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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 201 to 250 out of 356:

  1. You write: Agriculture: "the amount of sunlight reaching the ground in summer will not change because it is governed by the tilt of the earth."

    All of Northern Europe, lush with agriculture and forests, is at the same latitude as the Canadian tundra where the brutal cold kills all trees, with only lichens surviving. Your argument is simply wrong.
  2. Er ... Manny, can you explain your reasoning a little more? At a given latitude, on a revolving Earth, during a given 24-hour period, the amount of sunlight arriving will be the same at all longitudes, excluding the chances of a massive and short-lived sunspot occurring during that 24 hours. How do you work out that insolation will differ? The temperature difference you mention results form causes other than insolation, I would have thought.
  3. Manny, Charles C. Mann has a quite readable chapter devoted to the spread of malaria post-1492 in his recent book 1493. The story is a little more complicated than you indicate. There is a range of malaria-carrying mosquitoes. There is also a range of human responses, based on genetics. The Canadian malaria mentioned was probably vivax rather than the falciparum mentioned in Epstein.
  4. And, Manny, I agree with Doug. What you're trying to say with the comparison between Canada and Europe is as clear as mud.
  5. Mohyla103:

    Bernard J.:

    "Glaciers do not impound water, they hold it as frozen mass."

    Did you mean that glaciers can be actual dams that hold liquid water back behind them, or that glaciers act like a dam in that they hold precipitation (snow, not rain) at a higher altitude? If it is the latter, then I misunderstood the phrase "natural dam" in your original statement.


    Although I know what his answer is, you'd best direct the question at Tom Curtis, as he was the one who originally used the phrase.

    For someone who said:

    It's this attitude of alarming the public with misleading claims that make me skeptical of AGW reporting accuracy in general.


    it's important to ensure that you are not transferring your own misunderstandings on to those who are in fact reporting accurately.

    This would seem to apply more broadly to your commentary here, as much of your scepticism appears to originate from a confusion over the actual science, and/or about what people mean when they report it.
  6. I think Manny is confused as to why you have latitudal variation in climate. It is not due to differences insolation but to the many local influences on climate. For northern Europe, the warm Gulf Steam is the major factor.
  7. Bernard J @205, Mohyla has mistaken a simile for a literal description. As the "mistake" involves a typically ridiculous interpretation, there was IMO no basis for it. Therefore I presumed the "mistake" to be a debating technique and discussion with Mohyla to necessarily to be fruitless in that once people start to intentionally misunderstand you, they are not interested in sincere discussion.
  8. DSL @203, interesting about Plasmodium vivax. That it was not Plasmodium falciparum is made clear by the death rate of just 3% of those hospitalized with an infection in 1823. In contrast, Plasmodium falciparum that it creates a selective advantage for the sickle cell anemia gene which, though fatal if received from both parents, grants resistance to malaria if received from just one. The result is the strong correlation between Plasmodium falciparum and frequency of the gene for sickle cell anemia in the population (see maps below).





    Of course, the concern with global warming is not the spread of vivax but of falciparum.
  9. Doug H @202, I believe Manny has raised a legitimate point. The issue is that more than one factor can limit the growth of plants.

    With regard to energy, plants have two important sources of energy. Like all "cold blooded" creatures, the energy which drives the brownian motion within their cells, and hence powers the chemical operations of life comes from the environment, and is a simple consequence of the local surface temperature. As the temperature rises, the brownian motion becomes more vigorous so that chemical reactions (and hence growth) proceeds faster.

    Of coure, the characteristic of energy from the environment as heat is that it has a high entropy. Life cannot proceed without some reactions that result in a lower entropy than their surrounds, so all life also requires access to a low entropy energy source to drive these reactions. For plants, that is the energy from sunlight which they convert to low entropy sugars or starches. This does mean that at higher latitudes, available sunlight becomes a restriction of plant growth no matter what the temperature, because without sunlight there is no low entropy energy to drive the low entropy reactions that life needs.

    What Manny has pointed out is that, given that there is extensive forestation in western Europe at the same latitudes as the Canadian sub-arctic, it is the high entropy energy from the environment (warmth) which is the primary limiting factor at those latitudes. The assumption it was lack of the low entropy sunlight that restricted growth was not warranted.

    Indeed, given that plants do not just lie flat to the surface, but deploy their leaves to gain maximum sunlight, it is not clear that the geometric argument about sunlight carries any weight. Given that in a past era, there were forest at the South Pole, I would suggest that lack of direct sunlight is only ever a seasonal limitation of the growth of plants.
  10. Tom Curtis @ 209, thanks for the extra info - I am always confronted with just how little I know about anything! I must admit, I had never given a thought to the low entropy/high entropy energy source argument, so I have learned something new today - thank you.

    On the other hand, I was responding to Manny's dismissal of this:
    "the amount of sunlight reaching the ground in summer will not change because it is governed by the tilt of the earth."
    by saying this
    Your argument is simply wrong.
    which seemed like a drive-by pot-shot.
  11. Doug H @210, it struck me the same way. That does not, however, it did not hit the target.
  12. 211, Tom,

    While Manny's (and your) argument concerning sunlight versus temperature (i.e. multiple limiting factors on growth) is applicable to the case of plant life in general, we are talking specifically about crops that are useful for agriculture, and that produce a reasonable yield.

    Both yield and crop type are dependent on length of growing season among other factors.

    If you reference this map you can see that productivity for all northern latitudes is severely hampered (note that the coloration for Alaska is certainly wrong... it's been colored as a part of the USA, I'm sure, and not relative to its own actual crop yields).

    In particular, you will note that corn is never grown at northern latitudes. It must generally be planted in May and is not ready to harvest until October.

    When you add the problems with soil (much of the soil in northern latitudes having been scraped clean by glacial action, with no chance for later plant growth to replenish the soil), chances of achieving "good" crop productivity in northern latitudes due to climate change do not look promising.

    In my own direct experience, some years back I had a tremendous tomato garden on the south side of the house, despite being too far north to really expect to get good tomatoes. Being right against the foundation and chimney, the ground got very warm, and it was the one part of my property (ringed by trees) that got good sunlight through the growing season. The only drawback was that as the sun moved further south in August (just as the fruit should be reaching maturity), it would begin to dip below the tree line and shorten the length of the day.

    After about five years, my tomatoes wouldn't ripen. The trees at the south side of my property had continued to grow taller and to encroach over my lawn, with the end result that they cut off the sunlight too soon. I had lush, wonderful plants covered with fruit that never came close to maturity.
    Response: [JH] Fried green tomatoes? (:
  13. Bernard J. @ 205

    You're right, of course, that question should have been directed at Tom Curtis. I didn't notice a third person had entered the glaciers as natural dams discussion. Sorry to you and Tom Curtis for the mixup.

    I am all for clearing up misunderstandings, which is precisely why I asked the question. It wasn't until I read your post saying glaciers "do not impound water" that I realized there must be some misunderstanding because that is exactly what a literal dam does. My misunderstanding was not intentional.

    "...much of your scepticism appears to originate from a confusion over the actual science, and/or about what people mean when they report it."

    I'm not sure what other cases you're referring to? I will refer you to post 199 and the discussion with JMurphy leading up to it, where I showed that in fact my reading of the original sources was correct and it was Barnett who was confused and/or did not report data accurately in his paper. Clearing up misunderstandings is a good thing, be they my own or ones in published papers.
  14. Tom Curtis @ 207

    "Mohyla has mistaken a simile for a literal description. As the "mistake" involves a typically ridiculous interpretation, there was IMO no basis for it."

    You said that glaciers act as "natural dams", so I thought you meant:

    natural - it's a glacier, not man-made, therefore it's natural
    dam - something that holds back liquid water in a river system

    Please explain how my interpretation was "typically ridiculous"? It seems like quite a reasonable, if incorrect, interpretation to me.


    "Therefore I presumed the "mistake" to be a debating technique and discussion with Mohyla to necessarily to be fruitless in that once people start to intentionally misunderstand you, they are not interested in sincere discussion."

    I most certainly did not "intentionally" misunderstand you and to suggest I did is rude and debasing.

    Thank a lot for simply ignoring my mistake and assuming I was just out to cause trouble for the sake of trouble, instead of trying to further clarify your meaning first. It seems you have overestimated my intelligence here.

    I will ask once more, this time to the correct person. Please understand this is a sincere question:

    Did you mean:

    1) that glaciers act as true barriers that hold liquid water back behind them, and prevent/control its release downstream? or

    2) that glaciers act somewhat like a dam in that they hold precipitation (in the form of snow and ice) at a higher altitude? or

    3) something else?
  15. Mohyla @214, how can it be a sincere question when the question has already been answered?
  16. Sphaerica @212, I think the map is suspect in sustaining your point. The distribution of rice, wheat and corn production are clearly heavily influenced by demand side economic factors. Further, they clearly take a nation wide average so that Australia's vast deserts result in low or medium productivity despite Australia having some of the richest and most extensive wheat growing regions in the world. Transferring this to Canada, it means the current limited arability of the Canadian Arctic is averaged with the southern wheat growing areas of Canada, and are not indicative of grain productivity in those southern areas.

    Having said that, your more general point is well taken. With a six month growing season, it is difficult to imagine corn prospering within the Arctic circle, not matter what the temperature. Never-the-less, a there is substantial room for a northward shift in Canadian agricultural production before the Arctic Circle is reached. The projected 2050 wheat production areas below are well south of the Arctic Circle:



    On the other hand, a similar northward migration of wheat production between 2050 and 2100 would bring the northern regions of production within the Arctic Circle and a possible hard limit on northerly extent on production. As you say, the situation is complicated, but clearly the notion that a northerly migration of agriculture under business as usual will compensate for loss of productivity in tropical and temperate lands is not sustainable (either intellectual, or into the future). The situation is worse in the Southern Hemisphere with a definite hard limit on production in the form of the southern coast lines of the continents.
  17. Tom Curtis @215

    It seems I can't convince you of my sincerity, but I hope you will give me the benefit of the doubt anyway and continue the discussion.

    A simple direct answer from you would be more helpful in avoiding misunderstanding. Nevertheless, I think I understand now that you originally meant (2), but I interpreted it as (1), as (2) is a simile and (1) is the literal description. (?)

    You had originally said in 178 that these natural dams can absorb large precipitation events. I thought this meant it helped the watershed absorb the precipitation (rain) by holding the water behind it, like a dam. I wasn't sure I understood this correctly at the time so I searched online about glaciers as natural dams and all I found were articles about glacial ice or moraine dams, glacial lakes and outburst floods. I invite you to try this search yourself, and hopefully you will understand that me interpreting "natural dams" literally was not "typically ridiculous" but a natural misunderstanding of the phrase.

    Since your intended meaning seems to be like (2) could this have been better phrased as "glaciers act as natural reservoirs" since you seem to be referring to precipitation held in the glacier itself, not blocked up behind it in a glacial lake? Or am I still way off?
  18. Tom Curtis @217

    Correction: could this have been better phrased as "glaciers act as natural frozen reservoirs"?
  19. mohyla103 - That's clearly what Tom Curtis meant, it certainly was my interpretation when I read his original post, and at this point I should think the issue is clarified. Both snowpacks and glaciers (as, essentially, snowpack compressed to ice, undergoing flow through internal deformation under their own weight) are reservoirs of winter precipitation, feeding freshwater supplies down hill.

    Perhaps we could move on, now???
  20. KR Thank you for the direct answer. Sorry to all for cluttering the board with this but it truly was a misunderstanding.

    Yes, moving on then I do have one final question. Tom Curtis said that glaciers can absorb large precipitation events and thus help prevent floods. How does this happen?

    If it's snow, I understand a glacier can absorb it. However, wouldn't this snow still be available for later use downstream upon melting, regardless of whether it lands on a glacier or the ground? How does snow's absorption by a glacier confer an advantage or help prevent flooding?

    If it's rain, I don't understand how a glacier absorbs it at all. Logicman in post 176 said that rainwater just runs off glaciers and does not add to its mass. This seems reasonable and nobody corrected this but was he oversimplifying?
  21. mohyla103 - Please note that large precipitation events on glaciers will generally be snow - being on the tops of mountains, and all that. Rate of flow from a glacier is dependent upon melt at the base end of the glacier, not recent precipitation at the top (which affects available glacial melt mass years to multiple decades later). Snowpack, on the other hand, melts yearly.

    You won't see a lot of rain on glacial origin locations...
  22. I still don't understand how a glacier can absorb a large precipitation event (of snow) and help prevent flooding. A large dump of snow would not come rushing down the mountain all at once anyway, since it's not liquid. Presumably this large dump would melt slowly throughout the spring, and possibly into the summer. This seems like pretty good flood control. Obviously I'm missing something here... what is it?

    "Please note that large precipitation events on glaciers will generally be snow - being on the tops of mountains, and all that."
    Certainly rain is possible on some glaciers during summer days. The temperature can be warmer and even above freezing, it being summer, and all that. I'll take your sentence to mean that discussion of rain events is not relevant here, though.
  23. @ mohyla103

    Precipitation falling on a glacier is a case-dependent thing. Remember that the mass-balance of a glacier is a dynamic output of gains in the accumulation zone factored against losses in the ablation zone. Other variables are temperature, insolation, form of the precipitation, etc.

    That precipitation falling in the accumulation as snow typically gets compacted over time and eventually is converted into ice. During the summer melt, even the accumulation zone may contain melt pools or even melt lakes. These are drained via moulins into the body of the ice mass into the internal plumbing drainwork of the glacier.

    That precipitation falling as rain will largely be carried off via runoff of the outside of the glacier or into the interior plumbing. Glaciers not at their terminal extent often have a lake that forms at the terminal end of the glacier, impounded between the icy tongue of the glacier and the terminal moraine of rock, silt and soil that serves the function of a dam.

    These glacial dam-formed lakes can empty and fill according to the mass-balance of the glacier. High melt seasons can fill the lake beyond capacity, sometimes resulting into a catastrophic collapse and flood. When these occur, many thousands of people living in the flood plains below can perish in the massive walls of water and mud that ensue.

    How warming is affecting alpine glaciers is the reduction of the accumulation zones and the increases of the ablation zones. The result is a tilting of the vast majority of the mass-balances of the alpine glaciers of the world. Even those of the Himalayas (a post on this is in the works).

    HTH.

    Some resources for you:
    http://www.nichols.edu/departments/glacier/global%20glacier%20mass%20balance.htm
    http://www.nichols.edu/departments/Glacier/glacier%20survival.html
    http://glacierchange.wordpress.com/
    http://www.geo.uzh.ch/microsite/wgms/
  24. Daniel Bailey, thanks for your detailed explanation and links. I learned, among other things, that snow cover in the accumulation zone throughout the summer and not just snowfall in the winter is necessary to maintain the glacier's mass balance.

    The thing I don't understand is from post 178 from Tom Curtis. Since I'm not sure if he will answer me or not, perhaps you could help clarify this? He said that glaciers "help prevent floods, and prevent seasonal water shortages". I understand how they prevent seasonal water shortages, but how do they help prevent floods?
  25. mohyla I admire your persistence. Glaciers that do receive large rain events are generally in temperate settings. Take southern Alaska. During such rain storms not only do we have the precipitation from rain, but this also causes quite a bit of snow melt. Thus, the actual water that will drain off per unit area can be greater than elsewhere. However, glacier plumbing systems filtering the water through the snowpack etc is slow. This spreads out the increased discharge and does not lead to a spike that triggers floods. If we take the Himalaya summer monsoon than rain only falls low on the glacier and again the drainage system is not as efficient as non-glaciated areas.
  26. mohyla103, please note that mspelto is a widely respected, practicing/publishing glaciologist who is kind enough to make himself available here at SkS from time to time. Some of the above links I gave you refer to his work. He is also the author of several posts here at SkS and at RealClimate.
  27. I see! So when a previous poster said that rain simply "runs off a glacier" this wasn't entirely true, and it's the drainage system within a glacier that can actually help prevent floods by slowing down the rate at which the rain can flow downhill. I guess this is what Tom Curtis was talking about. It makes a lot more sense now; thanks for the explanation mspelto!

    ======
    A little aside here:
    While many may blindly accept the existence of AGW and accept any predictions of what the future holds for the planet simply because they hear about this in the mass media or pop culture, I cannot blindly accept it. This is not to say that I *will not* accept it, as has been implied here by at least one person. My position is simply that I won't accept something until I first see the evidence. Others telling me that there IS a mountain of evidence is still not going to sway me. I need to examine and try to understand it firsthand. That is why I am here on this site after all: to get deeper into the real evidence, all the while looking at it critically until I have a clear understanding of it one way or another. Skeptical Science really is an apt name for this website.

    As an analogy, many people believe aliens have visited Earth, but I'm not going to believe that just because others do, no matter what their number. The same applies to AGW and its predicted consequences. I'm not going to believe it simply because others do, no matter what their number. There is a difference though: there is actually a fairly solid scientific consensus on AGW and its consequences, as well as an abundance of published literature, so it is actually worth my time to go and exam the evidence.

    This seems like a reasonable position to me. I hope everyone on this board understands where I'm coming from now and if I ask any seemingly ignorant questions you will know my intentions are sincere.

    Thanks to those who have actually clarified things for me. You have not only helped me gain a deeper understanding, but the countless other "skeptical" visitors to this site who may be reading these posts.
  28. mohyla103:

    One out of twelve of the Apostles was a "Doubting Thomas."

    May the Force be with you.
  29. John Hartz

    ...and also with you. ;)
  30. Apologies for the delay in replying, mohyla103, but I have been working on something else and have only just gotten around to reading the relevant paper myself.

    Having done so, I believe you are once more focussing on details which are not as black-and-white as you seem to believe.

    Firstly, the fact that the relevant figure is 49.1% (i.e. the average snow and glacier-melt contribution to the annual flow of Chenab) over a 10 year period, suggests that the contribution is likely to have been over 50% during certain of those years. In fact, one of the graphs in the paper (showing mean monthly flow characteristics) showed how great were the deviations in monthly flow during the summer months.
    Also, that 49.1% contribution is concentrated in the four (mainly summer) months of June to October, so certain of those yearly rates can easily be over 50% at times during summer.
    Combine that with the 51.1% contribution to the yearly flow from the summer months, not all of which, of course, is due to glacier-melt but more than 50% of which could quite easily be due to glacier-melt during certain summer months of certain of the years of the study.

    Finally, you haven't taken account of two of the other figures in that study which showed seasonal (if I remember the term correctly) and permanent snow covered areas during March and September - again if I have remembered the correct months. During March the maximum coverage was roughly 80% but during September that that had dropped to roughly 20%. I can't believe that the amount of snow-melt would be a huge proportion of total snow/glacier-melt runoff anyway, but as the summer progresses the contribution from snow-melt would get less and less while the glacier-melt would at least remain constant but would actually probably increase. (See this abstract for further information). This means that glacier-melt would become a very large percentage of total snow/glacier-melt runoff so that, again, during certain years and certain summer months, glacier-melt would be "as much as...50-60%..."
    (You can see more about snow-covered areas in this study from 2001.

    So, to me, you have not shown that in fact your "reading of the original sources was correct and it was Barnett who was confused and/or did not report data accurately in his paper".
    You have made an unfair accusation for which you have not been able to provide clear evidence - you have read some abstracts and one paper, and then considered that you know more than Barnett and can accuse him of 'confusion' and 'inaccurate data-reporting'.

    You wrote that "[c]learing up misunderstandings is a good thing, be they my own or ones in published papers". I believe the misunderstanding is yours and not that of experienced scientists or the peer-review system.

    And, Barnett was NOT wrong (as far as I can see) to cite this paper as evidence, and the peer-review process did not miss any errors which you believe you have discovered.

    You should withdraw the accusations you have made, including the following :

    Considering the same kind of wording and figures appear in the abstracts of the other 2 papers cited by Barnett for this claim, I strongly suspect he and the reviewers committed the same error there.
  31. JMurphy,

    First, thank you for taking the time to continue the discussion. Unfortunately, the misunderstanding appears to be yours and I will explain it in detail below. See especially (2).

    1. "…so certain of those yearly rates can easily be over 50% at times during summer."

    You mention yearly rates, during summer. This is a logical contradiction, please restate. If you're talking about something being over 50% in the summer, then you're not talking about a yearly rate, you're talking about a summer rate or summer amount. If you're talking about a yearly rate, then it's not just during summer and summer peaks are irrelevant as a yearly rate is, by definition, averaged over the year.

    I do agree that the percentage of meltwater in the river can be over 50% at times during the summer. Is this what you meant to say? That may be true, but remember that this still refers to all meltwater, and we have no specific figure about glacial water to go by. In addition, please note Barnett cites "flow" for the Chenab not "summer flow" as you're talking about.

    2. "Also, that 49.1% contribution is concentrated in the four (mainly summer) months of June to October….Combine that with the 51.1% contribution to the yearly flow from the summer months, not all of which, of course, is due to glacial melt…"

    You're comparing apples and oranges here once again. Take a closer look at what these numbers represent. 49.1% refers to an amount contributed yearly by a source without mention of seasonal breakdown, whereas 51.1% refers to a fraction of yearly flow during one season without mention of flow source composition. There simply is no way to accurately "combine" these 2 sets of data to interpolate a summer glacial melt fraction, as you have tried to do, as their domains and ranges (?) are different. The data sets are, in fact, almost entirely independent of one another. Theoretically speaking, I could "combine" these two figures and get a percentage of meltwater in the summer river flow that is anywhere from 0.4% up to 96%! (I can show you the calculations if you so desire) Of course there are constraints due to known trends in timing of precipitation, but no definite numbers are presented. With a possible range like this, how you or Barnett could reliably determine not only how much of the summer flow is specifically from meltwater but also how much of that meltwater is specifically from glaciers is totally beyond me.

    We don't know how the 49.1% meltwater total breaks down season by season (let alone how it breaks down to glacial melt vs. snow melt within each season), as it is a yearly average. We only know trends. The seasonal values presented in the graph and table refer to total flow, not specifically to meltwater so are not helpful here. We also don't know how the 51.1% summer flow total breaks down source by source, i.e. how much of the 51.1% is from rain and how much is from meltwater. We know even less how the meltwater portion of 51.1 breaks down into snow vs. glacial. Only if we knew all of these things could we actually put a figure on the glacial melt contribution in the summer. For Barnett to concoct a figure for glacial melt like 50-60% when it's not present in the source is not very scientific and I don't believe he did this.

    Your point about variability from year to year is well taken! However, there is simply no way to assign a number, or even range of numbers, for meltwater percentage in exceptionally wet summers, at least according to this paper. It's even more ridiculous to try to put a figure on glacial melt alone during these periods, when the total meltwater amount isn't even known.

    3. "…but more than 50% of which could quite easily be due to glacier-melt during certain summer months of certain of the years of the study."

    You said "50% of which" in the above sentence. When I look back I see the referent of "which" is the 51% contribution to the yearly flow from the summer months. So what you meant is:

    …but more than 50% of the 51% contribution to the yearly flow from the summer months could quite easily be due to glacier-melt during certain summer months of certain of the years of the study.

    Doing the math, this means:

    …more than 25.55% of the yearly flow from the summer months could quite easily be due to glacier-melt during certain summer months of certain of the years of the study.

    Even if you can back up your use of 50% (?), how does 25.55% from glacier-melt support Barnett's figures? This statement of 50% of 51.1% does not support your argument at all. Perhaps this arises from a misreading of the 51% contribution to the yearly flow from the summer months as the 51% contribution to the yearly flow from summer meltwater?

    Once again, this paper did not present any figures about glacial melt alone, so it would take me quite a leap of faith to believe that Barnett somehow deduced them out of thin air with enough certainty to publish them.

    You're piling presumptions upon educated guesses here trying to explain where Barnett could come up with 50-60% but I don't see the evidence in the source anywhere for these particular figures. You've also misunderstood and/or misused the 49.1% and 51.1% figures in the source while making your educated guesses, as explained above in (2).

    The simplest explanation is that Barnett simply took the figure 49% for glacier and snowpack melt, rounded up to 50% and mistakenly cited glacial melt instead of glacier and snow melt. It seems he made the mistake of just dropping one word: snow. This is supported by the fact that in the abstract for his article, he actually does mention snowpack and glaciers together, and it's only in the sentence citing 50-60% that he seems to have forgotten to mention snow.

    4. "and then considered that you know more than Barnett"

    Nope, never said that, don't claim that. I'm sure Barnett's knowledge of this field is vastly superior to mine, but when we're talking about something as simple and limited in scope as checking a source and reading a plain English explanation of the figures, I do feel I'm on equal footing with Barnett and have the right to point out mistakes. But since when does pointing out someone's mistake mean that you think you know more than them? It just means you're observant enough to have noticed a mistake. I don't believe Barnett did this intentionally.

    5. I will not withdraw:

    "Considering the same kind of wording and figures appear in the abstracts of the other 2 papers cited by Barnett for this claim, I strongly suspect he and the reviewers committed the same error there."

    The reason is that this is not an "accusation" as you said, but a suspicion, and I worded it as such. A suspicion is unproven, but may be something worth looking into. It is a suggestion to others that the sources might be worth double-checking.

    6. Your point about the little remaining snow cover is well taken, and it's true that the ratio of glacier melt to snow melt would increase throughout the summer. However, since no figure was given in the paper about this, further discussion of this point will be fruitless with respect to the Barnett paper.
  32. mohyla103, we're going round in circles here and I admit to not making myself very clear in my last response - but you definitely have misread what I was trying to get across.

    Therefore, to make things as simple as possible, your claims of "misleading", "inaccurate", "misrepresentation of data", "sloppy use", "WRONG", "he definitely misrepresented data", "peer review completely missed the error", "proven to be wrong", "proves Barnett misrepresented the data" have yet to be proven because the average 49.1% you are basing all your claims on is just that - an average.
    Any of the ten years comprising that average may well have had snow- and glacier-melt contributions of over 50%. As well as that, certain periods may well have seen those contributions comprised totally of glacier-melt.
    Anyone who wanted to claim, therefore, what Barnett claimed, would need to have knowledge of the details of that 10-year study, as well as knowledge of snow- and glacier-melt in general. I have neither of those - do you ? If you don't, your claims are based on an average figure from one paper (which itself has references relating to snow- and glacier-melt, e.g. Hydrological characteristics of a Himalayan glacier and problems associated with discharge measurements in the glacier melt streams - Hydrology, 16: 30-51) and one average figure; whereas I reckon Barnett's claim is based on that paper (as well as its references), and his own knowledge of such studies. I also reckon that the peer-review system is sturdy and capable of making decisions as to which papers are substantiated and worthy of publication, and which aren't or which need further clarification.

    In the end, I don't have the time or resources to check every claim and rely on the science and scientists of each discipline to produce credible and reliable work. Even if that means accepting 49.1% as meaning the same as "as much as 50%", so be it. Obsession about words and extreme details are not my cup of tea.
    In fact, if you feel so certain about your claims, why not email him and let him know your feelings ? What have you got to lose ?

    timdotbarnett@ucsd.edu
  33. "Even if that means accepting 49.1% as meaning the same as "as much as 50%", so be it."

    I can accept that, too, of course. The point was the missing word "snow".

    You raise an excellent point, though, sources within sources. As that was original research and measurement data being reported, and there was no discussion about snow vs. glacial melt, I hadn't thought of checking further sources regarding the snow vs. glacial melt amounts, but perhaps it is in there somewhere. Then again, probably not or it would have been discussed in the original paper. I will try digging deeper into the other sources and will indeed contact Barnett if still nothing turns up to support his statement. I don't expect an answer but as you say, I've got nothing to lose.

    Thanks for the discussion. I believe we've come as far as we can on this one.
  34. Agreed, and I look forward to any further information you may be able to obtain, particularly from Barnett.
  35. Allow me to revisit the following statement in this article: "Spread in mosquite-borne diseases such as Malaria and Dengue Fever (Epstein 1998)"

    Like just about everywhere else, malaria was endemic in Florida in the early 20th century. From Malaria in Florida (D. B. Lieux, The Florida Entomologist, Vol. 34, No. 4 (Dec., 1951), pp. 131-135), there was 1,895 cases in 1919. By 1949, thanks in great part to DDT, the US was declared malaria-free (CDC timeline).

    Florida has a tropical climate, is home to the world's largest swamp and remains largely malaria-free. If malaria is not currently spreading to balmy Florida, what is the basis for your claim that, as the climate warms, malaria will spread to areas that are currently malaria-free?
  36. 235, Manny,

    Perhaps its because we've only yet seen a fraction of the warming we're on course to invoke, and not yet enough to generate a sizable change in something like malaria. Perhaps, also, a major factor in the control of malaria is the elimination of swamps near populated areas, and the vast tracts of urbanized pavement that have replaced much of the swampland anywhere near populated areas. Too, as with any disease, it will thrive better in a population of weak, unhealthy, underfed victims -- hardly a description of today's Florida.

    What makes you think that if malaria were going to spread it would have done so by now, and if it hasn't, there's nothing to worry about?
  37. The primary controlling factor in the U.S. is "prompt diagnosis and treatment of infectious individuals" (from LINK) I find no reason to believe that this will change.
    Response: [RH] Fixed link that was breaking page format.
  38. Manny#235: "If malaria is not currently spreading to balmy Florida"

    This just in from balmy Jacksonville, Fla (2010):

    Duval County health officials issued an unusual warning Wednesday: Beware of malaria.

    Tests show that a 31-year-old Jacksonville woman has become infected with the typically tropical disease despite having no history of international travel, the health department announced.


    For the present, US wealth and infrastructure can control diseases that are normally found in tropical climates. Fast-forward to a time when tropical climates are more widespread and demands on under-funded public health services are overwhelming their capacities. What will you tell us then?
  39. New Research, showing decrease in fertility:
    "...Our findings imply that climate change affects aboveground–belowground interactions through changes in nutrient availability."
    Interactions between above- and belowground organisms modified in climate change experiments
    Stevnbak et al., Nature Climate Change(2012) doi:10.1038/nclimate1544
  40. One major positive benefit of increased atmospheric C02 concentration which has yet to be listed here is the enhanced efficiency of mitochondrial respiration that it would provide to animals via the Bohr effect.

    Because the Co2 to O2 ratio determines the hemoglobin's affinity for O2 and plays a major role in vasodilation/vasoconstriction (C02 is a vasodilator while 02 is a vasoconstrictor), increasing the ratio of Co2 to 02 significantly increases the distribution of 02 throughout the body, thus enhancing krebs cycle efficiency and general mitochondrial respiration.

    More atmospheric C02 is beneficial for plants (as has been described in this thread) and animals.
  41. AHuntington1 cen you give a verifiable source to support that hypothesis? I very much doubt rising atmospheric CO2 levels will have a significant direct effect on human health for the simple reason that most of us live in cities, or near places with large CO2 fluxes between the atmosphere and terrestrial biota, which swamp the effects of even large increases in background CO2 levels.

    I did a quick search myself and found:

    A proposed potential role for increasing atmospheric CO2 as a promoter of weight gain and obesity
    L-G Hersoug, A Sjödin, and A Astrup

    Human obesity has evolved into a global epidemic. Interestingly, a similar trend has been observed in many animal species, although diet composition, food availability and physical activity have essentially remained unchanged. This suggests a common factor—potentially an environmental factor affecting all species. Coinciding with the increase in obesity, atmospheric CO2 concentration has increased more than 40%. Furthermore, in modern societies, we spend more time indoors, where CO2 often reaches even higher concentrations. Increased CO2 concentration in inhaled air decreases the pH of blood, which in turn spills over to cerebrospinal fluids. Nerve cells in the hypothalamus that regulate appetite and wakefulness have been shown to be extremely sensitive to pH, doubling their activity if pH decreases by 0.1 units. We hypothesize that an increased acidic load from atmospheric CO2 may potentially lead to increased appetite and energy intake, and decreased energy expenditure, and thereby contribute to the current obesity epidemic.

    Note particularly the point about CO2 levels being higher indoors. Perhaps not so beneficial afterall.
  42. AHuntington1, your post lacks substantiation with published science articles. The adverse consequences of abrupt climate change and precipitations patterns disturbances likely dwarf any possible benefit from your alleged enhanced Krebs cycle. I am curious to see references for the "CO2 to O2 ratio dtermines the Hgb's affinity for O2" assertion. Links?

    Furthermore, as we have discussed on this thread the CO2 concentrations used in commercial greenhouses range between 800 and 1200 ppm, far beyond even pre-industrial level doubling, and with all other factors controlled and optimized. Truly nothing like the real world, these greenhouses...
  43. The paper to which Dikran refers is available (refreshingly, for free) online here.
  44. Composer99 It is indeed nice to see a paper not behind a paywall for once! However, I'm rather skeptical about this paper; as I said I very much doubt the CO2 levels have risen in cities as fast as the background level has been rising, and there are many more obvious explanations for obesity in the first world, such as sedentary lifestyles with little physical exertion - I am giving a good example of that right now by sitting on a sofa typing on a computer, rather than going to the gym.

    Similarly, I'd be very surprised if atmospheric CO2 levels were having a significant, or even measurable, effect on metabolism, and even if it were it is not a given that an increasing metabolic rate is necessarily a good thing as far as long term health is concerned. Essentially I think this is a fine example of "clutching at straws", but I'd be happy to be proven wrong.
  45. Dikran Marsupial, it is extremely important not to confuse correlation and causation. There are many other, significantly more pertinent factors at work when it comes to the development of obesity in animals. Increased environmental estrogen levels is one example (which would affect wild animals and humans more proportionately than Co2)there are many more.

    Fascinating study, btw. Although, considering all the other factors at work, it is doubtful that respiratory acidosis causing the firing rate of the orexigen neurons to increase is the major contributing factor to obesity, IMHO.
    Increased Co2 might also cause weight gain by increasing krebs cycle activity and thereby producing more energy per glucose. Or it could be through increased bone uptake of Co2 (co2 is converted to carbonic acid by the carbonic anhydrase enzyme, and can then can be converted to bicarbonate which is taken up by the bones)- higher bone density.


    Philippe Chantreau, I'm so used to talking with people who know about nutrition that I assumed people would know what the Bohr effect is- my bad. Here's the wiki: http://en.wikipedia.org/wiki/Bohr_effect

    you said " Truly nothing like the real world, these greenhouses... "

    Isn't a greenhouse an ideal example of the greenhouse effect? A controlled environment is the only way to study a single variable, like Co2. Controlled studies, in greenhouses are the only way to reliably study specific changes in atmospheric gasses.

    To quote Friedrich Miescher 1885,
    "Over the oxygen supply of the body carbon dioxide spreads its protecting wings."
  46. AHuntingdon1 I asked for a verifiable reference supporting the hypothesis you put forward. A peer-reviewed paper that shows that rising CO2 levels have a significant effect on metabolism in vivo would be fine. I suspect there isn't one, for the reasons I gave in my previous post.
  47. Dikran Marsupial, well I missed your last post; I'm glad we agree that the study published in the peer reviewed NCBI which you posted, and its hypothesis, are most likely wrong.

    You used logic to determine the validity of a study. Peer reviewed does not mean proven. Co2 levels absolutely influence the rate of oxidative respiration via the Bohr effect- this has been well established.

    When considering the reduced ratio of O2 to Co2 at higher elevations the "lactate paradox" (whereby people accustomed to high altitudes display higher levels of krebs cycle activity[make more ATP] during exercise) no longer is a paradox (evidence for Co2 increasing krebs activity).

    This study,http://www.ncbi.nlm.nih.gov/pubmed/7581542 implies Co2 as a potent antioxidant.

    This study shows Co2 protecting the organism from hypoxia. http://www.ncbi.nlm.nih.gov/pubmed/720676

    Here's another interesting study. http://www.ncbi.nlm.nih.gov/pubmed/9139450

    The positive attributes of Co2 on the organism have been well established. The fact that it is hard to find a peer reviewed study on the overall benefits of Co2 and the appropriate atmospheric concentration in which said benefits are maximized, reflects the mentality of most nutrition scientists more than the evidence.

    Again, Co2 is good for plants and animals.
  48. Readers, please note that AHuntington1 appears to be a master of both the Gish Gallop and the non sequitur.

    First, he impresses all with his ability to recite terms in respiratory biology, accompanied with a supercilious attitude ("Dikran Marsupial, it is extremely important not to confuse correlation and causation" and "I'm glad we agree that...") that gives no thought to the qualifications of the people with whom he is speaking.

    Second, he is able to compile a list of fairly inconsequential papers that show potential effects of elevated CO2 levels in rats, and projects this into the grand idea that increased CO2 levels in the atmosphere will have positive (and no negative) effects on all living creatures.

    These papers in no way make the case for his grandiose claim about "the enhanced efficiency of mitochondrial respiration that it would provide to animals via the Bohr effect."

    So he sets the goal post, then moves it, while with slight-of-hand appearing to support it. He hopes that you don't notice that (a) the papers do not reflect on his original proposition at all (b) they are impressive enough to convince you he is right, (c) they focus on very specific aspects of biology which may or may not have actual, real-life positive effects on the species studied and (d) they have little to do with elevated atmospheric carbon dioxide levels.

    He closes with the woefully simplistic (and wrong) statement that "Co2 is good for plants and animals" which is all he knows most (uncritical) readers will take away from the discussion.
  49. How much C02 is good for us?

    My car heater can keep me alive in winter. It does not follow that using my car heater in summer is even better for me.

    As to metabolic processes and C02, simply look up what's been established w/regard to concentrations of C02 in naval submarines and for that matter spacecraft. More does not equal better.

    In any case, remember: The "C02 is good for us" gambit is a frantic attempt to change the subject of conversation from geophysics to another only vaguely related topic. When nothing more can be done to evade the physical problem of global warming it's imperative to switch conversation to something else. You're seeing that happen right here.
  50. Sphaerica, the qualifications of of the people with whom I am communicating are less important than the information they present ( -snip-). Dikran mentioned that obesity rates and Co2 have been rising hand in hand, I pointed out that correlation does not equal causation and mentioned that there are a multitude of other potential contributory factors.

    As to your second point- the majority of time that organisms evolved on earth (especially during krebs cycle evolution, which was a very early adaptation), Co2 concentrations have been significantly higher than the present day.

    The fact that neither aerobic nor anaerobic bacteria can survive without Co2 highlights this fact. http://jmm.sgmjournals.org/content/13/4/573.abstract

    The idea that I cite random mouse studies unrelated to my point is simply wrong. Numerous studies have shown Co2 to be protective against acute hypoxia. I also wanted to point out that Co2 is potentially a potent antioxidant.

    The lactate paradox ceases to be a paradox when the ratio of Co2 to O2 is considered. It is also interesting that people who live in high altitudes (and are exposed to a higher Co2 to O2 ratio) experience lower mortality rates, in general. High altitudes provide a real life example of a population that breathes a higher Co2 to O2 ratio. http://en.wikipedia.org/wiki/Effects_of_high_altitude_on_humans#Long-term_effects

    These are factual benefits from increases in atmospheric Co2 concentration, and I'm simply asking for them to be included in the above list of pros and cons.
    Response: [DB] Inflammatory snipped.

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