Increased Plant Productivity: The First Key Benefit of Atmospheric CO2 Enrichment

From MasterResource

By Craig D. Idso — April 21, 2022

Dr. Craig Idso, Chairman of the Center for the Study of Carbon Dioxide and Global Change, invites readers to join him in a new series of articles discussing the many ways in which rising atmospheric carbon dioxide benefits humanity and nature. His introductory post is here.

“Based on the numerous experiments listed there, I can tell you that, typically, a 300-ppm increase in the air’s CO2 content … will raise the productivity of most herbaceous plants by about one-third, which stimulation is generally manifested by an increase in the number of branches and tillers, more and thicker leaves, more extensive root systems, and more flowers and fruit.”

Perhaps the most well-known and significant biological benefit of Earth’s rising atmospheric carbon dioxide (CO2) concentration is enhanced plant production.

Over the past five decades literally thousands of laboratory and field-based studies have been conducted to examine growth-related responses of plants at higher levels of atmospheric CO2. These CO2-enrichment studies, as they are called, are near unanimous in what they have found—increased levels of CO2 significantly enhance plant photosynthesis and stimulate growth.

This favorable outcome results from the fact that carbon dioxide is the primary raw material utilized by plants during the process of photosynthesis to build and construct their tissues. Think of it if you will as the “food” that sustains essentially all plants on the face of the Earth. And, fortunately, the more CO2 plants “eat” or take in from the air during photosynthesis, the bigger and better they tend to grow.

My company, the Center for the Study of Carbon Dioxide and Global Change, has been investigating the effects of atmospheric CO2 on plants for decades now. On our website we maintain a Plant Growth database, where we have archived the results of thousands of CO2 enrichment studies on hundreds of plants

Based on the numerous experiments listed there, I can tell you that, typically, a 300-ppm increase in the air’s CO2 content (note that the planet has already experienced approximately half of such increase since the Industrial Revolution began and will complete this full 300 ppm increase before the end of this century) will raise the productivity of most herbaceous plants by about one-third, which stimulation is generally manifested by an increase in the number of branches and tillers, more and thicker leaves, more extensive root systems, and more flowers and fruit.

Figure 1. Percent change in various growth and yield-related parameters of two pea cultivars in response to a 169 ppm increase in atmospheric CO2. Data presented in this graphic were derived from Table 1 and Table 2 of Kumari et al. (2019).

Figure 1 above illustrates such growth and yield-related benefits for two pea plant cultivars in response to a 169 ppm increase in the air’s CO2 content. Averaged for both plants, this relatively small rise in CO2 increased plant height by 13.9%, dry weight by 35.4%, number of pods per plant by 18.7%, pod length by 11.6%, pod girth by 16.5%, number of grains per pod by 28.4%, average pod weight by 41.5%, pod yield per plant by 33.7% and total pod yield by 33.7%. Such increases are remarkable considering that they were brought about solely by the scientists increasing the air with extra CO2.

The growth response of woody plants to atmospheric CO2 enrichment has also been extensively studied. Reviews of numerous individual woody plant experiments reveal a mean growth enhancement on the order of 50% for an approximate doubling of the air’s CO2 content (i.e., a 300 ppm rise).

Figure 2. Eldarica pine trees grown at the U.S. Water Conservation Laboratory in the mid-1980s by Dr. Sherwood Idso under ambient CO2 air and air enriched with an extra 150, 300 and 400 ppm of atmospheric CO2. Photo copyright and courtesy of the author.

Figure 2 illustrates this phenomenon for pine trees grown in normal air and air enriched with an extra 150, 300 and 450 ppm of CO2.  Taken some 35 years ago, the person in the photo is my father, Dr. Sherwood Idso, who for many years worked at the U.S. Water Conservation Laboratory in Phoenix, Arizona, demonstrating the beneficial effects of atmospheric CO2 enrichment on plant growth, long before it became politically inconvenient to do so.

In one of his more famous experiments, my father grew sour orange trees in ambient and CO2-enriched air in the Phoenix desert for nearly two decades.  In that study, which was the longest such experiment ever to be conducted anywhere in the world, trees exposed to a CO2 concentration 75% greater than normal annually produced 70% more biomass and 85% more fruit.  And as icing on the cake, so to speak, the vitamin C concentration of the juice of the CO2-enriched oranges was between 5 and 15% greater than that of the juice of the oranges produced on the trees growing in ambient air.

Although much less studied than terrestrial plants, many aquatic plants are also known to be responsive to atmospheric CO2 enrichment, including unicellular phytoplankton and bottom-rooted macrophytes of both freshwater and saltwater species. Hence, there is probably no category of photosynthesizing plant that does not respond in a positive manner to atmospheric CO2 enrichment and that is not likely to be benefited by the ongoing rise in the air’s CO2 content.

So what do these growth-enhancing benefits of atmospheric CO2 enrichment portend for the biosphere?

One obvious consequence is greater crop productivity; and many researchers have acknowledged the yield-enhancing benefits of the historical and still-ongoing rise in the air’s CO2 content on past, present and future crop yields. In this regard, in my own studies of the subject I have calculated that the benefits of CO2 on agriculture are so important that without them, world food supply could well fall short of world food demand just a few short decades from now.

I have also calculated the direct monetary benefits of atmospheric CO2 enrichment on both historic and future global crop production. Over the past 50 years, that benefit amounts to well over $3 trillion. And projecting the monetary value of this positive externality forward in time reveals that it will bestow an additional $10 trillion on crop production over the next 50 years. Yet, as amazing as this estimate sounds, it may very well be vastly undervalued.

Figure 3. Percent change in grain yield for 16 different rice genotypes in response to a 300 ppm increase in atmospheric CO2. Source: Decosta et al. (2007).

Consider, for example, the fact that rice is the third most important global food crop, accounting for approximately 9% of global food production. Based upon data presented in my organization’s Plant Growth Database, the average growth response of rice to a 300-ppm increase in the air’s CO2 concentration is 33.3% (n = 428, standard error = 1.5%). However, as shown in Figure 3, a team of researchers who studied the growth responses of 16 different rice genotypes reported CO2-induced grain yield increases in those genotypes that ranged from near zero to a whopping +263%. Therefore, if countries learned to identify which genotypes provided the largest yield increases per unit of CO2 rise, and then grew those genotypes, the world could collectively produce enough food to easily supply the needs of all of its inhabitants, ending world hunger and staving off crippling food shortages that are projected to result in just a few short decades from now in consequence of the planet’s increasing human population.

Unfortunately, too many individuals and governments are locked into the false mindset that CO2 is a pollutant and so research has progressed but little on this front of late. Perhaps one day this will change when enough good people stand up and acknowledge as the father of modern plant CO2 research, Dr. Sylvan H. Wittwer, once stated, that “it should be considered good fortune that we are living in a world of gradually increasing levels of atmospheric CO2,” and that “the rising level of atmospheric CO2 is a universally free premium, gaining in magnitude with time, on which we can all reckon for the future.”

Only time will tell.


De Costa, W.A.J.M., Weerakoon, W.M.W., Chinthaka, K.G.R., Herath, H.M.L.K. and Abeywardena, R.M.I. 2007. Genotypic variation in the response of rice (Oryza sativa L.) to increased atmospheric carbon dioxide and its physiological basis. Journal of Agronomy & Crop Science 193: 117-130.

Kumari, M., Verma, S.C. and Bhardwaj, S.K. 2019. Effect of elevated CO2 and temperature on growth and yield contributing parameters of pea (Pisum sativum L.) crop. Journal of Agrometeorology21: 7-11.

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April 23, 2022 2:09 pm

The fact remains by observation that C3 plants have already evolved to use 1000+ ppm CO2 concentration in the atmosphere and retain that evolutionary characteristic today.

It’s either that, or it was divine intervention that did it. Choose your own solution.

Both solutions to the observation prove that CO2 is not an air pollutant and the correct amount of CO2 in the atmosphere is a subjective conjecture.

Rud Istvan
Reply to  Doonman
April 23, 2022 2:35 pm

1000 ppm is what greenhouses usually create for growing C3 fruits like tomatoes, and all the C3 winter fresh veggies. (Among human food plants, only maize, sugar cane, and sorghum are C4. Everything else is C3.)

Geoff Sherrington
Reply to  Doonman
April 23, 2022 6:09 pm

Can we then infer that these plants evolved naturally in a time when CO2 was much higher than now?
Any pointers to when that might have been, plus any measurements of high levels?
Geoff S

Reply to  Geoff Sherrington
April 24, 2022 8:09 am

Photosynthesis originated at a time of high CO2.
Look at the evolution of photosynthetic cellular structure in plants over the last billion years. CO2 was dropping as life was increasing.
The appearance of C4 and CAM in the cenozoic occurs because Earth’s atmospheric CO2 was dropping to levels so low that C3 plants were struggling to survive. In just the last 30 million years, the Earth’s atmosphere was so depleted in CO2 that plants were forced to evolve better CO2 extraction mechanisms.
Evolution by selective survival.
It’s good to understand the obvious benefits of more CO2 to plant growth.

Reply to  Doonman
April 24, 2022 10:59 am

also implies anthropogenic emissions from fossil fuels may be more of a centennial spike in the long-term than a 100K-yr plateau

Mark Pawelek
Reply to  Doonman
April 29, 2022 7:29 am

The correct amount of CO2 in the atmosphere is, IMHO, anything below 1% or 2%. I guess more than that may interfere with human respiration for older people.

Rud Istvan
April 23, 2022 2:28 pm

It isn’t just human food and timber productivity. C3 plants need to open their stomata less, so transpire water less, so can grow in drier conditions. That explains the greening of the Sahel, to be grazed by goats.

And ocean algae are also more productive, at the base of the ocean food chain.
In the North Atlantic, seine net surveys show that coccolithophore phytoplankton have increased in abundance by almost 10x in the past 30 years. Depending on where in the ocean (they are more common in more barren areas), they are between 5-40% of primary food production for zooplankton and fish larvae.Their carbonate exoskeletons are also a growing primary carbonate sink for CO2.

Reply to  Rud Istvan
April 23, 2022 2:50 pm

The whole world is far more productive in a higher CO2 atmosphere. !

And if, incidentally, some cold regions have become slightly warmer… that is also a huge bonus for life of all sorts.

Reply to  b.nice
April 23, 2022 7:27 pm

So why don’t the Canadians “get it?”

Sparkle Socks and a whole bunch of Trudeau Swooners are all in for eradicating “caaahbon”.

I find it amazing that there are any Canadians who aren’t rooting for global warming.

What’s hilarious is at the RV park in Florida where we snowbird, the large Canadian contingent are in the tank for the CAGW narrative. How self-unaware (and tan in Winter) can one get?

Reply to  H.R.
April 24, 2022 1:01 am

Half the people are below average intelligence, and average ain’t smart. TPTB are misleading them bigly, too.

Pat from kerbob
Reply to  H.R.
April 24, 2022 6:36 pm

There are many of us smarter than that but most are unwilling to poke their heads above the parapet.
Too many are like our new moron, I mean mayor, here in calgary who declared climate emergency on her first day
In a place that gets 6 weeks of summer a year.
Now that is a moron

Reply to  Pat from kerbob
April 25, 2022 10:32 pm

Pat: Too many are like our new moron, I mean mayor, here in calgary who declared climate emergency on her first day
In a place that gets 6 weeks of summer a year.”

One of the two of you needs to start “pining for the fjords.”

Reply to  Pat from kerbob
April 27, 2022 4:16 pm

I have observed over my 83+ years that one does NOT have to be very intelligent to be a politician! All one needs is enough similarly (mentally) endowed voters to PLACE them in office.

R Stevenson
Reply to  b.nice
April 24, 2022 8:08 am

Unfortunately doubling CO2 to 800ppm won’t make blind bit of difference to global temperatures; this can’t helped but there you are.

Reply to  Rud Istvan
April 23, 2022 2:55 pm

“Their carbonate exoskeletons are also a growing primary carbonate sink for CO2.”

That is why humans must keep replenishing atmospheric CO2 from sequestered/stored carbon stocks.

Letting the atmospheric CO2 level drop from its current “just sufficient” level would cause large famines in many countries.

Thank you China, India, and soon Africa and other developing countries, for helping maintain an atmospheric CO2 level that is,at least, partial workable for plant life..

Not optimum yet.. more to do, and developed countries are shirking their responsibilities.

Rud Istvan
Reply to  b.nice
April 23, 2022 3:37 pm

Actually, repeating a real calculation comment posted previously with source data. If plate tectonics did not recycle continuously produced marine carbonates via subduction, heating to free CO2, and release via mafic volcanos (ring of fire), all life would cease since CO2 would drop below 150ppm (stopping photosynthesis) in about 1 million to 1.5 million years.

Reply to  Rud Istvan
April 23, 2022 7:30 pm

Is there a Go Fund Me to prevent that?

Reply to  H.R.
April 24, 2022 12:49 am

Just use more fossil fuels. I do my best, and have two woodburners, too.

Reply to  Chaswarnertoo
April 24, 2022 1:52 pm

That is just part of the short term cycle. Makes no difference to atmospheric CO2

We need to add more CO2 from the longer term cycle.

That means COAL.

Carbon that has been accidentally sequestered for 100’s of thousands of years.

Reply to  b.nice
April 25, 2022 11:42 am

In a few thousand years when most of the coal is gone, we may have to consider using nuclear power to break down limestone in order to keep the CO2 levels up.

Reply to  MarkW
April 27, 2022 4:21 pm

The CO2 released and USED during those 100’s of thousands of years, has to go somewhere. It will likely be sequestered, accidentally or on purpose, where it can then be released again. Nothing on earth is ever truly ‘wasted’, it just gets recycled.

Allan MacRae
Reply to  Rud Istvan
April 23, 2022 7:51 pm

CO2 sanity from 2009:
“Long, long ago in a world far, far away…”
When all life on Earth comes to an end, will it be because CO2 permanently falls below ~200ppm as it is permanently sequestered in carbonate rocks, hydrocarbons, coals, etc.?
Since life on Earth is likely to end due to a lack of CO2, should we be paying energy companies to burn fossil fuels to increase atmospheric CO2, instead of fining them due to the false belief that they cause global warming?

Could T. S. Eliot have been thinking about CO2 starvation when he wrote:
“This is the way the world ends
Not with a bang but a whimper.”

Regards, Allan 🙂
And from 2016:
“As our planet descends into greater depths of woke psychosis, climate fraudsters propose that we call our current age the Anthropocene…”
Our current geological epoch, only 11,500 years old since the end of the last Ice Age, is called the Holocene.
I suggest the last few decades of false temperature data “adjustments”, widely touted by global warming fraudsters, should be called the Assholocene.

Reply to  Allan MacRae
April 24, 2022 1:02 am

Uptick for Assholocene.

Reply to  Allan MacRae
April 24, 2022 1:55 pm

Once all this anti-CO2 nonsense goes away, and people wake up to reality… the absolutely need for an atmospheric levels of 400+ ppm !

.. I see a time when CO2 is maintained in the atmosphere by using nuclear power to dissociate it from carbonate rocks.

Peta of Newark
Reply to  Rud Istvan
April 23, 2022 9:12 pm

Hence why we get Ice Ages.

Mechanism: CO2 and soil nutrients drop to low levels > the plants wither weaken burn and die > the land cools > the ice moves in.
How Ice Ages ever melt and plants recover is the miracle – what if the next one doesn’t melt?

Maybe we wanna be careful how much Roundup we throw around – or, preventative burning for that matter

David A
Reply to  Rud Istvan
April 24, 2022 5:18 am

Is there a lag in the plant absorption of CO2. (Increase CO2 say 10 ppm, then how long does it take a forest to reach its maximum size and CO2 use from that one time increase)

Nicholas McGinley
Reply to  b.nice
April 24, 2022 1:02 pm

That is why humans must keep replenishing atmospheric CO2 from sequestered/stored carbon stocks.”

Wait a second…were you not arguing strenuously in another thread that human additions from burning fossil fuels have nothing to do with the recent increases in the levels of CO2 in the air?
Yup…you sure were.

Clyde Spencer
Reply to  Rud Istvan
April 23, 2022 6:59 pm

… coccolithophore phytoplankton have increased in abundance by almost 10x in the past 30 years.

This is despite the clamor about ocean ‘acidification’ being a threat to ocean organisms.

John Hultquist
Reply to  Rud Istvan
April 23, 2022 8:25 pm

 “by almost 10x in the past 30 years”
Did you mean 10%?
100 increased by 10% yields 110;
100 increased by 10x yields 1,000.

 a growing primary carbonate sink “
Has this also increased 10x?

Peta of Newark
Reply to  Rud Istvan
April 23, 2022 9:07 pm

The ocean is more productive because we, via soil erosion, are filling it with Iron – the Liebig Limiting Nutrient for all oceanic life.
Next time we any of us see a ‘Flood’ on the TV news, notice what colour the water is.
If its orange, brown or red, that is Iron.
One example:

From the Grauniad: UK Floodwater

Also why, in China, the ‘Great River‘ was re-named due to activities of the farmers on its watershed.
Now known as the ‘Yellow River

Brisbane Flood Water.JPG
David A
Reply to  Rud Istvan
April 24, 2022 5:13 am

More Bio-mass with equal or even less water and no more land required. Sounds like a sudden drop to 280 ppm Co2 would create WWIII in a few weeks. ( Not that we are not getting there on our own)

Gary Pearse
Reply to  Rud Istvan
April 24, 2022 12:41 pm

(coccolithophores) “Their carbonate exoskeletons are also a growing primary carbonate sink for CO2.”

White Cliffs of Dover a classic example.

Tom Halla
April 23, 2022 2:30 pm

It was interesting how much rice yields varied with a CO2 increase, from 6% to 263%.

Rud Istvan
Reply to  Tom Halla
April 23, 2022 2:46 pm

Tom, not too surprising. Different cultivars require different soil nutrient levels (why they were developed in the first place for different geographic places), and some will reach their other growth limitations earlier than others. One of the knocks on higher yielding GMO rice cultivars is that they always require more fertilizer that may not be economically available in SE Asia.

On my dairy farm, we have the choice of fast maturing (3-4month) or slow maturing (4-5 month) corn simply because of the variability of spring planting conditions. Slow maturing always has higher per acre yields, but that gets washed away if planting is late (like this year) or if fall comes early. Sometimes we plant some of both as ‘insurance’. All GMO ‘Roundup Ready’ to enable no till to minimize erosion. The farm is all hilly contours in the Wisconsin Uplands.

Peta of Newark
Reply to  Rud Istvan
April 23, 2022 9:15 pm

Hope that farm is profitable.

In not so many years from now, many 10’s of millions of Autistic children are gonna coming hammering your door looking for compensastion for their malaise

Rich Davis
Reply to  Peta of Newark
April 24, 2022 8:50 am

Peta are you saying that glyphosate causes ASD? If so what was causing autism prior to 1976 when Monsanto introduced Roundup to the market?

April 23, 2022 3:20 pm

I have several led grow lights in my house which I have used for getting an early start for the spring garden. The plants have always thrived under the led lights, but I bet that the extra CO2 from being indoors is part of why the plants have done so well.

Peta of Newark
Reply to  goldminor
April 23, 2022 9:21 pm

Yes absolutely
Because Grow Lights, thanks to the true wonder (seriously) of the invention of The Blue LED, grow-lights provide a lot of exactly that = Blue Light

And THAT is what baby plants cannot get enough of of

Mature specimens prefer light with a pronounced red bias

It is a very reasonable proposition of how El Sol controls climate, sun-spots to be precise.
Am I correct that a ‘high activity sun’ with lots of spots and despite having the same Total Solar Irradiance’, produces much more Ultraviolet than otherwise and this blue biased light encourages young plants to grow better faster stronger

I’m sure they took full account of that in all the CO2 fertilation experiments they did

Pat from kerbob
Reply to  goldminor
April 24, 2022 6:42 pm

Me too, but I think it’s more about my gas stove, it’s been gradual but I’m pretty sure my house plants grow better since I switched to a gas stove
All that wonderful co2
And a bit of moisture

April 23, 2022 3:32 pm

Since GW and Covid – I have been swayed by friends who believe in the attempt at a Great Reset.

One of the aims of this reset is to control food production.

I was convinced into believing this as Bill Gates has purchased lots of farm land. He always seems to be involved somewhere…

Is the GW lie of man made Co2 – one of the ways they are trying to control crop production 🤔 if Co2 helps with food production, they won’t like that…

April 23, 2022 3:55 pm

100Ha of forest has to be removed to install a 1.5MW wind energy extractor. That unit could power a 20kg/hr green hydrogen plant to produce 52t of hydrogen annually at 30% CF. The heating value is 6.4TJ.

The same 100Ha of forest has annual sustainable productivity of 370t of biomass; hardwood and litter with a heating value of 7.4TJ at current forrest productivity. However if the CO2 continues to increase then the productivity will also increase.

The problem with the latter is that it is low tech in a world where big tech runs the show. The preferred option is the former where forests are gradually replaced with wind energy extractors and green hydrogen plants that require enormous quantity of resources. It is no surprise that big miners, big electricity and big governments support green hydrogen.

Australia’s latest iron ore magnate, Twiggy Forrest, is lining up his businesses to cash in on the green hydrogen subsidies. Think of all the steel needed to build green hydrogen plants running on weather dependent generators.

As a matter of interest, a 20kg/hr green hydrogen plant in Australia will set you back AUD14.5m. At current Australian NG price of AUD16/GJ it can produce a revenue of $38/hr feeding output into the gas main at 5% maximum permitted rate.

Eric Stevens
April 23, 2022 4:00 pm

I wonder to what extent climate models take into account the increased rate of CO2 uptake by the biosphere. My guess probably not at all.

Rud Istvan
Reply to  Eric Stevens
April 23, 2022 4:14 pm

They usually use the biosphere ‘Bern Model’, which as posted here previously is simply and grossly wrong.

Reply to  Eric Stevens
April 23, 2022 7:57 pm

They do not take into account the influence of land surface biomass on the moisture levels and convergence of moisture to land from oceans resulting from that existing moisture.

Climate models do not even attempt to model the process of deep convection, which requires at least 45mm of atmospheric water to create cyclic convection and become a convergence zone. The Sahara is a perpetual divergence zone being fed cool dry air from the stratosphere rather than pulling mid level moist air from the surrounding water.

Green fields dotted with wind turbines are modelled the same as tropical rain forests. There is no difference in the contribution the trees make to the atmospheric moisture that drives deep convection.

If climate models could replicate real world processes, they would be creating great alarm over chopping down trees in forested areas to make way for wind turbines.

George T
April 23, 2022 4:09 pm

+1 for more CO2 in the atmosphere. Cutting through climate alarmism is a challenge, but must be achieved. On a small scale, the war in Ukraine will bring the global community a glimpse into what happens when food is in short supply and indirectly why more CO2 is so necessary to fed the world. Those who toss around the word insurrection will get a history lesson on what the word truly means and it won’t look anything like Jan 6th. The global cabal behind the great reset and the agitation they have instigated (climate change, green energy, COVID, the war in Ukraine and the potential food famine) might have bitten off more than they can chew. Narcissistic behavior in the end fails to achieve anything of good. Bill Gates is an example. Please go away and leave us alone to pursue our lives in peace.

April 23, 2022 4:28 pm

You can see the CO2 effect in photographic evidence from gold rush days, both in California and British Columbia in historic photos that nearly go back to the development of the camera. Many photographs were taken in the early gold rushes, and show the local fauna and trees, and we can calculate from the tree ring data what some of those trees that were in existence from 1849-1859, to the same trees that are still living or have stump evidence. In contrast to trees that just started growing 15-20 years ago, and applying the same metric. The trees growing today are growing at a much higher growth rate.

Exact same aspect and growing site, albeit there has been a general warming since 1850 out of the LIA, and rainfall patterns might be a bit different so maybe some growth can be attributable to additional warmth/water. While most trees are C3, I can see a major difference especially in the poplar, willow and alder brush that now grows up to 30%-40% faster than just 50 years ago on my own 2000 acre private woodlot which is mostly Spruce and Douglas Fir. Used to be able to ride my horse through the forest, but can’t now, due to excessive under growth, and now a lot of dead blow down.

I put in a 4 mile private power line 40 years ago, and it took 25 years for the ‘brush’ to just reach the neutral above the phone line, (almost 30 feet high) before I had to cut it all down. Now after 15 years, I have the new poplar, willows, and alders just reaching the primary 14.4 HV line, about 10-11 feet higher than the neutral. My company has also planted millions of trees the last 50 years, and everything, including the weeds, deciduous brush and conifers are all growing on steroids. Which makes for a bit of a problem planting conifers, as they take a little longer to get established and make some height before being outcompeted by all the deciduous brush.

CO2 is certainly plant food and not a pollutant. We should be celebrating the warmth and the carbon dioxide, as is probably our best bet to survive any natural cooling trend.

Reply to  Earthling2
April 23, 2022 4:53 pm

You can see the CO2 effect in photographic evidence from gold rush days

Greta can see the CO2 in the air directly. No need for photos.

Reply to  Mr.
April 24, 2022 12:52 am

Proof that warmists are insane. They believe her.

David A
Reply to  Earthling2
April 24, 2022 5:34 am

Earthling2, would you please send this article and comments into space to counter the current government message from the idiots in charge that is telling ET that CO2 is poison.

It may save humanity from being extinguished due to obvious stupidity.

April 23, 2022 5:22 pm

It has been said here that the extra CO2 may enhance growth but the nutritional value does not increase and may decrease some.

Is that true?

Clyde Spencer
Reply to  mkelly
April 23, 2022 7:10 pm

Since the 1970s, there have been claims that even fertilizer reduces the nutritional value of fruits and vegetables. There may be some truth to plants growing more rapidly having less nutrition per gram. However, when we eat fruit, we usually eat the whole thing rather than a 10 gram serving. So, the difference, if real, is probably moot.

Reply to  Clyde Spencer
April 23, 2022 7:43 pm

A 10-gram serving is a nice bite off the end of a carrot.

My neighbor put in a variety of tomato (Goliath? I can’t recall) that approaches a kilogram per fruit. Sweet, too. I’ve never before seen such tomatoes. One thick slice and a dollop of mayonnaise? Heaven!

Old Man Winter
Reply to  mkelly
April 23, 2022 8:13 pm

I always heard that CO2 did enhance yields but nutritional value fell. Since it was from the same
people who lied about the goodness of golden rice, I didn’t put much credence in it. Even if the
nutritional levels fell a bit- ~2%-4%- the +10%-15% yield increase meant the total nutrients in the
crop was at least 5%-10% more than before. For those with little, even more volume keeps
stomachs from growling. They’ll take anything they can get!

I did find two posts from WUWT on this topic. Usually the commenters have other sources to read,


Reply to  mkelly
April 24, 2022 12:54 am

Faster growth leads to very slightly lower nutritional values per gram but the extra grams of yield more than make up for that minuscule difference.

David A
Reply to  Chaswarnertoo
April 24, 2022 5:39 am

And only lower value in some, not all nutrients. Note the comment in the article on the INCREASE in vitamin C. A little decrease in protein concentration is meaningless when discussing plant growth.

Reply to  mkelly
April 25, 2022 11:46 am

It is not true.

April 23, 2022 6:01 pm

I’m going g to try and relate this without expletives.
43 years ago as a 5th grader I did an experiment that showed that CO2 is good for plants and the planet.
Yet these @#$$%# PhD still haven’t figured it out.
I’ll take my Nobel now. Just the check. I’d probably whack a few morons with the metal thing.

Rick C
April 23, 2022 6:01 pm

So increased CO2 means much more plant food which can only lead to obese plants which will undoubtedly result in diabetic plants and increased morbidity resulting in food shortages, famine and the demise of humanity. Oh, the horror. We must stop any activity that produces CO2 immediately or we’re all doomed. /s

Reply to  Rick C
April 24, 2022 12:55 am


Jim Gorman
April 23, 2022 6:25 pm

Does anyone have any studies that relate both increased CO2 and higher than average temperatures at the same time? I assume somewhere temperatures in greenhouses and/or hothouses has been studied for the best temps. If those turn out to show that higher temps along with higher CO2 result in better productivity, well guess what?

David A
Reply to  Jim Gorman
April 24, 2022 5:41 am

CO2 increases T mostly at night. So yes, reduced frost damage is definite. It definitely makes plants more heat and drought tolerant as well.

Nicholas McGinley
Reply to  Jim Gorman
April 24, 2022 1:08 pm

Let’s see…
Low temp:
comment image

Higher temp:
comment image

I am gonna go with “higher temps makes plants grow faster.”

Controversial, I know, but that is where I am betting my chips.

Don Healy
April 23, 2022 6:32 pm

Do you have any data on plant production at lower CO2 levels, say 150, 200, and 250 ppm as compared to current. I believe the humanity faced an existential threat at the beginning on this interglacial when CO2 levels were only 170 to 180 ppm. It would be helpful to use this approach to bring attention to dramatic benefit current level are providing.

David A
Reply to  Don Healy
April 24, 2022 5:45 am

Going downwards from 280 PPM the decrease is somewhat exponential. If we were at 150 ppm now, the negative of the same PPM change we have experienced, WE would not be.

Steve Case
April 23, 2022 6:47 pm

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Peta of Newark
April 23, 2022 8:19 pm

Grab an umbrella folks, I’m gonna piss on your parade….

From the 1st referenced article:
Quote 1:”The genotypes were grown under two concentrations of Ca, i.e. 370±28 (ambient) and 570±42 (elevated) μmol mol−1

Quote 2: There was significant variation between genotypes in the response of yield to elevated Ca, with absolute increases up to 530gm−2 in yala and 347gm−2 in maha. In relative terms, percentage yield increases from ambient to elevated Ca ranged from 4% to 175% in yala and from 3% to 64% in maha.

yala = the spring planting season
maha= autumn planting season

NB: percentage yield increases from ambient to elevated Ca ranged from 4% to 175% in yala and from 3% to 64% in maha.

Ranged from 4% – I’m not hearing that story from NASA – they say ‘twice the area of the US‘ has gone green.
But wait. Twice the area of the USA means 20 million square kilometres of extra green. But there are only 50 million square kilometres of green (farms & forests) to start with on Planet Earth so where did NASA find all that much land?

And those results were obtained at 570ppm – is there enough coal/gas on Earth to ever get there?

From the 2nd referenced article:The study revealed that pea plants performed better under eCO2, with slight changes in development and yield attributing traits, depending on the cultivars. However, the beneficial direct impact of elevated CO2 (eCO2) on crop yield can counteract by elevated temperature (eT). Pooled data for two years indicated that growth and yield attributing traits like plant height, days to first harvest of pods, harvest duration, fresh weight and biomass, number of pods per plant, pod length, pod girth, pod yield were improved under eCO2. However, responses of these attributes were negated with eT.

NB My underlined bit = slight changes = what the authors themselves say when talking about the orange/blue graphic (Fig 1) we see above.

Something doesn’t quite ‘ring true‘ here

From the article here:However, as shown in Figure 3, a team of researchers who studied the growth responses of 16 different rice genotypes reported CO2-induced grain yield increases in those genotypes that ranged from near zero to a whopping +263%

Quote from quote: Ranged from ‘near zero’ to whopping 263%

Lets remember what Einstein and Feynman said, ‘It only takes one’
IOW: If that experiment was well organised and CO2 was really the cause of increased growth – why were there ANY results of ‘near zero

Depending on cultivar‘ we’re told.
Would I be out of order here to suggest that these people have just (re) discovered the notion/idea/practice of Crop Rotation
IOW: had the high yielding cultivars been grown in that soil previously because, if not, that alone could explain the increase

Sorry, boys & girls, crop rotation has been known about for millennia – where have you been all this time?

Quote:”In one of his more famous experiments, my father grew sour orange trees in ambient and CO2-enriched air in the Phoenix desert for nearly two decades. In that study, which was the longest such experiment ever to be conducted anywhere in the world, trees exposed to a CO2 concentration 75% greater than normal annually produced 70% more biomass and 85% more fruit.

Let me get this straight…..
my father‘ enriched the (entire??) Phoenix desert with CO2 for nearly 2 decades?
How did he do that, where did all that CO2 come from and where did it go?

Like the Christmas trees he grew, they were grown in a completely fake environment, in a greenhouse.
Thus they were sheltered from excess sun & wind (dessication) = why they used less water

They were also sheltered from incoming pests and disease – lets see how me/you/anyone would survive better without houses to live in.
Would extra Oxygen in the atmosphere compensate for not living in houses?

And also were were planted in Fake Soil = ‘greenhouse compost’ = ultra high fertility stuff that would completely over-ride the benefits of extra CO2.
In fact, what that greenhouse compost did was force CO2 into being the Liebig Limiting Nutrient – hence why the extra CO2 got the result it did.
And because plants use water from the soil primarily to move trace elements and micro-nutrients, a high fertile compost means they have to move less water to get that same amount of nutrient.
That whole crock about stomata and transpiration is exactly that: A Crock

Nobody really knows what they are talking about here, like all of Climate Science
But to make up for that, they grasp at straws such as the skyrocket fireworks of Figure 1 above while disregarding the written words of the experimenters themselves:
i.e. “slight improvement entirely negated by temperature rise” and as the experiments show, extremely dependant on cultivar choice = crop rotation

and sometimes no change at all in well designed experiments

Where are any real true honest scientists these days, don’t those words trash the entire theory of CO2 fertilations?

Reply to  Peta of Newark
April 23, 2022 10:07 pm

The land surface of the good Earth is 148,940,000 sq km. Approximately 13% of the land surface on Earth has been subject to some type of ‘greening’ attributable to CO2 since 1850, but probably also by enhanced warming since 1850, and probably more rainfall than during the LIA. We are only 170 years or so from when the LIA ended. This probably accounts for 90% of any warming we have seen since 1850.

The planet was probably a lot greener when the Sahara was a vast savannah grassland supporting many large rivers, lakes and animals/humans just 8,000 years ago, but that was more from orbital variations driving the monsoon patterns. Plus it was warmer in the early Holocene, and also probably wetter. We don’t even think about all the difference in greenery, including during glacial advances during ice ages when as much new land that was formerly covered in ocean, was now green, as land that had become covered in ice. Albeit CO2 levels were barely above extinction levels at 180 ppmv. But still life thrived right up to the ice sheets.

There has been additional greening everywhere on the land surface since 1850 at the margins, including all the irrigation of former lands not considered arable, which in itself is enormous on a global level. Natural warming since 1850, and increased CO2 levels, has led to the planet supporting nearly 8 billion people.

You’re not sneaking in some sugar in your tea, are you Peta?

From the interweb…and this is just the last 20 years.

🌍 NASA: The Earth is greener now than it was 20 years ago. The Earth has become five percent greener in 20 years. In total, the increase in leaf area over the past two decades corresponds to an area as large as the Amazon rainforests.Mar 5, 2021

Chris Hanley
Reply to  Peta of Newark
April 23, 2022 10:19 pm

See if I untangle the convoluted syntax: The experiments referred to were fraudulent viz. the plants grown under enhanced CO2 conditions were also grown under other favorable conditions whereas the controls were not, is that what you are claiming?

Reply to  Peta of Newark
April 23, 2022 10:33 pm

“From the article here:“However, as shown in Figure 3, a team of researchers who studied the growth responses of 16 different rice genotypes reported CO2-induced grain yield increases in those genotypes that ranged from near zero to a whopping +263%.”

The above comment in the article also puzzled me. Rice is a C3 type of plant which has a less efficient photosynthetic pathway than the C4 type of plant, such as Maize. The vast majority of plants are of the C3 type, and respond with significant increased growth to increased CO2 levels, whereas C4 types of plants respond only slightly, if at all, to increased CO2 levels.

Could the explanation be that the rice genotype that showed almost zero increased growth, is actually an experimental type of rice with modified genes to make it a more efficient C4 type of plant?

The following article addresses this issue.

“An international long-term research collaboration aimed at creating high yielding and water use efficient rice varieties, has successfully installed part of the photosynthetic machinery from maize into rice.”

Old Man Winter
Reply to  Vincent
April 23, 2022 11:51 pm

I found a WUWT article about C3 & C4 plants’ response to CO2-

Here’s a quote from the article:
“Note: There are several different kinds of photosynthesis. Plants that use “C3” or “CAM” photosynthesis benefit the most from higher CO2 levels. “C4” crops benefit the least, but even C4 crops benefit when under drought stress. Most crops use C3 photosynthesis. There are only four important C4 crops, all of them grasses: corn [maize], sugarcane, sorghum, and millet.)”

In central Minnesota, we had a 10 yr period where the weather turned hotter & dryer in July
& would stay that way for 2-3 months each year. The worst year was the last year- 2007-
where the corn was ~2′ shorter than normal. While I don’t have data, it seemed to hold up
better than similar dry years 25-30 years earlier. How much of that was genetics & how
much was CO2, I don’t know.

Reply to  Peta of Newark
April 23, 2022 10:36 pm

There are numerous free-air carbon enhancement trials being undertaken. These are done over a range of food crops and forest tree types.

This link gives results of one of the forests trials:

The trials are set up to reduce the differences between the CO2 fumigated atmosphere and the control forest so the only variable is the atmospheric concentration of CO2.

Increased forrest productivity is a universal finding with CO2 enrichment.

A downside in one of the studies I have read is that the wood grows faster but is less dense. The trees have heavier foliage on thicker but weaker trunks. Probably more prone to wind damage.

There have been locations of old forest areas in Victoria, Australia with 40+ year old trees that have been flattened in recent years. That suggests unusual conditions. Possibly a combination of wind, soil moisture and tree structure contributing to the damage. Certainly unusual to lose most trees over a large area in a single event.

David A
Reply to  RickWill
April 24, 2022 6:00 am

The root systems grow faster and expand with increased CO2. The vast majority of tree damage is heavy rains, saturated soil, and or high snow load, and high winds. Those conditions are highly variable.

Reply to  Peta of Newark
April 24, 2022 12:58 am

So all those tomato farmers are wrong to spend money on extra CO2. They’re all stupid are they Peta?

Old Man Winter
Reply to  Peta of Newark
April 24, 2022 1:01 am

Ranged from ‘near zero’ to whopping 263%”

The 5 main factors affecting plant growth are sunlight, temperature, water, humidity and nutrients.
Within the different cultivars, one of these may have limited the yields beyond which CO2 wouldn’t
have made a difference. Just a guess(?).

AFAIK, crop rotation is between different crops, not varieties of a species as they’ll have very
similar nutritional needs. Our crop rotation was alfalfa X 3 yrs, corn, oats, oats & then oats as a
nurse crop for the alfalfa we seeded simultaneously. No attention was paid to the oat variety.

I found an interesting video on raising citrus in a green house- a few surprises included!


Old Man Winter
Reply to  Peta of Newark
April 24, 2022 1:12 am

I forgot the graphic from NASA. What it says is the leaf area increased from 1985-2018.

OOPS! Fat finger!

Old Man Winter
Reply to  Old Man Winter
April 24, 2022 1:15 am

Here it is.

Reply to  Peta of Newark
April 24, 2022 4:40 am

“I’m gonna piss on your parade”

Into a gale force wind as usual… 🙂

David A
Reply to  Peta of Newark
April 24, 2022 5:48 am

Peta says, “Where are any real true honest scientists these days, don’t those words trash the entire theory of CO2 fertilations?”

Wow, in a word, NO. You Ignore the entire database, fail to understand it, and make unfounded and wrong assumptions, and then draw silly conclusions.

Michael in Dublin
April 24, 2022 7:15 am

The history of agriculture is the history of human adaption. I cannot believe that people cannot adapt to and benefit from changes in climate and the variations in weather conditions.

The mention of the sour orange reminded me of a large lemon with a dark orange skin that I saw on a farm nearly forty years ago. Is any reader familiar with this lemon and an information link?

April 24, 2022 7:55 am

More CO2 benefits plant growth has been known for a long time

CO2 in greenhouses greatly increase vegetable yield.
CO2 delivered by pipes to open field plots greatly increase growth of spinach and potato.

Botanists have known this for a long time, it’s not controversial. Over a century of research at least is easily found.

Loren C. Wilson
April 24, 2022 9:48 am

Hooray for the ability to feed more people with better quality food. And hooray for graphics that I don’t need a magnifying glass to read.

April 24, 2022 10:57 am

along with cheap LEDs, this is the other reason glaciation is no longer an existential threat

would be expensive to start, but we can drill out enough CO2-enriched automated farm tunnels to feed trillions

run up the CO2 to the highest we can genetically engineer crops to handle and eventually have food that’s far cheaper than today

no direct labor inputs, just have to keep the nutes flowing and lights on

Gary Pearse
April 24, 2022 12:31 pm

Dr Idso, a proposed experiment: explore, using the same techniques, what you get with 100ppm, 150, 180, 200, 250. It would be good to see what crops, etc., would cease to exist at what levels. The totalitarians are, after all, planning to remove CO2 from the atmosphere (seemingly unaware of Henry’s Law and the increased CO2 exhalation from the sea that would result).

Matthew Sykes
April 25, 2022 12:34 am

This isnt considered real science anymore. Today it is all BS and lies, agenda driven, woke, ‘clever’.

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