AGU says CO2 is plant food

Thirteen Years of Greening from SeaWiFS

Thirteen Years of Greening from SeaWiFS – image from NASA Earth Observatory

Color bar for Thirteen Years of Greening from SeaWiFS

Elevated carbon dioxide making arid regions greener

31 May 2013
AGU Release No. 13-24

WASHINGTON, DC—Scientists have long suspected that a flourishing of green foliage around the globe, observed since the early 1980s in satellite data, springs at least in part from the increasing concentration of carbon dioxide in Earth’s atmosphere. Now, a study of arid regions around the globe finds that a carbon dioxide “fertilization effect” has, indeed, caused a gradual greening from 1982 to 2010.

Focusing on the southwestern corner of North America, Australia’s outback, the Middle East, and some parts of Africa, Randall Donohue of the Commonwealth Scientific and Industrial Research Organization (CSIRO) in Canberra, Australia and his colleagues developed and applied a mathematical model to predict the extent of the carbon-dioxide (CO2) fertilization effect. They then tested this prediction by studying satellite imagery and teasing out the influence of carbon dioxide on greening from other factors such as precipitation, air temperature, the amount of light, and land-use changes.

The team’s model predicted that foliage would increase by some 5 to 10 percent given the 14 percent increase in atmospheric CO2 concentration during the study period. The satellite data agreed, showing an 11 percent increase in foliage after adjusting the data for precipitation, yielding “strong support for our hypothesis,” the team reports.

“Lots of papers have shown an average increase in vegetation across the globe, and there is a lot of speculation about what’s causing that,” said Donohue of CSIRO’s Land and Water research division, who is lead author of the new study. “Up until this point, they’ve linked the greening to fairly obvious climatic variables, such as a rise in temperature where it is normally cold or a rise in rainfall where it is normally dry. Lots of those papers speculated about the CO2 effect, but it has been very difficult to prove.”

He and his colleagues present their findings in an article that has been accepted for publication in Geophysical Research Letters, a journal of the American Geophysical Union.

The team looked for signs of CO2 fertilization in arid areas, Donohue said, because “satellites are very good at detecting changes in total leaf cover, and it is in warm, dry environments that the CO2 effect is expected to most influence leaf cover.” Leaf cover is the clue, he added, because “a leaf can extract more carbon from the air during photosynthesis, or lose less water to the air during photosynthesis, or both, due to elevated CO2.” That is the CO2 fertilization effect.

But leaf cover in warm, wet places like tropical rainforests is already about as extensive as it can get and is unlikely to increase with higher CO2 concentrations. In warm, dry places, on the other hand, leaf cover is less complete, so plants there will make more leaves if they have enough water to do so. “If elevated CO2 causes the water use of individual leaves to drop, plants will respond by increasing their total numbers of leaves, and this should be measurable from satellite,” Donohue explained.

To tease out the actual CO2 fertilization effect from other environmental factors in these regions, the researchers first averaged the greenness of each location across 3-year periods to account for changes in soil wetness and then grouped that greenness data from the different locations according to their amounts of precipitation. The team then identified the maximum amount of foliage each group could attain for a given precipitation, and tracked variations in maximum foliage over the course of 20 years. This allowed the scientists to remove the influence of precipitation and other climatic variations and recognize the long-term greening trend.

In addition to greening dry regions, the CO2 fertilization effect could switch the types of vegetation that dominate in those regions. “Trees are re-invading grass lands, and this could quite possibly be related to the CO2 effect,” Donohue said. “Long lived woody plants are deep rooted and are likely to benefit more than grasses from an increase in CO2.”

“The effect of higher carbon dioxide levels on plant function is an important process that needs greater consideration,” said Donohue. “Even if nothing else in the climate changes as global CO2 levels rise, we will still see significant environmental changes because of the CO2 fertilization effect.”

This study was funded by CSIRO’s Sustainable Agriculture Flagship, Water for a Healthy Country Flagship, the Australian Research Council and Land & Water Australia.

Notes for Journalists

Journalists and public information officers (PIOs) of educational and scientific institutions who have registered with AGU can download a PDF copy of this accepted article by clicking on this link: http://onlinelibrary.wiley.com/doi/10.1002/grl.50563/abstract

Or, you may order a copy of the final paper by emailing your request to Peter Weiss at PWeiss@agu.org. Please provide your name, the name of your publication, and your phone number.

Neither the paper nor this press release are under embargo.

Title:

CO2 fertilisation has increased maximum foliage cover across the globe’s warm, arid environments

Authors:

Randall J. Donohue and Tim R. McVicar
CSIRO Land and Water, Canberra, Australia;
Michael L. Roderick
Research School of Biology, The Australian National University, Canberra, Australia; Research School of Earth Sciences, The Australian National University, Canberra, Australia; and Australian Research Council Centre of Excellence for Climate System Science;
Graham D. Farquhar
Research School of Biology, The Australian National University, Canberra, Australia.
h/t to Dennis Wingo
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64 Responses to AGU says CO2 is plant food

  1. Peter says:

    OK, so the race is on to find something really devastating to the planet because of this greening… shouldn’t be too long.

  2. Larry Hulden says:

    From greenhouse experiments with elevated CO2 ppm we can calculate that the increase in yield per hectar for the the most important food plants is about 7% because of the increase in CO2 in the atmosphere from 1961 to 2011. I took data from the Idsos.

  3. Mark Hladik says:

    “Oh, no! It’s WORSE than we thought!”

  4. Mike jarosz says:

    Can someone send a copy to the EPA and Obama before he kills all the plants with his carbon taxes?

  5. philincalifornia says:

    Peter says:
    May 31, 2013 at 9:37 am
    OK, so the race is on to find something really devastating to the planet because of this greening… shouldn’t be too long.
    ———————————————–

    ………. you mean like today, for example:

    http://www.usatoday.com/story/news/nation/2013/05/30/climate-change-allergies-asthma/2163893/

  6. Hell_Is_Like_Newark says:

    The AGW crowd get rather shrill when they try to argue that increased CO2 is actually BAD for plants. Here are some example claims without comment from me (no link.. doing this from memory):

    Increased CO2 causes grains to have a lower protein content, therefor making them less healthy to eat.

    Higher CO2 will cause C3 weeds to grow faster and therefor reduce C4 crops such as wheat.

    Plants can’t handle such a rapid increase in CO2 and will ultimately be harmed.

    If anyone is interested to see studies on the effects of greatly elevated CO2 levels on various crops, CO2science.org has an excellent database of such.

  7. Henry Galt says:

    “The team’s model predicted that foliage would increase by some 5 to 10 percent given the 14 percent increase in atmospheric CO2 concentration during the study period. The satellite data agreed, showing an 11 percent increase in foliage after adjusting the data for precipitation, yielding “strong support for our hypothesis,” the team reports.”

    Not bad work for a model they have been running since 1982.

    Oh.

    Oh dear. I see…..

  8. Latitude says:

    to show this kind of response….CO2 would have had to be limiting before

    …you think

  9. Bobby Davis says:

    Too Funny Henry. I just sit back & laugh at these fools who try to explain the way the world works & how it’s always mankinds fault.

  10. Silence DoGood says:

    human beings 15ft tall will soon roam the Earth

  11. VikingExplorer says:

    Logically, 11% more greening would mean a lot of Carbon has been sequestered. So, why is the global C02 level still 14% higher? Answer: It’s not. The ML data is one single point on earth. It’s representing the source of the CO2, which are the hot equatorial oceans expelling CO2. The global CO2 levels, although impossible to measure, are presumably relatively unchanged. Btw, Segalstad has determined that man’s effect on the huge global CO2 cycle is about .2%.

    To summarize: Sun heats oceans, Oceans control atmospheric temperatures because of a massive difference in mass/energy storage, Oceans expel CO2, CO2 feeds plants. AGW’s reversal of cause and effect to this extent is scientific malpractice.

  12. Warren says:

    I think I learned this in… Let’s see… I think it was 1st Grade!

  13. RobRoy says:

    The intelligence of the trees will also increase and they no longer will allow us to pick fruit from them. (See apple trees in “The Wizard of Oz.”)

  14. 3x2 says:

    (CSIRO) in Canberra, Australia and his colleagues developed and applied a mathematical model to predict the extent of the carbon-dioxide (CO2) fertilization effect.

    Shocking … Carbon Dioxide and Water (+ Energy from The Sun) converts to Oxygen and Food for our sad, politically driven, lump of rock in Space.

    (Outside of a large meteor strike or a massive change in the output of The Sun…)
    H2O is a constant and CO2 is rising. So… More Oxygen and more ‘Planetary’ food. Watts not to like? Did we need the application of a mathematical model and a huge grant to demonstrate this?

    Hey, just had a thought. What if we needed to boost CO2 in order to feed our growing population? Instead of growing ever larger Dinosaurs in ages past we, in our modern era, use CO2 to ensure the feeding and well being of 6 Billion+ Humans. Radical, I know … Got to be worth a shot though?

  15. dbstealey says:

    AGU says CO2 is plant food

    They could have learned that right here.

  16. Kurt Austin says:

    It comes to me at no surprise. Plants tissue is composed of 40+% pure carbon. No CO2 — no growth! And where do they get it from? Almost ALL of it comes from CO2, atmospheric in terrestrial plants, and water dissolved in aquatic ones (CO2 is a highly soluble gas).
    At 400ppm plants are CO2 (growth) inhibited. Ideal would be around 1500-3000 ppm. There has historically been much more CO2 in our atmosphere than exists today. For example, during the Jurassic Period (200 mya), average CO2 concentrations were about 1800 ppm or about 4.7 times higher than today. The highest concentrations of CO2 during all of the Paleozoic Era occurred during the Cambrian Period, nearly 7000 ppm — about 18 times higher than today.

  17. @Henry Galt – Any relation to John?

    It is interesting to see studies coming out that don’t try to link to AGU, just presenting the facts

  18. Dave says:

    Would an 11% increase in green coverage make those areas more or less warm? Would it contribute to warming the planet or cooling it?

  19. John from the EU says:

    We knew this all along. So can we no stop with these ridiculous CO2 taxes here in Europe? And get the economy going again?

  20. Jimbo says:

    So, the satellites have been telling us the biosphere has been greening, Bangladesh has gained landmass and that most of the coral island atolls have grown or stayed the same size is good news. It’s a pity the TV media don’t highlight these problems.

    Bangladesh gaining land, not losing: scientists

    The dynamic response of reef islands to sea-level rise

    Sahara Desert Greening Due to Climate Change?

  21. Bart says:

    VikingExplorer says:
    May 31, 2013 at 10:03 am

    “AGW’s reversal of cause and effect to this extent is scientific malpractice.”

    You are correct, and it is evident in the data. The oceans are always upwelling CO2 laden waters in the tropics, and downwelling them at the poles. Any differential in the rate at which it upwells and downwells will either accumulate or drain from the surface system. The rate at which it does so is a function of temperature, and a first order model of that function is affine

    dCO2/dt = k*(T – Teq)

    where the parameter “k” determines the sensitivity to temperature, and Teq is an equilibrium temperature. As a first order expansion of a non-linear system, these coefficients may change over time, and may not even be smooth. However, in the last 55 years, they can be considered essentially constant. All of the major temperature sets are essentially themselves affinely related, but the best fit appears to be with Southern Hemisphere temperatures, suggesting this is predominantly an oceanic phenomenon.

    The relationship uniquely determines the level of CO2 in the atmosphere given the temperature record. As this plot using GISS temperatures shows, the only thing you need to determine atmospheric CO2 concentration at any time in the last 55 years to high fidelity is the starting point, the coefficients “k” and “Teq”, and the temperature record. Human inputs are essentially superfluous, which says that Nature handily sequesters them and shrugs them off.

    There has been a superficial resemblance between human emissions and atmospheric concentration over this time, but it is merely a coincidental match between two rising time series over a short interval of time – they do not match in all the bumps and wiggles the way the temperature series matches the CO2 rate of change. And, that superficial resemblance is even now diverging, as the stall in temperatures has concomitantly reduced the rate of change of CO2.

  22. john robertson says:

    As for catastrophic Anthropogenic global greening, let me give the team a freebie.
    As co2 levels rise in the air, an ancient doom will walk again.
    Oh yeah the trees will rise from their starvation induced slumber and destroy the works of man.
    If we do not act immediately and decimate all plants over 3m tall, the world of man will end in….

  23. mosomoso says:

    In my part of the Australian coastal fringe, regrowth is massive. Marginal pastoral land just goes back to scrub when you can’t afford to maintain it as mere holding pasture. Intensive ag, GM, chemicals, more selective ag, winding down of native timber industries in favour of steel frame and plantation lumber…it all means more green stuff, with or without added CO2. If someone clears a few acres, there are howls. If a lot more acres regrow, nobody comments. One process is sudden and provokes emotions; the other process is gradual and is hardly noticed. (There’s even a chance to conserve more wildlife. Thanks to modern synthetics, we no longer hunt koalas for their pelts, but thanks to our squeamishness about guns and poisons, wild dogs and cats tear all the wildlife to bits, as well as valuable stock.)

    Of course, when we go back into a warmer, drier cycle, it’s all going to burn – but the CO2 you can’t tax is CO2 that never happened, right? Like all the twigs and dung burnt by billions of the poor…their CO2 doesn’t count till they start getting light and heat from a decent, reliable source. Then the auditors arrive! But it’s never peak-dung or peak-twig.

  24. Jimbo says:

    There have been other similar papers in recent months.

    May 2013
    Abstract
    A Global Assessment of Long-Term Greening and Browning Trends in Pasture Lands Using the GIMMS LAI3g Dataset

    “Our results suggest that degradation of pasture lands is not a globally widespread phenomenon and, consistent with much of the terrestrial biosphere, there have been widespread increases in pasture productivity over the last 30 years.”
    http://www.mdpi.com/2072-4292/5/5/2492

    April 2013
    Abstract
    Terrestrial satellite records for climate studies: how long is long enough? A test case for the Sahel

    As an example, the Sahelian drought and the subsequent recovery in precipitation and vegetation will be analyzed in detail using observations of precipitation, surface albedo, vegetation index, as well as ocean indices.
    http://link.springer.com/article/10.1007/s00704-013-0880-6

  25. Ryan says:

    “The direct CO2 effect on vegetation should be most clearly expressed in warm, arid environments where water is the dominant limit to vegetation growth.”

    It’s probably a big leap for any plants that use CAM or similar processes. Being able to gulp CO2 at a slightly higher concentration would help them a lot. Does anyone have full access to see if they typed the findings according to photosynthesis systems?

  26. Blade says:

    Peter [May 31, 2013 at 9:37 am] says:

    OK, so the race is on to find something really devastating to the planet because of this greening… shouldn’t be too long.

    Exactly!

    The question is will they soon learn that Planetary Greening == Carbon Sequestration?

    Hansen: Damn that Carbon Cycle. Damn it all to hell!

  27. Nik says:

    Just when I was getting used to the idea that my home would turn into desert you spring this on me. I am going to sue!

  28. Bruce Cobb says:

    Good start. Now, if they could just admit that, far from being the evilmagic gas they and their cohorts make it out to be, it is in fact only beneficial to man, to plants, and the earth.
    Baby steps.

  29. Berényi Péter says:

    That’s settled, truly. The only thing we need to figure out is how it’s worse than we thought?

    Can I have my fat grant to study Anthropogenic Arborous Infestation of Pristine Mineralian Landscapes by Invasive Species?

  30. Jpatrick says:

    There are a lot of studies that involve growing plants in a “carbon dioxide enriched” atmosphere. One of the memorable of those studies is the on-going effort at Duke university, where they observe how trees respond to a CO2 enriched atmosphere. Here’s one example:

    http://www.sciencedaily.com/releases/2009/08/090803173246.htm

    Whether CO2 enrichment is “good” or not is a value judgment that may never get resolved. Not all plants respond the same, and the ones that respond most vigorously aren’t necessarily “good” plants.

    I’ve never met an alarmist who knows much about this subject.

  31. AndyG55 says:

    I’ve said it before. 280ppm is about the base level for continued plant sustinence. This is where the level drops down to in the preditor/prey scenario, and not much lower (that we know of).
    And that’s where is been (mostly) for a very very long time.

    Toward 700ppm, i say !!

  32. RockyRoad says:

    VikingExplorer says:
    May 31, 2013 at 10:03 am

    “AGW’s reversal of cause and effect to this extent is scientific malpractice.”

    Now that CO2 is scientifically recognized to be beneficial, can we take the Warmista’s efforts to curtail it to mean they don’t like humans–that they want a certain portion of them to starve? Likewise, that they are enemies of any other animal that depends on photosysthesis anywhere in their food chain?

    I hope someday it will be considered as bad to be a Warmista as to be a child molester. Certainly the logic is similar.

  33. richard says:

    This year is expected to be a global record for wheat and rice, hard to tell now with the cold across the US and other parts of the world. Always worth typing into google for agricultural records for whatever crop and country you wish. In general it is all pretty positive. Very different to the usual spiel from the doomsayers.

  34. Scarface says:

    “Even if nothing else in the climate changes as global CO2 levels rise, we will still see significant environmental changes because of the CO2 fertilization effect”

    In the draft it said:

    Because nothing in the climate changes as global CO2 levels rise, we will find something else to blame CO2 for and tax the hell out of people.

  35. Chad Wozniak says:

    @philincalifornia -
    Yeah, there will be more pollen if there is more plant growth due to higher CO2. Duh.

    At what point does broadcasting disinformation become a criminal offense? Sooner rather than later, mehopes. As I see it, lying by the news media should not be protected as free speech – it’s quite different when an entity with the ability to influence public opinion lies, than when a soapbox orator or writer of letters to his congressman does. The US news media, with the exception of Fox, the WSJ and a few other conservative outlets, strives mightily to deprive anyone they don’t agree with of his or her free speech rights – and of course der Fuehrer and his gauleiters in Washington have declarexd war on all dissenting journalists and all journalists who might point to theuir crimes.

  36. Mike Jonas says:

    Well, a few people are having fun tearing this paper to bits, but the really crucial statement in the report on it is “They then tested this prediction”. ie, they didn’t publish until they had successfully tested.

    Bit of a contrast, that, to the actions of the CAGW modellers.

  37. Chad Wozniak says:

    @rockyroad -
    Scaring schoolchildren with statements that they are going to die of global warming isn’t stopped sure sounds like child abuse to me. And if the “teachers” who do this get their jollies from it, they ARE molesting those kids.

  38. Bill Illis says:

    So far, the impact of increased CO2 is the following:

    - some tiny warming that one can’t actually notice;
    - a small decrease in Arctic sea ice in August and September; and,

    - an 11% increase in the productivity of the biome since 1982 including a greening up of desert regions !

    I’m sorry, I don’t see how one could conclude anything except the increased CO2 is very beneficial; not just for mankind but for the animals as well and especially for C3 vegetation, which doesn’t get to speak for itself.

  39. That more CO2 means greener planet was obvious by definition.
    What I would like to know is:
    Do they take photosynthesis (and its increase with the increase of the plant cover) into account in their equations and models as a feedback mechanism?
    Photosynthesis is a sequestration of solar energy.
    How do they figure it in their “forcing” calculations?

  40. AndyG55 says:

    Waiting for Trenberth to say that this is where his missing energy is.!
    Thing is that if we now reduce CO2 all that energy will get released back into the atmosphere.

    So sequestering and reducing CO2 is the very last thing we should do if we want to avoid catastrophic warming. (sort of only half, sarc)

  41. MrX says:

    CO2 makes the Earth greener. Who’d of thunk it? CO2 is the ultimate green energy producer. But green advocates are against it. If alien civilizations are watching us, it’s no wonder they don’t show themselves publicly. What do we have to offer but lunacy.

  42. Max™ says:

    Hmmm, plant related catastrophe… do Triffids count?

  43. kalsel3294 says:

    Hell_Is_Like_Newark says:
    May 31, 2013 at 9:52 am.
    I agree, having tried to argue all those points at the Skeptical Science playgroup some time back. None of the regulars there could see the obvious.
    Arguing the first point about reduced protein levels, firstly they wouldn’t accept that historically, all other things being equal, percentage protein levels normally fall as yields increase, and conversely rise as yields decrease as part of the natural cycle of cropping under varying seasonal conditions.
    Secondly they also simply could not get their tiny minds around the simple equation that shows that although % protein in the grain may fall, the increased yield means that on a per hectare basis, more protein was actually being produced for a given area of cultivation.

  44. Katherine says:

    Nice. They came up with a model, then validated it against observations. That’s how science should be done. Hard to believe it’s a CSIRO study.

  45. phlogiston says:

    The death of CAGW when it comes, will come with explosive pent-up force, and is likely to be the most monstrous and astonishing scientific fiasco of all time. There is a danger that in its wake all scientists will suffer from a public sentiment painting scientist as parasitic rent-seeking fraud-peddling politically-interfering misanthropic Khmer-Vert anti-economy anti-civilization anti-human compulsive liars. The day will come for laughing but at the same time keeping one’s head down.

  46. goldminor says:

    Chad Wozniak says:
    May 31, 2013 at 3:07 pm
    ———————————
    Nice point.
    Doesn’t it seem a bit natural that with 7+ billion humans now inhabiting this planet that a little extra co2 might be a good idea?

  47. AndyG55 says:

    If the planet is going to feed the expect human population in the future, we MUST release the carbon from underground storage into the atmosphere WHERE IT BELONGS !!!

  48. Baa Humbug says:

    Amazing. Incredible. Groundbreaking.
    Increase the food supply and the species that feed on it flourishes. I’m lost for words.

  49. Matt says:

    Photosynthesis, and a positive effect of more CO2 on plants is an invention of bad big oil. They, with all their money have even managed to get this into primary school all over the planet. Its definitively worse than we thought. Hopefully big government can save us….

  50. johnmarshall says:

    Not only is this CO2 increase good for plant increased growth but extra CO2 reduces the plant’s water requirement. this is why arid regions are getting greener not extra precipitation extra CO2.
    Farming under glass is made more profitable by increasing the greenhouse atmospheric CO2 up to near 2000ppmv.
    So a closed cycle would be– biowaste fermented to produce methane, this burnt to produce heat for the greenhouse and the exhaust piped in as well to supply the extra CO2. this produces more biowaste etc. etc. etc. You get the idea.

  51. Phil. says:

    johnmarshall says:
    June 1, 2013 at 2:45 am
    Not only is this CO2 increase good for plant increased growth but extra CO2 reduces the plant’s water requirement. this is why arid regions are getting greener not extra precipitation extra CO2.

    Not true for every molecule of CO2 one molecule of H2O (net) is needed:
    6 CO2 + 12 H2O + photons → C6H12O6 + 6 O2 + 6 H2O

    The point made in the paper is that it is the warm, arid regions which are getting greener which means that it’s the C4 and CAM plants that are benefiting. So it’s not food crops in the main which are increasing nor trees.

  52. Otis says:

    At some point vegetation, on a global average basis, will grow faster than it decomposes. Maybe that is where coal comes from; in the past, when CO2 was at much higher levels, plants debris accumulated, depleting the atmosphere of CO2.

  53. beng says:

    ***
    Phil. says:
    June 1, 2013 at 4:56 am

    The point made in the paper is that it is the warm, arid regions which are getting greener which means that it’s the C4 and CAM plants that are benefiting. So it’s not food crops in the main which are increasing nor trees.
    ***

    Huh? True, perhaps the moisture-marginal areas benefit the most, but there’s a vast amount of empirical data showing the benefits of more CO2. C3,C4 and CAM plants that grow in all types of environments from wet to dry. And most mid-range-moisture environments experience dry periods. Greenhouses pumping in 1000/1500 ppm CO2 only grow warm, arid-region species?

  54. Lars P. says:

    Bill Illis says:
    May 31, 2013 at 3:50 pm
    So far, the impact of increased CO2 is the following:
    - some tiny warming that one can’t actually notice;
    - a small decrease in Arctic sea ice in August and September; and,
    - an 11% increase in the productivity of the biome since 1982 including a greening up of desert regions !
    I’m sorry, I don’t see how one could conclude anything except the increased CO2 is very beneficial; not just for mankind but for the animals as well and especially for C3 vegetation, which doesn’t get to speak for itself.

    Bill, thinking in agricultural productivity, as Freeman Dyson said : at least 15% of our food is due to the increase in CO2.
    For 7 billion humans that is food for 1 billion!

    The 350 crowd would like to reverse the process and reduce food production by a respective amount? Sometimes I ask myself if they are really aware of what they stand for?

    This is a nice simple photo:
    http://www.plantsneedco2.org/html/PlantPPM2.jpg
    CO2science.org had a very nice database with plants, hundreads of studies organised per alphabet letters, but seems to be offline at the moment.

  55. Chris Schoneveld says:

    Wouldn’t one expect also an increase in atmospheric oxygen? After all that’s what plants emit in the process.

  56. Werner Brozek says:

    Chris Schoneveld says:
    June 1, 2013 at 12:07 pm
    Wouldn’t one expect also an increase in atmospheric oxygen? After all that’s what plants emit in the process.

    The problem is that this is not the only thing that is happening. By burning fossil fuels, we use up far more O2 than the extra O2 that plants produce. But the total amounts are totally insignificant anyway. If CO2 goes up from 0.03% to 0.04% and oxygen goes down from 20.96% to 20.95%, who cares? (It is not quite this simple, but close enough to give the relative importance of oxygen change.)

  57. Dr. Lurtz says:

    Shouldn’t we have a CO2 model first??

    /sarc

  58. Chris Schoneveld says:

    Thanks Werner, that makes a lot of sense. i couldn’t be bothered doing the sums but the “sequestering” (ha ha) of oxygen by the burning of fossil fuels would indeed far outway the extra oxygen produced by the increase of greenery.

  59. Mike M says:

    Phil – At issue is the minimum amount of water lost in transpiration as a function of stomata count – not stoichiometry. And as Beng pointed out there are plenty of studies showing healthy growth increases for trees from elevated CO2.

  60. johnmarshall says:

    Phil.
    the extra atmospheric CO2 reduces the plants transpiration which means less water is needed for growth so the extra CO2 increases the efficiency of the photosynthesis.
    See http://www.co2science.org

  61. chris y says:

    Lars P. says-

    “…as Freeman Dyson said : at least 15% of our food is due to the increase in CO2.
    For 7 billion humans that is food for 1 billion!”

    I decided to adopt the EPA estimate of around $7M as the value of an avoided human death. This money is often claimed to pay for renewable energy schemes or justify spending billions on pollution control schemes.

    If global emissions are approximately 30 billion tonnes CO2 per year, then 30 tonnes per year CO2 emissions keeps one person fed. At the EPA’s $7M value per fed person, apparently CO2 emitters can collect on $7,000 Trillion over the average life of about 70 years. Or equivalently, the CO2 rebate should be about $7,000,000/(30*70) = $3333 per tonne CO2. This is a rebate that acknowledges just one of the positive contributions of using fossil fuels.

    It explains why Ocophobes (people who are fearful of OCO, aka CO2) never want to discuss the benefits of CO2 emissions.

  62. Craig Moore says:

    Seems to be a breath of fresh air for Treebeard and the Ents.

  63. Leo Morgan says:

    Why do they assume this is only happening on land?
    What’s happening with seaweed and phytoplankton?

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