Guest post by Indur M. Goklany
This illustration from a recent article in Science magazine shows that CO2 is plant food. It is based on both empirical data and model results (not “data”). I know that looking at empirical data might seem like a novel idea to some people, but for some perverse reason, I find it more compelling.
On the right: Empirical Data. Growth of 21-day-old rice and S. viridis seedlings at different ambient CO2 concentrations ranging from 30 to 800 parts per million. NOTE: The very last set of pots on the extreme right is out of sequence. They are for 390 ppm, while the next to last pots are for 800 ppm.
On the left, Modeled Data:
Modeled changes in CO2 assimilation rate in response to changes in leaf intercellular CO2 partial pressure for C3 and C4 photosynthesis and for a hypothetical C4 rice. Curves 1, 2, and 4 have Rubisco levels typically found in a C4 leaf (10 μmol m−2 catalytic Rubisco sites). Curve 3 shows a typical response for C3 leaves with three times the Rubisco level of C4 leaves. Curve 1 shows the response of a C4 leaf with C4 Rubisco kinetic properties. Curve 2 models how a C4 leaf with C3 Rubisco kinetic properties would respond (a hypothetical C4 rice with C3 Rubisco kinetics). The comparison of these two curves shows the increase in CO2 assimilation rate achieved with C4 compared with C3 Rubisco kinetic properties within a functional C4 mechanism. Arrows to curves 1 and 3 show intercellular CO2 partial pressures typical at current ambient CO2 partial pressures for C4 and C3 photosynthesis. To generate the curves, model equations were taken from (11) and comparative Rubisco kinetic constants from (12). (B) [Reference numbers per source.]
Source: Susanne von Caemmerer, W. Paul Quick, and Robert T. Furbank (2012). The Development of C4 Rice: Current Progress and Future Challenges. Science 336 (6089): 1671-1672.
Finally, note that the top photograph on the right is for rice. According to Wikipedia, not always a reliable source, but in this case probably trustworthy:
[Rice] is the most important staple food for a large part of the world’s human population, especially in Asia and the West Indies. It is the grain with the second-highest worldwide production, after maize (corn), according to data for 2010.
Since a large portion of maize crops are grown for purposes other than human consumption, rice is the most important grain with regard to human nutrition and caloric intake, providing more than one fifth of the calories consumed worldwide by the human species.
In other words, not only is CO2 plant food, CO2 makes human food. Guess some folks skipped that biology class.
Discover more from Watts Up With That?
Subscribe to get the latest posts sent to your email.
It might be helpfull to note that C3 is the most dominating type of photosynthesis. That is while C4 will not gain much from additional CO2. C3 will still have plenty absorption power over concentrations of today.
Robert Brown:- Please look at the CO2 science web site (www.co2science.org) and read the experimental results on a large variety of plants grown in various atmospheric CO2 contents. whilst all plants do not grow at the same rate in the various concentrations they all do grow better.
Frank said “Don’t give me that “oxygen deprivation” guff.”
Its more to do with balance of oxygen and CO2 (see the submarine comment up there somewhere)
The diffusion between the air in the lungs and the oxygen /CO2 balance in the bloodstream operates best when atmospheric CO2 is less than somewhere around 10000 – 15000ppm CO2, (if the oxygen content is near normal). Its not so much “oxygen deprivation”, but the imbalance in the atmospheric concentrations. In submarines they boost the oxygen content to so that the ratio stays within limits.
Iirc we breath out around 30,00ppm, so as the atmospheric concentration climbs nearer that value, we are going to struggle more and more to transfer oxygen between the air and the bloodstream. Simple physics.
So we now we have clear proof for the very first time that CO2 is plant food . Woopee Do! Pure obviousness.
So we now also have proof that even though CO2 is a “trace gas” it’s incredibly important. Who could have guessed that?
I wonder what are things are in the atmosphere, in trace amounts, but are also incredibly important. Err clouds for example. I wonder what the volume fraction of water in a cloud is?
Indur M. Goklany, …’for some perverse reason’ you find empirical data more compelling than model results? Tsk … have you forgotten that models trump observation?
Walt Stone (@Cuppacafe) says:
June 30, 2012 at 6:18 pm
“Please repeat this experiment with phytoplankton and dissolved CO2.”
To take the example of where a continuous plankton recorder survey has been in operation for more than a half-century, in the Northeast Atlantic, during the corresponding rise in CO2, there has been an increase shown (Raitsos et al, 2005).
A global study also found an increase, as seen from from measured chlorophyll, when comparing data in 1998-2002 to that collected during a previous mission in 1979-1986 (Antoine et al, 2005).
Of course, part of the increase would be from other climate factors as well including nutrient upwelling. (A particularly blatant case is sea ice decline increasing plankton in the arctic, as even the NOAA reported, for a set of satellite observations covering 1998 to 2009
http://www.climatewatch.noaa.gov/article/2011/sea-ice-declines-boost-arctic-phytoplankton-productivity ).
Although a more indirect metric since also dependent on many other factors obviously, we can also tell phytoplankton is not doing badly from fish catches, as it is the basis of about the whole oceanic food chain:
http://www.theglobaleducationproject.org/earth/images/final-images/f-total-world-fish-producti.gif
Phytoplankton have been around for a very long time, and CO2 levels were far higher before. One example estimate is http://i90.photobucket.com/albums/k247/dhm1353/Climate%20Change/PhanerozoicCO2vTemp.png with hundreds of millions of years ago there having been as much as 7000 ppm atmospheric CO2 at times (where the Geocarb III part of its CO2 is a more convenient presentation of ftp://ftp.ncdc.noaa.gov/pub/data/paleo/climate_forcing/trace_gases/phanerozoic_co2.txt ). Current atmospheric CO2 is close to 400 ppm.
Raitsos, D. et al.; Reid, P.C.; Lavender, S.J.; Edwards, M.; Richardson, A.J. (2005). “Extending the SeaWiFS chlorophyll data set back 50 years in the northeast Atlantic”. Geophysical Research Letters 32.
http://dx.doi.org/10.1029%2F2005GL022484
Antoine, D. et al.; Morel, A.; Gordon, H.R.; Banzon, V.J.; Evans, R.H. (2005). “Bridging ocean color observations of the 1980s and 2000s in search of long-term trends”. Journal of Geophysical Research 110.
http://dx.doi.org/10.1029%2F2004JC002620
But, as usual on topics close to this, http://nipccreport.org/reports/2009/pdf/Chapter%207.pdf is among the best reading. See page 42 and beyond of section 7.1.3 on aquatic plants including algae and phytoplankton, on lab experiments and production increase at elevated CO2.
Mammals breathing 15% CO2, a high proportion, would still be in acceptable range of arterial blood pH at around 7.17pH (verses more ideal circulatory system wide average blood 7.4 pH).
With yet a higher proportion of CO2 it is less the physical molecule of CO2 than the extra H+ ions diffusing into a cell’s interior that alters Calcium ++, Potassium + “recifier” and Sodium + channels.
For example, when one of the K+ ion channels (inward rectifier) gets inhibited it depolarizes resulting in increased membrane excitability, which sets lungs up for sensitization of local nerve C-fibers to stimulii and that results in constriction of bronchii plus mucosa fluid retention.
Altitude sickness sensations of headaches and heavy headedness involve similar dynamic.
Presuming that all the oxygen in the atmosphere was produced by photosynthesis, why are oxygen and carbon dioxide so ridiculously out of balance in the atmosphere?
If primary productivity increased during the recent warming (as mentioned above), why are there indications that oxygen content in the atmosphere is falling (recent post)?
davidmhoffer says:
June 30, 2012 at 1:22 pm
Shhhhhh, don’t you realize this means that increased CO2 will cause the loss of endangered species of plants!!!
/sarc
AndyG55 says:
June 30, 2012 at 3:30 pm
Being a closet pendant, I’d say that that the word you really want here is fortunate, or perhaps felicitous.
The adjective fortuitous is widely misused to mean fortunate, or lucky, but its original meaning is “by chance.” If you want a $5-word for lucky, try propitious, or auspicious – those probably correspond more closely to your accurate observation.
So, while I quibble a little, and somewhat in jest about your choice of words, your point is a very good one, nevertheless.
That people argue against burning our cheapest, most abundant source of fuel – which just happens to make our plants grow more vigorously in the bargain – only helps prove my previous observation, which should be elevated to a maxim: Yes, Fools Really Are That Ingenious
The proof of the axiom is in the words of those who demonize coal and CO2.
In the areas of tree kill at Mammoth Mountain, CO2 makes up about 20 to 95% of the gas content of the soil.”
Don’t know a thing about CO2 root toxicity, but 20 to 95% leaves a lot of room for SO2, a vastly more toxic volcanic gas.
AndyG55 says:
July 1, 2012 at 3:52 am
Frank said “Don’t give me that “oxygen deprivation” guff.”
Its more to do with balance of oxygen and CO2 (see the submarine comment up there somewhere)
The diffusion between the air in the lungs and the oxygen /CO2 balance in the bloodstream operates best when atmospheric CO2 is less than somewhere around 10000 – 15000ppm CO2, (if the oxygen content is near normal). Its not so much “oxygen deprivation”, but the imbalance in the atmospheric concentrations. In submarines they boost the oxygen content to so that the ratio stays within limits.
Iirc we breath out around 30,00ppm, so as the atmospheric concentration climbs nearer that value, we are going to struggle more and more to transfer oxygen between the air and the bloodstream. Simple physics.
——————————————–
You forgot the “sarc” tag after “simple physics”. 🙂
Let me make sure I understand our area of disagreement (if any). Are you saying that CO2 does not have psychedelic properties?
I probably shouldn’t have mentioned it – we don’t need the DEA competing with EPA to demonize CO2! I should mention that there’s no danger of CO2 catching on as a recreational drug. As I’m sure you know, our respiration rate is determined not by O2 concentration in the bloodstream but by CO2 concentration. So a whiff of (concentration unknown, but high) CO2 makes you pant like a puppy-dog and feel like you’re suffocating. Might be useful for “dry waterboarding” (you did not hear this from me!), but not much fun despite the “trippy” effects.
Ok.. diffusion of gases is not simple physics 🙂
ps.. In the lungs diffusion through the semi-permeable membrane is oxygen one way and CO2 the other way, so both atmospheric concentrations matter. If you deliberately inhale a very high concentration of CO2, you most definitely will have issues with both.
There has been much wringing of hands and gnashing of teeth over the carbon dioxide accumulation in the atmosphere. The “Warmists” miss the point about it’s affect. The “Deniers” over emphacize it’s “lack of effect” and so we continue to discuss the impact of the compound around the wrong process.
There are enough studies suggesting a slightly negative feedback loop related to CO2 concentrations.
My take on the general issue related to the slightly higher temperatures observed in the most recent past century are as follows:
1. The temperature on this planet over the past 5 million years has gone down on long average around 5 degrees C. In the process, the temperature has followed a sawtooth like pattern with a very quick rise followed by a slightly slower drop rate with a total swing of around 8 degrees C. So far, the current temperature has not yet equaled the value of the peak of all of the previous interglacials. We are still around two degrees below the most recent previous peak. As temperatures continue to rise, more methane and carbon dioxide are released into the atmosphere by melting permafrost. Yes, the ocean absorbes the carbon, but not enough to override the increase in the atmosphere. Also, plants, enjoying the higher carbon concentration grow more, increasing their cooling effect on the overall process.
2. Plant respiration is a cooling process which counters and slows tempreature increases but is not the main process related to the temperature cycle. Rather, it is a moderator. Further, the development of C3 photosynthisys may be responsible for the change in the glaciation cycle from an average of 41,000 years to slightly more than 100,000 years, which has been the case over the past four cycles.
3. Four degrees below the peak or two degrees below current is enough to start significant ice accumulation and so to change the surface albido. The ice accumulates over the polar caps first and then begins to accumulate over land masses. In the past 50 million years – give or take a few million, the land masses are more in the northern hemisphere and so, there is more accumulation on the northern land masses and the northern hemisphere has experienced larger temperature excursions than the southern. Regardless of hemisphere, as the ice accumulates, several things happen. First, the albido begins to change and more radiation is reflected away. At the same time, ice accumulation lowers sea levels. Lower sea levels result in more land surface area. Initially, I suggest, more plant growth takes place, which adds to, and speeds the cooling already in progress. However, the cooling retards plant growth. In addition, cooling would retard the disintegration of the plant materials, thus trapping carbon, as in coal, but well before gelogic processes would create coal. Rather, this material is simply trapped in the soil, holding the carbon out of circulation. Remember the huge accumulations of carbon dioxide and methane in the permafrost?
4. How do we get the temperature to begin to drop in the northern hemisphere to initiate the next glaciation cycle? As the temperature rises overall, the ocean temperatures also rise. Temperature differential drives the Gulf Stream. The Gulf Stream carries warm water north along the American Atlantic Coast. The water is cooled by Arctic waters and then flows South effectively lowering Equitorial ocean temperatures. The Gulf Stream has an “averaging” effect on the oceanic temperature. Now, we talk about the Arctic Ice Extent and use that as a measure of warming. We are missing a possible point here. This point is related to the condition of the ice as opposed to the extent. There are a number of folks suggesting the Arctic Crossing will be available very soon. This is because, while ice still covers the Arctic area, it is not as hard and ice breakers can push through it more easily. By “hard” I mean the ice is much closer to thawing but hasn’t actually melted. I suggest that the “trigger” for the cooling, leading to our next glaciation is related to the actual “Arctic Sea Tempreture” instead of the momentary ice extent. At some point, the “driver” for the Gulf Stream will loose effect as a result of insufficient temperature differential, thus resulting in a major change in the flow. In effect, the Gulf Stream will stop or at least slow to the extent that the Arctic Sea will again freeze.
5. Once the cooling is well under way, the sea levels continue to drop. However, because of lower overall temperatures, plant growth begins to decline. This means increasing areas of land mass that is not fully covered by plant growth. Here the moderating tendency of plant growth to cool the environment is effectively reduced. In addition, these larger areas of land mass not covered by vegitation change the albido further to a more absorptive form and warming begins. The albido based warming is a positive feedback process in that as the warming progresses, ice melts exposing more land mass that does not have plant growth. The newly exposed land area represents significantly more total area than the loss of area resulting from the sea level rise related to the warming process. Hence the albido continues to accelerate the warming. Plant migration into the newly exposed areas is a slow but progressive process and eventually will overtake the warming effect of the bare land.
6. We are today at that threshold before the cooling can start. Because deforistation, human influence has effectively interrupted or delayed the beginning of the cooling process by reducing the overall global vegitation coverage. However, the continuing degradation of the Arctic ice, even if it has not receded in area, is an indicator of Arctic Ocean warming. This warming will eventually cause the shift in the Gulf Stream flow mentioned earlier.
7. Is this something we will see in our lifetimes? I don’t know. However, there are ice core indicators pointing to very sudden reversals in temperature movement in the past.
As a doctoral student in Plant Sciences, I would be curious to know if a CO2 fertilization effect is similar to a N fertilization effect. Up to a certain point increased N typically produces increased biomass. However, biomass is not marketable yield. There are crop species that require precise timing of applications, and too much or poorly timed applications produce increased canopy growth at the expense of marketable yield. In a few years I may be set up to study these questions.
Per Mammoth Lakes / Mountain:
It is a volcano. You get all sorts of odd gas poisonings on an active volcano. Concentration can run to 100% for a variety of gasses. Says nothing about likely CO2 levels globally. It also diffuses up through the soil (again up to 100%) and can be quite hot and dry.
Someday it will “blow” again and we get a SuperVolcano from it that will take out much of the desert Southwest (but hopefully not all the way to San Francisco… at least the projected ash zone stops a few dozen miles short of my home :-}
@Henry:
Talk to a farmer. Nitrogen and CO2 are different. CO2 generally promotes growth. Nitrogen promotes leaves.
http://www.thegardenhelper.com/fertilizer.html
Nitrogen for greens. Phosphorus for fruits and roots. Potassium for flowers and strength.
CO2 for any and all structures. Trace minerals as needed for enzyme systems.
@Walt Stone (@Cuppacafe)
http://www.co2science.org/subject/p/summaries/phytoplankton.php
Gee… plants are plants. Nitrogen limited, no change. With available nitrogen, they grow better with more CO2.
Field plants response to higher CO2 is not linear; that growing soil by the 3rd year of increased CO2 growing conditions has boosted Nitrogen mineralization for more soil Nitrogen bio-availabilty to the plant now growing there. Of course if there were nitrogen fixing root nodule possessing plants grown during the interim the exact % of bio-available Nitrogen will be higher (ex: crop rotation planted soybeans the 1st or 2nd year).
It is going into the 3rd & 4th years that higher CO2 really provokes greater bio-mass in that soil.
The higher CO2 growing plants over the first 2 years has provided enough Carbon for soil microbials to structurally form. Then as a portion of the underground microbes die back, some residues of their microbial mass Carbon will go on to be outgassed while the dead microbes accumulated Nitrogen mostly stays in the soil for re-use by plant grown there.
More Nitrogen available below ground, as a long term consequence of CO2 dynamic with soil
microbes, will give above ground more mass of plant shoots above ground. It is a feature of the natural growing domain’s ecosystem providing long term no-till fertilization ( which is added to more complicatedly by specific plant debris).
Moreover, any underlying higher % of CO2 also means a relative decrease in that plants uptake of CO3 (ozone) & thus prevents ozone’s own action that otherwise restrains % of free Carbon convertability into above ground biomass of plant shoots.
Extra C-O2 is plant food – is this the reason all autos with fossil fuel engines in the USA are required to have CAT’s; must convert the CO into CO2 or else!