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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

Printable Version  |  Offline PDF Version  |  Link to this page

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 301 to 333 out of 333:

  1. DSL, ok, I see that now. Main conclusions  The current loss of mesic trees in the Sudano-Sahel zone appears to be driven by the sharp drop in rainfall since the 1960s, which has effectively stranded anthropogenically distributed species beyond their rainfall tolerance limits.
  2. Well, I'm not entirely sure but the way I see it, AH1 argument is this:

    More atmospheric CO2 will lead to higher PaCO2 in circulating blood of live healthy animal subjects. This is a good thing because higher PaCO2 leads to reduced lymphocyte production of active oxygen forms and improved mitochondrial efficiency. The anesthesiology study on therapeutic hypercapnia applies to deperately ill patients on ventilators who are receiving what is called in medical jargon "heroic measures" so I consider it a stretch to apply that at any level to healthy subjects.

    In support of this theory, AH1 cites effects seen in high altitude acclimated subjects, under the assumption that these subjects experience higher than normal PaCO2 and that (it seems to be the argument) the higher PaCO2 is the reason for the beneficial changes. AH1 also asserts that people living at high altitude have better life expectancy.

    Let's examine the antioxidant part. It refers a number of studies by Kogan, Bolevich and Diliniak, with various others, that rely on chemoluminescence of lymphocytes. In this study it is found that the effect applies to healthy subjects but to only 30% of subjects with bronchial asthma, suggesting a possible decreasing sensitivity in subjects experiencing higher than normal PaCO2 due to the asthma. In this further study the same authors reach the following conclusion:
    "It may be held that the literature-described use of carbon dioxide for the treatment of bronchial asthma is justifiable only in a lower proportion of patients who have preserved a high sensitivity to the inhibitory effect of carbon dioxide on the generation of active oxygen forms." That's already not so encouraging, back in 1996.

    These studies are 16-17 years old and relied on chemoluminescence as an indication of lymphocyte activity.
    This articel, which predates the Kogan studies, shows some difficulties in interpreting CL results:

    http://www.ncbi.nlm.nih.gov/pubmed/7663293

    Further investigation revealed that the changes in chemoluminescence observed were rather a consequence of the CO2 concentration itself than that of CO2 induced lymphocyte inhibition:
    http://www.ncbi.nlm.nih.gov/pubmed/12033328

    I work with COPD and asthma patients quite often in a critical care setting. I have not heard of any form of hypercapnic therapy applied to these patients for the purpose of preventing free radicals formation.

    I looked at more recent reviews and did not see mention of hypercapnia. 17 years later, it does not appear that the line of research followed by Kogan, Bolevich and Diliniak was actively purseued by others.

    Permissive hypercapnia is normal in deperately ill ARDS patients because there are things taking much higher priority in these patients that bringing down the PaCO2, namely ensuring adequate oxygen delivery to the vital organs.

    Consideration on other claims to follow.
  3. Eric (skeptic),

    Of course the expansion is seasonal. That's the nature of the Hadley Cell (it migrates north and south of the equator with the sun).

    It can't, for the most part, expand only over the ocean and not over land. It doesn't work that way.

    And with the expansion, the arid areas must expand. This means Texas, Arizona, Oklahoma, Mediterranean Europe, and other places.

    There's no getting around this. The deserts will expand in places where human populations will be directly affected.
  4. Let's take a look now at the high altitude claims. Those were put forth seemingly under the assumption that a high altitude environment presents conditions similar to what will be experienced in an atmosphere with more CO2. For myself, I consider the analogy inappropriate considering how significant the hypoxia is in the examples considered. Nonetheless, let's see what the science says.

    As I recall, AH1, you argued that high altitude induced a higher than normal PaCO2 to PaO2 ratio, which would be called respiratory acidosis.

    Educational texts on the subject disagree:
    http://jan.ucc.nau.edu/~pe/exs336web/336altitude.htm

    It is also contradicted by this study:
    http://www.ncbi.nlm.nih.gov/pubmed/9079156

    Note that Sherpas do have a slightly higher PaCO2 than Caucasians, but at all altitudes. Note also: "Moreover, in Caucasians sojourning for 3 weeks at 5050 m, PaCO2 kept decreasing whereas pHa, PaO2 and SaO2 remained constant."

    In caucasian people, acclimatation to altitude led to a lower PaCO2. In fact, the study points to Sherpas having a higher PaCO2 purely as an adaptation to limit the respiratory alkalosis brought by all the other responses to hypoxia.

    I looked at the life expectancy of various countries and did not find evidence of an advantage to high altitude living:
    https://www.cia.gov/library/publications/the-world-factbook/rankorder/2102rank.html

    Nepal ranks #161, less than low lying countries without well developed health care, like Viet-Nam and many more. Modern advances have brought Sherpas' life expectancy to from 35 to 65. The islands of Sardinia and Okinawa have the highest rates of centenaries in the World.
    http://en.wikipedia.org/wiki/Sardinia

    The study on animal hearts cited earlier was given a somewhat selective quote. This study points to cattle heart adaptation to hypoxic conditions and says nothing about CO2. Here is the end of the abstract:
    "These changes are discussed as an intracellular mechanism which would serve to preserve oxidative metabolism in hypoxia, particularly under exercising conditions. The effective conservation of oxygen pressure head by this means is probably less than one mm Hg." The hypoxic conditions endured by these animals are severe enough to trigger a massive adaptation of the heart, whose sole purpose is to ensure adequate oxidative capability. No doubt that, put at sea levels, these would be some pretty darn athletic cows, at least for a little while, until they adapt to the new conditions. High altitude athletic preparation is well known and practiced because it enhances oxygen transport and oxygen use, not because it raises CO2. It is also well known that the benefits of high altitude preparation fade away pretty quickly when the body lives again at normal altitude.

    I cited a study discussing the ventilatory response to CO2 and was told that the point was missed. The point is that the brain stem centers that regulate ventilation have sensors that are extremely sensitive to CO2. The moment PaCO2 increases, ventilation kicks in to re-establish normal range. In other words, healthy people will not all of a sudden start to live with a higher PaCo2, altitude or not, higher amospheric CO2 or not.

    In summary:
    The claim that high altitude leads to higher PaCO2 is not verified in scientific litterature or physiology texts. Sherpas have higher PaCO2 at all altitudes. Their life expectancy is mediocre by world standards.

    Response to altitude related hypoxia actually reduces PaCO2.

    The claim that people living at high altitude live longer has no merit; it is not verified by worldwide demographics. Nepal ranks #161, Bhutan is #158. The top 10 include Monaco, Macau, Hong-Kong, Singapore and Gernsey, where people live pretty much at sea level. In japan (#1) the immense majority of the population resides in the low lying cities.

    I see no evidence of any altitude related PaCO2 effect on mitochondrial population and efficiency. What was presented instead is evidence of mitochondrial response to hypoxia.

    Although it was kinda fun to look up, I'm not sure I'm going to continue spend time on this.
    Response: [Sph] And that is how one presents a scientific argument and supports it with citations/references, rather than mere declarations of confident knowledgehood.
  5. doug_bostrom, you said, "You refuse to specify the benefits you anticipate from additional C02 in the atmosphere." OK, let me clarify a bit.

    Benefits depend on the rate of increased atmospheric Co2. A very slow, steady build up in Co2 levels would be ideal (allowing for organisms to properly adapt- it would be horrible if Co2 went from 400 ppm to 10,000 ppm overnight, we would all be dealing with hypercapnia as in altitude sickness) within a certain limit.

    The benefits, after adaptation has taken place (and metabolism is boosted depending on the degree of hypercarbia) are the benefits associated with higher altitude dwellers (because organisms adapting to the higher internal Co2 to O2 ratios of high altitudes are a perfect case study the effects of hypercarbic adaptaion, as I have pointed out). Namely, reduced mortality rates, reduced level of injury (due to the mild respiratory acidosis), and increased metabolic efficiency.

    Dikran Marsupial, but adaptation to high altitudes does provide a perfect illustration of higher internal Co2 to O2 ratios. Altitude sickness is an adaptive response to hypercapnia. The effects which high altitudes exhibit on adapted dwellers (higher metabolism, lower mortality rates, etc.) is what one would expect from higher exposure to Co2, through the mechanisms I have described (antioxidant, promoter of krebs cycle activity).

    Sphaerica, on 1. I agree with this statement (again, controlled studies, describing specific mechanisms are required to make the claim).

    on 2. The use of absolutes renders this statement obviously false.

    on 3. My argument is not one of ultimate value (in the sense of making a judgement on the overall "goodness" or "badness" of anthropogenic atmospheric Co2); this is the strawman that I identified earlier.

    4. I have not made this judgement, because it encompasses literally millions of other factors, and value judgements. I am just pointing out that the benefits that Co2 exhibits on organisms should be included in the cost-benefit analysis. Do you disagree? If so, why?


    Eric and DSL, I think my point has been misinterpreted a bit, but would you mind if we continue hashing out desertification on the other thread? This one is already quite long and is pretty all encompassing. When we come to some conclusions over there, the issue can be more easily incorporated into this thread.

    thanks,
  6. Oh what the heck since we're at it. Here is an interesting study on long term changes of plant mitochondrial metabolism in elevated CO2 environment.

    http://www.plantphysiol.org/content/145/1/49.full.pdf

    Quote from the end of the abstract:
    "However, despite growth enhancement and as a result of the inhibition in cytochrome pathway activity by elevated CO2, total mitochondrial ATP production was decreased by plant growth at elevated CO2 when compared to ambient-grown plants. Because plant growth at elevated CO2 increased biomass but reduced respiratory machinery, activity, and ATP yields while maintaining O2 consumption rates per unit of mitochondria, we suggest that acclimation to elevated CO2 results from physiological adjustment of respiration to tissue ATP demand, which may not be entirely driven by nitrogen metabolism as previously suggested."
  7. "we would all be dealing with hypercapnia as in altitude sickness."

    Funny, earlier hypercapnia was proposed as a good thing. I guess perhaps you mean to make a dosage dependent distinction.

    Nonetheless, this is what better sources say on altitude sickness:

    http://wiki.medpedia.com/Altitude_Sickness
    Quote:
    "Although treatable to some extent by the administration of oxygen, most of the symptoms do not appear to be caused by low oxygen, but rather by the low CO2 levels causing a rise in blood pH, alkalosis."

    Altitude sickness hypercapnia eh? right. I'm sorry AH1, you're full of it. I'm done here.
  8. Wow.. I missed this whole page when commenting earlier. Thanks for attacking the information! I really enjoy a good dialogue.


    Philippe Chantreau, I said high altitude natives have lower general mortality rates, not increased longevity.

    you said regarding Co2's antioxidant activity, "Further investigation revealed that the changes in chemoluminescence observed were rather a consequence of the CO2 concentration itself than that of CO2 induced lymphocyte inhibition:
    http://www.ncbi.nlm.nih.gov/pubmed/12033328"

    This is a very interesting study! But if you'll notice, it claims that CO2 can enhance chemiluminescence (a sign of oxidative damage [ http://www.sciencedirect.com/science/article/pii/0003986179901024 ]).
    Studies using chemiluminescence as a factor in determining the antioxidant nature of a substance would show a decreasing rate of chemiluminescence- because it is associated with lipid peroxidation.

    Furthermore, when you mention "In this study it is found that the effect applies to healthy subjects but to only 30% of subjects with bronchial asthma." you bring up in vivo evidence that supports CO2's role as an antioxidant. The fact that there is a threshold to its protective action is only reasonable.

    People with COPD or severe asthma already are exposed to higher internal CO2 to O2 ratios. The fact that there is an antioxidant benefit in 30% of asthmatics who participated in this study helps my argument.

    this study, http://www.ncbi.nlm.nih.gov/pubmed/9079156 , which you posted is interesting. It could disprove a (minor sub-)theory that I presented regarding the mechanism of mild respiratory acidosis reducing organ damage and thus mortality rates.

    I would think that the more extreme elevation a person is at (everest like), the more alkaline they would be in general (because of a respiratory response to reduced internal O2 levels). But people who are heavily acclimated to any higher elevation will be more acidic than people actively adapting to said elevation. Your study shows this to be true. People acclimated to 6000 ft above sea level would be more acidic in general than Sherpas on Everest.

    It also shows that the life-long acclimation to hypoxia of the sherpa makes him slightly more acidic (because of increased PaCo2 levels), through depression of respiration. I would expect white boys climbing everest to be hyperventilating like crazy and thus induce respiratory alkalosis. Remember that the rate of ventilation is the major immediate adaptive response to hypercapnia and high altitudes, which is depressed in those heavily acclimated (like the sherpas).

    you said, "Altitude sickness hypercapnia eh?"

    Yes, which will cause an immediate urge to hyperventilate changing respiratory acidosis into alkalosis- changing hypercapnia into hypocapnia.

    you said, "I looked at the life expectancy of various countries and did not find evidence of an advantage to high altitude living:"

    Oh yea, I'm sure you took all the other potential factors into account as well (such as rates of smoking, drinking, self-flaggelation, empty calorie consumption, intake levels of and quality of fat, average caloric intake, STDs, the fact that many countries vary wildly in internal altitude etc.)

    you said, "The claim that high altitude leads to higher PaCO2 is not verified in scientific litterature or physiology texts. Sherpas have higher PaCO2 at all altitudes."

    What?- doesn't this study show that those highly adapted to high altitudes (Sherpas) DO have increased PaCO2, and are more acidic than those who have not adapted as much?

    What do you think of the cow heart studies I mentioned (as opposed to the plant one you mentioned), which show elevated mitochondrial density in cows adapted to higher elevations (lower internal O2 supply in relation to CO2)?
  9. **Edit # 308- cow heart studies should read, "cow heart study"

    thanks
  10. 305, AHuntington1,
    I am just pointing out that the benefits that Co2 exhibits on organisms should be included in the cost-benefit analysis. Do you disagree? If so, why?
    First short answer: You haven't established benefits that CO2 exhibits on organisms, you've merely claimed them.

    Second short answer: Because I live in the real world, where imagined minor benefits do not outweigh proven major drawbacks.

    Beyond this, it is silly to make the presumption that increased CO2 will be beneficial to all species equally. In fact, try reading this article.

    Bottom line: I find your point to be both worthless and misleading. It adds nothing to the discussion. It's like being given a cyanide capsule and being told "look on the bright side, it tastes like almonds!"
  11. Sphaerica, you said, "You haven't established benefits that CO2 exhibits on organisms, you've merely claimed them."

    Well, way to ignore all of the evidence I have supplied so far. Please address my info, or stop posting.

    you also said, "Because I live in the real world, where imagined minor benefits do not outweigh proven major drawbacks."

    You are still attacking the same strawman...

    you say, "it is silly to make the presumption that increased CO2 will be beneficial to all species equally. In fact, try reading this article."

    Ok, well here's a new strawman, at least. Where did I ever say that elevated CO2 would be beneficial to all species equally? Where are you getting this from, if you don't mind me asking?

    Bottom line: consistently attacking strawmen and using red herrings does not make a point, nor even come close to proving me wrong. Implying that I do not live in the "real world" and that I am "imagining" things, drawing up bogus comparisons between CO2 and cyanide, using red herringss to distract from my point- these things are not acceptable in a scientific discussion and some of them border on ad hominem attacks.

    I will not engage in a discussion with you until you display the ability to carry on a respectable, scientific dialogue.
  12. Let's rinse and repeat, ahuntington1, since we've been through the citation mill again and still have not heard any specific claims useful for evaluating whether metabolic benefits of increased atmospheric C02 concentration might be worth attendant risks.

    Can you describe specifically how one's day might be so much better breathing an atmosphere with a higher C02 concentration? What would a subject notice? What would be the impact on mortality and susceptibility to adverse health experiences? What's the payoff outside of a test tube?

    If you can show in concrete terms how the population stands to benefit from increased C02 respiration, how likely are the specific benefits you've shown? Certain? Sometimes? Almost never?

    What's the risk/benefit equation here? Be specific. For instance, for a person living in Dhaka, Bangladesh is the payoff worth it?
  13. doug_bostrom, what attendant risks are you referring to? For humans to be negatively affected by atmospheric CO2 it would have to be over 4% (which is when deleterious effects begin occurring, if I remember correctly). Increasing atmospheric CO2 from 400 ppm to 10,000 ppm overnight would have negative health effects, but this is not very realistic.

    you asked, "What's the risk/benefit equation here? Be specific. For instance, for a person living in Dhaka, Bangladesh is the payoff worth it?"

    I have no idea- again it has to do with many other factors. Eg. if someone is starving or dehydrating increased CO2 would probably not be very effective.
  14. Ahuntingdon1, you're declaring bankruptcy for your premise. You know that, right?
  15. AHuntington1,

    1) You have not supplied a single citation which proves your point.

    2) It is a "strawman" only because you refuse to address the point. A positive which is outweighed by the negatives is of no value. It is a simple reality. The fact that you want to ignore that reality does not make it a strawman, it makes it an argument you want to avoid because it's one you can't win.

    Let me state it more clearly, then: Your point that CO2 will provide the benefit of improving mitochondrial respiration, true or false, is irrelevant because it ignores the other greater, negative impacts associated with CO2.
  16. doug_bostrom, um, would you please be a little more specific? Again, I have no idea what you are referring to (nor should I be expected to read your mind).
    thanks,

    Sphaerica, (-snip-).

    (-snip-)
    Response: [DB] Inflammatory and sloganeering snipped. Please ensure all comments comply with the comments policy before posting further.
  17. Oh yea, I'm sure you took all the other potential factors into account as well (such as rates of smoking, drinking, self-flaggelation, empty calorie consumption, intake levels of and quality of fat, average caloric intake, STDs, the fact that many countries vary wildly in internal altitude etc.)


    Oh, the irony...
  18. AHuntington1,

    I'll make it easy for you.

    1. My statement is that your statement about mitochondrial respiration is irrelevant, because the negative impacts of temperature and water availability will vastly outweigh any possible positive influence on mitochondrial respiration.

    2. There is no actual evidence that increases in atmospheric CO2 will result in improved health for any fauna through improved mitochondrial respiration.

    If you are in opposition to either of these statements, you are asked to supply specific references that clearly support your position. You are also asked to paste in the quotes of any segments from the conclusions which support your position (simply providing links to papers and claiming that they support your position will not be adequate, because it leaves you with too much latitude to simply fudge it).
  19. How weak of me to be suckered in to this again. For my defense, I have to say that AH1's stuff is really funny in a way. For the sake of the sincere reader examining this thread, here is some more:

    AH1 gives every indication that he searches the web with the purpose of finding every little bit that could be used to say "CO2 is good for us." In the course of doing so he finds stuff that he does not really understand and makes bold assertions that he later amends by trying to imply that he meant something different.

    We had this on post#250: "neither aerobic nor anaerobic bacteria can survive without Co2 highlights this fact." With a link to paper that does not exactly say what AH1 says it says.
    From the abstract:
    "the observation that relatively low concentrations of CO2 were adequate for satisfactory growth of certain anaerobes was of particular interest."

    Walker and Winslow showed as early as 1932 the ability of E.Coli to grow in the absence of CO2 on a medium more complex than the very basic one. That's obviously not the kind of depth where AH1 will go. Whatever.

    Then we get this:
    "High altitudes provide a real life example of a population that breathes a higher Co2 to O2 ratio", in the same post. When corrected on this, AH1 amended himself by saying that it was a "mis-type", and what he meant was that people living at high altitude have a higher "internal" CO2 to O2 ratio. I had to introduce the concepts of PaCO2 and PaO2, which are very familiar to those of us who really work with this and really save the lives of people in respiratory failure.

    He showed no evidence of that supposed imbalance. Instead he cites this article:
    http://jap.physiology.org/content/16/3/431
    The article says nothing at all about PaCO2 to PaO2 ratio but only reinforces the well known higher ability of high altitude residents to transport and use oxygen:
    "The higher O2 consumption per kilogram of FFM, C, or S in the high-altitude resident seems to be one of the many mechanisms developed by the body in its process of adaptation to the low O2 tension."

    I will add that, from a purely physiological point of view, CO2 elimination should be easier at high altitude. The body processes are unchanged and the PaCO2 resulting from metabolism remains about the same, but the absolute pressure of CO2 in the ambient air is much lower at high altitude, thereby facilitating CO2 elimination in the lungs.

    The published litterature suggests that high altitude dwellers are in fact in a steady state normal acid-base balance adapted to the lower pressure of CO2, exactly as one should expect from regulatory mechanisms:
    http://www.ncbi.nlm.nih.gov/pmc/articles/P(1)MC3068777/

    I note that this paper represents a change from the previous dominant idea, which was one of chronic alkalosis.


    I showed a study looking at Sherpas that found a slightly higher PaCO2 than other people. AH! AH1 jumped on it with the belief that it proved his point but he missed that part: "(1) respiratory alkalosis was a common finding both in Caucasians and Sherpas."

    He also seemed to have missed this part: "Apparently a more efficient adaptation to hypoxia allows Sherpas to limit alkalosis through a lower ventilatory drive and to maintain SaO2 at the same PaO2 by decreasing the [2,3-DPG]/[Hb] ratio."

    Sherpas limit alkalosis by a more efficient response to hypoxia but still experience it. I'll note that Sherpas seem to be unique in this ability; that points to a genetic difference that has not surfaced in other people living at high altitude like those in the Andes.

    The point is: there is no PaCO2 to PaO2 imbalance in high altitude dwellers. Alkalosis is the initial response and an incidental cause of the reaction to hypoxia. Balance is restored with aclimation. Alkalosis is seen in higher altitude excursions even in highly adapted dwellers. The alkalosis is brought by responses to hypoxia, not hypercapnia.

    AH1 tries to wiggle out of his gross error on altitude sickness by trying to imply that the sickness is due to alkalosis as an overreaction to hypercapnia and that is what would happen to people exposed to suddenly increased high levels of CO2 at normal pressure. Total nonsense. If one was suddenly exposed to high levels of CO2 at normal pressure, ventilation would increase in order to restore normal PaCO2, then would stabilize as that goal would be reached and alkalosis would not develop. In altitude sickness, hyperventilation persists despite alkalosis because of hypoxemia, leading to further alkalosis. The vascular changes associated with low Co2 and low O2 are currently believed to be the most likley causes of vessel permeability leading to pulmonary edema and cerebral edema.

    AH1 made an argument about people's death rates at high altitude. I took the bait and looked at life expectancy, which of course did not support his argument. Then he went on to remind us of the distinction in terms and listed all sorts of factors that are more likely to affect mortality rates than life expectancy. Right. Makes sense.

    It is difficult to devise a good metric for population health. Despite controversy, according to numerous demographics textbooks and the E.U. demographics department, one of the best, if not the best, indicators of population health is the expected number of years without disability or disease: healthy life expectancy. Its detractors have yet to come up with a better one.

    Let's see how that pans out.

    This paper has plenty of details, methods, etc, and nifty graphics on healthy life expectancy:
    http://www.who.int/healthinfo/paper38.pdf
    No evidence of special benefit to high altitude locales.

    Easier to look at: healthy life expectancy ranking

    http://www.photius.com/rankings/healthy_life_table2.html

    Conclusion: AH1 makes all sorts of claims for which he has no evidence, cites papers as evidence of assertions of his that the papers in fact do not support, misunderstands his own cites and that of others, selects quotes in his and others' citations, makes sweeping statements not supported by any evidence existing out there, adjusts his language when he's caught spewing nonsense. Impressive. This time I'm really done. I'd advise all to resist temptation better than me and NFTT.
  20. And mods, feel free to snip whatever content above you find inflammatory, as the substance will be unchanged.
  21. Last detail: "incidental cause" above should be "incidental consequence."
  22. one more thing
    AH1 (@313) is off by a factor of ten regarding harmful CO2 levels:

    "In summary, OSHA, NIOSH, and ACGIH occupational exposure standards are 0.5% CO2 (5,000 ppm) averaged over a 40 hour week, 0.3% (3,000 ppm) average for a short-term (15 minute) exposure [...], and 4% (40,000 ppm) as the maximum instantaneous limit considered immediately dangerous to life and health. All three of these exposure limit conditions must be satisfied, always and together."

    available here
  23. AHuntington1 wrote: "Dikran Marsupial, but adaptation to high altitudes does provide a perfect illustration of higher internal Co2 to O2 ratios."

    You are missing the point. How do you know that the effect is due to the difference in CO2 to O2 ratio rather than to other changes in body chemistry due to lower atmospheric pressure and lower oxygen availability. How do you know that the same effect will also be seen at sea level pressure with the concentration of O2 to which we are evolutionarily adapted?

    Now I suspect that if this were the case, then competent scientists would have performed the experiment to find out (e.g. monitor glucose metabolism in a sealed environment in lab conditions where all other factors can be controlled). The fact that you can't supply a single study where this has been done suggests to me that the scientists who work on this don't suspect that mechanism has a significant effect.

    So please answer this question directly and unambiguously: Is there anyone other than yourself that is promoting this hypothesis, yes or no?
  24. Dikran, there is no PaCo2 to PaO2 imbalance. It's rather the opposite. The article by Dr Zubieta-Calleja I cited above has the complete discussion. BTW, the address was damaged, this is the real link:

    http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3068777/?tool=pmcentrez

    The tutorial on altitude sickness I cited earlier is also very clear. Hypercapnia is not involved. Hypoxia is the primary cause of hyperventilation that persists to and beyond alkalosis. AH1 has no clue what he's talking about, he really should be ignored.
  25. Philippe Chantreau, you said, "Walker and Winslow showed as early as 1932 the ability of E.Coli to grow in the absence of CO2 on a medium more complex than the very basic one. That's obviously not the kind of depth where AH1 will go. Whatever."

    Whatever, indeed. http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2065164/pdf/brjexppathol00219-0137.pdf

    Please cite the article (and medium for that matter) you are referring to.

    you said, "I had to introduce the concepts of PaCO2 and PaO2 [...]"

    When I have introduced biological concepts on this thread, I have had to repeatedly describe them in great detail (when wikipedia is available). I didn't want to make extra work for myself by introducing PaCO2. Internal CO2 to O2 ratios are a simple way to describe PaCO2 to PaO2. I am very glad that you wield knowledge of biology, and are willing to criticize my information- thank you, btw.

    you said, "from a purely physiological point of view, CO2 elimination should be easier at high altitude."

    Of course it is, this is why adapted organisms have a reduced rate of respiration, thus having higher PaCo2 (and be slightly more acidic) than someone actively adapting.

    sou said, "If one was suddenly exposed to high levels of CO2 at normal pressure, ventilation would increase in order to restore normal PaCO2, then would stabilize as that goal would be reached and alkalosis would not develop."

    You are absolutely right. I concede this point, although atmospheric CO2 increasing as a result of burning (of fossil fuels or trees and grass) would cause a reduction in concentration of O2, all else being equal. Reduced atmospheric O2 pressure is a large potential effect of widespread human fires.

    you said, "I note that this paper represents a change from the previous dominant idea, which was one of chronic alkalosis."

    Thanks for fixing the link! It is an interesting paper which does change the previous (or current depending on who you ask)dominant theory as to acid/base imbalances at altitude. I am skeptical, though, because the mechanism for lower atmospheric O2 pressure causing alkalosis in Sherpas makes sense.

    you said, "AH1 made an argument about people's death rates at high altitude. I took the bait and looked at life expectancy,"

    Well you took bait that I didn't provide. I did say mortality rates (as did the wikipedia, and study I posted).

    you said, "The vascular changes associated with low Co2 and low O2 are currently believed to be the most likley causes of vessel permeability leading to pulmonary edema and cerebral edema"

    This is an interesting theory, but mortality rates from cardiovascular disease are significantly lower in people adapted to low pressure (whats a bigger problem, edema or heart disease?). this study http://circ.ahajournals.org/content/120/6/495.full (which I have already posted), shows significantly decreased mortality rates for people with cardiovascular diseases who are exposed and adapted to the low pressure of high altitudes (reduced respiratory rate, increased PaCO2 in relation to a steady PaO2 or higher internal CO2/O2 ratio).

    you said, "Sherpas limit alkalosis by a more efficient response to hypoxia but still experience it."

    Of course they do; to quote myself, in post #308 "the more extreme elevation a person is at (everest like), the more alkaline they would be in general (because of a respiratory response to reduced internal O2 levels)"

    you said, "Dikran, there is no PaCo2 to PaO2 imbalance. " Adaptation to lower pressure increases PaCO2- PaO2 is relatively stable at all altitudes.

    I am glad that you seem to accept (or at least not reject) the evidence I have presented regarding CO2's antioxidant activity.

    and again, thank you for addressing the points that I did make, I sincerely appreciate it.


    gws, thank you for pointing that out (perhaps this is what doug was on about), that totally should have read ~ 0.4% (or ~ 4000 ppm). Remember that 4000 ppm is a tenfold increase in current atmospheric levels.


    Dikran Marsupial, you said, "You are missing the point. How do you know that the effect is due to the difference in CO2 to O2 ratio rather than to other changes in body chemistry due to lower atmospheric pressure and lower oxygen availability. "

    Thanks for clearly making the point; The effects of adaptation to high altitudes (increased metabolic rate etc.) are consistent with what one would expect from increased exposure to CO2 (because of its antioxidant activity, and its role in protecting and properly distributing the body's O2 supply) which is one result of adaptation.
  26. Moderators - At this point, given the large number of recent posts on this thread circling around a single sub-issue, a side-track, raised by (but really, IMO, not supported by) a single poster, perhaps it's time to invoke the Comment Policy stating:

    "Comments should avoid excessive repetition"?
    Response: [DB] Agreed. That also constitutes sloganeering/PRATT.
  27. All that and still no answer to Dikran's question


    So please answer this question directly and unambiguously: Is there anyone other than yourself that is promoting this hypothesis, yes or no?
  28. AH1's style is strangely reminiscent of that of Damorbel's and a few others who cluttered the 2nd law's thread with endless repetition of grotesque nonsense and self contradictions. KR's suggestion is appropriate.
  29. This could be the "acceptance of AGW" tipping point for people in the US: drought-related bacon shortage predicted.
  30. A thousand years ago climate is warmer than today. But we can not see in that period any traces of the predicted apocalypse connected to warming. It means that in calculations and models of climatologists is lurking fundamental err.
    Response:

    [DB] Please familiarize yourself with this site's Comments Policy; additionally, please read the Big Picture post.

    Finally, commenting at Skeptical Science works best if you first limit the scope of your comment to that of the thread on which you post your comment and then follow up on those threads to see what respondents have said in response to you. There are quite literally thousands of threads here at SkS; if you do not engage with the intent to enter into a dialogue to discuss the OPs of the threads on which you place comments, you invite moderation of your comments.

    Note that your first statement is an unsupported assertion. When making assertions counter to that which is the understood state of the science, it is customary here to then also furnish a link to a reputable source which supports your assertion.

  31. setit-bagain:

    Assuming your comment survives moderation (it may not as it appears to be little more than baseless sloganeering) the simple fact is that your claim is unequivocally false. See here, or of course the IPCC AR4 (Working Group 1, §6.6) for summaries of the evidence.

    In addition, please substantiate your claims, with reference to the peer-reviewed literature that (a) there is a predicted apocalypse widely accepted among climate scientists, and (b) that even if this prediction is accepted, that it is false.

    Finally, your claim is, in and of itself, quite vague, so for a productive discussion please come up with a list of specific "fundamental errors" you feel exist, with substantiation in the literature to support your claims, and bring them up on the pertinent threads.
  32. And a further addition in addition to falseness - during HCO global temperatures were quite possibly warmer than today and definitely warmer in parts of the globe. However the transition to warm and cold was very slow compared to today's rate of change. Rate of change is what matter, not the absolute temperature.
  33. setit-bagain doesn't appear to be down with that whole "read the body of literature" thing. My life would be much happier if I never had to see that goofy Harris & Mann chart-picture-thing again.
  34. Having occasionally lurked for some time on SkS, I have a longstanding question for anyone who like to take a crack at it. I'd like to be able to offer to some of my skeptical friends and family an example of how AGW might be falsified. Let's say I'm conversing with a skeptic who (perhaps grudgingly) admits the reality of modest AGW but who considers it nothing to fret over, and certainly nothing to justify government intervention. Is there some precise, quantifiable outcome I can predict will obtain within 20 years from now if C02 remains above 400 ppm (or 450 or 500 or whatever), such that if it doesn't happen, I would have to concede I was mistaken as a "warmist"? Something along the lines of Haldane's famous rabbit in the Cambrian? Something I could place money on and collect in 2033?

    For example, could I say, if C02 remains above 400 ppm, then if by 2033 the global sea level average hasn't risen by at least 6 inches (or whatever) or the surface area of the Maldives has not been reduced by 10% (or whatever) or the Antarctic has not lost more than 5% (or whatever) of its ice volume or some other precise costly catastrophe does not occur before then, then we warmists were all mistaken?

  35. @KenD 50 years of cooling whilst atmospheric CO2 continues to rise, without evidence of substantial changes in the other forcings would constitute a pretty sound falsification I would have thought.  The good thing is that many climate models are available in the public domain, so at least the models are easily falsifiable by plugging in the observed forcings and seeing if the models can explain the observed climate.

  36. Sure, KenD.  

    1. Arctic sea ice will be effectively (<250k km2 area) gone in ten years at summer minimum.  According to Funder et al. (2011), Arctic sea ice extent hasn't been lower than current in about 8000 years.  The trend is currently greater-than-linear, and the linear trend has it effectively disappearing at summer minimum within eight years, about 70 years ahead of IPCC AR4 projections.  Even if we remain stable at 400ppm, sea ice is going to continue to decline thanks to the oceans continuing to move toward their equilibrium climate response to the stabilized forcing.

    2. Antarctic and Greenland land ice loss will continue over the next decade at least at the current rate found in Shepherd et al. (2013).

    3. Within fifty years, the process of ecological deconstruction or dis-integration will be obvious.  Species that can move rapidly will leave their niches and attempt to establish equilibria within environments.more suitable to their current configurations.  That may leave some slower and more interdependent species in the lurch.  Species may also respond genetically.  Then there are species that are up against the wall.  A wide range of studies, if academia is alive and well, should be reporting this type of significant change in the biosphere (already occurring, actually). 

  37. In other words, KenD, you don't have to wait for 2033.  You can win that bet right now.

  38. KenD,

    20 years is too short of a time frame, and making any one (or three) specific projections is dicey.  We're running a one-time experiment that has never happened in the past 100 million years... if ever.  There is no solid way to predict exactly what will happen when.  We know that bad things are going to start to happen now, but even then, no one will be able to connect the dots and unequivocally say "this is due to climate change."

    But things will get progressively worse.  The day will come in ten, twenty, or thirty years (maybe more, but I don't think so) when so many different things are happening and changing that the costs will be horrendous.

    With that said, whenever that day comes... there will still be more warming in the pipeline.  Climate change takes time, even though we have accelerated the process by a factor of 100.  So when the day comes that (if you could pick the right variables) you win your bet, it will already be way, way too late to do anything about it.  The genie will be out of the bottle. And things will continue to get worse from there.

    My favorite analogy for his is the man who jumped off of the roof of a skyscraper, and whenever he passed an open window, he was heard to say "So far, so good."

    But, to return to your question: no, I don't think so. There is no one particular parcel of evidence that you can reliably pick now, especially in a time frame as short as 20 years.

  39. Thanks for your helpful responses, DSL, Sphaerica, and Dikran. I'll see if one of my friends is willing to make a wager on the following, assuming we stay at or above current C02 levels (just shy of 400 ppm):

    If total ice sheet loss over the next 10 years is less than 3.44 trillion tons (344 billion tons times 10 years), then he wins and I lose.

    If Arctic sea ice is > 250k km2 area in 2023 at summer minimum, then he wins and I lose.

    The friend I'm thinking of is a fan of WattsUpWithThat, so I'm hopeful he'd be willing to bet on the above. I'm assuming these are pretty safe bets on my part?

  40. KenD:

    Instead of looking at the next 20 years, why don't you dig up some predictions made in the past - e.g., Arrhenius in 1896 - that have come true?

  41. KenD.

    Bet on volume rather than area, and you will almost certainly have money in the bank.

    And sadly, Sphaerica is correct about time spans and realisations.  The only slight point at which I would diverge is that I suspect that the genie's already been out of the bottle for a few years.

  42. Thanks, Bob and Bernard. Bob, I looked through some of the Arrhenius article, but I confess I'm not technical enough to home in on the best example of a prediction he made that has since come true. Bernard, if you were to place a bet on the minimum volume of Artic sea ice by 2023 (assuming C02 levels remain at or above current levels), what value you would bet on, assuming you want to keep your money safe?

  43. The economic impacts of climate change may be catastrophic, while there have been very few benefits projected at all.

    What about Figure 1 of this paper?

  44. Oops. I forgot to include the link:

    The Economic Effects of Climate Change

  45. Mark @344 - first off, almost all of the estimates in the Tol paper you reference are from the most conservative economists doing climate research (Nordhaus, Tol, Mendelsohn, etc.), so the paper almost certainly underestimates the economic damage from climate change (probably by a very large amount, in my opinion).  It's really interesting that it references Chris Hope, who now says that the social cost of carbon is in the ballpark of $150 per tonne of CO2, which is 1-2 orders of magnitude higher than Tol believes.

    Despite these underestimates, the paper still concludes that the net impact on GDP at 2.5°C will be negative, and we're already committed to about 1.5°C warming and still rising fast.  So I'm not really sure what your point is.

  46. Mark @344 - first off, almost all of the estimates in the Tol paper you reference are from the most conservative economists doing climate research (Nordhaus, Tol, Mendelsohn, etc.),

    Richard Tol is a conservative? That might be news to him! But OK...what do the "non-conservative" ("liberal?") economists say?

    Despite these underestimates, the paper still concludes that the net impact on GDP at 2.5°C will be negative, and we're already committed to about 1.5°C warming and still rising fast. So I'm not really sure what your point is.

    My point is that global surface temperature is rising by about 0.15 degrees Celsius per decade. So 2.5 degrees Celsius isn't likely to happen even in this century.

    In fact, per that paper, 1 degree Celsius warming from the present value was the peak of the positive effect on GDP. At 0.15 degrees Celsius per decade, that's more than 60 years in the future.

  47. Mark Bahner @ 346:

    1. What date is the 'present' you refer to in your assertion "1 degree Celsius warming from the present value was the peak of the positive effect on GDP"?
    2. What is good about knowing this will roll over us in 60 years, if the argument is used to delay taking action?
  48. New NASA study accepted by Geophysical Research Letters (Lau et al.) quantifies that wet places will get wetter and dry places will get drier--more floods and drought.  Heavy rain will increase, light rain will increase slightly, but moderate rain will decrease and no rain will be more frequent.  There is a summary with video of global map of changes.

  49. I'm not sure where to post this inquiry, and this thread seems the best, so it'll go here.

    I posted a link, a couple of weeks ago now, to a paper shared by Skeptical Science's Facebook page, onto my own feed.

    This resulted in an intense discussion with a pseudo-skeptic. Naturally, it had nothing particularly to do with the paper. Among the various arguments was one I have not encountered before, which was made in reply to a point I made about the problems related to the rate of current change:

    Your whole augment then is based not on the actual level of CO2 or temperature but that you can determine what the gradient of CO2 has been over the last 200 million years. Basic multivariable calculus just because you have a large change in the first derivative based on on variable doesn't mean that variable will dominate the function's value and to make that conclusion in any branch of science or engineering is prima facie false. Your system could simply be going through some oscillation before reaching a new steady state.

    I didn't pick up on the obvious misrepresentation ("Your whole augment then is based not on the actual level of CO2 or temperature but that you can determine what the gradient of CO2 has been over the last 200 million years") at the time.

    Anyway, my university calculus is, charitably put, rusty, so while I strongly suspect this claim is a load of bollocks (the notion that vast swathes of experimentally-verified atmospheric physics can be upended by basic multivariable calculus strikes me as ridiculous in the extreme) I'm not in a position to make a strong rebuttal (I did note that, indeed, trying to appeal to a principle of maths as a way of evading the evidence is bunk).

    Are there any other suggestions for rebutting this claim?

  50. Our current CO2 emissions rate is ten times faster than the rate which preceded the end-Permian extinction, 250 million years ago. Also, I've pointed out that fossilized leaves from the PETM confirm that a rapid CO2 increase (still not as fast as today's) stresses ecosystems.

    Scientists use more evidence than just first year calculus to determine climate sensitivity to CO2. Here's a figure from Royer et al. 2007 (PDF) which concludes that “a climate sensitivity greater than 1.5°C has probably been a robust feature of the Earth’s climate system over the past 420 million years”.

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