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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

"By the way, if you’re going to vote for something, vote for warming. Less deaths due to cold, regions more habitable, larger crops, longer growing season. That’s good. Warming helps the poor." (John MacArthur)

At a glance

“It's not going to be too bad”, some people optimistically say. Too right. It's going to be worse than that. There are various forms this argument takes. For example, some like to point out that carbon dioxide (CO2) is plant-food – as if nobody else knew that. It is, but it's just one of a number of essential nutrients such as water and minerals. To be healthy, plants require them all.

We know how climate change disrupts agriculture through more intense droughts, raging floods or soil degradation – we've either experienced these phenomena ourselves or seen them on TV news reports. Where droughts intensify and/or become more prolonged, the very viability of agriculture becomes compromised. You can have all the CO2 in the world but without their water and minerals, the plants will die just the same.

At the same time, increased warming is adversely affecting countries where conditions are already close to the limit beyond which yields reduce or crops entirely fail. Parts of sub-Saharan Africa fall into this category. Elsewhere, many millions of people – about one-sixth of the world’s population - rely on fresh water supplied yearly by mountain glaciers through their natural melt and regrowth cycles. Those water supplies are at risk of failure as the glaciers retreat. Everywhere you look, climate change loads the dice with problems, both now and in the future.

Please use this form to provide feedback about this new "At a glance" section. Read a more technical version below or dig deeper via the tabs above!

Further details

Most climate change impacts will confer few or no benefits, but may do great harm at considerable costs. We'll look at the picture, sector by sector below figure 1.

IPCC AR6 WGII Chapter 16 Figure FAQ 16.5.1

Figure 1: Simplified presentation of the five Reasons for Concern burning ember diagrams as assessed in IPCC AR6 Working Group 2 Chapter 16 (adapted from Figure 16.15, Figure FAQ 16.5.1).


While CO2 is essential for plant growth, that gas is just one thing they need in order to stay healthy. All agriculture also depends on steady water supplies and climate change is likely to disrupt those in places, both through soil-eroding floods and droughts.

It has been suggested that higher latitudes – Siberia, for example – may become productive due to global warming, but in reality it takes a considerable amount of time (centuries plus) for healthy soils to develop naturally. The soil in Arctic Siberia and nearby territories is generally very poor – peat underlain by permafrost in many places, on top of which sunlight is limited at such high latitudes. Or, as a veg-growing market gardening friend told us, “This whole idea of "we'll be growing grains on the tundra" is just spouted by idiots who haven't grown as much as a carrot in their life and therefore simply don't have a clue that we need intact ecosystems to produce our food.” So there are other reasons why widespread cultivation up there is going to be a tall order.

Agriculture can also be disrupted by wildfires and changes in the timing of the seasons, both of which are already taking place. Changes to grasslands and water supplies can 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 parts of the Middle East and sub-Saharan Africa, for example.


Warmer winters would mean fewer deaths, particularly among vulnerable groups like the elderly. However, the very same groups are also highly vulnerable to heatwaves. On a warmer planet, excess deaths caused by heatwaves are expected to be approximately five times higher than winter deaths prevented.

In addition, it is widely understood that as warmer conditions spread polewards, that will also encourage the migration of disease-bearing insects like mosquitoes, ticks and so on. So long as they have habitat and agreeable temperatures to suit their requirements, they'll make themselves at home. Just as one example out of many, 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 have some commercial benefits, these are considerably outweighed by the negatives. Detrimental effects include increased iceberg hazards to shipping and loss of ice albedo (the reflection of sunshine) due to melting sea-ice allowing the ocean to absorb more incoming solar radiation. The latter is a good example of a positive climate feedback. Ice melts away, waters absorb more energy and warming waters increase glacier melt around the coastlines of adjacent lands.

Warmer ocean water also raises the temperature of submerged Arctic permafrost, which then releases methane, a very potent greenhouse gas. The latter process has been observed occurring in the waters of the East Siberian Arctic Shelf and is poorly understood. At the other end of the planet, melting and break-up of the Antarctic ice shelves will speed up the land-glaciers they hold back, thereby adding significantly to sea-level rise.

Ocean Acidification

Acidity is measured by the pH scale (0 = highly acidic, 7 = neutral, 14 = highly alkaline). The lowering of ocean pH is a cause for considerable concern without any counter-benefits at all. This process is caused by additional CO2 being absorbed in the water. Why that's a problem is because critters that build their shells out of calcium carbonate, such as bivalves, snails and many others, may find that carbonate dissolving faster than they can make it. The impact that would have on the marine food-chain should be self-evident.

Melting Glaciers

The effects of glaciers melting are largely detrimental and some have already been mentioned. But a major impact would be that many millions of people (one-sixth of the world’s population) depend on fresh water supplied each year by the seasonal melt and regrowth cycles of glaciers. Melt them and those water supplies, vital not just for drinking but for agriculture, will fail.

Sea Level Rise

Many parts of the world are low-lying and will be severely affected even by modest sea level rises. Rice paddies are already becoming inundated with salt water, destroying the crops. Seawater is contaminating rivers as it mixes with fresh water further upstream, and aquifers are becoming saline. The viability of some coastal communities is already under discussion, since raised sea levels in combination with seasonal storms will lead to worse flooding as waves overtop more sea defences.


Positive effects of climate change may include greener rainforests and enhanced plant growth in the Amazon, increased vegetation in northern latitudes and possible increases in plankton biomass in some parts of the ocean.

Negative responses may include some or all of the following: further expansion of oxygen-poor ocean “dead zones”, contamination or exhaustion of fresh water supplies, increased incidence of natural fires and extensive vegetation die-off due to droughts. Increased risk of coral extinction, changes in migration patterns of birds and animals, changes in seasonal timing and disruption to food chains: all of these processes point towards widespread species loss.


Economic impacts of climate change are highly likely to be catastrophic, while there have been very few benefits projected at all. As long ago as 2006, the Stern Report made clear the overall pattern of economic distress and that prevention was far cheaper than adaptation.

Scenarios projected in IPCC reports have repeatedly warned of massive future migrations due to unprecedented disruptions to global agriculture, trade, transport, energy supplies, labour markets, banking and finance, investment and insurance. Such disturbances would wreak havoc on the stability of both developed and developing nations and they substantially increase the risk of future conflicts. Furthermore, it is widely accepted that the detrimental effects of climate change will be visited mostly on those countries least equipped to cope with it, socially or economically.

These and other areas of concern are covered in far more detail in the 36-page Summary for Policymakers from the IPCC AR6 Synthesis Report, released in March 2023. The report spells out in no uncertain terms the increasingly serious issues Mankind faces; the longer that meaningful action on climate is neglected, the greater the severity of impacts. The report is available for download here.


Last updated on 21 April 2023 by John Mason. View Archives

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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

Denial101x video

Here is a related video lecture from Denial101x - Making senses of climate science denial


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Comments 251 to 265 out of 265:

  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 - " 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. 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. 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?

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