thing about Beck’s 1942 CO2 peak, Finsinger & Wagner-Cremer (2008) found a similar peak in a reconstruction from Betula (birch) leaf samples from northern Europe. The really funny thing is that, like Beck, the stomata reconstruction exhibits a sharp drop in CO2 in the late 1950′s, bringing it into fairly good agreement with MLO.

    Beck’s early-1940′s CO2 peak could quite easily have occurred and not been resolved in the ice cores. Law Dome’s firn densification offset in the 20th century is 30 years. Each layer’s gas bubbles represent a 60-yr average of atmospheric CO2. A 60-yr running average across a simulated CO2 peak of 345ppmv in the early 1940′s looks a lot like the Law Dome CO2 curve… http://debunkhouse.wordpress.com/2011/01/05/antarctic-ice-cores-diffusion-confusion/

  58. Y’know, for once, this is something testable. They could raise identical plants, even possibly cloned plants, in different C02 environments, and observe the results. Even if it is generational, it could be tested in a relatively short period of time.

    So why are they essentially modeling a change against a possibly corrupt temperature record, instead of testing? Is testing no longer considered necessary at all to scientists?

  59. So…plants are releasing less water into the atmosphere because man is causing CO2 levels to rise? Hmm, I wish we had a scientific way of testing how much water is in the air (Humidity) and we had access to data over a long period of time – then we could support or disprove the supposed relationship.

    Oh wait, we do! Has humidity been decreasing in stable forest areas in correlation to the supposed relationship to stomata denisity? I bet we can’t find a relationship.

    Of course, if we do, then we have to show one causes the other (not just a correlation). But its a start.

    Also, I wonder if the stomata denisty is decreasing at the same rate across latitude? If not, it shouldn’t be related to CO2 but instead to temperature or some over variable since CO2 mixes so well in the atmosphere.

  60. Robert of Texas says:
    March 4, 2011 at 11:50 am
    So…plants are releasing less water into the atmosphere because man is causing CO2 levels to rise? Hmm, I wish we had a scientific way of testing how much water is in the air (Humidity) and we had access to data over a long period of time – then we could support or disprove the supposed relationship.

    The plants don’t respond any differently to anthropogenic CO2 than they do to natural CO2.

    Oh wait, we do! Has humidity been decreasing in stable forest areas in correlation to the supposed relationship to stomata denisity? I bet we can’t find a relationship.

    The negative plant feedback wouldn’t necessarily cause specific humidity to decline… It would just retard any increase that might result from warming.

    Of course, if we do, then we have to show one causes the other (not just a correlation). But its a start.

    Also, I wonder if the stomata denisty is decreasing at the same rate across latitude? If not, it shouldn’t be related to CO2 but instead to temperature or some over variable since CO2 mixes so well in the atmosphere.

    Or the CO2 is not actually well-mixed.

    Different plant taxa respond differently. Not all taxa are sufficiently responsive to CO2 to be suitable for CO2 reconstructions. In each of these studies, they build training sets to test the stomatal response of living plants to CO2 and other variables. They establish a mathematical relationship and then apply it to herbrarium and fossil samples of the same taxon to reconstruct past CO2 levels.

    The methodology has been extensively tested and the effects of other variables can be largely reduced by using a stomatal index (SI) rather than just stomatal density (SD).

  61. Plants are an example of a specie which has nearly destroyed its environment. Overuse of Co2 by plants has produced desert where nearly no plant can grow. Humans have the potential to destroy their environment, but the production of Co2 is not a problem.

  62. David Middleton says:
    March 4, 2011 at 10:59 am

    The funny thing about Beck’s 1942 CO2 peak, Finsinger & Wagner-Cremer (2008) found a similar peak in a reconstruction from Betula (birch) leaf samples from northern Europe.

    But if you take the stomata data from Van Hoof in The Netherlands (oak leaves at St. Odiliënberg), far closer to the main dataseries which caused the 1942 peak in Beck’s graph (Giessen, Germany), there is no peak at all:

    Even if a sharp rise of CO2 of 80 ppmv (160 GtC) is theoretically possible, it is physically impossible that the same amount disappears in less than 7 years. The current removal rate of CO2, while some 100 ppmv above (temperature dictated) equilibrium is 4 GtC/year…

    Your CO2 averaging model is quite different of what the firn densification models calculate, neither what is found in measurements: at closing depth, the average gas age is measured only 10 years younger at 75 m depth than at the surface and the averaging is more a Gaussean peak around that age than an average. See:
    http://courses.washington.edu/proxies/GHG.pdf page 4

    That means that a one-year peak of 80 ppmv, still would give a 4 ppmv peak in the ice core, but as the high level remained several years, according to Beck, it may reach over 10 ppmv in the Law Dome ice core, but it isn’t seen at all (accuracy of the ice core measurements: 1.3 ppmv – 1 sigma).
    Neither in coralline sponges: any huge, short peak is either from the oceans or from decaying vegetation. The former would give a moderate, but measurable increase in d13C, the later an enormous decrease of d13C. Which isn’t seen at all.

    In your web page you say:
    The air trapped in the 1939 layer should be a blend of air from 1909 to 1969.

    In fact, as the average gas age is only 10 years younger in average composition than the (1993) surface air at closing depth, where the ice is 40 years older than at the surface, halve of it is from the period 1983-1993, the other halve from 1953-1983 and near nothing from 1913-1953. After all, near the surface and even (much) deeper, the gases have plenty of time to migrate (up to 80 years)…

  63. This also demonstrates that plants prefer higher temperatures. Less evapo-transpiration results in higher local (for the plant) temperatures. The plants have voluntarily reduced their rate of evapo-transpiration through restricting their production of stomata to produce better growing conditions.

  64. It’s agonizing reading such stupidity.

    a doubling of today’s carbon dioxide levels — from 390 parts per million to 800 ppm — will halve the amount of water lost to the air,

    Uh, not really. See, using the same amount of water, THE PLANTS WILL GROW TWICE AS MUCH!
    Biologists and arithmetic are a mismatched pair, clearly.

  65. I find it interesting that plants have evolved a mechanism to deal with the allegedly unprecedented.

    Hmmm…

  66. Mainly desert areas, which are limited by water, would be affected by this. Vegetation would prosper with increased CO2. The extra vegetation would emit exactly the same H20 as the original cover emitted.

    Unfortunately the desert would now be less reflective, decreasing the albedo, absorbing more solar energy, increasing temperatures.

    I don’t care much though.

  67. “David Middleton says:

    Even if a sharp rise of CO2 of 80 ppmv (160 GtC) is theoretically possible, it is physically impossible that the same amount disappears in less than 7 years. The current removal rate of CO2, while some 100 ppmv above (temperature dictated) equilibrium is 4 GtC/year…”

    Only if we believe that removal of CO2 from the atmosphere is driven by chemical processes, rather than biotic ones. If biotic ones were the major cause of overall atmospheric CO2 efflux than the steady state level would be dependent on the affinity of RuBisCO for CO2 and the steady state level would hover around about 280 pp.

    Wait a minute……………..

  68. cedarhill says:
    March 4, 2011 at 3:31 am

    David Schofield March 4, 2011 at 12:45 am: how do plants grow bigger with more CO2 if they reduce the gas exchange so they can’t use it?
    If you double the amount of CO2 and if all other factors are the same, then you can halve the number of pores (think of them as “open ports”) and still get the same amount. If only a 40% decrease you’d still get a large percent uptake of CO2. Obviously, with water vapor the reverse would be true.

    Regardless, what is really interesting is the way plants regulate themselves. If the only control they have is the number of stomata they make. Which, in turn implies the plant has little control or no control over the volume of gasses going in or going out. But they can control their water uptake from the soils. If Darwin were a plant, he’d be able to describe why plants evolved this way. Shame Darwin isn’t a warming believer.
    ————————————

    If you accept that plants are in the business of surviving and thriving, it’s not difficult to imagine that they try to maximize resources.
    There wouldn’t be much point in deliberately depriving themselves of water when water is abundant, especially since exposure to increased CO2 concentration is far from harmful. Either plants are really dumb or there’s method in their madness.
    Stomata opening and closing is done by the plant so as to achieve a compromise between importing as much CO2 as possible while permitting the least possible waste of water.
    If there is an abundance of water available to the roots, a plant can be as extravagant as it likes with it as it tries to capture the maximum CO2 possible. That is, it can open wide the stomata.
    In a drought, the plant is obliged to constrict water loss at the expense of CO2 capture and nutrient transport up the shoot. The plant is frugal in order to stay alive.
    Of course, drought is not a permanent, nor a chronic state of affairs for most of the world’s vegetation, so plants allow more transpiration than is actually required because they’re keen to get a hold of more CO2.
    Plants are clever but they’re not geniuses and so the balance is not perfectly achieved, however they have long-term strategies such as making fewer stomata and they can adjust in the short term by opening and closing them quickly.

  69. We are learning a lot more about he climate (although I note that this latest bit is in fact very, very old stale news).
    We are now learning so much that I do believe that we are almost, I say Almost, at the point where we realise that we know almost nothing about what makes the climate to change and change, always change.
    Strange.

  70. “The Florida Everglades depend heavily on the slow, steady flow of groundwater from upstate. The siphoning of that water to development has raised questions about the future of the Everglades as a national resource.”

    Well, duh, that means more water available for the rest of us! If plants aren’t sucking as much water from the ground, then logically more water will stay in the ground to flow to the southern part of Florida, the Everglades. Honestly, I thought going to college was supposed to teach you critical thinking skills. And why would you stick in a blurb about land use development to imply linkage to CO2 and water flow to the Everglades? What has land development got to do with plant transpiration? Ignorance or Deceit?

    btw- for those of us who live(d) in Florida if plants transpire less then that means lower humidity during the summertime. I would say that’s a good thing not to sweat as much.

  71. Oh no, not again! More from the field of Climastrology: weasel words, model, if, could, may, possible and so on. Not Science!

  72. I thought that during the age of the dinosaurs, the world was much warmer and C02 levels were much higher than today. But the plant life was abundant, so there was more than enough for the herbivores to eat an grow large, so there was more than enough food for the carnivores.
    Everything grew bigger. Surely there was plenty of water to support all this massive growth?
    Am I misunderstanding something?

  73. For each additional CO2 assimilated by a plant, there is a corresponding additional H2O incorporated into a carbohydrate:

    6 CO2 +6 H2O -> C6H12O6 + 6 O2

    Thus plants will transpire less if photosynthesizing more. Stomata respond to minute changes in pH, raise the pH of the air, and stomata will close and vice versa. Increasing CO2 raises the pH of the air.

    This all begs the question:

    Are stomata there to let CO2 in or to let H2O out?

  74. This comes as no surprise to me. There have been studies of the effect on plants grown in artificially high CO2 atmospheres. In addition to spurring growth, there is usually an increase in drought resistance.

  75. These scientists are plain silly. Almost anywhere on the face of Earth except in rain forests where water availability is not a limiting factor, much sunlight reaches ground level. It means if individual plants use less water to produce the same biomass, plant density increases accordingly. Therefore gross volume of evapotranspiration remains about the same, just as stomata, which may be distributed among more individual plants or more leaves on branches, but their overall number does not change.

    My impression that the world around me is getting greener is not entirely out of track perhaps. And it is not “greener” in a political sense, but most places I remember from my childhood actually have more vegetation now than in the good ol’ days.

  76. In any event a higher level of CO2 makes plants healthier.
    As everybody knows, the CO2 level is enhanced to ca. 1000 ppm in Real Greenhouses.

  77. Now that plants transpire less water due to increased CO2 atmospheric content, they are now MORE drought resistant.
    Isn’t that good news?

  78. Funding Recipe:

    Take whatever you study (doesn’t matter what it is) and show how it will be affected by a doubling of CO2. (Matters not whether you are right or wrong.)

    -
    Our research funding systems have degenerated into a reliable source of balanced anger & humor.

  79. Imagine a drug that cures cancer. The authors of the articles being discussed would probably argue as follows: If this cancer cure drug is approved, millions more octogenarians will die each year.

    They would be right. Millions would die in their 80s or beyond, instead of in their 60s or 70s.

  80. Alan the Brit says: March 4, 2011 at 1:59 am
    Slightly OT: Recent BBC tv appearance (Tuesday) by maths guru Johnny Ball stated on tv that manmade CO2 content was only 4% of total. My understanding was that this figure was from the IPCC sources & sinks section of their report, can anybody confirm that at all?

  81. “Schrodinger’s Cat says:
    March 4, 2011 at 3:23 am

    If extra CO2 is used by the plant then extra water is required as well. The photosynthesis combines CO2 and water to make sugars.”

    This is true, but the comment below indicates why there is no contradiction. Kevin’s book was 30 years old. Perhaps 1.3% is now used for growth.

    “Kev-in-Uk says:
    March 4, 2011 at 2:55 am

    Of the transpired water passing through a plant only 1% is used in the growth process.”

  82. DocMartyn says:
    March 4, 2011 at 3:08 pm

    Only if we believe that removal of CO2 from the atmosphere is driven by chemical processes, rather than biotic ones. If biotic ones were the major cause of overall atmospheric CO2 efflux than the steady state level would be dependent on the affinity of RuBisCO for CO2 and the steady state level would hover around about 280 pp.

    Wait a minute……………..

    You react on what I said, not a quote from David Middleton…
    A doubling of pCO2 in the atmosphere gives an average increase of about 50% in plant growth, but much of that returns in fall/winter as vegetation decay. The current real longer term deposit of carbon in vegetation is somewhat over 1 GtC/year, based on oxygen production:

    http://www.bowdoin.edu/~mbattle/papers_posters_and_talks/BenderGBC2005.pdf

    The rest of the current ~4 GtC sink capacity is going into the oceans.

    Thus while the ocean-vegetation-temperature equilibrium would be around 280 ppmv for the current temperature, the yearly addition of fossil CO2 is larger than the current removal rate even with an increased pCO2 some 100 ppmv higher than equilibrium for both oceans and vegetation.

  83. Alan the Brit says:
    March 4, 2011 at 1:59 am

    Namely the 770 Gt or so natrual outgassing as opposed to the 25 Gt or so of manmade outgassing. It is used in the video clip at Climaterealist site presented by a school teacher (very eloquently I must say)!

    Eloquently but completely irrelevant. As Mike McMillan referenced from the IPCC:
    Natural releases: 770,000 MtCO2/year
    Human releases: 23,100 MtCO2/year
    Natural absorption: 781,400 MtCO2/year
    Increase in the atmosphere: 11,700 MtCO2/year

    Thus the natural balance is a net 11,400 MtCO2 absorption per year and thus nature doesn’t contribute to the CO2 increase in the atmosphere…

  84. I’ve read that the amount of water vapor in the (upper?) atmosphere has mysteriously decreased in recent decades. Any relation to the reported decreased water transpiration? (Apologies in advance if this has been covered above. I don’t have time to read all entries before sending this due to having to go out for several hours.)

    IanM

  85. Perhaps I am understanding this incorrectly but would not the need of less transpiration also mean a more drought tolerant plant? Ergo a plant more likely to survive through harsher conditions. In point of fact it almost makes it seem like plants thrive on a higher CO2 concentration and become much more hardy. This sound like a situation where the conclusion drawn is meant to inspire fear without examining the possible benefits ( why does that seem to be the only science nowadays? ) As I was reading the pess release I was actually getting excited as it meant that the amount of irrigation that has been used historically and you know meant that we had to tap into all that ground water stored underneath the earth and spew it into the atmosphere would not be needed as much anymore, that rainfall alone may be enough to water crops and the periods of dry spells would not be as ‘hard’ to weather. Of course I am probably just crazy in thinking in those terms as it is obvious plant respiration and its unknown direct effect on climate is obviously much more important.

  86. Question, If there is an increase in temperature would that not in turn lead to a longer growing cycle and therefore lead to a greater amount of CO2 absorption?

  87. Ferdinand Engelbeen, round and round we go, you think that the planet is a wet rock, where as I believe that from 40 meters down to 70 miles up the whole thing is a product of life.
    You adore dead, static, equilibrium descriptions of of living, dynamic steady states.
    To prove that the system is dead and chemical, you quote the IPCC, which shows the validity of your approach.

  88. Dave Springer says:
    ” We need a lot fewer unaccountable scientists wasting time and money in academia and a lot more engineers getting practical things done and being held accountable when they fail.”

    Dave (and many others!) I have been astounded by the depth of knowledge in this post and admit, as an engineer that biology was something I only touched on. Your posts have enlightened me!

    Dave, as an engineer, I have to say that we use proven science to do our work, using formula and laws proven by academia. Sadly the real brains these days are grabbed up by the financial sectors as they pay the best! Why else would we be chasing windmills!

    Worldwide, academia is a real mess…Can you or anyone else show me one Climatologist that has a degree in Climatology? If there is one, does part of the degree course include Math?

  89. So in 2000, AGW will cause less snowfall, but in 2011, it increases the moisture in the air, thus more snowfall.

    NOW we see: “Dilcher and his Dutch colleagues say that a drier atmosphere could mean less rainfall and therefore less movement of water through Florida’s watersheds.”

    So, I’m guessing that they’ll say, the increased evaporation due to warmer temperatures will stop, but only when we have less rain, or at least that what’s we’ll be hearing next; correct?

    IF we have less snow, it’s due to AGW.
    IF we have more snow, it’s due to AGW.
    IF we have more rain, it’s due to AGW.
    IF we have less rain, it’s due to AGW.
    IF they cancel future seasons of the TV show Wheel Of Fortune, it’s due to AGW too!!! ;-)

  90. DocMartyn says:
    March 5, 2011 at 9:02 am

    Ferdinand Engelbeen, round and round we go, you think that the planet is a wet rock, where as I believe that from 40 meters down to 70 miles up the whole thing is a product of life.
    You adore dead, static, equilibrium descriptions of of living, dynamic steady states.
    To prove that the system is dead and chemical, you quote the IPCC, which shows the validity of your approach.

    In this case, the IPCC figures are based on rather solid observations: fossil fuels sales, CO2, O2 and d13C measurements in the atmosphere and the oceans,…
    Of course a lot of details are not known to the kg of CO2 exchanged, but we have a pretty good idea where the exchanges are and the overall results, including year by year variability. We are less sure how much is exchanged for individual flows. But that doesn’t influence the total balance, which is more natural sink than source at least over the past 50+ years.

    Thus, while there are lots of errors and exaggerations in the IPCC reports, this is not one of them…

    And not one of my last hairs thinks that the planet is static. Of course it is dynamic, but the past has shown that temperature dictates the CO2 equilibrium setpoint of the atmosphere, incredibly linear, including all natural feedbacks from oceans and biosphere and more, of which many may be far from linear.

  91. If there are fewer stomata, or the stomata are closed more of the day, gas exchange will be limited — transpiration included.

    What a bunch of B.S.

    Here’s a different intrepretation. Plants absorb CO2 through stomata. Increasing CO2 may have caused the evolution of less stomata. Water loss is a problematic side-effect of required open stomata for CO2 absorption. If they want to support this thesis, show me data on the number of chlorophyll/unit area in these same plant specimens. Then I will predict water use efficiency. Until then, it’s just data without a cause and effect.

  92. Schrodinger’s Cat says:
    March 4, 2011 at 3:23 am
    “If extra CO2 is used by the plant then extra water is required as well. The photosynthesis combines CO2 and water to make sugars.”

    Agreed. Plants strive to find the optimum balance between all growth factors and have evolved mechanisms to balance changes in availability to always provide optimum growth. As CO2 levels goes up and more sunlight is available they can get better growth with better use of that unreliable but vital resource, water.

    Evidence for this is the current greening of the planet due to multiple factors being beneficial to growth.

  93. Ferdinand Engelbeen, you (none rotating) planet is far different from mine, yours in always on the knife edge leading to one of two catastrophic endings:-
    1) a slight increase in CO2, say from a volcano, increases CO2. This CO2 causes warming of the oceans and so increases the rate at which CO2 is released. This release causes warming and so increases ocean temperature. The Earths temperature increases, droughts and changing weather patterns causes desertification. The melting polar caps decrease land area due to flooding and increases the albedo. Run away heating, caused by CO2 heating the oceans and releasing CO2 in a positive feed back. The Earth boils.
    2) a slight drop in CO2 causes cooling. The cooling of the oceans increases the uptake of CO2. The atmosphere loses CO2 and cools. Cooling causes the ice caps to expand. The increasing ice causes a decrease in albedo. More and more land is covered in ice, causing cooler air and cooler oceans. More CO2 is removed from the atmosphere and the world becomes a snow ball, due to the positive feedback of CO2/ocean cooling.

    These outcomes are not probable, but certain, as your planet has no elasticity.
    You are incapable of understanding that additional inputs of 23,100 MtCO2/year are trivial when the typical influx is 770,000 MtCO2/year and the efflux is on the same order; 781,400 MtCO2/year.
    You inability to even analyze steady state kinetics is both alarming and sad.

  94. DocMartyn,

    I think you might be misunderstanding Ferdinand Engelbeen. His argument has always been that the recent increase in CO2 is due to human emissions. He’s convinced me with data and facts that the cause of most if not all of the the rise is anthropogenic. [And it took some convincing.]

    Ferdinand has mentioned a number of times that the rise in CO2 doesn’t seem to have caused any real problems. And that is the crux of the matter, isn’t it? If the rise in CO2 has only brought about some trivial warming – not a bad thing – and has the added advantage of promoting agricultural growth, then the scare stories about “carbon” have turned out to be not only baseless, but completely wrong. More CO2 appears to be on balance a good thing.

  95. Smokey says:
    March 5, 2011 at 2:00 pm

    Thanks Smokey, at last someone I have convinced!

    DocMartyn says:
    March 5, 2011 at 1:16 pm

    If you know something about dynamic processes, you should know that what you describe, a runaway process (and I have seen the results of a few in my working life!), can only be true if the fortifying factor of the two-way influences is larger than 2.
    In this case, there is a small influence from temperature on CO2 levels (8 ppmv/°C), as seen over the past 800,000 years. And there is a small influence of more CO2 on temperature (1°C/2xCO2 or 1°C for a 280 ppmv increase, based on radiation absorption). That is by far not enough to make it a runaway reaction. Not even to have much influence on the real temperature with the current (or future) increase(s) of CO2. And as already said by Smokey, mostly beneficial: longer growth seasons in the mid to high latitudes, more CO2 which increases growth…

    There are a lot of dynamic processes at work here, where, at a certain temperature, as much Gt CO2 is coming in as is going out the atmosphere, even massive quantities. Thus for a certain temperature there was a dynamic equilibrium (“steady state”) CO2 level over the past 800,000 years, but a different equilibrium for a different temperature. What do you think that will happen if someone adds a relative tiny amount of CO2 per year, but does that continuously for 160 years?

    And for those who haven’t heard of Le Châtelier’s principle, have a look at Wiki:

    http://en.wikipedia.org/wiki/Le_Chatelier's_principle

  96. Alan the Brit says:
    March 4, 2011 at 1:59 am
    Was it not in the Cambrian Expolosion that most plant/animal/plankton diversity existed, & CO2 was 20 times higher than it is today? Oh, we mustn’t be here then because life all died out because of the CO2, or maybe not?

    Plants do indeed have considerable form in terms of a history of dynamic interaction with atmospheric CO2, even to the point of having a dominant effect on the same.

    The paper linked below points to an evolutionary explosion of megaflora leading to trees as we now know them, during the Devonian and early Carboniferous, which sucked much of the CO2 out of the air – leading to responsive changes in plant anatomy, such as the density of stomata discussed in the paper from Bloomington.

    https://docs.google.com/viewer?a=v&pid=explorer&chrome=true&srcid=0B9p_cojT-pflYzZjNDc3YTYtNDFhOS00YmNlLWJiNjctOTU5ODBiYjM4NTM4&hl=en_GB

    The earth’s plant biota cannot be excluded from any discussion of atmospheric CO2 – it is as much biology as it is physics.

  97. Stomata density reduces but surface area increases. What is the net effect? In the quoted part I see no definite answer. As I understand it, plants with lower-density stomata and which transpire at a lower rate (per unit volume) retain water better and so are much more drought-resistant. They therefore require less irrigation, which is good news for dry agricultural regions. Sounds like win-win to me.

  98. ****
    Smokey says:
    March 5, 2011 at 2:00 pm

    DocMartyn,

    I think you might be misunderstanding Ferdinand Engelbeen. His argument has always been that the recent increase in CO2 is due to human emissions. He’s convinced me with data and facts that the cause of most if not all of the the rise is anthropogenic. [And it took some convincing.]
    *****

    Smokey, he convinced me, too. Not easy. So did Leif S, so far.

    Thanks, Ferdinand, for your detailed & unbiased work on this subject. This is how science should be done.

Comments are closed.