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Climate Hustle

More Carbon Dioxide is not necessarily good for plants.

Posted on 18 April 2011 by villabolo

An argument, made by those who deny man made Global Warming, is that the Carbon Dioxide that is being released by the burning of fossil fuels is actually good for the environment. Their argument is based on the logic that, if plants need CO2 for their growth, then more of it should be better. We should expect our crops to become more abundant and our flowers to grow taller and bloom brighter.

However, this "more is better" philosophy is not the way things work in the real world. There is an older, wiser saying that goes, "Too much of a good thing can be a bad thing." For example, if a doctor tells you to take one pill of a certain medicine, taking four is not likely to heal you four times faster or make you four times better. It's more likely to make you sick.

It is possible to help increase the growth of some plants with extra CO2, under controlled conditions, inside of greenhouses. It is based on this that 'skeptics' make their claims. However, such claims are simplistic. They fail to take into account that once you increase one substance that plants need, you automatically increase their requirements for other substances. It also fails to take into account that a warmer earth will have an increase in deserts and other arid lands which would reduce the area available for crops. 

Plants cannot live on CO2 alone. They get their bulk from more solid substances like water and organic matter. This organic matter comes from decomposing plants and animals or from man made fertilizers. It is a simple task to increase water and fertilizer and protect against insects in an enclosed greenhouse but what about doing it in the open air, throughout the entire Earth?

What would be the effects of an increase of CO2 on agriculture and plant growth in general? The following points make it clear.

1. The worse problem, by far, is that increasing CO2 will increase temperatures throughout the Earth. This will make deserts and other types of dry land grow. While deserts increase in size, other eco-zones, whether tropical, forest or grassland will try to migrate towards the poles. However, soil conditions will not necessarily favor their growth even at optimum temperatures.

2. CO2 enhanced plants will need extra water both to maintain their larger growth as well as to compensate for greater moisture evaporation as the heat increases. Where will it come from? Rainwater is not sufficient for current agriculture and the aquifers they rely on are running dry throughout the Earth (1, 2).

On the other hand, as predicted by Global Warming, we are receiving intense storms with increased rain throughout of the world. One would think that this should be good for agriculture. Unfortunately, when rain falls down very quickly, it does not have time to soak into the ground. Instead, it builds up above the soil then floods causing damage to the crops. The water also floods into creeks, then rivers, and finally out into the ocean carrying off large amounts of soil and fertilizer.

3. Unlike Nature, our way of agriculture does not self fertilize by recycling all dead plants, animals and their waste. Instead we have to be constantly producing artificial fertilizers from natural gas which will eventually start running out. By increasing the need for such fertilizer you will shorten the supply of natural gas creating competition between the heating of our homes and the growing of our food. This will drive the prices of both up.

4. Too high a concentration of CO2 causes a reduction of photosynthesis in certain of plants. There is also evidence from the past of major damage to a wide variety of plants species from a sudden rise in CO2 (See illustrations below). Higher concentrations of CO2 also reduce the nutritional quality of some staples, such as wheat.

 5. When plants do benefit from increased Carbon Dioxide, it is only in enclosed areas, strictly isolated from insects. However, when the growth of Soybeans is boosted out in the open, it creates major changes in its chemistry that makes it more vulnerable to insects, as the illustration below shows.

Figure 1: Plant defenses go down as carbon dioxide levels go up, the researchers found. Soybeans grown at elevated CO2 levels attract many more adult Japanese beetles than plants grown at current atmospheric carbon dioxide levels. Science Daily; March 25, 2008. (Credit: Photo courtesy of Evan Delucia)

Figure 2: More than 55 million years ago, the Earth experienced a rapid jump in global Carbon Dioxide levels that raised temperatures across the planet. Now, researchers studying plants from that time have found that the rising temperatures may have boosted the foraging of insects. As modern temperatures continue to rise, the researchers believe the planet could see increasing crop damage and forest devastation. Science Daily; Feb. 15, 2008.

Figure 3: Global Warming reduces plant productivity. As Carbon Dioxide increases, vegetation in Northern Latitudes also increases. However, this does not compensate for decreases of vegetation in Southern Latitudes. The overall amount of vegetation worldwide declines 

In conclusion, it would be reckless to keep adding CO2 to the atmosphere. Assuming there are any positive impacts on agriculture in the short term, they will be overwhelmed by the negative impacts of climate change.

It will simply increase the size of deserts and decrease the amount of arable land. It will also increase the requirements for water and soil fertility as well as plant damage from insects.

Increasing CO2 levels would only be beneficial inside of highly controlled, enclosed spaces like greenhouses.

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Comments 51 to 100 out of 143:

  1. I was thinking there are at least two ways of thinking of this issue. In the post above, mostly the discussion is about how plants respond to changing conditions. The other way is to think of it as where conditions exist.

    Expanding on item #4:

    Poleward movement of terrestrial surface
    isotherms is expected to average between
    3.8 km and 5.9 km per year if current trends
    of global climate change continue (1).

    If you pull out a globe, or open Google Earth, and look at where major agricultural areas are now, there are a fair number which will not be readily migrated poleward. Geographic features and political boundaries will make it so that this problem is much more difficult than the base cost of relocating farmers and the cities they are based out of.
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  2. KR at 10:06 AM on 18 April, 2011, I am constantly perplexed by claims such as yours that many charts are doctored or not properly referenced, when it is a simple matter of clicking on such charts to go to the original source.
    I do it as a matter of course.
    If I can do it, how come others cannot.
    What is the problem, lack of research skills or what?
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  3. May I second Adelady? Nature Does Not Care in the slightest about your survival, or any other species survival for that matter. If you survive - great. If you don't - equally great.

    Organisms comfortably adapted to a particular set of surprisingly stable conditions poke those conditions with a sharp stick at their peril. (How this can be done in the name of 'Conservatism' is beyond my comprehension - and parody!)

    Liebig's law puts the lie to the idiot 'CO2 is plant food - therefore more must be good' mantra full stop. You only have to demonstrate any substantial exception to such a glib fallacy in order to disprove it. If the initial meme is inane quibbling that the anti-meme is insufficiently nuanced is just captiousness.

    You can get too much of a good thing; quibbling about the complex (indeed, Chaotic) boundary of this 'too much' as if this somehow invalidates the general principle is pointless at best. 'Yellow doesn't exist because you can't define the point in the spectrum at which it becomes orange' is not a valid argument.
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  4. @ Albatross and KR: 'Tis a Travesty the Tricks employed by the Deny-O-Sphere to Hide the Decline...
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  5. @44 LukeW:

    "This post on CO2 is dreadfully simplistic and naive."

    Simplistic yes. That's what you get with a basic level rebuttal. Naive, I think not.

    In the Australian context of savanna woodlands increased vegetation in terms of trees will decrease not increase fire. Grass is what makes fire carry in the world's vast area of savanna biomes.

    "Most detailed crop physiology modellers will now take CO2 fertilisation into account when simulating crop growth. If there is enough water and nutrients growth will be enhanced. At the levels of CO2 enhancement practically experienced in the field is CO2 really having any impact of yield quality?"

    Please see the video (1:58; also, focus on 2:21) for a global perspective. That is observation as opposed to modeling.

    "At a whole landscape scale increased CO2 will improve transpiration efficiency and greater water runoff will result."

    Since I try to be as thorough and detailed as possible, you some of your statements and questions have already been covered in previous posts.

    As far as water depletion, irrespective of the benefits of transpiration, is concerned; I responded to that in the post right before yours (#43). I responded to the issue in the context of mechanized agriculture. Please refer to the second to last paragraph in that post.

    "Climate change will have winners and losers. If North America became warmer and wetter - their wheat yields would be boosted considerably, especially with some CO2 turbo-charging.

    As for more intense rainfall causing greater loss of soils and nutrients - I wonder - there is this thing called soil conservation - contour banks, minimum tillage or zero tillage. Great advances have been made in these areas over the last 40 years."

    "Winners and losers." Are you referring to plants in general or mankind in a rapidly changing world with famine; infrastructure damage; economic collapse and mass migration? Did I forget wars?

    As far as advantages in soil conservation, three points can be brought up.

    First; how much time and extra resources will we have to adapt with? How much time to adapt to worsening conditions for crops and socio-economic situations? IMO, expect serious trouble beginning this decade and escalating from there on.

    Second; overwhelming flooding like Pakistan and Australia will overwhelm the positive effects of soil conservation.

    Pakistan, for example, was so inundated over 20% of its landscape that some farmers could not even distinguish their former land from the rest of the terrain. That was due to the massive floods changing the landscape altogether.

    Third; low and zero tillage are at odds with mechanized agriculture, as far as I know.

    "What could have been mentioned at the other end is that CO2 can increase frost sensitivity (deniers would chip in here and exclaim it will never frost again)."

    That should be mentioned in a more advanced post. It is simply too much detail for the basic level reader to digest. It's best not to overload them with too much information. I feel I've already done that to a certain extent.

    "Anyway the case for winners and losers needs to be made. At nation state level, land use, biome, and ecological patch level. The article here is far too simplistic."

    The summation above has been covered in the previous statements

    IMO we will need a drastically different civilization to adapt to CAGW. A network of self-reliant villages, numbering no more than 500 persons each; is what I envision. But that's a different story.
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  6. "KR at 10:06 AM on 18 April, 2011, I am constantly perplexed by claims such as yours that many charts are doctored or not properly referenced, when it is a simple matter of clicking on such charts to go to the original source."

    Oh, what a surprise-members of the Denial-o-sphere coming to each other's defense. The issue here, John D, is *why* do people like BP & Gilles always choose to clip or modify the charts they post, in such a way as to give a false impression of what those charts are actually telling us?
    You, too, have a habit of reporting only *half* of a story-like the story regarding your beloved FACE trials. The FACE trials really don't properly mimic what a CO2-enriched world would look like. Even the Horsham Trial only looks at current conditions for rain-fed vs irrigated agriculture. Yet even those people running the Horsham Trial have conceded that increased CO2 leads to a decrease in nitrogen uptake by the plants-& that any gains in biomass are short-term, with acclimation setting in within 2-3 years. Yet you only mention the rather modest "benefits" of the FACE trials-why is that?
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  7. @51 Chris G:

    "If you pull out a globe, or open Google Earth, and look at where major agricultural areas are now, there are a fair number which will not be readily migrated poleward. Geographic features and political boundaries will make it so that this problem is much more difficult than the base cost of relocating farmers and the cities they are based out of."

    Yes Chris, I am very much aware of the constraints of migration. Particularly agriculture. However, I was referring to biotopes in general.

    Canadian boreal forests have soil that is thin, nutrient poor and acidic. Then there's the Siberian permadefrost which will basically become muck, swamps and a million methane bubbling lakes.

    I believe I can resolve this issue by adding one word to point #4. That word is "mostly".

    "While deserts increase in size, other eco-zones, whether tropical, forest or grassland will [mostly] migrate towards the poles; shrinking in land area as they do.
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  8. I want to be clear that Berényi linked to the original graph and publication in the image hyperlink. However, the graph as presented here was Photoshopped to remove 100 years of predictions that completely contradicted how he presented the information. I consider that deliberate distortion.

    The graph itself (unnumbered in the Hadley PDF) is something I couldn't find discussion of in that document - I don't know if it's talking about forests, all vegetation, what the sources are, etc., so I don't consider it a great reference in the first place.

    But much much worse when clipped and distorted.
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  9. So we have at least one FACE trial that shows that Rice grown under conditions of increased CO2 will have a decrease of N, on average, of 14%, P by 5%, Fe by 17% & Zn by 28% (according to Seneweera and Conroy, 1997). Ziska et al (1997) have reported a drop in protein content in crop plants when you combined increased temperature & CO2.
    Although I'm struggling to find a peer-reviewed reference, there is a general belief that warming will lead to a shortening of crop growing cycles, thus resulting in reduced crop productivity. Also, I've read that increased CO2 tends to boost *vegetative* growth at the expense of *reproductive* growth. As was pointed out above, as we tend to eat the reproductive material of most crop plants (like corn, rice & wheat), this is *not* a good thing.
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  10. If we want to see the effects of higher CO2 concentrations and hence higher temperatures on plant growth we should look and see what is happening at the molecular level. All of plant metabolism is controlled by various enzymes, literally thousands in any one organism. The key step in plant growth is the fixation of CO2 via the enzyme Rubisco (Ribulose-1,5-bisphosphate carboxylase oxygenase).

    Here are some recent findings on the biochemistry of Rubisco. The older studies showed that the enzymatic activity of isolated Rubisco (the enzyme responsible for the fixing of CO2 into organic metabolites) was increased at higher temperatures and higher CO2 concentrations. This allowed deniers to argue that this would be good for agriculture since it would allow for higher yields (forget about water and available nitrogen for now). However, there were always problems in getting reproducible levels of Rubisco activity (preparations had to be aged and/or treated to give maximum activity).

    Later research has shown that there is another layer of regulation affecting Rubisco activity (as is common with many enzyme system). A new enzyme, Rubisco activase, was found to be responsible for converting “inactive” to “active” Rubisco. And, surprise surprise, this new enzyme was found to be inhibited by higher temperatures and also inhibited by higher CO2 concentrations.

    This finding is probably responsible for the contradictory results found in experiments where varying temperatures and CO2 concentrations on plant growth have been conducted.
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    Moderator Response: [DB] Hyperlinked URLs.
  11. @ Ian Forrester. Yes, I'd read that very recently myself. Kind of puts the whole "CO2 is plant-food" argument into perspective!
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  12. Another thing which isn't considered by so-called "skeptics" is what impact increased CO2, combined with associated changes in temperature & moisture, will have at the root-soil interphase-especially as regards the incidence of root-borne diseases. Its not an area that's been researched at length, but what little info I've seen suggests that disease incidence will become worse under AGW conditions.
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  13. 1. Plants will need extra water. Where will it come from? Rainwater is not sufficient for current agriculture and aquifers are running dry throughout the Earth.

    Actually some plants, or should I say trees do better with more CO2. It has been proposed to reforest the Sahara which is possible because of increased CO2. The key attribute certain trees have is that CO2 causes the pores that transpire water to close, reducing water requirements.

    A side effect of this reforestation is to consume the so called AGG solving another problem.
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  14. "...look at where major agricultural areas are now, there are a fair number which will not be readily migrated poleward."

    That polewards movement notion is very much a northern hemisphere idea. Look at a map and draw a line around the globe. Start at Capetown, then across to Perth, Adelaide, Hobart, Dunedin and finish up at Montevideo or Buenos Aires.

    Apart from that sharply narrowing tongue of southernmost South America, there _is_ no poleward land to replace any of those productive areas of South Africa, Australia, New Zealand and Argentina.
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  15. villabolo

    You've descended into rampant pro-AGW defensive posture

    Woodland thickening across savanna biomes - apart from frozen area is about 14% of the world's area - thickening or shrub encroachment is happening across Australia, the southern USA and southern Africa. Less fire is why (with CO2 also assisting C3 trees and shrubs over C4s grasses. That's less fire and more tree/shrub thickening and so less grass means less fire.

    In terms of the latest floods - what rampant silliness compared to facts - in fact the land surface condition away from water courses in very good. No massive erosion at all.

    As for low and zero tillage at odds with mechanised agriculture - ye gods man ! - do you ever get out and see what is happening around Australia. Major transformations in last 20 years. Minimum tillage is a first world revolution ! In fact machinery especially designed to cope with minimum tillage. Tell Monsanto there is no market for minimum tillage (they'll ROFL).Away from broad scale cropping sugar cane industry almost now universally trash blankets after a green harvest - not burns - soil surface always well covered.

    Yes Australian floods may have taken out some production temporarily - but what like they've done for 100s of years with La Nina by cool IPO combination ! Come on AGW influence ?? .... in fact Australia is set for a record cotton harvest. Cotton Australia estimates the crop will top four million bales this year, smashing the previous record. But floods also fill dams and replenish aquifers - and thank heavens !

    "Winners and losers" means this - ENSO means rainfall is already not uniformly distributed. If as some suggest the Pacific becomes a more El Nino like mean state and the world warms - the thermocline the Canadian/US wheat belt moves north, temperature nearer C3 optima for wheat, higher rainfall and more CO2 - perhaps the CIA already know something we don't ! :-) (in this scenario eastern Australia gets the drought end of the oscillation).

    In fact given the IPO change - expect a cracker decade for Australian rainfall ahead - more Las Ninas and stronger ones. Boom time for producers?

    And of course with increased CO2 we haven't let the conventional breeders and genetic engineers loose yet? I would assume plenty of potential based on track record.

    My point is this issue is very complex and a universal assumption of worse on food security is not a well thought through response. If you are going to the do the CO2 fertilisation review - need to be much more thorough.
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  16. villabolo #57,

    I'm not trying to take anything away from what you said, and I am sure that you in particular understand shifting climate zones. I'm trying to add to what you said for anyone interested in further reading, and also somewhat responding to the mistaken meme that our agricultural systems can adapt and continue to feed us all without substantial cost.

    Yes, that was kind of my point. There is no land on which to develop agriculture south of, say, Victoria. If the climate zones shift 400-500 km southward, agriculture is over in that region.
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  17. @51 Chris G:

    Not a problem, Chris. I'm just a non scientifically trained enthusiast. I change point #4 in my post to the following below. Tell me what you think.

    4. The worse problem by far is that increasing CO2 will increase temperatures throughout the Earth; making deserts and other types of dry land grow. While deserts increase in size, other eco-zones, whether tropical, forest or grassland will try to migrate towards the poles. However, soil conditions will not necessarily favor their growth even if the temperatures are optimum.

    There will be some other minor changes throughout the post.
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  18. I think (not that my opinion should count for much) the original and the edited version are both fine. You can't get too nuanced in a basic version of this material without loosing the audience.

    FWIW, I found the article referenced by my first link.

    Hansen et al, 2006

    Relevant information is in and around Figure 6.
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  19. "You've descended into rampant pro-AGW defensive posture"

    Sorry Luke, but that's exactly the kind of language I've come to expect from someone who has descended into a "rampant pro-denialist defensive posture". If you want to be taken seriously, try removing some of the invective first.
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  20. The point remains, Luke, that claims of "CO2 being plant-food" are incredibly simplistic & inaccurate, yet the Contrarians want to take a chance with our agricultural future based *entirely* on this simplistic attitude-with what amounts to a grand experiment on the only atmosphere we have.
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  21. Luke @65,

    May I point out the irony of you lecturing Villabolo on being more thorough when you did not provide a single source from the reputable literature to support your assertions. Not one.

    A recent pamphlet prepared by the Royal Canadian Geographic Society (based on findings in the scientific literature) has this to say about conditions on the prairies, Canada's bread basket:

    "In fact given the IPO change - expect a cracker decade for Australian rainfall ahead - more Las Ninas and stronger ones. Boom time for producers?"

    And what do you base the above statement on? And what about this one:

    "If as some suggest the Pacific becomes a more El Nino like mean state and the world warms - the thermocline the Canadian/US wheat belt moves north, temperature nearer C3 optima for wheat, higher rainfall and more CO2"

    And a note of caution, Oz is not the centre of the universe when it comes to providing grains.

    I do agree with you that this is complex, and that the impacts may not all be bad, at least up to a point. Fortunately, those darn scientists (bless them) have been working on this for a long time, and the over whelming evidence is that a little warming (typically <2 C may benefit crops), but that beyond that things really start to tank. Listen to this (also click on "wheat" and "maize". Note that they are talking about local change sin temperature, not global, and that mean summer temperatures are projected to increase by 3 to 4 C.

    And if you doubt that droughts have a negligible impact on crops, then think carefully what happened in Russia last year, in 2007 in Europe in 2003, on the Canadian prairies in 2002. And there are many more examples.

    I have said this before, all the CO2 in the world is not going to help is the soil moisture drops below the permanent wilting point and under heat stress. Also, as others have pointed out, plants may be able to move, but people cannot necessarily, and then one is assuming that there is viable land to move to-- that last point should be obvious to someone living in a place like Australia, well at least it is to adelady.

    Oh, and what Marcus just said @70.
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  22. Take note readers, Villabolo is changing his/her post in the face of criticism. Note too that that is something "skeptics" rarely, if ever, do.

    So for someone her to make the comment that Villabolo has "descended into rampant pro-AGW defensive posture" is simply false. I would also contend that it is an ad hominem and therefore violates the house rules.
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  23. The downside of CO2 increases is understated. Reread the comments, and notice how many of the pro-pollution arguments are questions, insinuations, and vacuous logic attempts.

    There has been no discernible, global, growth increase in a world that's charged CO2 levels by 40%. In opposition to the US East Coast study referenced by whitsend is the notorious growth-lapse that became part of Briffa's "hide-the-decline" scandal.

    To increase yields, no one has laid out CO2-delivery pipes similar to the FACE experiments - every fertilizer BUT CO2. Having CO2 airborne counts of 400ppm is a shrug compared to the 800-1600ppm in the damp soil where the roots are feeding.

    The FACE experiments long ago minimized the value of the increased GHG pollution:

    Boosts are transitory:

    Even when care was taken to measure the isolated effect, the net conclusion was bad - nutritional loss:



    ... and a side-order of increased toxicity:

    And none of that compares to the economic losses as extreme weather pattern changes destroy crops - most recently western Canada, Australia, and Russia. And it doesn't matter if crops would have grown well ... if only someone had planted them there.

    And that all pales in comparison to the stress placed on the bottom of the ocean's food chain - phytoplankton:

    Deny, diminish, and distract all you want, but there's going to be a huge cost in altering crops and natural vegetation around the globe - for centuries to come.
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  24. I wonder myself, since I am not familiar with this subject much, whether migration of vegetation will be hindered by Hadley Cells. There are latitudinal barriers that deal with precipitation too, not just temperature or land area. Does anyone have any input on the possible implications that such systems would have on the extent of vegetation migration?
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  25. @65 LukeW:

    You'll be happy to know that I removed the reference to increased fires as a result of increased vegetation. I have a feeling that it could happen; but it's impossible to predict in the long run how much of the earth's surface is going to be prone to fire versus how much is going to be resistant, or about the same.

    As far as the issue of tillage, I previously mentioned the superiority of Permaculture. Yet, I emphasized that time constraints due to a most likely "perfect storm" of events-AGW related-is going to bring on social instability.

    Adaptability is a matter of how fast things happen. Common sense tells us that the faster a negative event occurs, the less able we are in adapting to it. In my opinion, as I previously mentioned, our society is going to get destabilized to the point where it's not going to benefit from anything.

    That's not to say that a variety of alternative technologies and techniques will not be used; but they will be used by members of a fragmented and disintegrating society. I foresee a good chance of our evolving into a feudal state in a hundred years.

    The only silver lining I see in all of this is a sizeable drop in the use of fossil fuels due to major economic shrinkage or outright collapse.
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  26. @72 Albatross:

    Thank you for noticing my ongoing editing.
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  27. No worries Villabolo. Along the same lines here is a correction to my post @71.

    I meant to say:

    "And if you doubt that droughts have a negligible impact on crops, then think carefully what happened in Russia last year, in Australian in 2007, in Europe in 2003, on the Canadian prairies in 2002. "
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  28. Villabolo "For one who is very much into quantifying things to death,"
    I like very much this one. You're right, beliefs are much easier when we don't care about quantifying. But sorry, I'm an annoying scientist, you know, the kind of those who wanted to know precisely what the orbit of Mars really is - who cares, actually ?
    concerning " common sense deductions based on the conclusions of science." , my own common sense tells me that I should first start with first order correlations and then look at more complex issues if necessary. An example :
    "Soybeans grown at elevated CO2 levels attract many more adult Japanese beetles than plants grown at current atmospheric carbon dioxide levels."

    Well, I can understand that beetles like more nutritive and may be richer plants. I would do the same - I prefer eating big and sweet fruit than small and acid ones. This doesn't prove that the overall effect is negative. And this a comparison experiment - meaning that probably beetles could choose between two different varieties. But if they had no choice, because every plant would grow in the same way, maybe they would be less concentrated on these plants. And they may be also adaption of plants to the new conditions, etc, etc... just selecting one effect and considering only its influence is far from giving the answer.

    Off topic comments removed
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  29. "my own common sense tells me that I should first start with first order correlations and then look at more complex issues if necessary."

    Your problem though, Gilles, is that you consistently mistake correlation with *causation*-even when there is no underlying justification for it. As to the soybean issue-its already been established that a combination of higher CO2 & higher temperatures results in a decrease in the nutrient content of many crop plants-& I doubt Soybean is exempt from this. Given that, its highly unlikely then that the insects are being attracted to the soybean plant by its higher nutrient content, but most likely due to its reduced defenses.
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  30. "I prefer eating big and sweet fruit than small and acid ones."

    Again, increased CO2 tends to lead to an increase in *vegetative* growth at the expense of reproductive biomass-including seeds & fruit. So again your correlation doesn't really hold up to the available evidence from other sources about the negative impacts of raised CO2.
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  31. BTW, Gilles-as a "scientist", wouldn't it be a good idea to *read* an article before commenting on it? I draw your attention to the following comments:

    "the team allowed beetles to live out their lives in one of three conditions: on a high CO2 plant, on a low CO2 plant outside the Soy FACE plot, or on a low CO2 plant grown outside the test plot but which had its sugar content artificially boosted."

    Now what they found was that *only* the bugs feeding on the high CO2 plant were seeing an extended lifespan & greater breeding times-& this had nothing to do with sugar load, & *everything* to do with changes in plant hormone levels-hormones which are a key to the plants defenses against insect attack. Please *read* the article, properly, before you embarrass yourself further.
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  32. So I guess the point is that-*maybe* increased carbohydrate in soybean leaves in making them more attractive to these beetles (the researchers were pretty vague on whether this was, in fact, the case) but the *real* problem is that the plant has a far reduced ability to defend itself from these attacks-meaning that the beetles will be able to breed & feast more effectively. Hardly a *positive* for agriculture.
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  33. Effects of Rapid Global Warming at the Paleocene-Eocene Boundary on Neotropical Vegetation, Jaramillo et al. (28 coauthors !), 2010.:
    “We observed a rapid and distinct increase in plant diversity and origination rates, with a set of new taxa, mostly angiosperms, added to the existing stock of low-diversity Paleocene flora.“ “The tropical rainforest was able to persist under elevated temperatures and high levels of atmospheric carbon dioxide, in contrast to speculations that tropical ecosystems were severely compromised by heat stress.”

    So as can see the above post still is just speculation ...
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  34. @65 LukeW:

    Luke, I didn't have a chnce to respond to all of your points in post #75 but I can't believe I missed this one (!?)

    "In fact given the IPO change - expect a cracker decade for Australian rainfall ahead - more Las Ninas and stronger ones. Boom time for producers?"


    Are you aware of what those rains did to Australia recently? Of course, even if it had not downgraded a sizeable portion of the wheat crop to animal feed status, look at the wonders it has done for Australia in general. Like flooding an area the size of Texas.

    John Cook would be pleased.

    And you want those La Ninas to get stronger?

    It looks like it's going to be a boom time for the rowboat industry.
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    Moderator Response: [Dikran Marsupial] tags fixed (hopefully correctly).
  35. "Rapid" is in geologic terms, and in the case of the PETM means ~20,000 years.

    The PETM was the cause of a global mass extinction event.

    That temperature change over 20,000 years is a viable likelihood in a matter of centuries in an unabated business-as-usual scenario.
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  36. (closing tag added)

    Marcus : correlation is not a proof of causation, but absence of correlation (or even negative correlation) is still worse ! and I don't see any hint that the increase of CO2 has made the yield of crops decrease in the world- since it has simply not decreased.

    I have no idea what beetles like, and maybe the defenses of the particular species they studied are weakened by more CO2 - but they don't give the final result on the total yield (do the damages made by beetles offset the increased yield or not ?), and of course there is nothing like a global estimate at a worldwide scale. Again, adding a set of cherry picked drawbacks doesn't say anything on the final result - with this method you can demonstrate what you want.
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  37. The PETM tropical data above is all from one area in Northern South America and it got wetter and hotter by 3C but not into the critical region above 35c where tropical vegetation starts to becoem heat stressed. Considering that the ITCZ moves north when the NH warms (which it would with a burst of CO2 due to the NH greater land mass) this results are probably predictable and say nothing about the southern regions of Amazon.

    Also on the land sink it seems everyone seems ot forgetting that our land sink in the last 40 years has be greatly increased by artifical fertilization and the extra reactive nitrogen artifically boosting growth everywhere but also killing biodiversity everywhere so we have to stop using it loads and so by by land sink!
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  38. “To explain the observations, the carbon must have been released over at most 500 years.”
    0 0
  39. On this page, is briefly described the global food market.:
    “Food production more than doubled (an increase of over 160%) from 1961 to 2003. Over this period, production of cereals—the major energy component of human diets—has increased almost two and a half times, beef and sheep production increased by 40%, pork production by nearly 60%, and poultry production doubled.”
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  40. To add to Bibliovermis's comments on Arkadiusz Semczyszak's link, some information from the paper itself :

    The PETM is associated with a large negative carbon isotope excursion recorded in carbonate and organic materials, reflecting a massive release of 13C-depleted carbon (4, 5), an ~5°C increase in mean global temperature in ~10,000 to 20,000 years (1), a rapid and transient northward migration of plants in North America (6), and a mammalian turnover in North America and Europe (7).

    Higher precipitation amounts could have been as important as high CO2.

    As already stated, it's a long time-period compared to now and higher precipitation may have been just as important. Also, I wonder how easily all those plants are going to migrate (and where to ?), and how we'll feel about a similar "mammalian turnover".
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  41. @78 Gilles:

    "Villabolo "For one who is very much into quantifying things to death,"
    I like very much this one. You're right, beliefs are much easier when we don't care about quantifying. But sorry, I'm an annoying scientist, you know, the kind of those who wanted to know precisely what the orbit of Mars really is - who cares, actually ?"

    I care Gilles. That's why it's nice to quote people in full context and show the rest of the sentence that has been cut off in mid stream. Please notice the comma left hanging at the end of my sentence you quoted.

    Just for your information, when one quotes a partial sentence, something known as an ellipsis is placed after the end of that sentence in order to inform the reader that he is not reading the entire sentence. An ellipsis, in case you're wondering, looks like this ...

    Since I care about the question that followed my amputated sentence let me restate it by quoting my own post. Please notice the ellipsis.

    "For one who is very much into quantifying things to death, let me ask you, Gilles; what level of CO2 increase can be tolerated by plants until a point is reached that noticeably effects them?...

    Besides, do you know the levels of CO2 that where used in the experiments which gave the dramatic results? They are likely to be much higher than our current C2 levels."

    It would have been nice if you had answered my question but that's all right. It's gotten a bit stale. However, we can discuss Mars' orbital mechanics as soon as someone claims it affects Earth's climate.
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    Moderator Response: [Dikran Marsupial] Please can you reduce the use of bold tags, it is equivalent to the all caps "shouting" that is against the comments policy.
  42. It is noteworthy example of this great area of uncertainty: Effect of soil moisture and co2 feedbacks on terrestrial NPP estimates,
    “Often, despite dramatic leaf level impacts due to climate changes, the natural ecosystem tends to buffer and does not show a dramatic response. Our analysis suggests that the interactions between the biotic and abiotic changes tend to have a compensatory /antagonistic response. This reduces the effect of the variable change on the overall system response. Our results indicate that the effect of soil moisture availability (and drought) is an important modulator of the terrestrial carbon cycle, and its impact for both present day as well as climatological feedback (under doubling of CO2 or ENSO like events) needs to be investigated.
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  43. @91 Dikran Marsupial:

    Sorry about that. I use bold tags in order to contrast my statements with those that I quote.
    0 0
  44. 91 : Of course, no, Villabolo. I don't know. And I'm not claiming I do. I don't like to issue assertions I can't substantiate.
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  45. Marcus at 12:09 PM, if after being provided with a link providing supporting reading for an argument being made, or an image that when clicked on, takes the reader to the site it originated from, if one is left with the feeling that they have been spoon fed only half the story, it is more likely that they have instead only read the portions that suited their point of view.

    I'm glad the you mentioned the Horsham FACE trials because it offers the perfect opportunity to compare your "half" of the story directly to the "story" presented in this powerpoint presentation by those who conducted the actual trials you are referring to.
    Just to summarise, you will find on Page 10 the yield response to elevated CO2.
    For the Horsham trials they are shown as 2007 +22%, 2008 +25%, 2009 +26%.
    For the Walpeup trials, 2007 n/a, 2008 +61%, 2009 +49%.

    On page 11, the grain protein response.
    For the Horsham trials 2007 -5%, 2008 -4%, 2009 -8%.
    For Walpeup 2007 n/a, 2008 -11%, 2009 -13%.

    Now a simple piece of primary school arithmetic should indicate that for a given plant, or a given area, the protein harvested has increased because the increase in yields more than offsets any decrease in protein.
    This is not something new, every year the very same thing occurs, yield and protein vary inversely.

    This effect is quantified also on page 11 where the increase in nitrogen uptake is summarised.
    For Horsham, 2007 n/a, 2008 +24%, 2009 +25%.
    For Walpeup, 2007 n/a, 2008 +63%, 2009 n/a.

    If you want the full story, go to the linked presentation and read for yourself then compare what you have claimed in your post with what the scientists who ran the trials have presented.
    Even your concerns about diseases has been mentioned on page 12.
    Elevated atmospheric CO2 and wheat production in Australia

    Anyway all this concern focusing on nitrogen as if it is the main fertiliser is in itself only half the story. Whilst nitrogen is essential it does not have to be made available through artificial fertilisers. It is made available through totally natural processes, but can be opitimised by the use of legumes either to fix nitrogen into the soil through the root systems or as sacrificial crops, and there is plenty of nitrogen freely available.
    The reality is the use of artificial nitrogen fertilisers is an economic issue. Each year the cost of applying it is weighed against the expected increase in returns, and it is not every grower who will apply it every year.
    If the full story on fertilisers is to be addressed then the likes of phosphorous, potassium, sulphur etc are the ones to worry about. These are the fertilisers that are sucked out of the soil in large quantities and must be replenished by man if production is to be maintained.
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  46. A must-read paper about the FACE experiments in Journal of Experimental Botany is here:

    In fact, that issue has several (free access) review papers on climate effects on agriculture that several commentators here would benefit from reading...
    0 0
  47. #47 KR at 10:01 AM on 18 April, 2011
    That's a fascinating chart, Berényi. Why did you clip it?

    Because the last time I've checked there was a difference between past and future. The former can be remembered while the latter not.

    It means the curve up to the point where I've clipped it can be checked using actual data, beyond that it is pure fantasy. You know, science is about theories verified by measurements. Claims that are unverifiable in principle belong to other (admittedly fascinating) realms of the human endeavor.
    0 0
    Moderator Response: [DB] Thank you for explaining the dodgy presentation of your graph.
  48. John D, we've been over this before. (1) The results you quote are, from memory, *only* for the most ideal conditions-something you fail to point out. (2) If the results were as positive as you claim, then why are the lead researchers so circumspect about the results? Indeed, the researchers make a specific point of the reduced nitrogen content. They also point out that gains in yield are only short term, due to acclimation. So it seems the only person telling *half* the story-John D-is *you*. You deliberately ignore the half of the story that doesn't fit your agenda.
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  49. Oh &, John D, I think you forgot to mention this part of the story: "Fungal biomass of Fusarium pseudograminerarum significantly increased in wheat grown under eCO2.
    In absence of high levels of varietal resistance, crown rot will result in a reduction in yield (and quality) in future climates, particularly in drier years". Sort of puts a dint in your theory that CO2 magically improves yields under *all* circumstances.
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  50. "And you want those La Ninas to get stronger?" YES PLEASE !!
    Would make us billions ! (with some collateral damage too but life wasn't meant to be easy)

    You would like another 20 year drought cycle instead ...?

    La Nina = recovery, replenished dams, refilled aquifers, breeding cycles, Murray Darling flowing, fish migration and spawning, new seed stores, bird breeding - it's great stuff.

    Villabolo - I believe in climate change - but we need precision in the arguments - and a robust few of historic climate variation. (1) ENSO - first (2) IPO - second (3) climate change a long way back at 3rd - but eventually could become the main game albeit an unpredictable one (with winners and losers)


    La Ninas and IPO among others

    El Nino-like mean state

    Remember I was only speculating about winners and losers. But US agriculture becoming an AGW winner would be ironic wouldn't it?
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    Moderator Response: [mc] fixed link text. Please provide context for links. Link-only comments are not usually helpful and may be deleted.

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