Earth’s Response to Increasing CO2: An Example of Hormesis?

August 11th, 2014 by Roy W. Spencer, Ph. D.

One of the dubious assumptions undergirding the environmental movement is that the Earth was in an optimum state of health before humans arrived on the scene and screwed everything up.

But this is a religious assumption…which I don’t have a problem with, until it is foisted on the masses as “science”.

The idea that everything humans do to the environment is bad is an emotional one, not scientific, especially when the “pollution” we are talking about (CO2) is necessary for life on Earth.

There is a concept in toxicology called “hormesis”, around since at least the late 1800s, which states that for many chemicals the biological response is actually positive at low doses, before it becomes negative at high doses. I spent some time last week with Ed Calabrese, who has published extensively on the hormesis concept (here is a review paper by him, which includes a discussion of how the hormesis concept got unfairly grouped in with the homeopathy movement).

For a very simple example, there is a wide variety of minerals necessary for human health in low doses, but which are toxic at high doses. Food and water are also necessary in low doses…but will kill you in high doses.

More generally, there is also evidence that even for chemicals which are not necessary in the human body, low doses can actually make a person healthier because some level of environmental stress on the body makes the body more resilient. For example, some non-zero level of bacteria and virus exposure helps keep us healthier. I’m told there has been some research that suggests that inhaling low levels of radon is beneficial..or at least benign. Physical exercise tears apart human tissue…but helps build more muscle as a response to the demands placed on the body.

The hormesis concept is anathema to regulatory organizations such as the EPA, which want to regulate “pollution” to infinitesimally small values, no matter how many people those regulations might kill in the process. The supposed justification is linear dose-response curves which basically assume that there is no beneficial level of a “pollutant”, and even that the smallest level of exposure will cause harm.

Needless to say, the possibility that low doses of many pollutants might actually be beneficial to human health would be a real paradigm changer in the regulatory community.

This is the basis of statistical epidemiological studies which claim thousands of deaths each year from exposure to benign things like Justin Bieber’s music.

For those who like graphs, the following cartoon shows what I’m suggesting in qualitative functional form for carbon dioxide:


An Earth scientist who has not already sold his soul to the government regulation bureaucracy might legitimately ask, “I wonder if some level of enrichment of atmospheric CO2 is actually a good thing for life on Earth?”, as suggested by the green curve in the above graph.

The straight red line (linear dose response) is, in contrast, what is usually assumed…that any increase beyond that believed to exist before humans arrived is necessarily bad for Mother Earth.

But atmospheric carbon dioxide is necessary for life on Earth, and has risen from a pre-industrial concentration of only 3 parts per 10,000, to (still only) 4 parts per 10,000 today. The result has been global greening and a moderation of global temperatures (at least partly due to more CO2, in my opinion). Theoretically expected negative impacts on severe weather and marine life have, so far, failed to reach any believable level of cause-and-effect, beyond normal natural variability.

(And if you are tempted to cite statistics of a record number of whatever events, I will ask whether humans are also responsible for the recent “grand maximum” record high sunspot activity out of the last 3,000 years? Was that Bieber’s fault, too? Or maybe Manbearpig’s fault?).

I’ve had plant physiologists tell me it’s almost as if nature has been sucking as hard as it can on atmospheric CO2, and has depleted it to the point where only the hardiest life forms can exist. But as we add more CO2 to the atmosphere, nature quickly gobbles up 50% of the extra, leading to a more luxurious and robust biosphere.

So, it is reasonable from an unbiased scientific perspective to examine the possibility that more CO2 is actually good for life on Earth…not just the biosphere, but atmospheric effects as well. After all, we’re not talking about X-rays here…we’re talking about the elixir of life, CO2.

Is there a level beyond which more carbon dioxide would be bad? Probably…but I don’t think we know what that level would be. And, just to be on the safe side, if there was a way to stop producing CO2 without killing millions (if not billions) of people in the process, I might be in favor of that.

But that’s simply not possible with today’s energy technologies. Renewable energy sources cannot contribute to more than 15-20% of total energy demand in the coming decades, so we are stuck with fossil fuels for the time being.

I really don’t care where our energy comes from, as long as it is abundant and affordable for the world’s poor. In the meantime, we need to stop thinking in simple linear dose-response terms which is contrary to so much real world experience and exists mainly to make jobs for regulators and companies that are made rich through subsides rather than through free choice by the public.

65 Responses to “Earth’s Response to Increasing CO2: An Example of Hormesis?”

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  1. Karl says:

    From a retired environmental engineer, I couldn’t agree more. The dose response curve as used by EPA is responsible for lots of extra dollars in cost for no significant improvement in health. I am not saying EPA’s approach is not necessary for some pollutants but EPA has gone way overboard in my opinion and we all pay for it in dollars.

    • jeff gierloff says:

      If you are part of an agency like the EPA, you will write regulations to solve obvious problems, like getting the lead out of gas to combat smog. Smog can also be combated by imposing fuel efficiency standards.

      Once the regulations have been written, there is no longer a justification for your salary, so for self preservation, you’ll want to write more regulations, same ones but diminishing pollutant, with no benefit but to keep the bureaucrats employed, to the economic harm to the rest of us.

  2. jake says:

    “…simple linear dose response…”

    My family never believed in these, but could not agree on exactly when the response changed.

    Pa: One more whiskey will make me just right!

    Ma: You turned stupid, three whiskeys ago!

  3. jimc says:

    Indeed, the plant physiologist’s statistic of 50% of excess CO2 being immediately consumed is telling – and would be more so if he knew where it is going (plants, solution into oceans, etc.). I suppose the time scale precludes some things, like being converter to limestone. Will anyone do the study?

  4. But atmospheric carbon dioxide is necessary for life on Earth, and has risen from a pre-industrial concentration of only 3 parts per 10,000, to (still only) 4 parts per 10,000 today.

    That suppose to be the controller of the climate system of the earth, in contrast to solar and all the secondary effects? I think not.

    • Brian H says:

      Without man’s intervention, the natural trend of CO2 concentration is to be driven down to the ragged edge of plant starvation. Plants are greedy and stupid.

  5. BOMBSHELL: Study shows greenhouse gas induced warming dropped for the past 14 years

    Posted on August 5, 2014 by Anthony Watts

    Paper finds a decrease of IR radiation from greenhouse gases over past 14 years, contradicts expected increase – cloudiness blamed for difference.

    A paper published in the Journal of Climate finds from 800,000 observations a significant decrease in longwave infrared radiation from increasing greenhouse gases over the 14 year period 1996-2010 in the US Great Plains. CO2 levels increased ~7% over this period and according to AGW theory, downwelling IR should have instead increased over this period.
    According to the authors,

    “The AERI data record demonstrates that the downwelling infrared radiance is decreasing over this 14-yr period in the winter, summer, and autumn seasons but it is increasing in the spring; these trends are statistically significant and are primarily due to long-term change in the cloudiness above the site.”

    The findings contradict the main tenet of AGW theory which states increasing greenhouse gases including the primary greenhouse gas water vapor and clouds will cause an increase of downwelling longwave infrared “back-radiation.”


    • except clouds are not “greenhouse gases”. Also, the results are local, so unlikely that they are globally applicable.

      Nevertheless, if the results were just the opposite, they would have been heralded as proving the models are correct. Oh well.

      • Leonard Weinstein says:

        Clouds are not greenhouse gases, but they contribute to the atmospheric greenhouse effect as well as changing albedo. BTW, absorbing gases are also not greenhouse gases, they are just called that as being analogous to the greenhouse effect in causing warming. Both clouds and absorbing gases only cause warming with the combination of moving the average location of radiation to space to higher altitude, in combination with the lapse rate relative temperature drop at higher altitudes. The fact that clouds are local does not matter. They occur over as much as 60% of the surface on average, and it is the average that counts.

      • coturnix says:

        No they are not, but they are created from the condensation of the greenhouse gas – water vapor, and as such should not be thought of as a separate phenomenon in the ‘big picture’. I mean, it is possible theoretically to imagine clouds without wv or wv without clouds, but in reality they always come together. This btw why some people (myself included) consider the ’33c’ GHE to be misleading since it includes cloud contribution on the input and not feedbacks. In reality, GHE is more like 10-15C from the most crudest calculations, may be less – i don’t remember for sure.

        After all, in priciple wv and clouds both do exactly the same thing: absorb and re-emit incoming and outcoming em energy.

        • Geoff wood says:

          Leonard and coturnix, do we agree that the coupling of any low emissivity atmosphere to a high emissivity surface will reduce the effective surface emissivity? Do we agree that all interacting matter radiates and that the ‘reason’ for interaction is gravitational containment? Do we agree that a self graviting sphere of ‘any’ gas will, through forced interaction radiate ultimately its gravitational potential energy through thermal interaction to space?

          • coturnix says:

            Low-emissivity atmosphere? But it is high emissivity=absorptivity that makes it efficient as a “greenhouse agent”! Atmosphere is not of low emissivity it is just the cold temperature of its upper boundary that makes it appear such.

            Not not all matter radiate equally well, that’s what emissivity is all about, although it seems that for practical purposes most things around us except for gases, polished mirror-like metal surfaces and some exotic ceramic substances such as silicon, zinc selenide etc. are nearly black-bodies at ambient temperatures.

            Gravitational containment is a reason for a lot of things like life for example.

            A sphere of gas? Do you mean like the sun for example? Before the nuclear reactions turned on it was radiating solely the gravitational energy-“derived” (though gravitational energy doesn’t really exist) photons. But what does it have to do with earth? The earth’s atmosphere doesn’t contract and so cannot radiate its ‘gravitational energy’.

  6. mpcraig says:

    This might be a little off topic or completely relevent. The official US government position is that increased CO2 is “carbon pollution” and cutting carbon emissions by 30% from the US power sector will “make Americans healthier”

    I predict the graphic on that page will some day be on par with the Reefer Madness posters from the US in the thirties.

    • Bill says:

      Sadly, pot prohibition is only very, very slowly going away and the Feds often ignore state law and prosecute anyway. Hopefully the legalization/decriminalization will accelerate. But the fact that we still have it nearly 100 years later does not make me optimistic about other stupid policies.

      • I couldn’t care less about the ‘moral’ aspects of pot smoking. People are free to engage in unhealthy choices if they so wish. However, I do have concerns about freely available low cost drugs of this type and then high risk taking teenagers driving motor vehicles and subsequently getting me or my family members killed. So I don’t regard the policy as completely stupid. (Unlike CO2 regulation which is completely stupid.)

        • coturnix says:

          So maybe, put in jail for life people who did a crime under the influence, and not those who didn’t! Including teenagers. How about that?

      • more soylent green! says:

        Legally speaking, Federal law trumps state law — But what is the constitutional basis for the federal laws (and regulations) restricting marijuana?

        The current administration is not prosecuting recreational and medical pot users in states where it is legal (but why not, if the Federal laws are valid, you might ask). In other jurisdictions, I dunno.

  7. ossqss says:

    I wonder what a plant psychologist would prescribe for the CO2 addiction these poor plants have? Pehaps more CO? Oh wait!;-)

  8. Time will tell as more and more data keeps coming in. My point is there is much doubt and no real black and white scientific data out there.

  9. benpal says:

    Excellent “skeptical” article. “Skeptical” because it questions popular (?) assertions which are taken as axioms, no scientific evidence provided.

    As to the benefits of radon, there are quite a number of radon therapy institutions in Europe. Does radon really have positive effects? I don’t know, but it doesn’t seem to be dangerous at low doses.

    • Brian H says:

      DNA repair requires a certain amount of exercise to remain robust and effective. Radon exposure will do.

  10. JohnKl says:

    Hi Roy,

    Personally, I wonder what the Hormesis response curve to increasing CAGW rhetoric would look like. Perhaps a line begining at zero and declining at a 45 degree angle! The positive response sure seems elusive.

    Have a great day!

  11. Mike Maguire says:

    Sunshine +H2O +CO2 = Food(sugars) +O2

    Add some key minerals, usually from the soil and you have photosynthesis.

  12. Marcel Crok says:

    Thanks for this blog, Calabrese’s work is really interesting. What did he himself say about a possible hormetic effect of CO2 on the planet? Seems a difficult to prove hypothesis…
    (I interviewed Calabrese extensively a few years ago and wrote an article for science insider about it:

    • Jody McDaniel says:

      For proving the hypothesis, or at least seeing if there is a correlation, can the annual CO2 rates be compared against satellite vegetation images? Do we have enough of a log of satellite images to compare? I realize the timelines might be very different, but it could be interesting to see. I would also like to see crop yield information against the CO2 data as well.

    • Brian H says:

      Considering that the planet bloomed at levels =>10X higher than current, you’ll have a long wait for any negative excess concentration effects.

  13. Tom Anderson says:

    “We try to keep CO2 levels in our US Navy submarines no higher than 8,000 parts per million, about 20 times current atmospheric levels. Few adverse effects are observed at even higher levels.” — William Happer, Cyrus Fogg Bracket Professor of Physics at Princeton University, Testimony to Senate Energy Committee, July 10, 2002. Cited at WUWT:

    The Watts post addresses a Lawrence Livermore study that 1,000 ppm of CO2 reduce human decision-making capacity. Watts’s conclusion, based on U.S. submarine experience, is that the Lawrence study is one more scare tactic to denigrate normal to high atmospheric CO2 levels.

    • Brian H says:

      See my “=>10X” comment above. Man’s mission statement from GAIA is to maximize CO2 levels by combusting coal reserves and reversing limestone and chalk formation.

  14. gbaikie says:

    **Is there a level beyond which more carbon dioxide would be bad? Probably…but I don’t think we know what that level would be. And, just to be on the safe side, if there was a way to stop producing CO2 without killing millions (if not billions) of people in the process, I might be in favor of that.**

    There would a level in which CO2 would become problematic
    and I would say that is around 1000 ppm.
    For example wanting classrooms to have 1500 ppm or less of CO2, is somewhat reasonable. And when consider cities having elevated levels of CO2 as compared to global average, then taking measures to ensure classrooms had 1500 ppm or less
    would cost more than they would currently. Or if you want to create a baseline, in which humans in general tend to be more alert, having CO2 level at or below 1500 ppm, is reasonable point. Now if you sleeping, in large gathering of people your environment may 2000 ppm or higher- but this different than classroom. And generally if Global CO2 rises this in turn increases current elevated areas to higher levels. So for example poorly ventilated building become are more serious problem, and cities which have high high levels of CO2, become even higher.
    So I think if we get up to say 650 ppm, and it looks possible we might within 50 get significantly higher, one might begin to get serious about it. So maybe in 50 years in future it might need to be re-assessed.

    **But that’s simply not possible with today’s energy technologies. Renewable energy sources cannot contribute to more than 15-20% of total energy demand in the coming decades, so we are stuck with fossil fuels for the time being. **

    Of course it’s possible to significantly reduce CO emission by using nuclear energy. So one take off about 10 billion tonnes per year within decade, if governments would get serious about increasing use of nuclear power.
    Wind or solar have not done anything to reduce CO2, and could argued [quite successfully] that their use has increased CO2 emission. And wind and solar energy are very unlikely within, say 10 years, they stop increasing CO2 emission.
    And idea that wind and solar could reduce CO2 is unrealistic. And of course solar and wind use resources and create pollution in their manufacture, maintenance, and final removal [and having lowest lifetime of any other system which generates electrical power].
    So public has been forced to pay for wind and solar energy in total amounts in the trillions of dollars, and they have had zero benefit.
    If the public is willing to pay as much as trillion dollars they are far better avenues than wind and solar.
    One could be more aggressive with developing ocean methane hydrate deposits, and particularly related to scientific understanding of them. So tens of millions per year, total amount globally spend maybe as much as 100 billion dollars.
    Another long term action could space exploration, with focus on finding minable resources in space- which begins with water for rocket fuel, and also includes such thing a PGMs [].

    For example if we would have had well funded space exploration, and well managed, we would have far more samples from space- such from lunar poles, Mars, and etc, rather our limited supply of lunar sample we got from Apollo program, more than 50 years ago.

  15. Thanks, Dr. Spencer. An interesting article.
    Yes, CO2 is the “elixir of life” indeed (At least for me, a carbon-based life-form).

    Deserts ‘greening’ from rising CO2:
    Increased levels of carbon dioxide (CO2) have helped boost green foliage across the world’s arid regions over the past 30 years through a process called CO2 fertilisation, according to CSIRO research. From Deserts ‘greening’ from rising CO2 (CSIRO, the Commonwealth Scientific and Industrial Research Organisation. Australia’s national science agency. 3 July 2013)

  16. For my liking, my favourite book on the subject is still Oliver Morton’s EATING THE SUN, where he writes in the introduction:
    “On this day, and the next day, and every day, a scarcely conceivable 4000 trillion kilowatt hours of energy reached the top of the earth’s atmosphere as sunshine… And over the course of the day, that energy served to turn hundreds of millions of tonnes of carbon dioxide into food and living tissue. And as a result the world stayed alive. That’s what really happened today.”
    On this basis, I did a little spreadsheet calculation* comparing solar power and its influence on Earth’s surface temperature to the IPCC surmised influence of CO2 power on that temperature resulting in a ‘that emperor has no clothes’ type conclusion – which could be quite amusing if we weren’t forced to waste trillions of dollars for those non-clothes…

  17. Steve Case says:

    More CO2, warmer weather, longer growing seasons, more arable land and less ice and snow, has been successfully marketed as a catastrophic disaster.

    A testament to the power of propaganda if ever there was one.

    • Slipstick says:

      Your list is a bit short. You forgot to mention increased coastal flooding from rising sea levels destroying habitats and requiring huge investments in mitigation and protection for coastal cities, changes in seasonal food availability endangering migrating animals, destruction of marine ecosystems by acidification of the oceans, migration of tropical diseases to heavily populated mid-latitudes, changes in weather patterns destroying economies in some areas while boosting others, leading to conflict, etc., etc., etc.

      Certainly, the Earth and its ecosystems and humanity will adapt to the climactic changes, just as they always have, but the difference this time is the rate of the changes, far faster, by an order of magnitude or two, than in the past, and the costs both in the ecological and economic terms will be huge.

      • Robert JM says:

        You obviously don’t know that solar forcing goes from 0 to 1300W/m2 in six hours, which is a few million times larger than CO2 forcing!

        • Slipstick says:

          Yes, that’s true, for one continuously, periodically changing segment of the planet, not globally.
          Why is it when faced with unpleasant, but irrefutable, possibilities, the response tends to be partially true, utterly illogical, and inapplicable, nonsense?

      • Bob Rodstone says:

        “…but the difference this time is the rate of the changes, far faster, by an order of magnitude or two, than in the past, …”
        Oh, I think you are forgetting something. A few million years ago, a big rock came hurtling out of the cosmos and smacked the Southern part of what we now call Mexico. Climate changed real fast, like within a year. Fossils show dinosaurs being literally frozen to death in a mud pit.
        Poor dinosaurs didn’t have a chance….

        • Slipstick says:

          Ummm…is your point that the catastrophic changes wrought millions of years ago make the comparatively smaller, slower changes of our near future inconsequential? If so, I hope you were kidding.

  18. geran says:

    Such a great start! Many sentences worth making into a bumper sticker, if somehow shortened:

    **One of the dubious assumptions undergirding the environmental movement is that the Earth was in an optimum state of health before humans arrived on the scene and screwed everything up.

    **But this is a religious assumption…which I don’t have a problem with, until it is foisted on the masses as “science”.

    **The idea that everything humans do to the environment is bad is an emotional one, not scientific, especially when the “pollution” we are talking about (CO2) is necessary for life on Earth.

    But, then this:

    **Is there a level beyond which more carbon dioxide would be bad? Probably…but I don’t think we know what that level would be. And, just to be on the safe side, if there was a way to stop producing CO2 without killing millions (if not billions) of people in the process, I might be in favor of that.

    Why cop out???

    Mankind cannot increase CO2 levels to catastrophic levels, even if we tried.

    So, allow me to rephrase:

    Is there a level beyond which more carbon dioxide would be bad? Not with Earth’s systems on guard. And, just to be on the safe side, we will stop trying to “save” the planet by destroying human freedom.

    (But, I might just be another extremist….)

    • Fonzarelli says:

      Geran, have you ever heard of the “mass balance” argument (engelbeen..) which explains how a small addition is responsible for the rise in co2? I think the argument is a crock of crap and am wondering what you think of it. Thanx…

      • geran says:

        Hi Fonz,

        Yes, I’ve heard of it. I think as you do.

        If you’ve ever tried to actually measure CO2 in the atmosphere, you know some of the problems. For one, you can take a reading and get a result, then 5 minutes later, take another reading and get a totally different result. The next day, the readings may be close to what you previously read, or even worse. The next day, readings are the other way.

        You really need highly sophisticated equipment, over long periods of time, properly maintained and calibrated, to get anything you can trust as accurate. Most citizens do not have access to such equipment and we have to trust someone else to read and record CO2 data correctly. And, you know where that leads.

        We can make a fairly accurate estimate of how much CO2 is produced by fossil fuels. It is a lot. But, it is dwarfed by nature. And, nature is STARVING for CO2. The weeds in my yard will scarf up any CO2 molecule they can–that’s why they are so healthy.

        And, trying to use isotopes to identify CO2 from fossil fuels gets even worse results…

  19. Werner Brozek says:

    Speaking of radon, radon, for example, can be beneficial to your health in small doses, eg 32 hours a year in a radon mine shaft. For example an hour at a time, three times a day for 11 days. It definitely is not for all sicknesses, but it seems to do wonders for arthritis. Montana in the U.S, has about five radon mines around Boulder. People are not stupid. They would not come back whenever they felt the need if it did not help.
    Radon is like the sun. Too much sun and you can get skin cancer or a sunburn, but in small amounts, you get vitamin D. See:

  20. Dr. Strangelove says:


    Though controversial, I believe in hormesis. A good example of hormesis is vaccination. We inject pathogens to infants and they become immune to the pathogens. EPA put a legal limit to occupational radiation exposure at 50 mSv per year. The natural radiation in Ramsar, Iran is 260 mSv per year. Apparently the Iranians are resistant to high radiation presumably due to exposure to it.

    Another example of hormesis. I watched in National Geographic a man who regularly gives himself poisonous snake bites. He became immune to the poison. More amazing his blood became an antidote to snake poison. He puts his blood in vials and hospitals inject it to victims of snake bites.

  21. The Hormesis concept is very favourable to the development of nuclear energy.

    If low doses of radiation are good rather than bad it would seem that much of the anxiety about that industry is misplaced.

    • numberer says:

      “…anxiety about [nuclear power]…”

      I think the anxiety is more about the slight possibility of a high dose emanating one day, i.e. an accident. My nephew works in a nuclear power plant and he doesn’t glow in the dark – yet.

      • It’s a matter of balance.

        The UK coal industry killed tens of thousands but it was accepted at the time.

        I don’t think Hormesis applies to coal dust or diesel particulates, only materials that can be broken down by the body over time.

  22. numberer says:

    “Earth’s response to increasing CO2 levels: an example of hormesis?”

    Short answer – No.

    The essence of hormesis is awakening a latent response of an ORGANISM to an influence, in such a way that there is over-shoot in the reaction; an organism which has already evolved internal , adaptive, systems for survival. Earth is not an organism in this sense – unless you believe in “Gaia.”

  23. AlecM says:

    My view is that [CO2] will peak at ~450 ppmV before declining as we enter the depth of the new Little Ice Age, about 2045.

    The CO2 increase will help many to survive the short growing seasons in the Northern lands.

  24. Denis Rushworth says:

    Among many others, T. D. Luckey has spent a lifetime studying radiation hormesis and has shown that low doses of the order of that received by living on earth or a bit above range in benefit somewhere between beneficial and essential. See for example.

    Our Heath Physics (radiation safety) consensus still insists on the linear no-threshold theory, costing us $millions or $billions per year in needless and perhaps harmful costs in industries trying to exploit nuclear and radiation energy.

    Sound familiar?

  25. Aaron S says:

    Random points about the history of CO2
    A. With less atm CO2 than today, the oceans were over 6m or 20ft higher 120kyr ago during last glacial minimum of the current ice age.

    B. We remain in a major ice age with only 2 comparable ones in earth history… we are generally in a starved CO2 environment. Why are there 90 Ma yr old ocean deposits in colorado? There was no ice and an ocean split north america bc earth was much hotter. The earth that was lush and tropical and CO2 was almost an order of magnitude higher. Ohh, and corals were doing great.

    C. There are thresholds with co2. There was a coeval coeval shit in the abundance of plants (grass) using the C4 metabolic pathway relative to C3 trees and flowers. The shift occured once we went under 500 ppm in the late miocene to early pliocene (about 4 to 6 million years ago). This led to the open grasslands that provided the ecological niche that humans evolved to fill.

  26. albert says:

    Some weeks ago was published a peer-reviewed scientific report saying that only about 3.7% of CO2 emissions are anthropogenic. The rest is natural.

    • Fonzarelli says:

      Yes, but the “mass balance” argument claims that the small percentage gets plopped on top so to speak and then an equilibrium sink takes out fifty percent of the rise… (I ain’t buyin’ that but that’s the argument that they’re making)

  27. David L. Hagen says:

    Perspective on CO2 Toxicity from NIH Haz-Map

    Signs of intoxication have been produced by a 30 minute exposure at 50,000 ppm [Aero 1953], and a few minutes exposure at 70,000 to 100,000 ppm produces unconsciousness [Flury and Zernik 1931]. It has been reported that submarine personnel exposed continuously at 30,000 ppm were only slightly affected, provided the oxygen content of the air was maintained at normal concentrations [Schaefer 1951]. It has been reported that 100,000 ppm is the atmospheric concentration immediately dangerous to life [AIHA 1971] and that exposure to 100,000 ppm for only a few minutes can cause loss of consciousness [Hunter 1975].

    “[American Conference of Governmental Industrial Hygienists. Documentation of the TLV’s and BEI’s with Other World Wide Occupational Exposure Values. CD-ROM Cincinnati, OH 45240-1634 2007.]”
    Haz-Map of HSDB: CARBON DIOXIDE CASRN: 124-38-9

    I.e. try to keep CO2 below 50,000 ppm (5%) to avoid getting giddy! (Go beyond 5% and you can asphixiate yourself!!!)

    Methanol Toxicity
    “Methanol occurs naturally in humans, animals and plants. It is a natural constituent in blood, urine, saliva and expired air.” However, ingesting too much is toxic to humans, causing blindness and death. Methanol, NIH.

    Methanol poisoning can cause blindness and death. The lethal oral dose in humans is 2 to 8 ounces. Most cases have occurred after ingestion. Methanol poisoning after inhalation or skin absorption in the workplace has been reported. [ACGIH] Symptoms of methanol poisoning include initial CNS depression and vomiting followed by metabolic acidosis and severe vision impairment 8-24 hours later. Coma, respiratory failure, and death may ensue. [CHEMINFO] In high-dose reproductive studies in animals, methyl alcohol causes testicular damage and birth defects. [Frazier, p. 179-80] Patients may present with inebriation and gastritis. There is a characteristic latency of 6-30 hours after exposure. Combined osmolar and anion gaps suggest poisoning by methanol or ethylene glycol, but also may occur in severe alcoholic ketoacidosis or diabetic ketoacidosis. [Olson, p. 33, 278]

    NIH HazMap Methanol

  28. David L. Hagen says:

    See the benefits of higher CO2 at: More CO2 in the air means more plant growth.

  29. richard verney says:

    Surely we know that the world was far from in an ideal state when humans inherited the mantle.

    During the time of the dinosaurs, conditions were far more favourable, hence the reason why creatures both in the sea, and on land (including insects) were far bigger, with plant and tress life also flourishing.

    This truly was a time of plenty for life, as can be seen by life’s favourable response to the then existing environmental conditions.

    A similar conclussion can be reached by looking at tropical rain forests, and to compare bio diversity in that environment compared to bio diversity in cold arid frigit tundra/arctic environments.

    A similar conclusion can be reached by considering the size of land animals. With the exception of bears, all the large land animals are from warm climes.

    The take how is that life thrives in warm and wet conditions; that is utopian.

    Indeed, if man could not adapt either himselve (with clothing/furs) or his environment (building houses to substitute for caves, and fires for warmth), there would be very few places habitable, for man, on planet Earth.

    It is quite clear that, in the time that we are living, the Earth is far too cold, and all life would greatly benefit by some extra warmth.

    CAGW is not about conditions being difficult for life, merely inconvenient for humans, and then only should there be significant sea level rise.

    Changing climate is no problem, since species simply migrate, but I do accept that it becomes more of a problem for other animals since man has done so much to destroy natural habitats such that they may find it difficult to migrate to another suitable environment.