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Positives and negatives of global warming

What the science says...

Select a level... Basic Intermediate Advanced

Negative impacts of global warming on agriculture, health & environment far outweigh any positives.

Climate Myth...

It's not bad
"Two thousand years of published human histories say that warm periods were good for people. It was the harsh, unstable Dark Ages and Little Ice Age that brought bigger storms, untimely frost, widespread famine and plagues of disease." (Dennis Avery)

Here’s a list of cause and effect relationships, showing that most climate change impacts will confer few or no benefits, but may do great harm at considerable cost.

Agriculture

While CO2 is essential for plant growth, all agriculture depends also on steady water supplies, and climate change is likely to disrupt those supplies through floods and droughts. It has been suggested that higher latitudes – Siberia, for example – may become productive due to global warming, but the soil in Arctic and bordering territories is very poor, and the amount of sunlight reaching the ground in summer will not change because it is governed by the tilt of the earth. Agriculture can also be disrupted by wildfires and changes in seasonal periodicity, which is already taking place, and changes to grasslands and water supplies could impact grazing and welfare of domestic livestock. Increased warming may also have a greater effect on countries whose climate is already near or at a temperature limit over which yields reduce or crops fail – in the tropics or sub-Sahara, for example.

Health

Warmer winters would mean fewer deaths, particularly among vulnerable groups like the aged. However, the same groups are also vulnerable to additional heat, and deaths attributable to heatwaves are expected to be approximately five times as great as winter deaths prevented. It is widely believed that warmer climes will encourage migration of disease-bearing insects like mosquitoes and malaria is already appearing in places it hasn’t been seen before.

Polar Melting

While the opening of a year-round ice free Arctic passage between the Atlantic and Pacific oceans would confer some commercial benefits, these are considerably outweighed by the negatives. Detrimental effects include loss of polar bear habitat and increased mobile ice hazards to shipping. The loss of ice albedo (the reflection of heat), causing the ocean to absorb more heat, is also a positive feedback; the warming waters increase glacier and Greenland ice cap melt, as well as raising the temperature of Arctic tundra, which then releases methane, a very potent greenhouse gas (methane is also released from the sea-bed, where it is trapped in ice-crystals called clathrates). Melting of the Antarctic ice shelves is predicted to add further to sea-level rise with no benefits accruing.

Ocean Acidification

A cause for considerable concern, there appear to be no benefits to the change in pH of the oceans. This process is caused by additional CO2 being absorbed in the water, and may have severe destabilising effects on the entire oceanic food-chain.

Melting Glaciers

The effects of glaciers melting are largely detrimental, the principle impact being that many millions of people (one-sixth of the world’s population) depend on fresh water supplied each year by natural spring melt and regrowth cycles and those water supplies – drinking water, agriculture – may fail.

Sea Level Rise

Many parts of the world are low-lying and will be severely affected by modest sea rises. Rice paddies are being inundated with salt water, which destroys the crops. Seawater is contaminating rivers as it mixes with fresh water further upstream, and aquifers are becoming polluted. Given that the IPCC did not include melt-water from the Greenland and Antarctic ice-caps due to uncertainties at that time, estimates of sea-level rise are feared to considerably underestimate the scale of the problem. There are no proposed benefits to sea-level rise.

Environmental

Positive effects of climate change may include greener rainforests and enhanced plant growth in the Amazon, increased vegitation in northern latitudes and possible increases in plankton biomass in some parts of the ocean. Negative responses may include further growth of oxygen poor ocean zones, contamination or exhaustion of fresh water, increased incidence of natural fires, extensive vegetation die-off due to droughts, increased risk of coral extinction, decline in global photoplankton, changes in migration patterns of birds and animals, changes in seasonal periodicity, disruption to food chains and species loss.

Economic

The economic impacts of climate change may be catastrophic, while there have been very few benefits projected at all. The Stern report made clear the overall pattern of economic distress, and while the specific numbers may be contested, the costs of climate change were far in excess of the costs of preventing it. Certain scenarios projected in the IPCC AR4 report would witness massive migration as low-lying countries were flooded. Disruptions to global trade, transport, energy supplies and labour markets, banking and finance, investment and insurance, would all wreak havoc on the stability of both developed and developing nations. Markets would endure increased volatility and institutional investors such as pension funds and insurance companies would experience considerable difficulty.

Developing countries, some of which are already embroiled in military conflict, may be drawn into larger and more protracted disputes over water, energy supplies or food, all of which may disrupt economic growth at a time when developing countries are beset by more egregious manifestations of climate change. It is widely accepted that the detrimental effects of climate change will be visited largely on the countries least equipped to adapt, socially or economically.

Basic rebuttal written by GPWayne

Last updated on 1 August 2013 by gpwayne. View Archives

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Related Arguments

Further reading

National Geographic have an informative article listing the various positives and negatives of global warming for Greenland.

Climate Wizard is an interactive tool that lets you examine projected temperature and precipitation changes for any part of the world.

A good overview of the impacts of ocean acidification is found in Ken Caldeira's What Corals are Dying to Tell Us About CO2 and Ocean Acidification

Comments

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Comments 251 to 300 out of 333:

  1. For the record, irrational appeal to authority is a common logical fallacy, which is hardly inflammatory (he could easily defend himself and prove me wrong. Why is it ok for Sphaerica to accuse me of logical fallacies without being "snipped" but not vice versa?

    If this is an inappropriate place for such questions to be issued, I apologize in advance. Also, great site! I really enjoy the comments sections.
  2. AHuntington1 - I believe the issue is that you have made numerous assertions without backing evidence, such as "...increasing the ratio of Co2 to 02 significantly increases the distribution of 02 throughout the body..." and "More atmospheric C02 is beneficial for plants (as has been described in this thread) and animals." I haven't seen the latter in this thread, and in fact if you look at the relevant CO2 is plant food thread you will see that this is actually not the case - heightened CO2 has mixed, and in general negative, effects on plants due to effects such as changes in the hydrological cycle.

    You have then moved the goalposts - raising separate points (lactate mechanisms, antioxidants, hypoxia) - using references showing that insufficient CO2 is harmful, but not producing any evidence that excess CO2 is helpful. The term "Gish Gallop" applies to the rhetorical tactic of raising many unrelated points without fully addressing (or completing a reply to critiques) any of them, and it does seem to apply to your posts so far.

    If you are going to make claims, you need to support them. You have not.
  3. KR, the first statement is backed up by the Bohr effect, and the fact that Co2 helps prevent acute hypoxia (potentially deadly lack of oxygen supply). These two facts show how Co2 (and especially a higher ratio of Co2 and O2) does indeed increase oxygen distribution throughout the body significantly. Co2 also displays antioxidant activity.

    I don't see the comments in the plant food thread that you are referring to. Do you deny that one major positive factor in plant growth (among others, such as soil type, and water quantity) is the quantity of Co2 in the area? Do you disagree with the litany of studies that show crop yield increases when Co2 increase was the only changing variable?
  4. AHuntingdon

    I don't think you understand how the Bohr effect works. It's the difference in affinity of haemoglobin for O2 in the lung (low CO2) and in O2-starved (high CO2) tissues that increases efficiency of O2 supply to O2-starved tissues. If you increase CO2 in the lungs, you decrease the ability of haemoglobin in the lungs to take up O2 due to the very same chemistry. That will not increase O2 supply to internal tissues. You may also reduce the differential in O2 affinity between the lungs and O2-starved tissues, which will reduce effiency of supply of that O2 to O2-starved tissues.

    And no, CO2 is not considered a "major" factor affecting plant growth. Nutrients and water are far more important in nature. Only when the latter are in sufficient quantities (as in a greenhouse) do you see a substantial CO2 effect. That effect decreases as CO2 concentrations increase -- i.e., there is a law of diminishing returns. It is far less obvious for C4 than for C3 plants. You should read the CO2 is plant food thread in detail before commenting here.

    BTW...You should be aware the IPCC accounted for the fertilization by CO2 when assessing the effects of increasing CO2 on crops. They predicted an initial increase in production followed by substantial decreases after further increases due to effects on climate.
  5. AHuntington1, how does high altitude increase the CO2 to O2 ratio? As pressure decreases, the mass of any given atmospheric element per unit of volume decreases and that applies to all of them: oxygen, nitrogen, carbon dioxide, all other well mixed gases. CO2 concentration within the range of altitudes at which humans can live does not vary in any significant way.
  6. Stephen Baines, a higher affinity for O2 in the hemoglobin results in less oxygen transfer out of the blood, to tissues. More Co2 means less O2 is absorbed immediately into the hemoglobin, but the O2 that is picked up is easily distributed.

    Philippe Chantreau, that is a good point, and I did mis-type. People at high altitudes breathe less O2 (and Co2), but continue to metabolize glucose, which produces water and Co2. Thus, people at high altitudes are exposed to a higher ratio of Co2 to O2 internally. But yes, the atmosphere is less dense all around.
  7. As for plants, I certainly concede the point that other factors (outside the greenhouse) might negate the benefit of Co2 as an aerial fertilizer. I have read the page and am still on the fence regarding overall cost-benefit analysis regarding the aerial fertilizer argument.

    But, just as the potential benefits of aerial fertilization is listed in the above pros and cons, I would like to see potential benefit to mitochondrial respiration in fauna listed as well.
  8. AHuntington1 - I would point to Gonzilez et al 1996, "Direct lnhibition of Plant Mitochondrial Respiration by Elevated CO2", among others.

    When considering elevated CO2 it is vital to consider the full spectrum of effects - heat, ocean acidity, C3 versus C4 plant responses, and the fact that other aspects of the environment may be the limiting effects on biology.

    You claim elevated CO2 is, overall, beneficial - that's really not supported by the evidence available.
  9. "More CO2 means less O2 is absorbed immediately into the hemoglobin, but the O2 that is picked up is easily distributed."

    Yes, my point exactly. For all you know, the two things cancel out, or worse. You've provided no real evidence that increasing ambient CO2 has a net positive impact on O2 use efficiency. It could just as easily be a negative impact.

    In any case, even if you were correct, it is besides the point. As KR notes, the point of the OP is not that increasing CO2 is always bad for everything under all circumstances. It's that, taken together, the effects of increasing CO2 on organisms and human society will be on balance very negative. That's true even when we acknowledge the positive effects of increasing, including CO2 fertilization of plants.

    By focusing on a few physiological processes, you're missing the forest for a few cherry trees.
  10. AHuntingdon1 I asked you for a peer-reviewed* study that supported your hypothesis that increasing atmospheric CO2 has a significant metabolic benefit. You were only able to provide papers supporting some of the component parts of the hypothesis. Ideally one would like to see the self-skepticism that would be indicated by a straight answer that clearly stated that there were no papers that supported the hypothesis itself.

    No regarding the obesity paper, as you said I used logic as the basis for my skepticism of that hypothesis. The same logic underpins my skepticims of your hypothesis, I doubt rising background levels of CO2 have a great effect on CO2 levels indoors or in urban environments, where CO2 levels are likely to be determined by local source and sinks. You did not address that issue. If CO2 levels did have a significant effect on metabolism (i) we would be able to see those benefits in human health and (ii) it would be easy to perform the experiments to confirm the link and there would be a paper on the subject by now.

    *yes, I do know that peer-review is no guarantee of correctness, however it does at least mean that the paper has passed the preliminary sanity check of peer review.
  11. AHuntingdon1 wrote "People at high altitudes breathe less O2 (and Co2), but continue to metabolize glucose, which produces water and Co2. Thus, people at high altitudes are exposed to a higher ratio of Co2 to O2 internally. But yes, the atmosphere is less dense all around."

    I very much doubt this is correct. The amounts of CO2 produced from glucose metabolism are going to be very small compared with the amounts in the atmosphere already. Unless of course you are indoors in which case CO2 levels are not primarily determined by background CO2 levels and so your initial hypothesis is invalid anyway.
  12. Dikran Marsupial, with each breath we exhale something like 35,000 ppm of Co2. A much higher percentage of Co2 than current atmospheric levels.

    I thought I did say this, but I have not come across any peer reviewed papers that espouse the theory that increases in atmospheric Co2 provide a net benefit. The fact that this study is hard to find/NA does not reflect a lack of evidence on the benefits of Co2 (as there are many studies) as much as it reflects the mentality of most biological scientists (especially nutritionists).

    ps. It's funny that you spell my name Huntingdon- this was common way to spell the name before words became more standardized.

    Stephen Baines, but they don't cancel out. The Bohr effect is a bit counter intuitive; A higher Co2 to O2 ratio provides a lower affinity for O2 in the blood, and more ability to transfer O2 to the tissues(plus Co2 is a vasodilator, thus allowing more blood to flow in general). A lower Co2 to O2 ratio provides a higher affinity for O2 in the blood, and less O2 transfer to the tissues (plus O2 is a vasoconstrictor).

    KR, interesting article. Remember, my claim is that increasing atmospheric Co2 (by any means, to a certain extent) can have positive effects on animals via increased respiratory efficiency. I never made an overall cost-benefit judgement. I just want it added to the list of potential benefits.
  13. AHuntington1 said at #250:

    High altitudes provide a real life example of a population that breathes a higher Co2 [sic] to O2 ratio.


    I'm curious to know on what basis you make this claim. Is the ratio of the partial pressure of carbon dioxide to the partial pressure of oxygen at altitude significantly greater than at lower altitude?

    It is also interesting that people who live in high altitudes (and are exposed to a higher Co2 [sic] to O2 ratio) [sic] experience lower mortality rates, in general.


    I suspect that the phenomenon to which you refer has more to do with the fact that non-essential metabolism is more likely to be reduced at higher altitude. There is a credible suggestion that calorie/joule use (which has an effect on metabolic rate) in humans is proportional to life span, just as it is in so many other species.
  14. AHuntington1 Firstly appologies for mis-spelling your name. Secondly, while exhaled air my be something like 35,000 ppm of Co2, but the volume of a breath is negligible compared to the volume of the atmosphere. The CO2 in exhaled air only has a significant effect on the air we breathe in if we are indoors (this is now the third time I have pointe dthis out), and if you are indoors, CO2 levels are not controlled by the background CO2, but by local sources (such as your exhalations), and hence rising atmospheric CO2 levels will have not have any significant effect on CO2 levels in the room, and hence no significant effect on metabolosim.

    You claimed that increasing CO2 levels would have beneficial effect on metabolism, but only present evidence that one element of the causal chain can be observed. This is pretty weak evidence, and in my opinion, the way you are presenting your case (i.e. overclaiming and ignoring counter-arguments) does you no favours whatsoever.
  15. AHuntington

    "...but they don't cancel out. "

    This is just an assertion. You haven't provided any evidence. The papers your cite can't be evaluated as they are only abstracts of papers in Russian. You could try to make a theoretical case using heamoglobin-O2 saturation curves, taking into account the effects of ambient CO2 on uptake of CO2 in lungs and tissue CO2. Experimental evidence would be more convincing, however.

    My guess is that the influence of ambient CO2 variations on O2 uptake in the lungs and release in tissues will be relatively small, and are likely to offset. It doesn't seem sensible that the effect of increasing ambient CO2 on CO2/O2 ratios in the lungs would be smaller than the effect on CO2/O2 ratios in the tissues. I could be convinced otherwise, but I would need to see evidence. You are not really providing any.
  16. AHuntington1 - "...my claim is that increasing atmospheric Co2 (by any means, to a certain extent) can have positive effects on animals via increased respiratory efficiency. I never made an overall cost-benefit judgement. I just want it added to the list of potential benefits."

    I would point to the opening post, which states that
    Negative impacts of global warming on agriculture, health & environment far outweigh any positives.
    You claimed that "More atmospheric C02 is beneficial for plants (as has been described in this thread) and animals" - a statement on net effects. But you have not supported your statement with any significant evidence. In fact, your initial claim of changes in CO2 to O2 ratios improving metabolism appears to be nonsense, which you've abandoned to move on to other arguments/moved goalposts.

    Again - while there are positive and negative effects from global warming (including the potential effects you have argued, but not supported), the negatives far outweigh the positives.
  17. Dikran Marsupial, we are talking about internal exposure to Co2. you said "The amounts of CO2 produced from glucose metabolism are going to be very small compared with the amounts in the atmosphere" and I pointed out that sugar metabolism produces enough Co2 to allow us to exhale roughly 35,000 ppm with each breath(~100 times more Co2 than the air we breathe). Glucose metabolism creates a huge amount of Co2 compared to atmospheric levels- thus we need to exhale. I am not saying that humans breathing contributes any significant amount of Co2 to the atmosphere, but it does significantly effect internal exposure to Co2.

    Stephen Baines, you are the one who made the assertion that I misunderstood the Bohr effect. The burden of proof is on you at this point, but I will re-post the wikipedia. http://en.wikipedia.org/wiki/Bohr_effect

    and quote a passage from the link, "hemoglobin's oxygen binding affinity is inversely related both to acidity and to the concentration of carbon dioxide.[1] That is to say, a decrease in blood pH or an increase in blood CO2 concentration will result in hemoglobin proteins releasing their loads of oxygen and a decrease in carbon dioxide or increase in pH will result in hemoglobin picking up more oxygen. Since carbon dioxide reacts with water to form carbonic acid, an increase in CO2 results in a decrease in blood pH."

    You are the one who has it wrong.

    Bernard J, see my response to Philippe Chantreau in post #256 on this page. The passage that you quoted was a mis-type on my part, and I have specified the issue.

    People at high altitudes consistently have higher basal metabolic rates. http://jap.physiology.org/content/16/3/431
    Respiratory acidosis is a potential symptom of traveling to high to fast (a sign that Co2 to O2 ratios increase at high altitudes)

    KR, my only request is that the positive aspects that increased Co2 levels have on animals should be considered in the cost-benefit analysis.

    My statement is not one of net effects, but of specific effects which should be included in the analysis. Increased Co2 levels, within a certain threshold, do increase crop yields- ceteris paribus - and that potential benefit is taken into account in the above analysis. Likewise the benefits of increased Co2 on fauna and bacteria (within a certain threshold)should be taken into consideration as well.
    Response: [Sph] Correction as per request.
  18. KR, you said "your initial claim of changes in CO2 to O2 ratios improving metabolism appears to be nonsense, which you've abandoned to move on to other arguments/moved goalposts."

    This is totally false. Is improved distribution of O2 to the tissues bad? Does it not improve mitochondrial respiration? Do antioxidants reduce respiratory efficiency?

    You are simply ignoring my arguments.
  19. AHuntington1,

    You are conflating detailed analysis of CO2 in organisms with the more general inference that these detailed aspects combined with increases in atmospheric CO2 must result in beneficial outcomes.

    This inference is (a) unwarranted and (b) not in any way supported by actual scientific studies in the literature.

    Your position is akin to saying that (a) "theoretical physics suggests that tachyons may move faster than light" therefore (b) "faster than light travel is possible and will be achieved in our lifetime."

    Your assertions do not warrant their conclusion, especially when such a conclusion was (to begin with) as specific as a benefit in "mitochondrial respiration in fauna."

    Even if this were the case, the claim would be laughable. As the dying man crawls through the desert, parched by drought, weakened by hunger and baking in the heat, you can cheerily say to him "yes, but aren't your cells respiring so much more comfortably in this atmosphere?"
  20. Sphaerica, no I am not. I said all else being equal -ceteris paribus- increases in atmospheric Co2, within a certain threshold, has been shown to have beneficial effects on plants (which has been thoroughly hashed out) and animals (through Co2's role as an antioxidant, vasodilator, and protector of the body's O2 supply).

    Evoking the image of a man suffering from sever dehydration and starvation in the desert is completely irrelevant and blatantly panders to the most basic of human emotions. This behavior is totally inappropriate in a scientific debate.
  21. AHuntington I have now pointed out the same flaw in your argument several times (namely that background CO2 levels don't have much of an effect on CO2 levels where we actually live), and each time you have studiously ignored it.

    You have not shown that increasing atmospheric CO2 levels have a beneficial effect on animals in vivo. Increasing internal CO2 having a beneficial effect on mitochondrial respiration does not establish that rising atmospheric CO2 has a beneficial effect on animals because (a) you have not shown that rising atmospheric CO2 leads to significantly higher internal CO2 (b) you have not shown that increasing mitochondrial metabolism is necessarily beneficial.

    However, I suspect you will duck this point yet again.
  22. AHuntington

    You yourself acknowledged @256 that, according to the Bohr effect, increasing CO2 would decrease O2 uptake in the lungs. Until you can explain to us why that does offset the effect of increased O2 loss from haemoglobin to tissues, I can't see why I should accept your claim.

    We cannot evaluate your evidence because we cannot read those papers. Can you read them? It would not be skeptical of us to simply take your word.
  23. @AHuntington1 #270:

    Whenever I see a commentor such as yourself use the term, "scientific debate" alarm bells go off. Are you here to learn more about the science or to play a "Gotcha" game with whomever deigns to question something that you have posted?
  24. AHuntington1,

    Yes, but "all else being equal" doesn't at all apply in this case, so what's the point of the entire line of thought, except to beat a dead horse or to mislead the unwary?

    As far as what is appropriate to a scientific debate... you say this as if you are being perfectly rational and even in your approach, which clearly you are not. Your posts are full of debate tricks (not the least of which is an excess and as yet unearned degree of hubris).

    Your position is categorically untenable. You Gish Gallop a lot, "speaking" with an authoritative "I know, listen to me, children" tone, but you prove absolutely nothing. In the end, you expect people to accept your position simply because you declare it to be true.

    Fact: Increased CO2 levels, while beneficial in some cases, are not that beneficial.

    Fact: Different plants respond better than others to increased CO2... are you sure that it will be productive crops and not the weeds that really enjoy the elevated CO2 levels?

    Fact: Water availability is far more important. Droughts, expanding deserts and other ramifications of climate change will be far, far more important than whatever meager benefits are derived from "improved mitochondrial respiration" in some plants.

    Fact: Temperature is far more important. Increased temperatures, which change the range of temperatures that impact a plant in various seasons, will be far, far more important than any benefits derived from increased CO2.

    You have failed to prove your point, and your point amounts to sleight of hand... if climate change doesn't raise temperatures, increase droughts, and drastically change agriculture on the planet, the increase in CO2 will be great!
  25. Dikran Marsupial, i did miss that point; I also never mentioned that humans who live in cities/ use air conditioning would be the primary organism to benefit from elevated Co2. If Co2 levels are significantly elevated in cities and/or houses with ACs the organisms who would primarily benefit from increased atmospheric Co2 would be those furthest from modern development.

    Rising atmospheric Co2 does increase internal exposure to Co2 (as soon as a person becomes acclimated, and stops hyperventilating); the internal Co2 level is affected by atmospheric conditions and rate of breath. This is seen when people are acclimating to higher altitudes- increasing internal Co2 can cause temporary respiratory acidosis, or hyperventilation can cause respiratory alkalosis. Once people become acclimated they breathe normally, increase internal Co2 to O2 ratios and become more efficient sugar metabolizers (lactate paradox).

    If you think that mitochondrial efficiency is not beneficial, I don't have much to say. Do you really think that less ATP is better than more? Look at the higher metabolic rates of people living at high altitudes and the epidemiological data regarding these people. One positive example is the generally lower mortality rates among them. This is good evidence to support the hypothesis that a higher metabolic rate is beneficial.


    Stephen Baines, you said "explain to us why that does offset the effect of increased O2 loss from haemoglobin to tissues"

    Because the tissues will always be more oxygen starved, and acidic than the lungs and the blood that just pick up O2. Therefore the freshly oxygenated hemoglobin in a higher Co2 environment will always be able to pass oxygen to the tissues (which by definition, must always have less O2 and more Co2 or acidity than the freshly oxygenated blood and lungs).


    John Hartz, I wasn't playing "gotcha". He attacked a big straw-man, and then painted a picture of me literally mocking a starving and dehydrated human being crawling through the desert. If Sphaerica wasn't displaying an irrelevant appeal to petty emotionalism, I have never seen one- and that behavior is not appropriate in any discussion, let alone a scientific one.


    Sphaerica, I do not "Gish Gallop" alot. The facts that I present are completely relevant to the points I am making. If you can't understand how, I recommend re-reading my posts, and learning about metabolism (and logic).

    Fact 1 is clearly your opinion (as ultimate ends, and values are not scientifically testable).

    Fact 2 is true, but irrelevant. Fertilizer and water also "help weeds too", would you recommend eliminating their use in agriculture?

    Fact 3 is true, but also irrelevant as I did say all else being equal (I have been repeating this to no avail).

    Ditto for fact 4. Basically I am getting tired of repeating myself and defeating straw-men. Everyone else seems capable of rational discussion; why are you constantly changing the subject?

    you said "if climate change doesn't raise temperatures, increase droughts, and drastically change agriculture on the planet, the increase in CO2 will be great!"

    ..then we basically agree, and you will stop posting strawmen, yes?
  26. Stephen Baines, I might have slightly misunderstood your question. Co2's ability to dilate the blood vessels allows for more blood (with less O2) to flow, equalizing the loss of O2 per hemoglobin. Contrast this with more O2 (in relation to Co2), which causes blood vessels to constrict and hemoglobin to horde O2.
  27. AHuntington1 wrote: "Fact 3 is true, but also irrelevant as I did say all else being equal (I have been repeating this to no avail)"

    Yes... because it is observed reality that all else is not equal. Ergo, your entire line of argument is a meaningless diversion into fiction. Yes, if gravity did not exist then people could 'fly' about with ease... but why exactly do you want to talk about things which are not true?

    So yes, truth and reality are "irrelevant" to your position. Which is rather the problem.
  28. AHuntington1,

    I have no intention of re-reading your posts, because they weren't worth reading the first time. Your high opinion of yourself does nothing to raise my opinion of you.

    Fact 1 is not opinion, it is something you need to disprove if you want to advance your pet theory.

    Your complete dismissal of facts 2 through 4 demonstrate that you are living in a fantasy world of denial, which explains how you can present the amazing Gish Gallop that has taken you to this point and still expect to be taken seriously.
    ..then we basically agree, and you will stop posting strawmen, yes?

    Thanks for that closing comment, because it perfectly illustrates my point that your posts are full of debate tricks. You are playing games with words and any reader that cares to step back and look at what you've written can easily recognize this. Thanks for making it so obvious.

    Given this, please spell out the strawman argument that you claim I have created.

    Fact: The influences of climate change on crops, temperature and water availability, and hence the dangers to the human food supply, far, far, far outweigh any tangential and as yet ill-defined (by you) supposed benefits of improved respiration.

    Hence, your entire argument falls flat. You've spent hundreds and hundreds of words arguing about what amounts to an inconsequential detail.
  29. AHuntington1,

    If you think that mitochondrial efficiency is not beneficial, I don't have much to say.


    I have no idea if it's beneficial or not because you haven't presented any actual evidence one way or the other. If my cells are getting all the oxygen they need, making it easier to get more probably isn't going to make a difference.

    If you're trying to convince others of something, saying "I don't have much to say" is an odd tactic to use when you haven't yet provided any evidence to convince them.

    Do you really think that less ATP is better than more?


    I don't know, but I suspect there is probably a point where more ATP provides no additional benefit, in the same way that providing more water to an organism beyond a certain point provides no additional benefit. What I don't know is whether we are ATP-starved and there is additional benefit to be had, and what that benefit might be.

    Look at the higher metabolic rates of people living at high altitudes and the epidemiological data regarding these people.


    Gladly. Where is it?

    One positive example is the generally lower mortality rates among them. This is good evidence to support the hypothesis that a higher metabolic rate is beneficial.


    I look forward to seeing that evidence. I was under the impression that higher metabolic rates led to more oxidative stress and shorter lifespans, and that this was why animals that were slightly starving all the time lived notably longer than animals that were well fed (without being overweight).

    He attacked a big straw-man, and then painted a picture of me literally mocking a starving and dehydrated human being crawling through the desert. If Sphaerica wasn't displaying an irrelevant appeal to petty emotionalism, I have never seen one- and that behavior is not appropriate in any discussion, let alone a scientific one.


    Note that Spaerica was making the very valid point that all else is not equal, and that given the other effects of higher CO2 levels include drought and heat, it's a bit pointless telling an organism suffering from those other known effects that they should be glad of the possibly slight beneficial effect they are also experiencing. It wasn't an appeal to emotionalism, it was putting your claims into context so the net effect of higher CO2 levels is more apparent.
  30. AHuntington1 Sorry this is getting tiresome. I asked for evidence that the mechanism you mention actually has a significant benefit in vivo and you still have provided precisely nill. Epidemiology of those living at altitude is not evidence that the differences between population are due to differences in CO2, so it is a non-sequitur.

    I am willing to accept your point about increased metabolic activity, but you are still expecting me to take your word for it that (i) the observed increase in atmospheric CO2 has even a measurable effect on metabolism and (ii) that increase matabolism is purely beneficial.

    If there were a measurable effect from the sort of changes in CO2 that are likely to ocurr due to anthropogenic emissions then it should be a cause for some skepticism for you that you don't seem to be able to point to a study that directly proposes this mechanism or demonstrates evidence to suggest it is significant.
  31. I note that AHuntington1 continues to fail providing scientific references to his assertions. His argument seems to consist of associating a supposed higher efficiency of mitochondria when exposed to higher levels of CO2 with overall benefit for animal and human health, together with increased oxygen delivery due to the vasodilatory effect of CO2. It seems a little self contradictory, is beyond a stretch and is not supported by the litterature as far as I could tell. In fact, the whole argument is rather confused and conflates different reactions as well as apparent assumptions.

    AH1 asserts that people living at high altitude experience an increase CO2 to O2 ratio in their blood compared to low altitude dwellers. I could not find articles supporting that assertion. All known adaptations to high altitude, whether short or long term, are responses to hypoxia and physiological solutions to hypoxemia.
    I searched "lactate paradox" and found rather a lack of knowledge than anything allowing to make sweeping statements on whole body response, let alone mitochondrial metabolism.

    Interestingly, one study found increased mitochondrial efficiency, but associated with low levels of carbon monoxide.

    http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0041836

    As I could recall, vasodilation/constriction regulation is quite complex and involves both O2 and CO2, but also NO, and effects are different at the central and peripheral levels. If regulation is normal, there is no reason to believe that the range of O2 and CO2 will vary from what we need, since regulatory response will keep the levels where they need to be. People with COPD, who live with high levels of CO2, are not known to derive benefits from the higher CO2.

    This treats of O2 mediated vasoregulation:

    http://ajpheart.physiology.org/content/295/3/H928.full

    I have so far not found articles treating of mitochondrial metabolism's response to increased CO2. Other chemicals, however, are the subject of intense study.

    Studies of high altitude functional adaptation do not make much mention of mitochondrial metabolism either. However, it is worth noting that prolonged stays at high altitude lead to decreased density of mitochondrial populations, as well as reduced muscle mass (references below). The possibility of increased mitochondrial efficiency has been proposed but, to my knowledge, not investigated, and in any case would be associated with a decreased mitochondial population density, so the overall benefit is highly dubious. It has more signs of being an adaptation to the intense stress of hypoxia.

    Here are a few references on the subject, and about the so-called "lactate paradox", which does not appear to show in all situations.

    http://jap.physiology.org/content/83/2/661.abstract

    http://www.bio.davidson.edu/Courses/anphys/1999/Dickens/Dickens.htm

    http://www.ncbi.nlm.nih.gov/pubmed/19139048

    http://www.ncbi.nlm.nih.gov/pubmed/1623889

    It also appears that ventilatory response to CO2 is not significantly different among altitude acclimated subjects, although it is slower. Some hypotheses as to why that may be are briefly discussed at the end of this paper:

    http://jap.physiology.org/content/94/3/1279.full.pdf
  32. Philipe Chantreau, talking past me and scoffing at my claims, without refuting them (or even addressing the evidence I present), does not prove anything. What specific assertion have I made that is “confused” or “conflates different reactions as well as apparent assumptions”. If you don’t tell me what you are referring to, I will not know what it is (nor will any other reader).

    Of course adaptations to higher altitudes are responses to hypoxia of varying degrees (adapting to mild hypoxia provides the benefits that athletes who train at high altitudes exploit). Mild hypoxia would be the result of increased internal Co2 to O2 concentrations (but the Co2 would protect from severe hypoxia to an extent). I have read the Everest study on mitochondrial density, how do you square that with studies like this? http://www.sciencedirect.com/science/article/pii/0034568770900113

    To quote, “Hearts of domestic cattle from two groups, one born and raised at sea level and the other born and raised at an altitude of 4250 m, were studied to determine whether any mitochondrial adaptations to high altitude could be demonstrated. Direct counts of mitochondrial number revealed a 40 % increase in the high altitude hearts [..]”

    Here is some information on altitude training published by San Diego State University. http://coachsci.sdsu.edu/csa/vol24/table.htm

    To list some information presented in the link:

    “ALTITUDE USES MORE GLUCOSE THAN SEA-LEVEL
    Brooks, B. A., Roberts, A. C., Butterfield, G. E., Wolfel, E. E., & Reeves, J. T. (1994). Altitude exposure increases reliance on glucose. Medicine and Science in Sports and Exercise, 26(5), Supplement abstract 120.” This implies increased Kreb’s Cycle activity at high altitudes.

    “ALTITUDE DECREASES RELIANCE ON FREE FATTY ACIDS AND INCREASES DEPENDENCY ON BLOOD GLUCOSE
    Brooks, B. A., Roberts, A. C., Butterfield, G. E., Wolfel, E. E., & Reeves, J. T. (1994). Acclimatization to 4,300 m altitude decreases reliance on fat as a substrate and increases dependency on blood glucose. Medicine and Science in Sports and Exercise, 26(5), S21, Supplement abstract 121.” This implies increased Kreb’s Cycle activity at high altitudes.

    The lactate paradox not showing up in every instance does not disprove my claim that adaptation to high altitudes (therefore exposure to lower internal O2 to Co2 ratios, capable of inducing mild hypoxia) increases krebs cycle activity.

    You said, “This treats of O2 mediated vasoregulation: [..]” -I don’t quite see what your point is here, would you mind elaborating a bit?

    You also said, “It also appears that ventilatory response to CO2 is not significantly different among altitude acclimated subjects, although it is slower.” -Well, yea (and what do you mean by “it is slower”?). Why would the ventilatory response differ among people already acclimated to high altitudes? The study you posted did find a difference between high altitude natives and people living at sea level. To quote your study, “The major findings of this study were as follows. First, under conditions of euoxia (PETO2 _ 100 Torr), total ventilatory sensitivity to CO2 in HA natives is around double that of SL natives at SL.”


    So, would you mind elaborating a bit more on your point here?

    You need to be more specific in your criticism for me to be able to address your concerns.


    Dikran Marsupial, I have provided evidence for Co2’s antioxidant effects (in vivo) and Co2’s ability to increase oxygenation of tissues in vivo via the Bohr effect.

    Here are in vivo studies supporting Co2’s role as a fat soluble antioxidant.
    http://www.ncbi.nlm.nih.gov/pubmed/7770796
    http://www.ncbi.nlm.nih.gov/pubmed/7581542

    And here are some in vitro studies.
    http://www.ncbi.nlm.nih.gov/pubmed/9190222
    http://www.ncbi.nlm.nih.gov/pubmed/9139450

    Also consider therapeutic hypercapnia- boosting internal CO2 levels- to avoid lung injury. http://ajrccm.atsjournals.org/content/168/11/1383.full

    Interestingly (to quote the above link), “Acidosis, notably hypercapnic acidosis, is protective against organ injury in multiple experimental models”. This might explain the lower mortality rates in people at high altitudes.

    On question (i), adaptation to hypoxia does affect metabolism (see above links), and increasing internal CO2 to O2 ratios will induce this adaptation (via mild hypoxia). High altitudes are one perfect example of this.

    That leaves (ii); I cited the higher metabolic rates of people living at high altitudes, and the fact that they experience lower mortality rates.

    (see the wiki link I posted earlier and http://circ.ahajournals.org/content/120/6/495.full )

    These at least correlate increased metabolism with lower mortality rates. Do you have any evidence suggesting higher metabolic rates to be harmful? Or which suggest less ATP produced per glucose being beneficial in comparison to more?


    JasonB, you said, “I was under the impression that higher metabolic rates led to more oxidative stress and shorter lifespans” -Oxidative stress is dependent on many environmental factors, luckily Co2 is an antioxidant; supporting oxidative metabolism on the one hand and reducing oxidative damage on the other. Even if that theory is correct, Co2 would be protective.

    Look at the Wikipedia link I posted earlier, and the above link for evidence of reduced mortality rates among those at high altitudes. I will re-post the link I cited earlier regarding the higher metabolic rates of people at high altitudes here: http://jap.physiology.org/content/16/3/431

    You said, “Note that Spaerica was making the very valid point that all else is not equal,” -It is actually a completely invalid and irrelevant strawman that Spaerica built up against me, which you have now started attacking.

    To repeat myself (again), I am not making a judgment on the overall cost-benefit analysis, I am making a specific biological argument, in a specific context. I am only asking for this point to be included in the analysis (just like other ceterus paribus arguments which have already been included).

    The amount of resistance I am encountering when making this point is quite odd for the comments section of a website called skepticalscience.com; the inability to recognize my argument, as I have laid it out, characterizes dogmatism.


    CBDunkerson, See above strawman.


    Spaerica, See above strawman. Also, I am getting tired of reading attacks against my writing style, and accusations of “gish gallop” and various logical fallacies without making any attempt to specify what part of my argument you are actually attacking. My writing style is practically meaningless compared with the content of my argument (which you have consistently ignored) and attacking it borderlines on ad hominem. I will not reply to any more or your posts, unless you actually specify what you are talking about- unless you have something to say about the information I present.

    ..Geez, sorry for the long post. thx
  33. Taking the conversation back to square one on "C02 is a metabolic benefit," leaving aside whether that's true or not is it your assertion ahuntington1 that metabolic benefits of C02 are worth wholesale modification of Earth's atmosphere with attendant knock-on effects?

    Can you describe specifically how my day might be so much better breathing an atmosphere with a higher C02 concentration that the disadvantages are outweighed?

    Once you've shown in concrete terms how I'd stand to benefit from increased C02 respiration, next you need to show how confident you are in your predictions. Guaranteed? Maybe? A long shot?

    What's the risk/benefit equation here, in other words?
  34. doug_bostrom, you asked, "is it your assertion ahuntington1 that metabolic benefits of C02 are worth wholesale modification of Earth's atmosphere with attendant knock-on effects?"

    No, that is not my assertion. Where did you read that; can you quote me saying that?

    I am not making predictions on net effects. In fact, the more you make predictions on net, potential, future effects the higher propensity you have to be wrong.

    As to how increasing Co2 might help you in your daily life (whether through higher atmospheric levels or "therapeutic hypercabia") is up for you to decide for yourself, based on the available information and your specific health status. The same is true for Vitamin C, D, retinol and calcium.

    You asked, "What's the risk/benefit equation here, in other words? "

    I don't know (nor have I claimed to know), but the beneficial aspects of higher atmospheric Co2 should at least be part of the cost-benefit analysis.
  35. *edit, post 284. "I don't know (nor have I claimed to know), but the beneficial aspects of higher atmospheric Co2 should at least be part of the cost-benefit analysis."

    should read,

    "I don't know (nor have I claimed to know), but the beneficial aspects which higher atmospheric Co2 would exhibit on mitochondrial respiration should at least be part of the cost-benefit analysis."

    -thanks
  36. Well, emulating your level of justification for claiming that metabolic benefits of C02 should be considered w/regard to climate change--namely none-- then I claim we should consider the thermal expansion of the dry land on Earth in response to climate change as a possible benefit.

    Work it out; it's a surprising number.

    On the other hand, just as with speculation on how we might enjoy breathing more C02, there are downsides to all the thermally gifted "free land." For every km2 we get in handily expanded dry land we lose way more in freshly drowned land.

    Which leads to the further benefit of increased marine habitat, I suppose. Doubtless somebody's pushing that idea, too.
  37. ...edit 284. should read "therapeutic hypercapnia" ...my bad
  38. doug_bostrom, that is an interesting theory. Not to get too off topic but, I must ask, what do you mean by "For every km2 we get in handily expanded dry land we lose way more in freshly drowned land."?

    Would this be the result of increased evaporation and H2O in the atmosphere? Are you saying that total rainfall would increase on the planet during heating due to the greenhouse effect? (i vaguely remember reading something about Co2 causing the greenhouse effect which would cause increases in water vapor, which would wildly exasperate the greenhouse effect)

    Is this essentially the theory you refer to?
  39. doug_bostrom, you said, "emulating your level of justification for claiming that metabolic benefits of C02 should be considered w/regard to climate change--namely none--"

    This is ridiculous. Just saying that I have no justification, after I repeatedly provide it is willful ignorance (or just poor communication). What aspect of my argument is flawed? What are you talking about, specifically? If you can not be specific, you probably are dealing with an emotional attachment to a belief.
  40. Honestly, the metabolic benefits of Co2 to plants already is considered here. Why should the metabolic benefits of Co2 in relation to animals/bacteria not be considered?

    This is the question you must answer. Or you could dispute the information I present.
  41. Why should the metabolic benefits of Co2 in relation to animals/bacteria not be considered?

    What, with no actual claims attached? You've just said upthread that you make no conjectures on what might specifically happen in the way of metabolic benefits.

    How does one evaluate "it might be good?"

    W/regard to my "free land is good" argument vs. the "drowning land is bad" negative aspect, I'm sure you're aware of the sea level issue? Another thermal expansion problem, unfortunately, coupled w/ice loss.
  42. Doug_bostrom, If I did make such a concession, it was a typo. My claim is that elevating Co2 within a certain range increases kreb's cycle efficiency (metabolic rate), thru its antioxidant activity and its role in increasing the efficiency of oxygen distribution to the tissues via Bohr principle (as I have said many times).
  43. Ahuntington1: I am not making predictions on net effects

    That's a remarkable typo. Reminds me of the epic crash of the ski jumper that was shown as part of the program intro for ABC Sports events. Just seemed to go on forever!
  44. doug_bostrom, let me clarify my meaning here, I am not making predictions on net effects regarding the overall cost benefit analysis of anthropogenic Co2 emissions. I am making a claim on the specific effects that elevated Co2 has on the organism, which should be included in any cost benefit analysis. I am not claiming that anthropogenic Co2 emissions are either good or bad- overall. A missing factor in any cost benefit analysis can skew the result one way or the other.

    Does that help clear up the issue?
  45. when I say overall, I mean including every other potential factor (eg. maybe the analysis would add points for increased rates of mitochondrial respiration and take points off for old people dying of heat stroke).
  46. No, it doesn't help anything. You refuse to specify the benefits you anticipate from additional C02 in the atmosphere.
  47. AHuntington1 I offer this as helpful advice. SkS is interested in a fair portrayal of the science. We would also wish these metabolic benefits to be considered if there is good evidence to suggest they actually exist.

    So far you have pointed to a mechanism that suggest that there may be an effect, but have not provided any evidence that unequivocally suggests there is a measurable effect in vivo all things being otherwise equal. Evidence of a change in glucose metabolism at altitude is not evidence of this as there all things are not equal as the reduction in atmospheric pressure means there is less oxygen, rather than just higher CO2. It doesn't surprise me that respiration is less efficient at altitude (as we are not evolutionarily highly adapted to life at altitude) and therefore requires more energy. As a result, we are skeptical of you claims, but are willing to be persuaded.

    Is there anyone other than yourself that is currently proposing this hypothesis?
  48. My understanding of AHuntington1's position so far:

    1. CO2 will improve mitochondrial respiration, which he presents with evidence of small scale, controlled and very focused laboratory experiments.

    2. His statement is presented without any evidence of an actually realized positive benefit in at least some living creatures, and certainly not all.

    3. He self-admittedly makes no statement of the ultimate value of this benefit in the real world because he has not/will not put it into the context of all of the real world negative impacts that will accompany such a "benefit."

    4. He has not (presumably because he agrees it does not exist) presented any evidence that such a benefit would mean that increased CO2 levels will ultimately be more beneficial than harmful to human civilization (which, in the end, is the whole point, isn't it?).
  49. On another thread AHuntington1 and DSL were debating the potential of Hadley cell expansion to cause drying in the horse latitudes which would be considered a negative consequence.

    While Hadley cells are expanding, the expansion is seasonal and it is unclear what will happen in the future, see http://journals.ametsoc.org/doi/pdf/10.1175/2009JCLI2794.1. The effects of measured expansion in the Hadley cells depends greatly upon geography. The result over the ocean is fairly certain, there has been expansion. The result over land is very uncertain, see for example http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2538841/ in which they state that the greening of the Sahel is a potential (and rare) example of a beneficial tipping point. See section starting with "Sahara/Sahel and West African Monsoon (WAM)" and note that there are large uncertainties. Reading these two references I'm not even sure that Hadley expansion has any relevance at all in the Sahara and Sahel.
  50. No, Eric. I was objecting to AHuntington's apparent claim that desertification was a primarily human-caused phenomenon.

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