The rapidly rising levels of carbon dioxide in the atmosphere affect plants’ absorption of nitrogen, which is the nutrient that restricts crop growth in most terrestrial ecosystems. Researchers at the University of Gothenburg have now revealed that the concentration of nitrogen in plants’ tissue is lower in air with high levels of carbon dioxide, regardless of whether or not the plants’ growth is stimulated. The study has been published in the journal Global Change Biology.
Researcher Johan Uddling has been working with Swedish and international colleagues to compile data on how raised levels of carbon dioxide impact on plant growth and nitrogen absorption.
Plant quality impaired by increased carbon dioxide levels
The study examines various types of ecosystems, including crops, grasslands and forests, and involves large-scale field experiments conducted in eight countries on four continents.
“The findings of the study are unequivocal. The nitrogen content in the crops is reduced in atmospheres with raised carbon dioxide levels in all three ecosystem types. Furthermore, we can see that this negative effect exists regardless of whether or not the plants’ growth increases, and even if fertiliser is added. This is unexpected and new,” says Johan Uddling, senior lecturer at the Department of Biological and Environmental Sciences at the University of Gothenburg.
Significance of food quality, biodiversity and productivity
When carbon dioxide levels in the air increase, crops in future will have a reduced nitrogen content, and therefore reduced protein levels. The study found this for both wheat and rice, the two most important crops globally. The study also reveals that the strength of the effect varies in different species of grassland, which may impact on the species composition of these ecosystems.
“For all types of ecosystem the results show that high carbon dioxide levels can impede plants’ ability to absorb nitrogen, and that this negative effect is partly why raised carbon dioxide has a marginal or non-existent effect on growth in many ecosystems,” says Johan Uddling.
Accepted “truths” do not hold
Reduced nitrogen content in atmospheres with raised carbon dioxide has previously been attributed to a kind of dilutive effect, in which nitrogen absorption fails to keep pace with the increase in plants’ photosynthesis and growth.
“The findings of this study show that this interpretation is simplified and partly incorrect. We are seeing reduced nitrogen content even when growth has not been affected. Moreover, the effect is there in trials with powerful fertiliser, which indicates that it is not down to limited access to nitrogen in the soil. Future studies should look at what is causing the effect, but it appears to be linked to plants’ capacity to absorb nitrogen rather than to changed levels in the soil,” says Johan Uddling.
###
Link to article: http://onlinelibrary.wiley.com/doi/10.1111/gcb.12938/abstract
And a video that suggests this study might very well be off the mark:
After a first glance on this i have the impression that co2 makes the plant use the nitrogen more effectivly. Less quality what ever that subjective statement means, are of no importance. More food are bether than no food.
From the linked Abstract: “free-air CO2 enrichment (FACE) experiments in grassland, cropland and forest ecosystems”
—-
How are they enriching the free air in grassland, cropland and forest ecosystems? Does anyone have access to this paper to check the methods stated? It seems to me that it would be quite difficult to enrich a random ecosystem in the open air (what I take “free air” to mean) with CO2. Additionally, how does this CO2 enrichment affect the full life cycle of the plants? Do they grow fast and leave more/fewer seeds? Does the grassland die out and have a different plant makeup?
There are so many questions about this research paper and the data they should have gathered and reported on, it hurts.
Done a long time ago with spectacular results:
http://sealevel.info/ScientificAmerican_1920-11-27_CO2_fertilization.html
Currently done at Duke University and descriptions with photos available from their site as well as from other sources, just search the web. Obviously much better control than in 1920, but so what. Same results!
In this current Abstract the authors claim only a 10% decrease in Nitrogen in their high CO2 and we don’t know if this was protein nitrogen. Anyway, a 10% decrease is irrelevant.
You can go to this site to get a number of links for these types of experiments. Lower nitrogen is a common finding, but this does not necessarily mean lower protein.
https://en.wikipedia.org/wiki/Free-air_concentration_enrichment
Or just search for FACE experimentation. Plenty of articles available.
Thank you! That is just fascinating.
rd50
The linked article is quite interesting. They started with 3 greenhouses and then expanded the test to 30,000 sq. meters (approx. 7 acres). The large field test was situated next to a blast-furnace, with “underground central pipe and branch pipes encircling lengthy plots.” They reported increased growth rates of 70-300% depending on crops.
I haven’t checked the Duke website yet. Thanks for link info.
What does make sense here is that it is known that, when provided higher atmospheric CO2, plants are more efficient in water and nutrient usage. It is wrong to assume that means that nitrogen uptake is being squelched by CO2. Instead, nitrogen uptake from the improved efficiency is simply less in these plants because they need less—no need for more.
My read is that plants at low CO2 concentrations, have higher nitrogen content because they are stressed by the conditions. Now we are seeing what healthy plants do.
Yes, there are fewer stomata needed, and who knows what else, in a CO2 enhances atmosphere.
I can think of a whole bunch of reasons for what they found, if it is even a real effect.
Plants in shade grow more stem to reach the light. Plants in high wind produce more lignin for strength.
But these represent expensive adaptations for the plant over what would be used in the sun and without adverse winds.
My sense is that this study is about as unscientific as a study can get.
In other words, a typical CAGW alarmist piece.
The 1st thought I had was why would they try to find negatives for increased plant growth with increased CO2 levels applied – the world knows plants love CO2. Then I realized the entire AGW playbook is negative if it involves CO2.
I’ve been waiting for the study that claims increased CO2 causes ED. It is becoming ‘more likely’ that this will happen.
kokoda, “ED” can stand for many things; from “eating disorder” to “erectile dysfunction.” Can you please specify what you meant when you stated, “ED”? Thanks.
JimS….Your 2nd choice.
Let’s just go with ‘all of the above’, even if some are mutually exclusive.
That’s how they do it in ‘climate science’.
Of course it causes ED! That why they are obsessed with “hiding the decline”.
Martin….creative thought, and humorous
“When carbon dioxide levels in the air increase, crops in future will have a reduced nitrogen content, and therefore reduced protein levels. The study found this for both wheat and rice, the two most important crops globally. The study also reveals that the strength of the effect varies in different species of grassland”
Poorly written, or bad conclusions?
Did they measure protein content of any plants?
Of wheat or rice?
Why does it not simply state “The study found reduced protein levels of wheat and rice grown when carbon dioxide levels are increased”?
Why do they refer to the future, and use words like “therefore”?
What does the actual study actually show?
“The findings of this study show that this interpretation is simplified and partly incorrect. We are seeing reduced nitrogen content even when growth has not been affected.”
It sounds to me like they contrived a set of circumstances, in which lack of some nutrients in the soil prevented CO2 from enhancing growth because of the least limiting factor principle, and then applied a broad conclusion which involves interpretation and supposition… instead of rely strictly on measurements.
I don’t think the marijuana growers have any problems at all with nitrogen uptake. The stuff really has a nitrogen kick these days… So my friends tell me.
These “scientists” are also making the assumption that all the extra CO2 in the atmosphere was produced by man, which isn’t the case. Also the CO2 concentration in the atmosphere in the past has been 20x higher than it is now. By their logic, plants would not have been able to ingest N2 and therefore not synthesise amino acids and should have died out. The fact that the biodiversity on the planet is so high and that I am typing this would indicate that high concentrations of CO2 are neither harmful to the climate nor directly or indirectly harmful to life of either plants or animals.
Perhaps vegans should pay attention. The rest of us can rest easy with the knowledge that there are lots of creatures that can convert carbohydrates into protein.
Publication as a ‘peer reviewed’ paper in a Journal i s meaningless as far as veracity of the research is concerned. It seems that all that is needed nowadays though is to pass ‘peer review’ and the claim is made that the result is valid. However, science requires repeatability. Therefore, research is only of real interest once it has been replicated by another completely independent team of researchers.
This is continually glossed over in the rush to get press releases and abstracts out to convince politicians and the gullibles. I doubt very much if this research will be repeatable – but it has already achieved its aim as has the 97% figure.
My corn was planted the last week of April. It is now passing 5 feet tall and greener than ever, despite the bugs that also thrive in the “garden of eden” conditions which Joe Bastardi correctly predicted for the midwest US. El Nino or not, the NOAA has been way off! The beans will also Harvest early this year. Each year we harvested more then expected from past experience, even in the drought and extreme heat of 2013.
I will look into having some crops analyzed to compare against normal values for protein content. If this claim is really valid, there should be a trend over the last 50 years of decreasing protein content in row crops. A laboratory and models are unnecessary when reality tests your theory just fine. This is just another example of academia lacking common sense.
“The plants will grow slower even if they grow faster”. What?
Who should we believe? The rent seekers who wrote this paper?
Or our lying eyes?
http://icecap.us/images/uploads/Greenhouse_Gases.jpg
Those pictures are faked, just like the moon landings.
That is right!
Look, in the first picture, the angle was from slightly above the man’s head, but by the last one, it was from below his eye level. Obvious optical illusion!
Dang these lying eyes of mine.
My sexy new neighbor waving that suntan lotion at me from across the yard probably looks like the Sea Hag close up.
wow.. pictures.. thats some science
Optical astronomy…wow.. pictures.. thats some science
Mr. Mosher,
I am wondering what you mean to say?
Are you of the opinion that the pictures are fake, and/ or the captions not true?
Many people have observed that a picture can be worth a thousand words. I do not think anybody would say that a picture captures the essence of the scientific method, but a picture like the one above certainly does it illustrate a point very clearly: That plants can and usually do grow much faster under higher CO2 concentrations.
Now, if one thinks this is not true then that’s one thing, or if the particular picture is fake that’s another thing.
But certainly this picture tells a story which could be detailed at great length and still not give a person as impactful of an overall presentation as the single picture.
Besides for that, scientific studies, like courts of law, can and do use many forms of evidence and presentations of evidence, as well as data.
To make a separate point, if one considers the act of viewing something as letting one’s eyes send a picture to the brain, then the reading of a thermometer can be considered, in a way, as using “pictures”.
Subject to the same source of error my sarcastic first comment just above…line of site errors.
I recall from my college days hearing detailed and repeated statements on the subject how important lunes of sire are when reading certain instruments.
MRI, computerized tomography, radar, interferometry…and a zillion other forms of imaging are critical aspects of a wide range of scientific endeavor!
Talking! Phht!
This study does agree with many others from 1990s and 2000s.
Dahlquist
What other studies from 1990s and 2000s?
Richard
Richard
Apologize…Was offline awhile. Thats just one of many you can look up on search…Use same title.
It’s titled “Interactive effects of nitrogen and elevated co2 on crop plants.” By
Vanita Jain and Renu Pandey.
http://WWW.academia.edu/3510698/INTERACIVE_EFFECTS_OF_NITROGEN_AND
ELEVATED_CO2_ON_CROP_PLANTS
Dahlquist
You claimed “many” studies from the 1990s and 2000s support the paper cited in the above essay. When pressed you cited and linked to one paper and it refutes your assertion.
The paper in your link says
emphasis addedd: RSC
Richard
Richard
Read further down the paper. Also, other studies done on various species of plants point out both benign and negative effects… C3 vs. c4, etc. Lot’s of studies.
It seems that they’re saying the co2 causes some species to grow too fast and they aren’t able to take up nitrogen as effectively because of the growth rate.
richard, read through the paper a bit. It is an interesting one and it does echo a number of the points raised elsewhere is thread by commenters. Specifically to the issue of protein and protein concentrations, look at the page numbered 239. (Numerous citations are name-dropped liberally throughout)
Note here though: the question seems to be less whether it does or not, then whether we care or not. For instance, in the one protocol it noted a 14% loss under a 100% N load. But only a 9% loss under a 50% N load. Which seems rather absurdly backwards. But there’s a reasonable discussion about the nitrogen uptake networks and their regulations that may relate to this. Not stated in relation to protein reduction is plant mass. For if we only reduce proteins 14% under heavy fertilization — and on 9% under moderate fertilization — but have, say, 50% more plant mass, then this seems like an overall win on the nutrition angle.
Jquip
I have read the paper cited and linked by Dahlquist. I quoted from it but you and he have not.
I refer you to my reply to Dahlquist that is here.
Richard
“iii) Effects of eCO2 on productivity and N acquisition did not diminish over time, while the typical eCO2-induced decrease in plant N concentration did…”
So they seem to be saying that the decrease in nitrogen concentration is a temporary effect.
Right?
Then they go on to say:
“Our results suggest that, at the decennial timescale covered by FACE studies, N limitation of eCO2-induced terrestrial productivity enhancement is associated with negative effects of eCO2 on plant N acquisition rather than with growth dilution of plant N or processes leading to progressive N limitation.”
Which brings me back to the question of how they can suppose to raise CO2 over a broad area, outside, over long spans of time?
Plus a lot of other questions.
richard:
Am I to understand that this is what you consider a rebuttal of the statements I made? Or is this just color commentary that I should ignore?
Jquip
I DID rebut your silly post by linking to my rebuttal of the similar nonsense to yours from Dahlquist.
I now refer you to all the posts from Menicholas in this sub thread. You may have a point if you can answer all the points Menicholas makes in critique of the paper which is really under discussion in this thread.
This sub-thread exists because Dahlquist repeatedly made the untrue assertion that there are “many” other papers which say the same as the paper which is really under discussion in this thread, so I asked him to justify that assertion. His response was to cite only one paper and it REFUTES his assertion.
You are trying to deflect the discussion onto that paper cited by Dahlquist. But the ONLY pertinent thing said in that paper is its agreement with the paper under discussion; i.e. the paper cited by Dahlquist says
Richard
Dahlquist
Sorry, a good try but no coconut.
You said there are “many” papers “from 1990s and 2000s” that say the same as the paper cited in the above essay. When pressed to substantiate that assertion you cited and linked to ONE paper and it does NOT agree with the above article.
As I quoted, your link says
You have come back with a reply that says in total
THAT WILL NOT DO!
I asked you to justify your assertion about other studies. Repetition is NOT justification.
And what “it seems” to you “that they’re saying” about “some species” does not alter the fact that they do say “the response to elevated CO2 concentration is usually positive”.
Richard
Richard,
You quoted the Jain and Pandy paper as pointing out that the “response to elevated CO2 concentration is usually positive.” You should note that this was in the context of photosynthetic output. The paper went on to say (all quotes are from the same paper):
“As a result of this primary response [referring to the improved carbon assimilation], and a range of secondary responses,including growth, dry matter allocation, and nutrient composition and assimilation,may change”
“Therefore, factorsthat may affect availability and uptake of N are critical in determining plant and ecosystem responses to high CO2”
“The overall nitrogen concentration in plants on dry weight basis decreases when they are grown in enhanced CO2 (Jain et al., 2007)”
“Further, the total amountof nitrogen per plant is often unaltered (Hocking and Meyer, 1991a) or reduced (Conroy et al., 1992) in enhanced CO2”
.
I highly recommend that you take the advice of Dahlquist and Jquip and read beyond the first page of the paper.
Hmm, this seems to be getting a little tense.
Maybe while we are on the subject of coconuts, plant growth, and improved/decreasing yields…we should take a small intermission to consider my efforts to raise a crop of coconuts here in Fort Myers.
If that is not a sufficiently entertaining notion, perhaps we could try this:
https://youtu.be/Gl97GJvYGdM
Jimmy
I DID “read beyond the first page of the paper” cited by Dahlquist.
I refer you to my above response (that is here) to the similar twaddle to yours but from Jquip.
Among other things, I say there
Strewth! The truth hurts warmunists! And that is demonstrated in this thread by the desperate attempts of trolls to refute the truth that plant growth is increased by elevated atmospheric CO2.
Richard
I suppose it is allowed for posters like Richard s Cortney to creep back into a post late at night when everyone is sleeping and the post has been laid to rest, to continue to manipulate and trash talk people who aren’t there to respond in order to make himself look smart and good…A real TRUTH SEEKING SKEPTIC who cannot stand to hear the truth about a minor, possible aspect of co2 increase. It simply cannot go without an attack on one who brings up a possible problem with co2 in a discussion forum.
It is not my responsibility to lead Richard by the nose to anything. I gave him what I had and was truthful and respectable with him. Criticizing another for not doing what you yourself are perfectly capable of doing is lazy and childish. Richard had every opportunity to listen to me, jquip and Jimmy and refer to the study which contained references to 30 or more other studies and did state that co2 does have some negative effects on some plant species. He just needed to entertain an open mind and do his own research, rather than bag on me for not doing his work for him.
After this exchange, I did a search of him and found many people who know him for similar bashing on people. He has a bad reputation for this. I would hope he can learn that bashing people for stating a truth and referring others to some good info is not a reason to insult and harangue that person, as we have similar goals in opposing the CAGW agenda. However, I am not going to go about bashing someone for stating something about the issues with co2 because I simply don’t like to hear it, as Richard seems to have done to me.
Clean your act up Richard S. Courntey. Please. It would be a favor to all of us who have had to endure tour BS.
Dahlquist
Dahlquist
I don’t “creep” and my latest posting yesterday was at 8.00 in the evening.
I suppose it is to be expected that someone will not know the world has different time zones when he is too ignorant to know elevated atmospheric CO2 concentration increases plant growth.
Dahlquist, you made an untrue claim.
You repeated your untrue claim.
I pressed you to substantiate your untrue claim.
You could not – and you cannot – substantiate your untrue claim.
Skeptcism consists of demanding that unsupported claims be substantiated.
You now say
The “truth about a minor, possible aspect of co2 increase” is that YOU LIED and you are whinging because I exposed your lie. There are NOT “many” papers from the “1990s and 2000s” that agree with the paper exposed in the above essay.
Your claim to know of many such papers was a LIE, and you are upset because I exposed the truth. And that exposure is NOT an “attack”: the only “attack” was by you and was on the truth.
Take your thumb out of your mouth, dry your eyes, and ask Mummy to give you a cuddle. When you grow up you will learn that some of us will always demand that you justify any fairy tales you promote as being reality.
Richard
Increased levels of carbon dioxide (CO2) have helped boost green foliage across the world’s arid regions over the past 30 years through a process called CO2 fertilisation, according to CSIRO research.
http://www.oarval.org/CSIRO-Foliage1982-2010.jpg
From “Deserts ‘greening’ from rising CO2”. CSIRO, the Commonwealth Scientific and Industrial Research Organisation. Australia’s national science agency. July 3, 2013.
At http://www.csiro.au/en/Portals/Media/Deserts-greening-from-rising-CO2.aspx
This page was removed from the CSIRO Website.
See Deserts ‘greening’ from rising CO2 (Watts Up With That? July 8, 2013)
http://wattsupwiththat.com/2013/07/08/deserts-greening-from-rising-co2/
“global garden gets greener”
http://earthobservatory.nasa.gov/Features/GlobalGarden/
Even to a non-scientist like me, this study seems to have obvious flaws all over it.
My question is, why aren’t the botanists and agro scientists speaking out about this? Surely at some point, scientists in these distantly related (from climate science) disciplines must call BS on studies like this.
Katherine009
Botanists and agro scientists have been talking about this for years. Higher levels of co2 affect many plants ability to take up nitrogen efficiently. The article here is correct.
Dahlquist
Talk is cheep. Research is not.
Cite previous studies you agree if they exist. Otherwise, please stop making false assertions that waste space in the thread.
Richard
I don’t know of any studies that show that higher CO2 concentrations actually inhibit nitrogen uptake (although many studies claim to show this). But there are numerous studies that show plants grown under higher CO2 concentrations to have lower nitrogen contents and even take up less (so it’s not just a dilution effect). For example:
http://onlinelibrary.wiley.com/doi/10.1046/j.1365-2486.1998.00101.x/abstract
http://www.nature.com/nclimate/journal/v4/n6/full/nclimate2183.html
Richard
I only had a few minutes to briefly scan a few studies and there are many on various crops and plants. Many of the articles do state the negative effects of increased co2 on some species. (read further down the one I cited you). Also, search “interactive effects of nitrogen and increased co2 in plant growth”. It’s not all bad Richard, but I’m doing a few things other than blogging here. Apologies.
D
This issue is whether the conclusion is correct…they’re implying that the nutritional content of the plants is lower due to higher CO2.
Katherine009
Thankyou. Well said. As you say
The only responses to your fine posts have been untrue assertions that “many” other papers say the same.
Richard
Dahlquist
Sorry, but that does not wash.
I refer onlookers to our above conversation that starts here.
Richard
The nitrogen content of the air has already decreased from 78.09% to 78.08%; we are all doomed. To Paris!
Where is troll Joel?
I struggle, hard, to preserve respect for the established research community and the earnest types who do “climate research” for a living, often with impressive qualifications. I struggle to take seriously their earnest narratives and their sense of eco-morality. But with transparently fraudulent output like this, the struggle becomes almost a hopeless one. This is totally dishonest shite.
The story “Decreased nitrogen uptake with increasing airborne CO2” could just as well be spun as: “Increased nitrogen uptake as a sign of CO2 starvation stress”.
YouWe paysyourour moneyYouThey takesyourtheir choiceBy analogy, oxygen which (last time I checked) was necessary for aerobic respiration and thus essential to life, also kills us by gradually oxidizing our cells and tissues and making them age. So if the political wind required it, even oxygen in the air could be made into a villain.
Its time we started protesting this by withholding the tax we pay that goes to climate propaganda.
The study is a metastudy of previously reported work. The authors found 35 previous peer-reviewed studies, ranging in time from 1992 to present. Some of these were many years long studies of grasslands and others were one year studies of other ecosystems. Some looked at above ground biomass only, some included root systems. The CO2 enhancement was in the range 200ppm to 300ppm above ambient levels. Some of the studies involved two levels of nitrogen augmentation.
By combining grassland, cropland and forest results the fitted regression is Y = 1.15 (0.08) X – 10.3(2.0) where the values within brackets represent 95% confidence intervals; r2= 0.68 and n = 242. Where Y=enhancement to nitrogen accumulation (in percent) and X is enhancement to net primary production (in percent). r2 is a goodness of fit measure, and n is the number of independent measurements of which some studies produced far more than one. For example, if the same researchers provided reports on two species of plants, then such accounted for two independent observations.
Note the following about this relationship:
First, the slope is greater than one by 15% (plus/minus 8%). What this says in effect is that for enhanced net primary production the accumulation of nitrogen is larger by 15%. By visual inspection I would say that if the relationship were done for croplands alone the effect would be more positive yet as the smaller number of results for grassland and forest have a much smaller slope–possibly even negative.
Second, The intercept is negative (-10.3%). What this says is that for those experiments in which enhanced CO2 had no positive effect on net primary production, then those plants showed a decline in nitrogen accumulation. Now, someone with more knowledge of plant physiology than I will have to say if this makes sense or not. However, it is this second observation that appears to drive the stated result of the paper, which is to say that enhanced CO2 will lead to a reduction in protein content of foods, because the positive slope says that if enhanced CO2 drives net primary production strongly then net nirogen accumulation eventually become positive.
Third, I did not see any discussion of the various methods by which nitrogen content is evaluated.
Kevin, do I take you to mean you paid to download the whole thing?
No I can read from my office at the university. The study is a lot less than it seems. Read my second point in particular. The relationship is one of “enhanced nitrogen accumulation” as long as there is also some enhanced net primary production. If the enhanced CO2 produces no or little increase in net primary production, then there is some depletion of nitrogen. It is the negative intercept in the relationship that they are drawing all attention towards. It is also a strange finding. It must be that in some plant spcies, or under some circumstances, the enhancement of CO2 triggers a response that reduces available nitrogen–for example the CO2 triggers growth of some fungus or bacterium that nails the nitrogen fixing bacteria or something like that.
That is a good summation, Kevin. I will add that when my family was huge in the cattle/dairy business, we placed far more emphasis on total nutrient content than on protein content, because the former yielded better, bigger, healthier cattle and more milk production from the cow herd.
This study looks like a lot about nothing. Interesting, but still ……
This paper is so pay-walled that even the references are off limits without a fee. Is this science or business?
The paper claims to undertake ecosystem-scale experiments using FACE (free-air CO2 enrichment). That in itself is an immense undertaking, as each species of plant may respond differently to enhanced CO2 and productivity and composition would need to be measured at each section of the plant –including the roots. They would also need to keep each other variable in each ecosystem controlled in order to call this an experiment.
In just the forest ecosystem alone it would require the study of hundreds of species, and they purportedly did this on forests, grasslands, and crops (all crops?!). I can’t decide, am I more befuddled by their “surprise” findings or that they managed to fit all of this research into a 14 page paper.
The claims they make actually go against the conclusions from dozens of previous papers so they will surely face rigorous scrutiny within their own field.
i) It’s very hard to determine how robust such a huge undertaking that this paper is claiming to be without actually seeing their methodology. But it’s odd that they determine a correlation of r^2 = 0.68 between eCO2 (actual composition not given in the abstract) and nitrogen composition universally among all ecosystems. That’s not what previous research has found.
ii) They found that decreasing N content was universal regardless of increased plant productivity, again, not what previous research has found.
iii) “Effects of eCO2 on productivity and N acquisition did not diminish over time, while the typical eCO2-induced decrease in plant N concentration did. Our results suggest that, … N limitation of eCO2-induced terrestrial productivity enhancement is associated with negative effects of eCO2 on plant N acquisition.” It’s actually hard to decipher this. It appears they are making a contradictory statement with this; effects causing decreasing N acquisition doesn’t change over time but the “induced decrease” in plant N concentration does diminish.
Perhaps they will next publish on WHY all the previous research is wrong and they are right, but I won’t hold my breathe.
http://www.nature.com/scitable/knowledge/library/effects-of-rising-atmospheric-concentrations-of-carbon-13254108
RW,
I completely agree with everything you wrote here.
Very important points about the scope of the undertaking, and trying to control variables.
“It’s actually hard to decipher this. It appears they are making a contradictory statement with this; effects causing decreasing N acquisition doesn’t change over time but the “induced decrease” in plant N concentration does diminish. ”
Glad to here someone else say this…I was wondering if it was just me.
They seem to be saying the effect is temporary. And then a bunch of gobbledygook that is difficult to parse.
As I recall, one of the greatest benefits to enhanced CO2 is the reduction in the need for photorespiration in the plants due to a lesser need to gain sufficient CO2 for carbon fixation and growth. This substantially lowers the metabolic costs of obtaining sufficient CO2 and increases growth substantially. One of the byproducts of photorespiration (PR) is ammonia so a reduction in PR could easily result in a reduction in N production depending on environment, soil, etc. etc. The authors in their laconic abstract (no real facts about how they tortured the plants in their test sites) do imply that all the test sites had low nitrogen-“As the ecosystems were markedly N limited”- which makes their sweeping conclusions rather unsupportable without testing in more N rich conditions. They also note N was reduced in plants at all sights without stating the forms the N was in. Basically, you have nitrate, nitrite, ammonia, ammonium, aminoacids, proteins as well as nitrogen-containing alkaloids, DNA, pyrimidines etc. Any analysis needs to characterize these forms clearly to understand why N is lower and whether this reduction is a detriment or benefit to the plant. What they conclude is unjustified based on their results and indicates a desperate search to validate the negative effects of CO2 while spinning and ignoring the facts to support their position.
Exactly Dan.
This does not appear to be a study of food production, or the nutritional value thereof.
Just saying plants have less concentration of nitrogen in their tissues does not seem to be a very conclusive point of evidence for a future with less protein in grain crops.
And if there is more grain produced in total, but each kernel is slightly less protein dense, this could be a net plus in many respects.
If each kernel has less protein but is equally viable, this would seem a net benefit for the plant.
Like most organisms that are on the Earth, billions of years of evolution has equipped plants with finely tuned mechanisms for increasing the chances of survival of that plant under varying circumstances.
I would be interested to see a study of the health of each plant, disease and pest resistance, ability to reproduce, etc.
Obviously, as conditions change, some organisms will prove more suited and better able to take advantage of new benefits, or more able to survive hardships.
No matter what the particular condition which is changing.
Does this have something to do with the increased efficiency of the Rubisco protein in the leaves?
Reality check
It is lack of nitrogen, either in amount or timing of supply that limits the synthesis of carbohydrates from CO2 not, as this paper claims, the other way around. See review by Lawlor:
http://jxb.oxfordjournals.org/content/53/370/773.full
“Photosynthetic carbon and nitrogen assimilation and N‐supply
The role of N in agricultural production is intimately connected with photosynthesis. In photosynthesis, the ‘physical energy’ of photons is converted into the ‘chemical energy’ of ATP and reduced metabolic intermediates, primarily NADPH, which are used in the synthesis of carbon and nitrogen assimilates of many different types, particularly carbohydrates and amino acids (Foyer et al., 2001). These ‘fuel’ the synthesis of biochemical components of organs and ultimately provide the structure of the whole plant (Lawlor et al. 2001). The basic mechanisms of assimilate production are considered for they are central to the understanding of crop production.
The supply of CO2 for C3 photosynthesis is inadequate in the current atmosphere (360 μmol mol−1) and photosynthetic rates and crop growth and yields are increased by c. 30% under UK conditions if this is doubled. ”
One cannot just analyses the components of the plant under differing eco systems and make the claims made by the authors of this paper. Responses in crop production are often step changes bring one to the next limiting nutrient and unless these steps are explored in detailed multifactorial response trials covering all required nutrients the results are misleading.
True dat!
Very well said sir.
This paper is such rubbish…
If anything, current CO2 levels are still too low:
http://www.geocraft.com/WVFossils/PageMill_Images/image277.gif
CO2 is still at the lowest levels since complex life evolved 600 million years ago.
12.000 years ago at the end of the glaciation period, CO2 levels fell to just 170ppm; just 20ppm away from photosynthesis shutting down and all life on Earth going extinct….
We should be ecstatic that CO2 levels are recovering to safer levels, and are already enjoying a 20% increase in crop yields from the CO2 rise from 280ppm to 400ppm….
BTW, why do the “scientists” that wrote this paper think ALLLLL commercial greenhouse operators keep their CO2 levels at 1000+ppm??? Why indeed…
CO2 generators have long been a staple for serious aquarium enthusiasts too. A search will produce DYI, ebay and professional CO2 gear.
I think they are right. But not for their reasons. The most abundant protein on this planet is Rubisco. It is the protein needed by a plant to capture CO2 and convert it into sugar. It is one of the most inefficient enzymes ever, despite millions of years of natural selection. That has to do with the fact that CO2, on a molecular level, resembles O2. So CO2 must compete with O2 for binding and finally, conversion into a new compound. Of course, O2 will not do so it prevents CO2 from binding. Under higher CO2 concentrations, this effect decreases, which allows the plant to produce less Rubisco, and hence, less protein. The plant becomes more efficient at using its assets. Which translates into: the higher the CO2, the happier the plant. Below 200 ppm, Rubisco shuts down and the plant dies. As will most forms of life on this planet. So enjoy your blessings.
Precisely.
Just as plants need less water under higher CO2 levels, so too do they require less N.
It’s a good thing.
Your hypothesis is testable by comparing the effects of higher CO2 on C3, C4 and CAM plants. It could well be that differing levels of Rubisco account for any observed variation in N uptake.
A great insight. Thank you. That must be why they did not mention any particular protein in their freely available abstract.
Exactly, and why they did not study specific crop yields, for example.
Big dealio if plants have less of something which they require less of if there is more CO2!
Their conclusion implies that plants are unable to adapt to higher CO2, while the truth is exactly the opposite.
Plants are highly adaptable, and adapt automatically to varying conditions. The job of a plant is not to store nitrogen in it’s tissues…it is to reproduce successfully and compete more effectively.