Sunday, April 3, 2022

Climate change and debunking the ‘CO2 fertilization effect’

Young beech trees retain their leaves throughout the winter months

Scientist-like persons hired by the fossil fuel industry have long maintained we should celebrate an ever-increasing level of carbon dioxide in our atmosphere. This gas, a key building block in the photosynthetic process, can enable plants to grow faster and get larger. It’s been called the “CO 2 fertilization effect.” Many crop yields are projected to increase. And bigger woody plants, the reasoning goes, can amass more carbon, thus helping to slow the rate of CO 2 increase in a handy negative-feedback loop.

In other words, they argue that climate change is good for plants, which in turn will help curb climate change. It’s an elegant win-win situation, and environmentalists no longer have to lose sleep over skyrocketing carbon dioxide. However, as with many supposed “truths,” this argument falls apart upon close examination. It’s like in 1981 when former President Ronald Reagan said “Trees cause more air pollution than automobiles do.” He was referring to terpenols (responsible for the pleasant piney-woods aroma in the forest), which can react with auto emissions to form ozone. In the larger picture, trees reduce air pollution of all sorts – and sequester carbon as well – on a colossal scale worldwide. His statement was “true” in a minor, technical sense for a single pollutant, but it was misleading, and for all intents and purposes, false.

In a similar vein, climate-change apologists have a kernel of truth here. Around 95% of plants on Earth can take advantage of more abundant carbon dioxide. In greenhouse trials, plants did indeed get larger when more CO 2 was pumped in. This would suggest that most food crops, with the exception of millet, sorghum, and a handful of others unable to use extra CO 2 , will be larger and possibly mature more quickly. Hooray! So far, so good for the petroleum lobby. Unfortunately, as CO 2 levels increase, the nutritional value of our food goes down the toilet. Dr. Samuel Myers, a Harvard University principal research scientist in environmental health, lays it out bluntly in a January 28, 2018 Scientific American article entitled “Ask the Experts: Does Rising CO 2 Benefit Plants?”

According to Dr. Myers, “We know unequivocally that when you grow food at elevated CO 2 levels in fields, it becomes less nutritious…[food crops] lose significant amounts of iron and zinc—and grains [also] lose protein.” While this correlation is well-established, it is not yet known just why nutrient leaching of crops happens as CO 2 spikes. Dr. Myers and his team assert that if atmospheric carbon dioxide reaches the predicted concentration of 550 parts per million by 2050, the nutritional value of major food staples could drop low enough to cause widespread health effects. He estimates that 300 million to 350 million more people, mainly in food-insecure regions, will become protein-deficient by mid-century as a result of crops’ diminished quality. In addition, as many as 1.4 billion women and small children will suffer anemia due to iron-depleted crops, all thanks to the highly touted CO 2 fertilizer effect.

Another well-documented and equally mysterious plant response to a profusion of carbon dioxide in the air is that plant leaves across all species thicken. The “fat-leaf effect” would be a mere curiosity, except that the thicker a plant’s leaves get, the less carbon it is able to sequester. Oops. On October 1, 2018, scientists at the University of Washington published a study on this phenomenon in the journal Global Biogeochemical Cycles. The researchers combined their previous leaf-thickness measurements on plants grown in elevated-CO 2 chambers with current global climate models. They calculate that beyond 2050, the world’s forests will have lost the capacity to store roughly 6.4 billion tons of carbon dioxide each year. To put it in perspective, that’s about one-fifth of yearly worldwide carbon emissions from fossil-fuel burning.

A weakened forest “carbon sink” needs to be incorporated into future climate modeling, say the University of Washington team who carried out the study. To throw another wet blanket on the rosy spin some would put on rising CO 2 , weather extremes become more common and intense as global temperatures shoot upwards. Floods, droughts, and even extended hot spells all strain our food supply. Plus, the CO 2 fertilizer effect appears to be self-limiting. Exactly to what extent it can boost plant growth, though, is ultimately not known. A somewhat related sidebar is that poison ivy seems especially good at using extra carbon dioxide to grow bigger faster. Not only that, it has recently come to light that its toxic urushiol oil gets increasingly potent as CO 2 numbers climb. I’m itching to find out if this unpleasant side effect of climate change helps convince a few oil-patch advocates to change sides.

Paul Hetzler is a former Cornell Cooperative Extension Educator. To help the planet, he tries not to exhale.

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Paul Hetzler

Paul Hetzler has been an ISA Certified Arborist since 1996. His work has appeared in the medical journal The Lancet, as well as Highlights for Children Magazine.

You can read more of his work at or by picking up a copy of his book Shady Characters: Plant Vampires, Caterpillar Soup, Leprechaun Trees and Other Hilarities of the Natural World

28 Responses

  1. Shane M Sloan says:

    Oh, you mean the science like people at SUNY ESF? They also teach of this. You’re disgusting for framing things this way. There may be lobbyist hired people who say these things, but there are also real scientists saying it. So now go ahead and explain the life cycle of renewables. You can’t. You’re horrible. You’re the problem.

    • nathan says:

      So frame in a meaningful way? throwing a bunch of shallow insults means even less. rather pointless….

  2. Big Burly says:

    Well Paul … I have followed with much interest, learning much from earlier posts on this platform.

    This piece ? Hmmm. Way too much emanating from so called science findings these days turns out to be opinion, rather than what I learned during many years in school before science research became beholden to the vagaries of the latest political whim and grant funding.

    The ginormous deposits of hydrocarbons around our planet were formed during a part of the planet’s history when CO2 concentrations in the atmosphere were a couple of multiples of what is recorded today — not fossils as in dinosaurs and such animal life, plants in profusion on a scale we are still trying to measure. Humans would likely have not been able to survive in the form we are today in such conditions. But today’s readings are VERY far from those days.

    If you have links to how Dr. Meyers is able to empirically demonstrate his unequivocal statement, they will be welcome.

    It is sad that your otherwise good reputation for sound information is so sullied by this article. One can only hope someone posted it in your name as a April Fool’s’prank.

    • The difference between opinion and science says:

      Your comment of “science research became beholden to the vagaries of the latest political whim and grant funding.” is right our of FOX News “This is an absolute joke- there is no such thing as man-made climate change- these ‘scientists’ have an agenda and have to justify their budgets!!!”. So, who is is really following a political script here? Hmm, whom am I going to believe?– FOXNews or the primary Harvard Scientist on Planetary Health? Tough choice. Also, it ain’t that difficult to search on google yourself to get the reference that you seek. A number of Dr. Corey’s peer-reviewed science papers references on the topic of how impacts of increasing atmospheric CO2 concentrations on human nutrition can be found at this website:

      • Mike says:

        Hmmm…. Let’s see, Harvard gets 40 Billion in endowments, 9 million in Covid relief and 800 million in government grants. Money and corruption, killing a democracy near you!

        • The difference between opinion and science says:

          Typical FOXNews response that I mentioned earlier (right out of FOX News “This is an absolute joke- there is no such thing as man-made climate change- these ‘scientists’ have an agenda and have to justify their budgets!!!”.” You can go down the rabbit hole of conspiracy theory, nonsense, and ignorance or make public decisions that we make need to be driven by hard science.

          • Dana says:

            Does anyone who watches FoxNews engage in critical thought? That is where truth goes to die…

            • JohnL says:

              Lord help us Dana. Your only argument seems to be to use ‘FoxNews’ deflection. The expression ‘Follow the Money’ is as applicable now as it was when it was used to explain President Nixon’s scandal. Global warming, er, Climate Change, or whatever you’re calling it now, is a multi-multi-billion dollar industry built on shaky (not settled) science at best. You’ve heard of Occom’s Razor, I assume. That’s very applicable here also.

              • The difference between opinion and science says: says:

                John, your reasoning is nonsense and you’re clearly throwing up a smokescreen to avoid the real issue of truth and trust. Is everything big and has a lot funding resources bad? Are charitable organizations bad? Is Microsoft bad? Is NASA bad? Is the Metropolitan Museum of Art bad? Lets stick to hard facts and reputable analysis of data and do away with cliches such as yours that deflect dealing responsibly with making sound decisions.

                • JohnL says:

                  Wow TDBOASS, you’re an all or nothing guy/gal aren’t you. I wasn’t addressing any of those things you mention, although most of them do also, in one way or another, fall under the ‘follow the money’ mantra. Bogus charitable organizations, like the Clinton Foundation, are just one example of something that is very heavily governed by that theory. But I digress. I’m just saying that, like power, money corrupts, and lots of money corrupts completely, and that’s where I think the climate change/global warming powers that be, are today. That’s my opinion, and as in all of my postings, I’ll admit that there’s always a slim possibility that I could be wrong.

                  • Todd Eastman says:

                    “Slim” is a relative term…😎

                  • The difference between opinion and science say says:

                    Like you were saying, you’re expressing an OPINION, NOT FACT. Like someone who wrote an earlier in this string of comments–“there are many thousands (probably tens of thousands) of climate change studies” that were conducted by a worldwide host of private, academic, science agencies, government, industry, individuals, and many other misc institutions, and, in which, an overwhelming majority have concluded that humans are drastically changing our climate. These studies have collected, compiled, and massive amounts of data that has led them to their conclusions. Where are your facts, data, and evidence to support your opinion that money is corrupting this this vast array of scientific studies? I see this is a problem with our society now, when one doesn’t agree with a view, rather than researching the topic and supplying facts and references, one commonly relies on baseless accusations, false innuendoes, conspiracy theories, and just plain made-up falsehoods.

                    • JohnL says:

                      Like I myself said above, what I’ve posted are MY opinions based on stuff I’ve read, discussions I’ve had with others, and application of not an insignificant amount of common sense. When I send links for specific articles and sources, everyone on your side goes ballistic and starts using the Fox News Deflection (FND). So, TDBOASS, we’re just going to have to agree to disagree. I know I’ve outlived the predictions of the end of the world a couple times already, and I hope we both live long enough to find out which one of us is right. Live long and prosper, my friend.

  3. Boreas says:

    Indeed the Carboniferous period did show a lowering of CO2 levels over a period of 50 million years or so. But photosynthesis also requires two other major components – clean water and abundant sunlight. And it also required wet forests and swamps covering much of the land above water along with healthy groundwater – AND a healthy ocean.

    Are the forests – albeit possibly helped by elevated CO2 levels alone – going to do us any good if we cut them down and burn them? Draining swamps? Polluting the oceans, streams, and lakes? Depleting and poisoning soils and freshwater aquifers?

    Obviously, an increasing CO2 level certainly isn’t our only problem. Focusing on what “good” elevated CO2 levels may do takes our eye off of the big picture – too many humans altering the globe and its natural systems that have taken well over a billion years of life and chemistry to develop. The carbon cycle isn’t the only cycle we need to study. We also need to know how the MIX of atmospheric CO2, oxygen, and nitrogen are being effected by humankind’s deforestation, depletion, and pollution.

    Cigarettes were once touted as a health benefit by THAT industry in my lifetime! Research needs to be independent of politics, greed, and agendas. And people need to become skeptical of studies born of those parents.

  4. Nathan says:

    Even if plant growth did better with elevated CO2, the amount of deforestation, polluting of rivers, lakes, estuaries, oceans and it’s acidification. There is a net reduction in CO2 abosrbtion. Now with artic tundra defrosting and releasing massive amounts of Methane, the greenhouse effect will incease much more dramatically. There is a tipping point somewhere approaching where hydromethane in the oceans will start releasing even more methane. with 100x more global warming power than CO2, we have no way to easily remove that methane. when we cross that line the glaciers will melt at much faster rate, ocean currents start to faulter from influx of fresh water. The hurricanes, tornadoes will get much bigger and frequent. States like florida will become unlivable. we will loose much more living and farming lands. Think of millions of displaced people in USA, no food, water, at 100 degrees daily in southern belt.

  5. Zephyr says:

    I have no doubt there will be many phenomena that are hard to understand with regard to climate change, but there is no denying that something is causing the earth’s temperature to rise steadily which is already manifesting itself in observable huge problems for the world: sea level rise, changing currents, increased frequency and intensity of storms, changes in animal migrations, changes in growing seasons, changes in flora and fauna, etc. And, we also have factual evidence that the CO2 level in the atmosphere is increasing, so apparently even if this theory is correct about plants increasing their carbon sequestration it is obviously not enough to offset the overall trajectory. We have the measurements to demonstrate this.

  6. JT says:

    Trees need macro-nutrients such as nitrogen, phosphorus and potassium plus micro-nutrients such as calcium, magnesium and sulfur to grow. I would presume that trees would not be able to utilize the excess CO2 if any of the other required nutrients are lacking in any particular area. There will always be a limiting factor that determines how much growth a tree can obtain.

  7. Mike says:

    It’s more like a lose / lose situation. Pick one, fossil fuel funded research, or the current administrations scam carbon made solar panels and windmills. Shouldn’t the Adirondacks be covered with them by now? After all it would be saving the earth. If Hochul can give the Bills 850 million, why not fund a couple billion for a new Solyndra project in Lake George or Lake Placid or both! Imagine all the jobs, university funds, and earth saving it would create. Hey, Cornell only gets 8 BILLION in endowments and 13 million for covid relief they could a little something too.

  8. Charlie Stehlin says:

    “weather extremes become more common and intense as global temperatures shoot upwards. Floods, droughts, and even extended hot spells all strain our food supply.”

    > My thoughts initially when reading the above story were related to this one line above. If the planet heats up and it gets too hot, plant life will suffer. Plants need moderation, not extreme heat or cold which will occur if the temperatures keep rising. Not good! It’s easy to say, “Well, I won’t be around much longer what does it matter to me if the earth turns into an oven!” And then conscience comes in and those thoughts go out the window as I do care. It’s such a sin, such a waste, the disregard we have for this our only home. People will believe a FOX News propagandist before they will a scientist as has been revealed these past some years! It’s too bad there aren’t laws which penalize falsehoods coming from the lips of small-minded, unrealistic ideologists.

  9. Zephyr says:

    I think I’ll continue to read what actual scientists and experts say about climate change instead of listening to Fox News or what my buddies are sharing on Facebook.

  10. Paul says:

    I too like to follow the science here. It was clearly a mistake for scientists a few decades ago to be telling us that climate change is not “weather”. “We are not talking about the weather we are talking about a gradual increase in global temperatures”.

    Fast forward to now, and every article and piece you see written or spoken of on any weather event, fire, flood, drought, anything is a result of – “human caused climate change”.

    Which is it?

    • Zephyr says:

      It’s both really. You can’t look at a single weather event and say that proves or refutes climate change, but you can look at multiple weather events and see patterns related to climate change. For example, anyone who has visited or spent much time along our coasts for decades will note that sea level rise is an important factor whenever there is a major coastal storm. The impact of the coastal surge in a big storm is exacerbated by the already higher water level. Same with the droughts out West. They are historic, adding to the problems with wild fires. But, you can’t look at one forest fire and say it’s due to climate change, but it could be that the fire spreads more rapidly, covers a larger area, and is harder to put out due to the effects of climate change. The one I always get a chuckle at is every time we have a cold snap in the winter or a big snowy winter someone chimes in that it proves there is no climate change. Yes, that is false.

  11. Todd Eastman says:

    How funny that so many people that believe in an unprovable concept like “God”, need absolute truth about the findings of scientists to feel manmade climate change is a real and present danger… 🙄

    • Balian the Cat says:

      Even funnier that they will stand around denying it even as the water rises around them rather than admit they were misled by greedy/powerful people who’s wealth stream would be affected if everyone could simply agree on reality. THOUSANDS of peer reviewed studies have demonstrated that CO2 levels and with them global temperature have risen in direct correlation to the Industrial Revolution, but Dr. Oz says CO2 isn’t a problem so here we are.

  12. Charlie Stehlin says:

    “How funny that so many people that believe in an unprovable concept like “God”

    “Even funnier that they will stand around denying it even as the water rises around them”

    >It’s called ignorance, and apathy, and narcissism (all about their wallets or purses), etc…… It’s about politics too, not science. This morning I heard on WAMC that some place in Australia had a month’s worth of rain rreecently….in one day. I suppose when it starts affecting their wallets they’ll start acting, start voting for the other party, not the propagandist, fanatical, far-rightists whose division and hate hopefully will come to an end soon!

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