Sometimes I wonder if science hasn’t been infected with some sort of mass delusion about CO2. Watch this amazing video on CO2 and plant growth from CO2Science.org, then read below the claims made in this UC Davis press release.
Rising CO2 levels threaten crops and food quality
Rising levels of atmospheric carbon dioxide interfere with plants’ ability to convert nitrate into protein and could threaten food quality, according to a new study by researchers at the University of California, Davis.
The scientists suggest that, as global climate change intensifies, it will be critical for farmers to carefully manage nitrogen fertilization in order to prevent losses in crop productivity and quality.
The study, which examined the impact of increased carbon dioxide levels on wheat and the mustard plant Arabidopsis, will be published in the May 14 issue of the journal Science.
“Our findings suggest that scientists cannot examine the response of crops to global climate change simply in terms of rising carbon dioxide levels or higher temperatures,” said lead author Arnold Bloom, a professor in UC Davis’ Department of Plant Sciences.
“Instead, we must consider shifts in plant nitrogen use that will alter food quality and even pest control, as lower protein levels in plants will force both people and pests to consume more plant material to meet their nutritional requirements,” Bloom said.
Climate change, CO2 and agriculture
Historical records have documented that the concentration of carbon dioxide in Earth’s atmosphere has increased by 39 percent since 1800. If current projections hold true, the concentration will increase by an additional 40 to 140 percent by the end of the century.
This trend is of concern to agriculture because elevated atmospheric carbon dioxide levels have been shown to decrease the rates of photorespiration, the naturally occurring chemical process that combines oxygen with carbohydrates in plants.
At first, this reduction in photorespiration boosts photosynthesis, the complementary process by which plants grow by using sunlight to turn water and carbohydrates into chemical energy in the form of plant sugars. In time, however, the increase in the rate of photosynthesis tapers off as the plants adjust to increased atmospheric carbon dioxide, and plant growth slows.
The nitrogen connection
Nitrogen is the mineral element that plants and other living organisms require in the greatest quantity to survive and grow. Plants obtain most of their nitrogen from the soil and, in the moderate climates of the United States, absorb most of it through their roots in the form of nitrate. In plant tissues, those compounds are assimilated into organic nitrogen compounds, which have a major influence on the plant’s growth and productivity.
Earlier research has shown that when atmospheric carbon dioxide concentrations increase by 50 percent, the nitrogen status of plants declines significantly.
More specifically, findings from previous research by Bloom and colleagues suggested that elevated levels of carbon dioxide decreased photorespiration and inhibited nitrate assimilation in plant shoots.
New UC Davis study
In their most recent study, Bloom’s team examined the influence of elevated carbon dioxide levels and, in some cases, low atmospheric oxygen concentrations, on nitrate assimilation in wheat and Arabidopsis plants using five different methods.
Data from all five methods confirm that elevated levels of carbon dioxide inhibit nitrate assimilation in wheat and Arabidopsis plants. The researchers note that this effect could explain why earlier studies by other researchers have documented a 7.4-percent to 11-percent decrease in wheat grain protein and a 20-percent decrease in total Arabidopsis protein under elevated carbon dioxide levels.
“This indicates that as atmospheric carbon dioxide concentrations rise and nitrate assimilation in plant tissues diminishes, crops will become depleted in organic nitrogen compounds, including protein, and food quality will suffer,” Bloom said. “Increasing nitrogen fertilization might compensate for slower nitrate assimilation rates, but this might not be economically or environmentally feasible.”
He noted that farmers might be able to increase their use of nitrogen-rich ammonium fertilizers to ease the bottleneck of nitrate assimilation in crops but would have to carefully manage fertilizer applications to avoid toxic accumulations of ammonium in the plants.
To develop solutions for dealing with the impact of major increases in atmospheric carbon dioxide levels on crops, further research is needed on how plants assimilate nitrate and ammonium, Bloom said.
Working with Bloom on this study were Martin Burger of UC Davis’ Department of Land, Air and Water Resource; Jose Salvador Rubio Asensio of UC Davis’ Department of Plant Sciences; and Asaph B. Cousins, currently of the School of Biological Sciences at Washington State University.
Funding for this study was provided by the National Science Foundation, the U.S. Department of Agriculture and Spain’s Agencia Regional de Ciencia y Tecnologia.
About UC Davis
For more than 100 years, UC Davis has engaged in teaching, research and public service that matter to California and transform the world. Located close to the state capital, UC Davis has 32,000 students, an annual research budget that exceeds $600 million, a comprehensive health system and 13 specialized research centers. The university offers interdisciplinary graduate study and more than 100 undergraduate majors in four colleges — Agricultural and Environmental Sciences, Biological Sciences, Engineering, and Letters and Science. It also houses six professional schools — Education, Law, Management, Medicine, Veterinary Medicine and the Betty Irene Moore School of Nursing.
Media contact(s):
- Arnold Bloom, Plant Sciences, (530) 752-1743, ajbloom@ucdavis.edu (He is away from campus until Wednesday but can be reached by e-mail.)
- Pat Bailey, UC Davis News Service, (530) 752-9843, pjbailey@ucdavis.edu
Dave Springer says:
May 14, 2010 at 7:38 am
“Glad some commenters mentioned that higher CO2 level results in plants using water much more efficiently. Adequate supplies of fresh water for irrigation and sanitation is a large and growing problem…. More and better crop rotation with soybeans on wheat fields should be high on the list of things to do for a lot of good reasons.”
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I would like to see the use of clover or clover/rye grass winter cover crops whenever possible. Also despite the YUCK factor. The use of waste water as fertilizer. Unfortunately all sorts of chemicals are now shoved down the drain so the waste water can contain hazardous chemicals. Septic tanks are another possible source of “fertilizer”
Owen says:
May 14, 2010 at 2:20 pm
This comment is for Anthony Watts. You do a disservice to the general public by taking a study reviewed and accepted by Science, one of the more rigorous journals to pass review, and treat it like it is a bit of lunacy….
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I suggest you read Don Keiller comment.
May 14, 2010 at 2:35 am
“Ah an update of the old (and discredited) “progressive nitrogen limitation” hypothesis. This suggested that “limitations in the supply of nitrogen needed to support increased plant growth should over time reduce or eliminate any effect of atmospheric CO2 concentration on net primary productivity.”
Now that hypothesis has been debunked they seamlessly move on to “food quality” fears. Small reductions in %nitrogen under elevated CO2 have been noted for years. The key problem with this paper is that it reports results on the non-crop plant (Arabidopsis) and wheat- the latter is known to exhibit this %nitrogen reduction effect.
Thus, major crop species studied by Jablonski, L.M., Wang, X. and Curtis, P.S. 2002. Plant reproduction under elevated CO2 conditions: a meta-analysis of reports on 79 crop and wild species. New Phytologist 156: 9-26. showed that rice, soybean, barley, wheat and maize) were considerably more productive when exposed to elevated concentrations of atmospheric CO2, while only two of them (barley and wheat) exhibited (small) decreases in seed nitrogen content under such conditions.
To put these % seed Nitrogen reductions in perspective- according to the most recent publication of The National Academies Press – Dietary Reference Intakes for Energy, Carbohydrates, Fiber, Fat, Protein and Amino Acids (2002) – the Recommended Dietary Allowance for both men and women is 0.80 g of protein per kg of body weight, which for the average (75 kg) man amounts to 60 g protein per day. Hence, for the average Westerner, comsuming a typical Western diet, instead of having 2.72 times as much protein as they require each day, they would have only 2.67 times as much protein….”
If this is an example of “one of the more rigorous journals” then science is in very bad shape. This is nothing but recycling an old study and removing the positive aspects so it can be used to scare Joe Q. Public just in time to get the latest “cap and Trade passed.
I guess “Science” just joined the ranks of the “National Enquirer” except the “Enquirer” is more honest.
Something that needs clarification here is how much nutrition the consumer of the crops will actually receive. We don’t usually eat the entire plant. The essential question for the consumer is the nutritional value of the part(s) of the plant that we use for food.
Owen says:
May 14, 2010 at 2:20 pm
I am a world class scientist with 40+ years in my field, well published and patented. I agree that Science and Nature WERE outstanding journals 20 years ago. I canceled both subscriptions a year ago because their standards had fallen precipitously. Even though I perceived this downward trend many years before, I waited for a long time, since I had been an ACS member, AAAS member, Nature subscriber, and NYAcadSci member for an average of 30 years. I hoped these journals would get better, but they became progressively worse and worse, bottoming out in the latest round of chicken little alarmism, demagoguery, and AGW political lobbying.
I would recommend without reservation that any and everyone discontinue their subscriptions to these second rate journals. It is even too late to clean them up. They and their inbred cronies in academia have put a permanent blot on the reputation of the hallowed halls in which science has gone forward for centuries.
I hope that we, as a scientific civilization may be able to recover. This AGW scam has made Piltdown Man and Lysenkoism look like Junior Varsity stunts.
But if you REALLY want to know how strongly I feel…
Kum Dollison says:
May 14, 2010 at 12:55 pm
“The Nitrogen fixing plants (eg soybeans) will grow larger, and, I’m assuming, become more efficient at “fixing’ nitrogen in the soil. In other words, the nitrogen content of soil should increase as CO2 increases in the atmosphere.”
Of course! Why didn’t I think of that. Some farmers that have the manpower to do it, have planted nitrogen fixers between the rows of grain. Amish let beans grow up their local garden cornstalks. We provide the potash from firewood and phosphorus from spent laundry detergent, and plants are perfectly optimized.
The lack of Nitrogen resulting from the doubling of CO2 cannot be coming from the atmsophere, as simple displacement should be occuring. Mine Safety teaches that it is Oxygen that gets displaced, but says nothing about Nitrogen. I will assume Nitrogen instead of Oxygen for sake of argument.
Reducing 78% N2 to 77.6% N2 is a decrease of 4.7 x 1oE8 %. Not even worth considering.
The soil is a different matter. Rotation of crops should cover the problem.
Other factors need to be considered, like how fast is a crop produced with doubled C02, and how quickly the soil must be rotated out for a season.
It is possible that they have a valid concern. A lower percentage of protein would not be contradicted by the fact that plants grow better with more CO2, because plant growth I believe is largely supported by cellulose, not protein (please correct me if I’m wrong here). It is also consistent with the fact that tomatoes grow better with more CO2: I don’t know why we couldn’t have a higher yield of tomatoes at the same time that we have a lower percentage of protein in the tomatoes.
That said, I agree with some of the other skeptical comments. I am not swallowing this press release, I’m only pointing out that some of the skeptical arguments in comments don’t appear to hold up.
rbateman says:
May 14, 2010 at 3:42 pm
“…..The soil is a different matter. Rotation of crops should cover the problem.
Other factors need to be considered, like how fast is a crop produced with doubled C02, and how quickly the soil must be rotated out for a season.”
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No need to “rotate it out for a season just plant legumes such as beans, peas, soybeans, clover…. most are cool season plants to begin with. Since the CO2 makes plants grow and mature faster it means the second winter cover crop can be planted earlier, allowing more time for the plants to fix N2. If neededthe cover crop can be tilled under as “green manure”
“”” Richard Sharpe says:
May 14, 2010 at 2:21 pm
George E. Smith says on May 14, 2010 at 1:34 pm
Yes Richard, The peer review process is fool proof; after all those chaps at the CRU were not fools; they knew that in order to keep their gravy train running, they had to suppress peer review of contrary scientifc observations that didn’t support their thesis.
And as I have said above; it is those “charlatans in industry” who support that entire gravy train with their evil profit tax dollars.
But you are not alone or a new phenomenon; people who swill at the public trough are always the first to complain about their conditions.
Perhaps if you paid for your opinions out of your own pocket; you might see things a bit more realistically.
George, can I suggest you take your sarcasm detector in for a tune up?
I am one of those “charlatans” in industry too … “””
Richard, I am a unisex, non-denominational, equal opportunity sarcastigator; so my literary works are available to anybody to wear if the shoe fits; or discard when not applicable.
Glad to hear I’m not carrying this load all by myself !
The paper makes the claim that increased CO2 levels block the assimilation of nitrogen from nitrates in the soil. It is not a case of depletion of nutrients in the soil or of less N2 in the atmosphere. It is a biochemical assimilation mechanism that is affected.
Perhaps less protein is a good thing.
http://heartscanblog.blogspot.com/2010/05/blame-gluten.htm
That just proves everything will be dead but Cowpea.
“[…] as lower protein levels in plants will force both people and pests to consume more plant material to meet their nutritional requirements,” Bloom said. […]“
Do these fools think humans are bovine? Why not allow cows to eat more plant material and we eat more cows? Why would we eat more wheat? Why not other froms of protein? How did beans, nuts and other high protein vegetables do in the ‘study’? Or did they not bother to check?
The studys’ assumptions are utter crap based on GIGO models. :o)
Somebody needs a “grant application” refresher course, this argument seems rather weak. It has CO2, and a scary scenario, but just seems to be lacking something….
I don’t recall seeing the word “catastrophic”, that might help?
Richard Sharpe says:
May 14, 2010 at 11:58 am
I am sorry Dr P.H, but I put my faith in the Peer Review Process. It is fool proof and the way to true enlightenment. You have been fooled by those charlatans in industry again!
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REPLY: Sorry, Richie, I’ve studied the impact of greenhouse gases since 1979, concentrating upon methane flux from wetlands and methane mitigation from animal manure and wastewater treatment. I’ve published in peer-reviewed journals and know the business well, being in the field of public health.
The charlatans that bother me are the cabal of climatologists who attempt to manipulate public opinion with nonsense like this drivel from UC Davis.
The buildup of carbon dioxide doesn’t concern me nearly as much as mercury accumulation in the food chain from coal combustion. That’s what I’d like to see industry focus on, rather than carbon dioxide.
A wealth of information about CO2 concentration and nitrogen activity can be found here.
In one peer reviewed article from 2005 it was found that in durum wheat the nitrogen level in the leaves decreased with higher CO2 but at the same time the nitrogen level in the stems and seeds increased. Both biomass and grain yields increased under all nutrient and water regimes where CO2 was higher. This agrees with article which is the subject of this post. The authors measured the leaf nitrogen content and found it lower with increased CO2. However, they failed (purposely?) to grow the plants to maturity and measure the nitrogen content in the seed. It appears that the plants in the higher CO2 regime are able to use less nitrogen to generate more leaf mass and then deposit the excess nitrogen in the seeds where it will be of benefit to the next generation.
The UC Davis study of wheat and mustard going only so far as nitrogen content of the leaves is borderline fraud if you ask me. This whole freaking AGW movement is replete with fraud. Heads need to roll. Lots of them from both academia and governments and media. Sorry to be so crude and angry but this stunt from UC Davis really chafed my hide after just a little bit of investigation of the prior art revealed its unscrupulous nature.
You left the ‘L’ off the end of the link and it didn’t work as a result. Fixed it for ya. Good article on the adverse health effects of wheat glutens, by the way. It’s exactly what I was alluding to in my first comment in this thread.
Good info here:
Wheat Production in Stressed Environments
The page the link goes to has a nice table on it with not just leaf nitrogen content but the grain as well in various conditions of nitrogen deficiency, heat stress, and CO2 concentrations. In normal nitrogenous soil and with no heat stress the protein content of the grain increased slightly with a doubling of CO2 in all three tested strains but more importantly the total dry weight of the grain increased by large amounts with increased CO2 under ALL regimes including nitrogen deprivation and heat stress. The plain fact of the matter is that total yield of grain and protein increased in all regimes where CO2 concentration was doubled and it increased by a huge amount under normal conditions. There is more info in the pages before and after the one I linked.
Any wheat farmer knows that anything that increases the yield of wheat will decrease the protein % given a fixed amount of available N. That’s why when conditions are more ideal for wheat during a particular growing season than expected, the yield is high but the protein is low. This is exactly what happened in 2009 by the way. Because the spring was so wet and wheat plantings were so late, most farmers assumed the yield would be low, so they did not put on much N. However, the cool summer was ideal for wheat and resulted in record yields but low protein because the farmers did not apply enough N for the yield.
The following link from NITROGEN MANAGEMENT FOR HARD WHEAT PROTEIN ENHANCEMENT by Brad Brown, Extension Crop Management Specialist explains why:
http://www.cals.uidaho.edu/swidaho/Nutrient%20Management/increasing_wheat_protein.htm
It states “As available moisture increases due to higher rainfall, yield increases while protein decreases. Protein decreases because the plant’s requirement for N increases as yield increases, and wheat will use limited available N primarily for increasing yield by increasing head number, seed number, or seed size. Even under irrigation, the first increment of N, when available N is low, is used by wheat for increasing yield at the expense of seed protein. It is not unusual under low N conditions for the first increment of N added to actually reduce grain protein. Only when most of the N required for yield has been supplied will further N additions raise protein. At this point, when additional N increases protein, the protein increase is directly related to the amount applied.”
So the reason increased CO2 reduces protein is because it increases YIELD. If you know the yield is going to increase, you just add more N and you then keep the protein % high as well.
There are so many people that know this, who are not even scientists, that its amazing the article passed peer review.
To re-formulate my previous comment: are we talking about the nutritional value of the fruit or the root, the germ or the bran, the berry or the bramble? Some spit out their watermelon seeds, some don’t, some skin their potatoes, some don’t, there are browsers and grazers, sapsuckers and termites, bark beetles and honey bees, aphids and elephants. If you are going to do nutrition, be specific.
Sorry about the double comment a few back. I must have used a word in it that triggered the WordPress spam filter and the moderator had to dig it out of the spam queue manually. I tried changing a single word and resubmitted but it still didn’t show up. Now both of them appeared. I moderated a popular wordpress blog for a few years so I know there are certain words used by spammers (“p i l l” is one of them thanks to v i a g r a spammers and unfortunately “p i l l o w” trips it too. Sometimes a user’s name has a verboten word buried in it and every one of their comments lands in the spam queue. If you have hundreds of spam comments to sort through daily where the vast majority actually are spam then it’s quite a chore to read them all looking for the odd one coming from a legitimate user. I thank the moderators here for their tireless efforts – I know how much time it takes to run a clean & popular wordpress blog.
[Reply: Thanks, most folks have no idea how tedious it is to sort through the hundreds of spams a day, in addition to moderating/approving several hundred more posts that appear in the comment queue. Your post fixed, BTW. ~dbs, mod.]
There should be a campaign to inform Lisa Jackson at the EPA that co2 is not a pollutant. Yes, she has said it is.
Roger Carr says:
May 14, 2010 at 12:44 am
oldseadog says: (May 14, 2010 at 12:20 am) How does this fit with the tomato growers in the Netherlands who put added CO2, up to 1500ppm I have read, into the greenhouses and get better yields?
It probably fits well, because the research here does not seem to dispute “bigger” but does question “better”. We need to know the comparative nutritional values between the with and the without tomatoes before making a judgement on this basis. oldseadog.
More food to eat is better. If the food is larger with “the same” nutritional value that smaller food had then there’s more to eat. That’s better. Who could question that? I’m sure you agree.
But just in case you don’t you could take a trip to Africa, or the Philippines, etc., and tell the people there less food is better because if they had more food of the same nutritional value then that isn’t better. 😉
@moderators
I moderated a little differently than you guys but I think my way resulted in a lot fewer comments. It also resulted in a lot less time spent moderating. The big difference is I required registration to post a comment. Creating an account and logging in likely discouraged a lot of casual one-time commenters. Then I had the mode enabled where the first comment from any new user automatically landed in the moderation queue and all subsequent comments until the first comment had been approved. If the first comment didn’t appear to be from a troublemaker (we had lots of them) I’d add his email address to the first level (I called it the gray list) spam filter so all his subsequent comments would land in the moderation queue. If after a time the commenter proved to be well behaved and well meaning I’d remove his email address from the gray list and he/she would then be free to comment at will without moderation. If the new user turned out to be a headache (quality, combativeness, rude, crude, or otherwise socially or intellectually unacceptable) I’d move his email address to the blacklist provided by the Akismet service (wordpress add-on) and then subsequent comments would land in the Akismet spam queue. As a result I could pretty quickly scan the Akismet list where legitimate comments stood out from the spam like a sore thumb and the regular WordPress moderation queue didn’t have an awful lot in it as most of the users were in the trusted (unmoderated) category.
For a few dedicated trolls who’d create new accounts under new names and behave long enough to get unmoderated I’d resort to using an IP block in the web server itself. There were only a few IP blocks accumulated over a few years. Our activity level was about a quarter million page views a month which is probably quite a bit short of WUWT these days. It took me about 15 minutes every day to do the recurring moderation chores using that scheme and most of the users saw their comments published immediately. What sometimes took a little more time was explaining to some users why their comments were all moderated while other users’ comments were not moderated.
[REPLY – Well, we who question (the extent of) AGW are sensitive to the heavy hand of censorship so prevalent on nearly all AGW blogs. So Anthony, in the spirit of Liberalism Classic, likes to let folks to have their say as far as reasonable. We will occasionally clip and snip but we like to keep that to a minimum. ~ Evan]
~SNIP~
…They are going to save the earth by stopping those silly scientists that want to pull all the co2 out of the atmosphere.
What a spin? The scientists just want us to return to the levels of preindustrial times(280ppm) and stop mans increase of it, the earth just worked fine at those levels. I havent heard one scientist tell us they want to get our levels down below that? just reduce man’s contribution.
What most dont understand is that even though emissions from man are only a fraction of the total co2 emissions on top of what nature does, there is no mechanism to absorb the extra man puts in, the result is what we put up there is accumulating, that is why we have 40% higher co2 than 100 years ago.
Back to the co2 will stop us starving? So where are all the bumper crops we should be getting know with 40% higher co2, not happening unless its in a greenhouse where there is plenty of water, nutrients etc! Co2 is hardly the limiting factor in any crop, in my part of the world its H20 and our crops have suffered because of less of it due to guess what…..a change in climate……have a think about why that may be!
Its a fool’s folly to suggest that more co2 will be good for agriculture, there are plenty of other known affects to agriculture, for example some pests thrive on co2 enriched plants……bet we wont here about that from [~SNIP~ Don’t use that word here. First and last warning. ~dbs, mod.]