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.

References

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.

Who knew?  A study came out way back in 2016 showing that most people still had antibodies against tetanus, or “Lockjaw” even 60 years after their last vaccination. It’s a reminder of what successful vaccination can look like. It also shows the extraordinary ability of the human immune system to acquire lifelong protection — that doesn’t happen with all diseases, but it does with things like influenza, polio, measles, and mumps, and possibly tetanus and diphtheria.

The study on 546 people and the authors suggest that the need for a ten year booster should be reassessed, but six years after the study came out the CDC and the Australian government are still saying we need “ten year boosters”. Is anyone even looking at this data?

Shifting to a 30 year schedule could save the US government US$280 million each year. Big-Pharma won’t be too happy about that, and maybe that’s the point.

by Fiona Macdonald, April 2016

We’ve all grown up knowing that we need to get a tetanus booster at least once a decade in order to be protected from the potentially fatal disease.

That strategy has been incredibly safe and successful, with these days only around 31 cases of the disease being reported annually in the US. But a new study suggests that although there’s nothing wrong with being overly cautious, we could still be protected from the disease by getting just one booster every 30 years – and save a whole lot of money in the process.

… the new research looked into how long 546 adults were actually protected against diphtheria and tetanus, and found that they contained antibodies against the diseases for up to 30 years after receiving their last booster – way longer than previously assumed.

Here’s the astonishing graph of antibody titres in people after vaccination against tetanus. Note the scale on the x-axis, that’s a “y”. This is not days after vaccination — it’s years! Scores above −2 log10 IU/mL are considered “protected” against tetanus (marked with a dashed line). That’s nearly everyone who was studied — all 546 people involved.

The fatality rate for real tetanus is a rather nasty 13%.  But tetanus itself is so rare, that only 3 people a year die of it in the United States. However anaphylaxis rates with the vaccine are 1.6 per million, so the practice of boosting every ten years “should be reexamined” (see that discussion below).

From the caption: “95% of the population will remain protected against tetanus for 64 years after vaccination.”

Humoral immunity to tetanus as a function of age and time after vaccination. Tetanus-specific serum antibody responses were measured in adult subjects and plotted versus age (A) or time after vaccination (B). Dotted line in each panel represents level of antibody required for protection, equivalent to 0.01 IU/mL. B, Solid blue line is the fitted regression line representing the antibody half-life decay rate, and the shaded blue region represents the upper and lower bound of 95% confidence interval (CI) for the cross-sectional antibody half-life estimation. Dashed blue line represents a 1-sided lower bound 95% CI based on a 14-year half-life and indicates when tetanus-specific antibody titers would decline to 95% seroprotection by crossing the protective threshold of 0.01 IU/mL (ie, −2 log10 IU/mL) at 72 years after vaccination. Dashed green line is based on an estimated 11-year half-life [7] and indicates that 95% of the population will remain protected against tetanus for 64 years after vaccination.

Protection against Diptheria is likewise “not too shabby”:

“…95% of the population will remain protected against diphtheria for 30 years after vaccination.”

Nearly all those samples were still above the “line of protection” even a lifetime later.

Humoral immunity to diphtheria as a function of age and time after vaccination. Diphtheria-specific serum antibody responses were measured in adult subjects and plotted versus age (A) or time after vaccination (B). Dotted line in each panel represents level of antibody required for protection, equivalent to 0.01 IU/mL. B, Solid blue line is the fitted regression line representing the antibody half-life decay rate, and the shaded blue region represents the upper and lower bound of 95% confidence interval (CI) for the antibody half-life estimation. Dashed blue line represents a 1-sided lower bound 95% CI based on a 27-year half-life and indicates when diphtheria-specific antibody titers would decline to 95% seroprotection by crossing the protective threshold of 0.01 IU/mL (ie, −2 log10 IU/mL) at 42 years after vaccination. Dashed green line is based on an estimated 19-year half-life [7] and indicates that 95% of the population will remain protected against diphtheria for 30 years after vaccination.

There is a very sane discussion of the cost benefits of over vaccinating, even with a very safe vaccine that has minimal side effects. Currently tetanus is given in the combined DTP vaccine (Diphtheria, Tetanus, Pertussis (whooping cough). Children get five (5!) repeat shots.

Tetanus is rare in the United States, with approximately 27 cases reported annually from 2008 to 2012 [29]. Although tetanus is highly lethal in unvaccinated patients, disease severity is sharply reduced in fully vaccinated individuals [2, 30–33]. Of 124 cases of tetanus, all 14 deaths occurred in patients who had received ❤ doses of vaccine or had unknown vaccination status, whereas all 110 patients (100%) who received ≥3 doses of vaccine survived [31, 32]. From 2001 to 2008, the Centers for Disease Control and Prevention (CDC) identified 233 tetanus cases (29 cases per year) for an annual incidence of 0.1 case per 1 million persons [33]. The overall case-fatality rate among the vaccinated, the unvaccinated, and those with unknown vaccination history was estimated at 13.2%. This indicates that tetanus is exceedingly rare, with a mortality rate of approximately 3 deaths per year among a population of >300 million.

Diphtheria is nearly nonexistent in the United States, with no cases reported from 2008 to 2012 [29]. This indicates that it is less common than other rare reportable bacterial diseases, including tularemia, plague, cholera, or anthrax [29]. Serious adverse events after vaccination against tetanus and diphtheria are uncommon, but anaphylaxis is estimated at 1.6 cases per million doses, and brachial plexus neuropathy may occur at a rate of 5–10 cases per million doses [3]. When multiplied by an estimated 16 million doses of tetanus and diphtheria (Td) vaccine administered annually in the United States [32], severe adverse events include approximately 25 severe allergic events and 80–160 cases of brachial plexus neuritis. Because overimmunization provides a negligible increase in protection [32], this suggests that the risk-benefit ratio of a decennial adult booster vaccination schedule should be reexamined.

Food for thought.

REFERENCE

Hammarland, E. et al (2016) Durability of Vaccine-Induced Immunity Against Tetanus and Diphtheria Toxins: A Cross-sectional Analysis, Clinical Infectious Diseases.  2016 July 01; 63(1): 150.