Now it's more CO2 that will threaten crops

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
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kwik

It must be Grant Forcing. Where do they get their grants from?
Lisa Jackson?

oldseadog

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?

Peter Miller

I thought every study to date showed plants grew faster/better with more carbon dioxide in the air. In other words, the evil gas is a natural fertiliser – presumably this has been ignored in this study.
Off topic: here comes another whitewash:
http://news.bbc.co.uk/1/hi/science_and_environment/10112136.stm

Steveta_uk

plants grow by using sunlight to turn water and carbohydrates into chemical energy in the form of plant sugars
Really? Where do they get the carbohydrates from?

Darell C. Phillips

It’s not that carbon dioxide is harmful to the plants but more that carbon dialectics are harmful.

Morley

It is unfortunate that there are so few numbers in this press release and those that do exist, provide no real data. The authors would like us to believe that protein content can be reduced in certain plants by “doubling CO2”. From what baseline concentration isn’t stated. This report is an example of headline-seeking behavior, not provision of information or better yet, data. Such a press release should be ignored.

Jackie

“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”
So let’s get this straight, if CO2 levels were the norm in 1800, the rising of CO2 levels to todays +40% CO2 should already be interfering with plants’ ability to convert nitrate into protein and food quality should already be threatened. Is that the case?
This is just more delusional science.

Julian Braggins

Obviously they don’t read the multitude of controlled CO2 trials results from papers reviewed in CO2Science on a regular basis. They would have saved a lot of money, but oh wait! the conclusions are different!

In 1978, a CO2 blowout happened during oil exploration in Naihai County, Guangdong, China. Around the well, CO2 concentration was 3 times higher than in normal air. Both rice and wheat production increased for 3 years around the well. It was reported in newspaper of that time and you can even find here if you can read chinese:
http://rywen.net/view/186846

Dave N

“Historical records have documented that the concentration of carbon dioxide in Earth’s atmosphere has increased by 39 percent since 1800”
So where’s the nitrogen deficiency right now?
“Earlier research has shown that when atmospheric carbon dioxide concentrations increase by 50 percent, the nitrogen status of plants declines significantly.”
50 percent more than what?
“Data from all five methods confirm that elevated levels of carbon dioxide inhibit nitrate assimilation in wheat and Arabidopsis plants”
How much is an “elevated level”?
I hope the article isn’t as vague as the press release.

Roger Carr

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.

Dave N

oldseadog
May 14, 2010 at 12:20 am
Presumably they didn’t check tomatoes, and apparently anything other than wheat and mustard? I guess the first is a logical choice, but which breed(s)?

Policyguy

OK,
I would very much like to see responses to this post.
UCD is next door and I have a number of direct contacts. However, I would rather engage on the science about this CO2 / Nitrogen connection.
Thoughts?

Chris P

I have visited greenhouses on Jersey growing enormous heavely laden tomato plants. And strawberry plants banked up, and filling the greenhouses with large fruit. Achieved by adding CO2. This was many years ago, when the concerns were all about feeding the world, and prospects of mass starvation. It left me with much hope for the future. The people of the world could be saved, I thought by greenhouses and CO2.
….But then, what would I know?

GrahamF
Tony Hansen

If increased CO2 increases plant growth and increases yield (but soil nitrogen is not changed) then one would expect a higher yield with lower protein.
Of course they will have this covered. Wont they?

Schrodinger's Cat

I found it!
“Further research is needed..”
When nothing else makes sense, look for the pitch for more funding.

No details of how the experiments were performed in this press release. If they used single plants growing in a closed chamber then the results are meaningless. I recall seeing a reference in the past to dramatic lowering of CO2 concentrations in the center of a cornfield and googling this topic resulted in the following interesting reference:
http://digitalcommons.unl.edu/cgi/viewcontent.cgi?article=1187&context=agronomyfacpub
which, on page 18 of the PDF (page 132 of the original document) has a graph of measured CO2 2 m above a cornfield and one sees drops of 30 ppm in CO2 concentration in the 3 minute record that is shown. It would be very interesting to see what happened when one gets a day with very little wind. This CO2 lowering effect of plant communities is probably why we see such dramatic increases in plant growth and crop yields with atmospheric CO2 increases. In plant communities, especially ones made up of rapid growing plants, CO2 concentration is a rate limiting step for growth. Incidentally, the reference above is from 1969 and one would think that plant physiologists would be aware of this literature.

UK Sceptic

This, in posh parlance, is what we in the UK call purloining the micturation. Worse, they are doing it at our expense.
Sorry to repeat myself but these people call themselves SCIENTISTS?

Kate

“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.”
…Got that?
“Further research is needed”.
Translation:
Oh! My God, the “Global Warming” money is running out!!! Quick! Put out another hysterical press release about increasing threats of mass destruction caused by the increase in man-made CO2 emissions!
Never mind the facts, just get it out there now!!!

Alan the Brit

I was going to respond in the vulgar form. However, being an Englishman & Brit, & a reasonable gentleman, I merely suggest that this paper sounds to me like a complete load of small round things usually found in mens trousers! (Fellow Brits know the term well!) Was there any scientific study actually done at all other than blowing bubbles in their beer to remove the CO2? Straws & clutching spring to mind.
A bit like the old joke about the three uni profs & the monkey! I won’t go any further – perhaps one day!

Peter Miller

And another thing, the wheat we grow today bears little resemblance to the wheat we grew a century ago.
Today’s plants are much shorter with a bigger ear of seed, resulting in much higher yields. In other words, evolution and genetics will solve the problem – if indeed there is a problem.

old construction worker

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?’
But, it’s a lower quality yield. LOL

jorgekafkazar

I’d sure like to see someone reproduce this work. They’ve released their complete methods and data?

Mike McMillan

Love the music.
This is absurd, the kind of specious argument you get when someone is grasping at straws, like when the Luddites argue against golden rice because “Well, it won’t save All the children of Asia from blindness,” or “it doesn’t provide All the betacarotene growing children need in their diets.”
With any crop, whichever input (sunlight, water, soil elements, CO2) is in shortest supply limits the growth of the plants. By curing the shortage of trace gas CO2, that moves the next least abundant input, apparently nitrogen compounds, up to number one. That’s a problem akin to having more money than you need, one you can live with.
Here’s my oft posted take on CO2’s effect on Illinois corn production.
http://i29.tinypic.com/120ilbc.jpg

Dave

I dont quite understand the panic here.
OK, if plants grow faster, they will reduce the food content per kilo of plant. That sounds reasonable, if they are limited by the amount of nitrogen (which only applies in the wild – farmers can simply add more fertiliser, surely? As in a greenhouse…)
However it seems to me that the amount of food produced doesnt go down, indeed it may rise, as less food per kilo of plant is offset by more kilos of plant grown.
So the only real effect is that you may have to eat more bulk for the same calories, which if anything will help the western obesity problem….
Or am I being too logical for the religious theorists??

Sera

The money shot- ‘further research is needed’. If further research is needed, then shut your piehole until your research is finished.

HR

You know climate crazines isn’t a modern thing. I was looking through google books at some older texts and came across a Popular Mechanics from 1950. It’s reporting warmer winters. It quotes Dr Clarence A Mills who speculates that if the warming trend continues “may result in smaller adults in the US …….. There may also be a retardation of mental keenness and the rate of development”
As a non-US person I wouldn’t dare comment!
http://books.google.com.au/books?id=6NkDAAAAMBAJ&pg=PA126&dq=spitzbergen&lr=&as_drrb_is=b&as_minm_is=0&as_miny_is=1850&as_maxm_is=0&as_maxy_is=1950&num=100&as_brr=1&cd=4#v=onepage&q=spitzbergen&f=false

Merovign

You can’t really draw a conclusion from a press release. I’ve been studying studies lately (in another field) and I’ve been stunned at how universally study data does not support summaries and press releases. “Popular Science” (as in what’s reported to the world) is more mythology than I’d wanted to believe.
I’d want to know if they starved the plants for nitrogen (relatively speaking), and what the change in the rate of plant growth was – i.e. did CO2 inhibit absorption of nitrogen or did growth outstrip the availability of nitrogen?
Also, if increased CO2 causes some secondary slowing of growth in plants, why have other long-term studies caused growers to create special high-CO2 environments for more expensive and/or smaller volume crops? Are they just not very bright, or is the science just not as “settled” as the press release makes it sound?
Hopefully someone with better access to the data will get some answers from the authors, and/or they will have the time to answer here. If I can gather enough actual referenced data I’ll try to get through myself, but here I am at 2am checking the news before I sleep…

Phillip Bratby

It’s the result of post-modern science. Black is the new white.
Prof Bloom – nominative determinism in action!

ROM

I am a layman, an old retired grain farmer but I have a standing invitation to short monthly internal seminars held in our large, for Australia,[ 200 Ag researchers and field support staff ] locally based Crop Research Institute.
This very subject came up yesterday in a discussion around another seminar subject.
The researchers here are conducting an international collaborative research project which includes China and other countries, all of which they exchange researchers with on a regular basis.
The research project which involves a number of international Agriculture Research organisations on a number of international sites and a number of different broad acre field crops and crop types, drifts controlled and high level concentrations of CO2 , I think of around 1000 ppm CO2 is the aimed for concentration , over small sections of open field crops to ascertain just what effect increased CO2 levels have on growth, quality and other plant characteristics under actual field simulated conditions and over the life of the crop.
One of the conclusions from the experiment so far and as expected, is that photo synthesis and plant bio-mass and yield do indeed increase substantially with the extra CO2 for exactly the same water availability and plant nutrient availability as the non CO2 enhanced adjoining crop.
However yesterday I heard from one of the researchers in the discussion after the seminar and for the first time that the grain and plant protein quality may be reduced with increasing CO2 levels due to changes in the plant biological processes under higher CO2 levels.
There were some possible biologically based reasons given for this effect but I didn’t note them so!
I don’t know any further details and my impression was that it was too early days yet to be drawing any firm and definite conclusions about this effect.
And these guys and gals don’t have any contacts that I know of with UC Davis.
I won’t vouch for the total accuracy of my recollections but the quality question under increased levels of CO2 just came out of the blue and was completely unknown to myself prior to the discussion after the seminar presentation and with the contacts I have in there, I probably would have heard of this previously if the information was around.
[ I am a trustee on behalf of the State’s grain farmers for the land, bought by the farmers some 45 years ago for this now major Ag research institute to be established on ]

Scarface

Plants get such bad quality, that dinosaurs only could grow to 30 meters. Bad indeed…

Iren

Its not just the Netherlands. Its standard practice for greenhouses to pump in CO2 to increase yield. I’ve also seen mention of open field use of CO2 on crops which was also successful.
I heard an item on the radio this morning about the lizzards and laughed out loud. Talk about desperation. Lizzards are cold blooded and need heat. They’re much more likely to die in cold weather.
Honestly, they must think everyone is stupid. Even the most disinterested, unengaged person’s antennae must be rising at the ridiculous nonsense they’re coming up with and expecting us to swallow.

Eric (skeptic)
Chris

and next they will show, that water and fresh air are pollutants…

Ralph

Pushing the term “junk science” to the limit.

Don Keiller

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.
Another Alarmist red herring.

ukipper

> researchers have documented a 7.4-percent to 11-percent decrease in wheat grain protein.
Surely the increase in mass at harvest due to CO2 fertilisation would more than compensate for any slight reduction in protein per Kg?
> the increase in the rate of photosynthesis tapers off as the
> plants adjust to increased atmospheric carbon dioxide,
> and plant growth slows.
What timescales are required for this ‘tapering off’? Years or months? It’s the effect on fast growing annual crops that matter – and according to all the research I’ve read, they all benefit from increased CO2.

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.
Emphasis mine.
Just how *low* were those atmospheric oxygen concentrations — equivalent to, say, 18,000 feet?
And what were those five different methods? Withholding water, application of herbicide, exposing plant roots to actinic light, girdling the stalks, and over-watering?
A lot of alarmism with not a lot of information to back it up. Kinda typical of a press release…

Frederick Davies

“Sometimes I wonder if science hasn’t been infected with some sort of mass delusion about CO2…”
Do not confuse “Science” with “scientists”:
Science is not what scientists do; scientists are those who do Science.
NOT the other way round.

Jimbo

So now I know why gardeners are asked to pump co2 into their greenhouses at 1,000pmm :o)
This is what happens when so much money goes into one scientific field, you get bare faced lies. Now look at some other examples of Co2 and increased plant growth.
C02 And Increased Plant Growth
http://aspenface.mtu.edu/
http://www.news.wisc.edu/17436
http://news.duke.edu/2009/08/carbonseed.html
http://www.ias.sdsmt.edu/STAFF/INDOFLUX/Presentations/14.07.06/session1/myneni-talk.pdf

Chris

I have heard about the whole ‘CO2 makes plants grow faster but causes them to contain less protein’ before. A newspaper in New Zealand reported a new Australian study that found climate change could threaten the koala (which exclusively eats eucalyptus leaves) because there wouldn’t be enough time in the day for them to eat all the leaves they needed for protein. Koalas are quite slow animals and sleep a lot, kinda like sloths. I have no idea if there is any truth to this reduced protein theory – any botanist readers?

Erik

@oldseadog says:
May 14, 2010 at 12:20 am
How does this fit with the tomato growers in the Netherlands
———————————————————————–
It’s a perfect match – inhailing the plant makes the grower higher – exhailing the Co2 makes the plant grow higher

arthur clapham

Tomatogrowers in England pipe Co2 into huge glasshouses and achieve up to 40%
increases in yields, lets hear it forCo2 providing more food for expanding world populations!!

These people haven’t cottoned on that CO2 is necessary for plant-life, and therefore for oxygen replenishment…

Al Gore

“Earlier research has shown that when atmospheric carbon dioxide concentrations increase by 50 percent, the nitrogen status of plants declines significantly.”
Yeah? So? Last time I looked, the anthropogenic proportion of Co2 was around 3%. Hardly threatening to increase the entire mass of Co2 by 50%.
Besides which – I’m tired of all these scare stories. When you’ve seen too many horror films, you kind of become immune to them, and even start to see the fake blood and Gore as just that: fake.

Jimbo

“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.”
Why don’t they test all cereal crops? Maybe they did but looked for an example of diminished protien and published accordingly! You really do have to wonder about these people, it’s all bad i.e. a large increase in wheat production is nothing compared to a relatively small decrease in protein in wheat. Hey, eat nuts, beef, fish, eggs etc.
What alarmist claptrap!!

old gifford

http://www.guardian.co.uk/environment/blog/2008/jan/28/supermarketgoesgreenwithto
Tomato plants kept in greenhouses at farms in Chichester and Stansted are fed carbon dioxide, which, combined with photosynthesis, produces better tasting tomatoes. In the process of creating carbon dioxide, heat is generated, heating the greenhouses and turning a turbine that then produces electricity which feeds into the national grid.
Green energy says that this combined heat and power (CHP) process benefits everyone involved and generates no waste.
Green energy UK founder and chief executive, Doug Stewart, said:
Electricity from growing tomatoes is extremely positive because it has multiple benefits and no waste – all the heat is used for warming the greenhouses, the CO2 is ‘fed’ to the plants and the electricity goes to consumers and businesses who want green power.

Jarmo

Are they saying that protein content of plants absolutely decreases with higher CO2? Or, are they saying that the protein content of plants does not increase at the same rate as organic mass? Could not find a specific statement.
The positive impact of CO2 on growth and plant yields has been recorded in numerous studies, see http://www.co2science.org/subject/a/summaries/agwheatpollution.php

mike

this sort of thing fits in well with the hartwell paper that anthony linked to yesterday (thanks anthony, fascinating paper). its recommended reading.