A Few Things Ill Considered

A layman's take on the science of Global Warming featuring a guide on How to Talk to a Climate Sceptic.

Friday, March 24, 2006

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The CO2 Rise Is Natural

(Part of the How to Talk to a Climate Sceptic guide)

This article has moved to ScienceBlogs

It has also been updated and this page is still here only to preserve the original comment thread. Please visit A Few Things Ill Considered there. You may also like to view Painting With Water, Coby Beck's original fine art photography.

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17 Comments:

  • At March 28, 2006 1:57 PM, Anonymous Kit Stolz said…

    Spectacular "plot" on CO2 and temps in the last 140,000. (I only wonder why it's called a plot and not a graph). Anyhow, that's exactly what I was looking for two weeks ago, to illustrate a journalism story. I'm keeping that one on file.

    By the way, have you seen this "CO2 Science" report on the "over-hyped" stories about the melting of the Greenland and Antarctic ice sheets? I'd be curious as to your reaction.

    http://www.co2science.org/scripts/CO2ScienceB2C/articles/V9/N13/EDIT.jsp

     
  • At March 28, 2006 2:49 PM, Blogger coby said…

    plot vs graph, just mixing things up a bit, that may bit a bit of Aussie influence, I lived there a few years. Technically speaking, plot may be more accurate as it is making a line out of a series of points...anyway.

    Like the proverbial broken clock, CO2 Science may be right about this one. The story in the link was a little dense and not what I thought it would be. I don't agree that any of the papers are flawed, but do think the recent press coverage was overblown. I even saw one story that led with "6 metres sea level rise by 2100" which is definately *not* what these papers were saying.

    Personally I think ice sheet collapse and sea level will rise much more than any of the current predictions and the scientists are over cautious. The next decade will be very revealing.

    Re graphics: keep an eye on this fellows work.

     
  • At March 28, 2006 7:11 PM, Anonymous Anonymous said…

    A bit of a straw man argument, because very few arguments against the anthropogenic causation of global warming deny that human beings are contributing to CO2 increases.

    The issue is whether or not those CO2 increases are driving the observed warming.

    We are talking about 180 to 280 ppm: parts per million.

    Can you explain the physical chemistry of this? I understand that CO2 is transparent to higher frequency light but reflective of infrared.

    But if I build a greenhouse of a million square inches (1000 x 1000 inches) but only cover 300 square inches of it with glass (18 inches per side vs. 1000 inches per roof side), I won't expect much greenhouse effect, whether or not my 300 square inches are distributed evenly throughout the 1 million square inch roof or not.

    Isn't water vapor a much greater contributor than CO2?

    Thanks

     
  • At March 28, 2006 8:25 PM, Blogger coby said…

    Re "straw man", there are still people who make this argument, some in relatively sophisticated forms. See this post.

    Re the physics, CO2 is "radiatively active" at IR frequencies, it absorbs this radiation on its way up and then re-emits it in random directions (ie half of it back to the surface). 280ppm to 380ppm is not small proportionally, it is 35% increase. CO2 is responsible for 9-30% of the GHE, which keeps the planet 33oC warmer than it would be without any GHG's. A very rough calculation: that means 3-10oC of GHE is due to CO2, add 35% and you get 1 to 3.5 additional degrees of warmth. There are many things wrong with such a simplistic approach, but it does serve to show that the concept is not contrary to common sense.

    "Isn't water vapor a much greater contributor than CO2?"

    Yes it is. Around 60-85%, but it is a feedback, not a forcing. See this post. And this related one.

     
  • At April 05, 2006 7:15 AM, Blogger Wag the Dog said…

    But if I build a greenhouse of a million square inches (1000 x 1000 inches) but only cover 300 square inches of it with glass (18 inches per side vs. 1000 inches per roof side), I won't expect much greenhouse effect

    A bit of a flawed analogy. The "greenhouse effect" is actually a misnomer, since actual greenhouses made from glass do not rely on the greenhouse effect to work. They maintain heat by reducing convection. If one were to open a small window in the roof of a greenhouse, the temperature inside will plummet. Also you can build a greenhouse from rocksalt that is transparent to IR and the temperature inside will still rise.

     
  • At June 21, 2006 9:55 AM, Anonymous Anonymous said…

    What do you say to someone who claims increased CO2 is benificial? That an increase in CO2 levels will lead to increased plant growth.

     
  • At June 21, 2006 6:17 PM, Blogger coby said…

    Yes, this is an important one and it is missing. I will try to get something on that very soon...

     
  • At February 20, 2007 6:00 PM, Anonymous Anonymous said…

    Aren't you the guy who said that the ice around the ice cores melts at the bottom, where the ice meets the ground, so accumulation doesn't reach up into space.

    After half a million years the ice (from snow accumulation) would reach into low earth orbit if it hadn't melted at the bottom.

    Do you have any proof that the ice melts at the bottom?

    Do you have any proof that there is no altitude increase (about several milimeters per year} at the Vostok Lake Station?

    Is the Vostok Lake Station increasing in altitude?

     
  • At September 06, 2007 12:56 AM, Blogger Simon said…

    > Aren't you the guy who said that the ice around the ice cores melts at the bottom, where the ice meets the ground, so accumulation doesn't reach up into space.

    We have sea ice and we have land ice. We observe water flowing under the land ice, it must have come from somewhere. Since the land under the land ice is permafrost, it won't be coming from natural springs, they're frozen, ergo the water must be coming from the glacier. Under a couple of kilometres of ice the pressure is high enough to lower the melting point of water so super-cooled water will flow. This leads to the geomorphological features of glacial erosion you can see in many mountain ranges across the world, the process of freeze-thaw is a well known, well documented, well observed phenomenon.

    > After half a million years the ice (from snow accumulation) would reach into low earth orbit if it hadn't melted at the bottom.

    Yes. But long before that it would have melted from the bottom, moved away from its original source of accumulation because the ice would buckle and move under its own weight and there would be an isostatic geological effect of the earth's crust sinking into the mantle under this ice mass.

    > Do you have any proof that the ice melts at the bottom?

    Glacial stream. Glacial lakes. We have geophysical evidence of it going on right now because we can do NMRI and see it under there, we can do seismology and see the change in density across the boundary between solid and liquid, we can see water flowing out from under glaciers, it happens, go to your nearest glacier and watch.

    > Do you have any proof that there is no altitude increase (about several milimeters per year} at the Vostok Lake Station?

    Ah - I see, so because one station increases in altitude it must all be wrong. I get it.

    > Is the Vostok Lake Station increasing in altitude?

    Yes it is. Is the ice thinning around Lake Vostok? Is there therefore less ice pushing down the earth's crust at Lake Vostok? Is there therefore some sort of isostatic glacial rebound going on? I don't know. Probably. Or maybe there is local accumulation of ice because it's a big old world and you'll have noticed that there are massive variations across the globe of temperature and precipitation.

     
  • At November 07, 2007 9:01 PM, Blogger stvrob_63 said…

    1. For the major CO2 absorbtion peaks there is already enough CO2 in the atmoshere for complete absorption. However increased concentrations of CO2 would broaden the minor peaks somewhat and result in increased absorbtion. Be aware that the potential increase in IR absorbtion is in proportion to the logarathim of the increase... it is not linear. Also, be aware that it works both ways...If an increase in CO2 Absorbs outgoing IR, it also absorbs incoming (solar)IR.
    Overall.. In my opinion, the potential for CO2 to affect Earths radiation balance is trivial. Earths radiation balance is contolled by solar radiation, albedo, and water vapor.
    2. The overall topic is..."The CO2 rise is natural". A large and poorly understood portion of it might be. Careful work with Ice Core studies and O-isotopes strongly suggest that CO2 levels rise in RESPONSE to warming temperatures. This shouldnt be a suprise. Since the vast majority of the CO2 actively particiapting in the carbon cycle is dissolved in the ocean, and since the oceans warm at a slower rate than the atmosphere, it only makes sense that warmer temperatures cause the CO2 to repartition between the atmosphere and the ocean. (CO2 has greater solubility in cold water than warm water). In the days prior to all the global warming excitement, this would have been a reasonable and rational position.
    3. What is everyones problem with CO2 anyway!....CO2 is the basis for all life on earth. Did you know that, CO2 concentrations are the primary limiting "nutrient" to photosynthesis? (assuming that water is not limiting). Did you know that many modern plants have evolved special physiological cellular adaptations to deal with low levels of atmosheric CO2. (C4 plants and CAM plants)
    Why did the dawn of agriculture coincide with the beginning of the present interglacial warming? Certainly their were humans living in the tropics where the climate was warm enough for agriculture during the ice age. Is it remotely possible that CO2 concentrations were insufficient during the ice age to to maintain anything but a hunter gatherer existance? If a device were invented tomorrow that could reduce the concentration of CO2 in the atmosphere to the "preindustrial" level of 280 ppm, do you honestly think it would be worthwile to do so? Before you answer, remember that the population of Europe and possibly much of the rest of the world decreased 60 to 70 % between 1,400 and 1,700...Freezing weather, famine, and plaque.

     
  • At November 07, 2007 10:11 PM, Blogger stvrob_63 said…

    By the way, to whomever started this blog thread...
    the link you used in the discussion in the beginning of this topic:

    http://www.brighton73.freeserve.co.uk/gw/paleo/20000yrfig.htm

    Directly conflicts with the information you posted in a different topic about it being warmer than it has in the past 20,000 years. Apparently this temperature reconstruction predates Mann's Hockey stick fiasco.
    Also, note that the Vostok core data should not be interpreted to be an indication that the CO2 caused the associated climate changes in the levels. This data is entirely consistent with CO2's solubility response to change in ocean temperature (represented by the dueterium isotope concentration). In fact, the best match between the deuterium (as a temperature proxy) and the CO2 concentration occurs with about a negative shift of 1,200 yrs in the CO2 data. (IE, the CO2 data LAGS the temperature proxy by around 1,200 yrs)

     
  • At March 23, 2008 8:46 PM, Anonymous Yves said…

    "By the way, to whomever started this blog thread...
    the link you used in the discussion in the beginning of this topic:

    http://www.brighton73.freeserve.co.uk/gw/paleo/20000yrfig.htm

    Directly conflicts with the information you posted in a different topic about it being warmer than it has in the past 20,000 years. Apparently this temperature reconstruction predates Mann's Hockey stick fiasco.
    Also, note that the Vostok core data should not be interpreted to be an indication that the CO2 caused the associated climate changes in the levels. This data is entirely consistent with CO2's solubility response to change in ocean temperature (represented by the dueterium isotope concentration). In fact, the best match between the deuterium (as a temperature proxy) and the CO2 concentration occurs with about a negative shift of 1,200 yrs in the CO2 data. (IE, the CO2 data LAGS the temperature proxy by around 1,200 yrs)"

    1) The lag might be valid for past warmings, albeit with a large uncertainty range. OTOH this graph also shows clearly that... the present CO2 levels are unprecedented for 20000 years, unless if one wants to believe in Jaworowski's statements and Beck's flying circus stories. But in that case the "ice core show that CO2 lags temperature" is simply irrelevant since the ice core data are assumed to be unreliable by those paladins,

    2) The fact that of ocean degassing leads to higher CO2 levels is not a censored truth but a basic in climate studies. But that effect has to be quantified, which is not straightforward because of the complexity of the carbon cycle and of the time lags in ocean warming. AFAIK, the effect is of the order of 10 to 15 ppm per degree for the whole ocean. It can't explain all or even most of the recent CO2 rise.

    3) The fact that in the past CO2 rises were delayed consequences of T rises is logically independent from any effect of CO2 on T: it doesn't prove, nor disprove, an effect. If an effect of CO2 on T can be proved otherwise (it can, at least in the lab and as a contribution of the natural greenhouse effect), then it is a positive feedback from the carbon cycle response to T rise, just like water vapour is a positive feedback from the water cycle response to T rise.

    4) Which "hockey stick fiasco" ? Mann's studies have been validated, at least by the scientific community (National Academies of Sciences, peer review).

    Best

    Yves

     
  • At March 25, 2008 10:10 PM, Blogger stvrob_63 said…

    Yves,
    thanks for your response. I was wondering if anyone visited this blog anymore.
    1. I generally agree with your first point, that the graph shows a significant increase in CO2. However, this same data set has been casually and in my opinion, irresponsibly thrust before the public specifically as an example of the "obvious" cause and effect between CO2 and temperature. But that is Mr. Gore's moral dilemma, I understand that responsible scientists would not endorse that view, I merely meant to point that out. (incidentally, the cause and effect relationship implied by Mr Gore is wrong for another reason other than the time-lag. Methane concentrations also increase along with the CO2 concentrations. Even if temperature, CO2 and methane moved up and down together without the time lag, it would be illogical to conclude that CO2 was driver for both the temperature AND the methane)
    2. I concur, ocean degassing is not a censored truth, yet you must admit that a simple qualitative application of Henry's Law and its importance regarding this issue severely lacking in the information available to the public. Your comment about the effect generally being on the order of 10 to 15 ppm/degree may be about right, but you miss the point when you say it can't explain the recent rise in CO2. perhaps the opposite question is more relevant, if we have oversaturated the atmosphere with some 85 ppm CO2 over its equilibrium with the ocean, the ocean is then undersaturated with respect to CO2. As CO2 levels continue to increase, the oceans may become more effective in scavenging CO2 from the atmosphere. It is even possible that, givin the sampling rate of the Vostok and other cores, that numerous meanderings of atmoshpheric CO2 levels away from their equilibrium levels with the oceans have occured in the past.
    3. I didnt mean to imply that the ice core samples disprove CO2 as a climate forcing. This can be disproved in other ways. I only meant to point out that this data does not reinforce the argument for AGW. I concur with the fact that CO2 absorbs infrared at specific wavelengths, and that the absorbtion should be approximately proportional to the logarithim of the CO2 concentration. However, this forcing is too small, its "unsensational" A boring 1.0 to 1.5 C per doubling of the CO2 concentration. I most strenously object to the present AGW ideas of adding additional hypothetical forcings on top of this value when in fact THERE IS NO BASIS FOR EVEN PREDICTING THE SIGN of these forcings.
    4. So the National Acadamies stopped short of calling him a liar and you think that means his Studies have been validated by the scientific community? This single episode has been an embarrassment to the whole community and has done more to unwravel the AGW cause than any other single factor. The world faces a great many difficult and challanging problems. We shouldnt have to put up with people who cheat to thrust their cause to the front of the list.

     
  • At March 27, 2008 8:44 AM, Anonymous Yves said…

    Hello stvrob,

    Happy to hear from you. It can take some time to respond and I'm hectic now. So:

    1) I don't remember that Gore in his discourse wanted to make a case about ice cores proving a direct cause-to-effect relationship. The explanation was embarrassed and the temperature scale was not shown - BTW if there were so simple, re 100 ppm equates to 5°C, we wouldn't even be here to discuss :) . AFAIK he probably wanted to imply that a 100 ppm change in CO2 conc (or a 1100 ppb change in methane) equates to a move of geological importance, equivalent to the consequence of a 5-6°C warming.
    As for CO2 being responsible for both T and CH4/N2O that is possible in theory, it depends on the timescale:
    CO2 up (volcanoes) --> T up --> more CO2 (oceans, permafrost) and CH4/N2O (biosphere/pedosphere and at a later stage release from clathrates) --> more T, up to a new equilibrium on T, CO2, CH4, N2O and last but not least water vapour/clouds. That might have occurred at the PETM, 55 Myrs ago (see Wiki for an entry point on PETM). However even if the mechanism were confirmed, the timescale is crucial and millenia of CO2 excess might have been necessary to cause the catastrophe.

    2) Yes estimates I gave are for the dT / dCO2 equilibrium and do not encompass real, out of equilibrium phenomena. However that addressed the "T induced ocean degassing" as cause of CO2 rise, in that the departure from T/dissolved carbon equilibrium is necessary as a driving force for degassing. If there atmospheric CO2 in excess to the equilibrium value, it will recycle through the ocean waters but much of the excess will be sent back to the atmosphere. In other words, the primary sources of the excess over "T/CO2 equilibrium" cannot be "T induced CO2 degassing" unless invoking some very amplifying positive feedback causing a transient "overshoot". Nevertheless any evidences of such mechanisms as cause of the recent CO2 rise belong to the realm of the "unknown unknowns" and have yet to make their case in the scientific literature.

    3) 1 to 1.5 °C per CO2 doubling is maybe boring in our hectic society but is huge in a geological viewpoint, especially if a notable fraction of the excess CO2 is suspected to remain for centuries (AFAIK beyond the ~30 years lifetime of most of the excess CO2, around 20% of the excess has a 300 years lifetime corresponding to ocean homogeneisation timescale and a lower proportion, a few percents, has a 100000 years lifetime). The expected effect of a CO2 doubling is indeed difficult to quantify because of the water vapour feedback, applying as consequence of initial T rise (Clausius-Clapeyron) but with huge uncertainties about cloud effects. And, the equilibrium value of 3°C estimated from glacial/interglacials and other events can be correct but not applicable to our present earth because of land use change, etc... (from memory I cite Peter Wetzel who posted in Realclimate).

    4. Having seen the report from the National Academies of Sciences I don't remember having seen any mention of fatal flaws in Mann's papers; there were some methodologic flaws and some overweight conclusions (1998 being likely - 66 to 90% prob - the warmest individual year of the second millenium is "likely" overweight) but Mann et al. reconstructions have been independently reproduced, including by the more variable Moberg et al. reconstruction. The scientific debate is going on and the IPCC decided to include all of them in a synoptic in 2007 instead of Mann's only. BTW, stating that the late 20th century is "likely" the warmest period in the 2nd millenium is not more an extraordinary claim than stating that the Sun is likely the brightest for the past 8000 years, as shown by the solar science community (more exactly Solanki et al.).

    Best

    Yves

     
  • At March 27, 2008 2:31 PM, Anonymous Yves said…

    Re Yves:

    Hi Steve,

    My last sentence about which message Gore probably tried to carry in his presentation wasn't clear enough at its end; I rather meant: 100 ppm change in CO2 (along with 1100 ppb change in methane) equates to "a move of geological importance, which latest occurrences were likely consequences of changes of insolation which also resulted in 5-6°C warming". My confusion.

    As I remember at this point he rather said this by reversing the scales; something like: "20000 years ago there were 100 ppm less CO2; T was 5-6°C colder, the sea level 120 m lower and Manhattan was covered by glaciers 1 km thick". I admit that even though technically true it was quite misleading, implying by association that 100 ppm CO2 equates to 5-6°C warmer (and 7 m sea level rise, by another association about Greenland melting) in an undetermined time scale but considering the IPCC projection ranges presented later, rather in the order of the century.

    Best

    Yves

     
  • At April 03, 2008 10:02 PM, Blogger stvrob_63 said…

    Yves:
    I appreciate your response, and really I have no arguement with what you are saying, except to point out that I don't think you are aknowledging how much damage can be caused by misleading the public. For instance, the Vostok cores reveal a fascinating degree of detail of Pliestocene earth history. I sense that you are the type of person who can appreciate how such detail could improve our understanding of the Pliestocene. (Why was the climate so different than it had previously been? Why did it fluctuate between extremes? Do the conditions which caused these changes still exist? how long will it last? What kind of evidence should we look for to tell the difference between an interglacial period and the end of Pliestocene-like climate conditions?)
    Yet you seem not to be too bothered by Mr. Gore's misstatements; but think of the impact he has made. People believe him, they gave him the Nobel prize! Ultimately, public opinion will decide which course we take. If the scientific community won't even try to object how can it expect to influence the public in the future? As a hypothetical, what if a complete and thorough analysis of ice core data were to reveal, for instance, that a very short-term spike in atmoshpheric CO2 levels could be correlated closely with the end of intergalcial conditions and rapid onset of glacial conditions. Do you honestly think that such a study would be taken seriously?

    You and I seem to be in general agreement on the basic principles and understand that we do not presently know everything. Yet I don't understand yours or others unwillingness to object when these principals are used to mislead. Is 1 to 1.5 °C per CO2 doubling a cause for concern? I don't know and neither do you. But what purpose does it serve to present poorly supported hypothetical feedbacks to increase this value to alarming levels? The public is given the impression that all of this is well supported. If it becomes clear that this is wrong, there will be no way to take take this back.

    Which brings us to the National Academies of Sciences and their (at best) lukewarm support of Mann. I wish that they had spoken more clearly and without ambiguity, but I cannot agree with you that their report can be read as a validation of Mann's hockey stick. Clearly they chose their words carefully to avoid controversy, but their findings do not vindicate Mann. In fact, most of the critisims of his work appear to be confirmed by the report. Perhaps the polite and generous tone and the deliberate non-confrontational word choices have been mistakenly interpreted? This would not be suprising, apparently most of the media coverage regarding this report have been similarly mistaken. Some parts of the report appear to be a polite sort of warning, (one which appears to be largely ignored).

    Look how the committee chooses its wording in some of the different passages:
    "It can be said with a high level of confidence that global mean surface temperature was higher during the last few decades of the 20th century than during any comparable period during the preceding four centuries." (In other words, We already knew this)
    "This statement is justified by the consistency of the evidence from a wide variety of geographically diverse proxies." (IE we didnt need to rely on Mann's data to conclude this)


    And.. in regard to general applicability of multi-proxy methods in general.."Our confidence in the results of these reconstructions becomes stronger when multiple independent lines of evidence point to the same general result, as in the case of the Little Ice Age cooling and the 20th century warming." (In other words, Mann's results seem suspicious because they contradict other proxy studies which are believed to be more reliable)

    "Based on the analyses presented in the original papers by Mann et al. and this newer supporting evidence, the committee finds it plausible that the Northern Hemisphere was warmer during the last few decades of the 20th century than during any comparable period over the preceding millennium"...(OK so its "plausible"...an interesting idea but will it fly?)
    "The substantial uncertainties currently present in the quantitative assessment of large-scale surface temperature changes prior to about A.D. 1600 lower our confidence in this conclusion compared to the high level of confidence we place in the Little Ice Age cooling and 20th century warming." (In other words, its an interesting idea, but we don't buy it, we think the pre-hockey stick interpretation makes more sense).

    It has been a few years, but I urge you to review the report again objectively, forget about any media spin you might have read in the past and try to understand how cautious the committee had to be in their choice of words.

    This purposful misleading of the public, and the increasingly obvious impotence of the scientific community to be able to do anything about it, I find very troubling. Those who do speak out are immediately attacked, meanwhile the system has evolved to immediately reject anything which could possibly threaten the idea of anthropogenic global warming. As an example, look at RealClimates recent attacks on the work of a certain astrophysicist from Jerusalum Univ. He has developed some very interesting ideas about our solar system's orbit around the galactic center and its correlation with ice ages. Their attacks on his ideas were sickening, I couldnt begin to imagine why they even felt threatened by his ideas, and it was clear they had no idea what they were even talking about (it was actually pretty entertaining though, I must admit, A bunch of climate science wanna-be's arguing about spiral arms and galactic rotation with a world renowned astro-physist) None-the-less, its disturbing to me that our climate "consensus" has now expanded to exclude new and interesting ideas about the causes ice ages.

    Anyway, I've written more than I've intended, I do appreciate the dialog. Best wishes to you and good night.
    'Steve

     
  • At July 11, 2008 11:09 PM, Blogger yezi said…

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