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New IPCC report

  1. Feb 2, 2007 #1

    Mk

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    Anyone have it? How can I get it?
     
  2. jcsd
  3. Feb 2, 2007 #2

    Andrew Mason

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    Homework Helper

  4. Feb 3, 2007 #3
  5. Feb 3, 2007 #4
    :rofl: Just for your amusement I thought I'd show you the balls up that '2000 leading scientists' made in their recent IPCC report thingy.

    Check out the attachment, this is the table from the recent IPCC summary except I've annotated it to highlight its flaws.

    1. 2,000 leading scientists cannot add. Add up the separate contributions to global sea level rise (that they have given themselves) and you will see that it does not equal the total rise in sea level (that they also give themselves).

    2. They say that the sea level is rising by 30 cm/century, actually they're wrong, it's more like 3 cm/century.

    And just for the record it's not just me that's saying this, the mistakes were pointed out to me by an esteemed professor.
     
    Last edited by a moderator: May 9, 2012
  6. Feb 4, 2007 #5

    To be fair, though, isn't that the draft, or a draft and not the final edited copy?
     
  7. Feb 4, 2007 #6
    This is how it showed on the IPCC pages yesterday.

    http://www.ipcc.ch/SPM2feb07.pdf

    Still is, the table is at page 5. Notice how there are all grey edit remarks througout the official document.
     
  8. Feb 11, 2007 #7
    'sublimation point' question...:

    Hello.

    I have no science background, but I have possibly the most important question of all, and I'm hoping someone can answer this:

    *What is the 'Pre-Saturation Point'(possibly 'sublimation point') of Carbon PPM build-up in our Atmosphere?
    *Someone wrote that we are between 360-380 PPM, and although I cannot say how I came up with this number, I think '358' is a very critical number that predicts a range barrier that we should maintain below.

    *There must be a 'Fail Safe' Point of which we cannot pass, and obviously we do not want to reach 'Saturation', for then our BioSphere would collapse.

    I'm also wondering what would be 'noticeable' if we were within that range.
    I know our phytoplankton and blue green algae are dying in our oceans, and also our glaciers are experiencing some meltdown; so I don't things things are doing very good at the moment at all and I'm very worried.

    thankyou,
     
    Last edited: Feb 11, 2007
  9. Feb 15, 2007 #8
    The IPCC places CO2 levels @ 379 ppm as of 2005

    Don't be so frightened of CO2 levels, i is not that significant, as I can show you in the Vostock ice core data where CO2 levels hovered between 260ppm and 280 pmm for 8k years while temps plummeted over 6 degrees celcius !
    I think we should curb burning fossile fuels, but not because of so called "global warming". I call it weather redistribution. :smile:

    B.T.W. anyone try linking the changing magnetic fields of the earth with this "weather redistribution" ?
     
  10. Feb 16, 2007 #9
    Excellent point; I'm trying to figure that out myself.

    The IPCC report summary implies the "fail safe" point may be about 450 ppm (vs today's approx 379 ppm) atmospheric CO2. They don't actually say "safe threshold", but that's the lowest level mentioned in the report summary.

    The IPCC says to stay under this limit requires reduction of cumulative carbon emissions over the remaining 21st century from about 670 gigatons carbon to about 490. I think they made a simple math error in failing to account for compound annual increases in the 1st number (which should really be about 1900 GtC), further info here:

    https://www.physicsforums.com/showpost.php?p=1231537&postcount=59
    https://www.physicsforums.com/showpost.php?p=1231935&postcount=60

    However let's assume the 2nd number is valid -- limiting cumulative carbon emissions over the remaining 21st century to 490 GtC is required to limit atmospheric CO2 to 450 ppm, which in turn limits global warming.

    But -- there's a significant discrepancy between the 490 GtC plus what we actually observe. 490 GtC over 93 yrs averages at 5.2 GtC/yr, which is WAY above what the safe threshold is, according to IPCC and other numbers.

    E.g, according to the IPCC, global warming was well underway by 1945, caused by anthropogenic CO2 emissions. However at that point emissions were only about 1.5 GtC/yr: http://en.wikipedia.org/wiki/Image:Global_Carbon_Emission_by_Type.png

    This is discussed further in this post:

    https://www.physicsforums.com/showpost.php?p=1245532&postcount=3

    So it just doesn't add up. If the annual temperature increases up to mid-20th century are significantly caused by anthropogenic CO2, this implies the safe upper emissions limit is much lower than the IPCC number of 490 GtC cumulative over the remaining 21st century (5.2 GtC/yr average).

    That in turn implies either (a) much greater reductions are needed or (b) some kind of mistake in the calculations were made. Both items can't be true: that global warming was happening at 1.5 GtC/yr, yet reducing emissions to an average of 5.2 GtC/yr is safe.
     
  11. Feb 16, 2007 #10
    The fail safe flipping point of the flickering climates is an ice age myth. it is very understandabkle that the idea emerged seeing the isotope proxies jump up and down seemingly in two stages, interrpreted as cold warm, but the bulk of the evidence clearly proofs beyond doubt that it's mainly about arid-moist flicks and unrelated to greenhouse effect.

    More details in the NERC discussions, compiled here:

    http://home.wanadoo.nl/bijkerk/refuting the Greenland paleo thermometer1.pdf

    http://home.wanadoo.nl/bijkerk/refuting the Greenland paleo thermometer.pdf

    But cleaning up that mess, by no means signifies that all its conclusions have faded already from memory. That will take a generation.
     
    Last edited: Feb 16, 2007
  12. Feb 21, 2007 #11
    I'm not a scientist, but if we correlate this 'PPM' number with the reason we are presently witnessing our glaciers breaking apart/melting, and our oceans dying the 'slow death'(per se), and the extinction rate of some species(never seen before in our life time), I'd say the data is overwhelmingly convincing.

    *What's shameful is that our Government, Corporations, the common people, etc,, are going to have to 'suffer a catastrophe' before anything is significantly done.
    I think sometime about Nov. 2006, there was a story about some chemicals being strewn into our upper atmosphere to reflect U.V. rays from our Sun..., well that says something too.

    I imagine as we 'burn off' our fossil fuels, we will also wreck the composition of our Atmosphere to the point where we will see larger and larger meteors come crashing through to Earth(since we won't be able to burn up Kinetic Mass as well as we could have).

    *Maybe as that continues, people will care less about their Stock Porfolio Investments, and pay attention to this Emergency, and Conserve(even if it means 'slowing down the Global Economy.....before we have nothing at all).
    :frown:
     
  13. Feb 21, 2007 #12

    Thankyou for that.

    I have no faith in our 'Corporate Government' to put any brakes on the economy at all. With our National Debt as sky high as it is, and the Greed as great as ever, even if they knew the number was '450' PPM(I think that is past 'Saturation'), I think they'd do nothing.
    They don't know how to divide their Ego from their material wealth pursuits, and they will risk everyone's life in the process of being unconscious to the reality of things.

    *China is growing exponentially, and so is India, and I doubt our Bio-Mass is keeping pace with their 'needs'.
    *Past growth rate models are going to be obsolete, and by the time we can offer any accurate predictions, I'm about certain that we will have been too late, and have shot past this 'Fail Safe' point(which I am certain is '385').

    And then there is the 'chance of Synergy', and if I am correct about that, there is no computer model capable of knowing how fast we 'go off the slope' of our charts. *Its best/safe to keep below '385'.

    *I must say at this point, that I have been fixed on something from the mystical practice of 'Kabbalah', and the concept from the Ancient Hebrews which predicts the 'Mossiach'(who comes at the most 'Critical Moment of Time').
    No one seems to know what 'most critical moment of time' is, but I do.
    It is when Anthropic Theory of Life is threatened(along with our BioSphere), and that is do to the 'burn off' of our Carbon Fuel.
    The Gematria number is '358' for the 'Mossiach', and 'Gematria' was based upon 'Chemistry'. Hence, why we have '144' Interstellar Molecules(130 Neutral and 14 Positive).
    That is the number of what the Kabbalists call the 'Perfection'('144'), and it is not by accident that these numbers correspond.
    .

    *'358' is critical to me for obvious reasons, and '385' is playing with fire.

    I'm not a Religionist, but in the 'Hebrew', they speak about 'The sound of Trumpets' when the 'Messiah'/Mossiach comes.
    *What do you think that means?
    Imagine when the Atmosphere rips a hole(kind of like a tea pot boiling, and you hear its whistle).
    I hope no one is laughing(its happened to me on other sites already), because I am very serious to say the least.

    So ask: What is the most critical moment of Time? It can only be one thing....'Our Time becomes threatened with extinction'; and we have a 'Choice' to save ourselves(and we must 'Act'; we have no choice actually).
     
  14. Sep 12, 2009 #13
    The accurate value for climate sensitivity is 0.277 K/(W/m^2), which is 3 times smaller than the generally accepted value of 0.8 K/(W/m^2). Thus the climate change on doubling CO2 from 300 ppm to 600 ppm will be 1.0 degree, not 3 degrees. Because the IPCC data show that doubling CO2 will not double absorption of infrared radiation, the Beer-Lambert law is not being followed, because of diminishing returns after more-than-50% absorption. Thus further doublings of CO2 to the point of suffocating levels can only result in a fraction of a degree increase. Therefore global warming by CO2 increases has been wildly overestimated. The same IPCC data show that water vapour is 1.5 times as important as CO2 as a greenhouse gas, and it still seems to follow the Beer-Lambert law (doubling the concentration doubles the absorption). Thus climate changes are more sensitive to changes in water vapour than to CO2. Since water vapour is released on the combustion of alcohols (including methanol and ethanol) and alkanes (including methane, propane, gasoline and diesel fuels), but not coal, and by transpiration in plants in forests and crops, efforts to mitigate climate change by reducing human-produced water vapour would run in exactly the opposite direction to efforts to reduce climate change by controlling CO2 alone. However, the formation of clouds from increased water vapour would provide a negative-feedback mechanism which is difficult to model accurately.
     
    Last edited by a moderator: Sep 12, 2009
  15. Sep 12, 2009 #14

    Evo

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    Hi Roger, unfortunately, due to the fact that we have no one on staff that can moderate discussions on climate science, we do not allow calculations made by members and your blog is not an acceptable source, so your link was deleted. You are, however, welcome to discuss the various climate data and reports from scientifically accepted sources.
     
  16. Sep 12, 2009 #15

    Xnn

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    The amount of water vapor released from combustion by human activity is insignificant compared to the amount evaporated every day. However, a more important factor is the capacity for the atmosphere to hold water vapor. Since increasing CO2 levels allow the atmosphere to hold more water vapor, climate sensitivity includes the warming from water vapor.

    The IPCC has correctly modeled the sensitivity of climate to CO2 levels. Included in this is a reasonable level of uncertainty. Denial of the basic science is not a constructive stance.
     
  17. Sep 12, 2009 #16
    It would also be interesting to calculate the energy required versus energy available to evoporate the additional water vapor required to keep that feedback going.
     
  18. Sep 12, 2009 #17

    sylas

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    These claims are false.

    My understanding of the physicsforums rules is that claims like this are not allowed as a basis for discussion unless it can be shown that the claims are made also in peer reviewed scientific literature.

    So what can I do now, consistent with the rules? Roger's bare claims are here without any adequate basis; are we still going to have to go through and explain what is wrong with them?

    I can do that. I can provide links to other posts, where I have already gone through the various points where Roger is in error, with proper referencing as required. I'm busy most of today, but if this post is allowed to stand, then I happy to put in the time to find all the posts and cross reference to those older discussions.

    I reported the original post as I thought it was only going to be a waste of time. The claims are trivially wrong, and full of really fundamental errors. This is the very lowest possible standard of so-called skepticism, and I would prefer we did not have to waste time with it. Roger himself is unlikely to be persuaded by anything I might say, which is his prerogative and I don't mind about that. People who are honestly confused and unsure about the whole issue deserve better than distractions with material so grossly in error. Discussions here, as I understand it, should be focused not on Roger's personal notions and errors, but on the various different perspectives (and there ARE different perspectives) that are considered within the working of mainstream peer reviewed published scientific research.

    So. I will put up a response later that is focused entirely on the substance. I just want to add this meta-level comment on the conventions and expectations for discussion on this forum, as I understand it. I have no authority, however; and will defer to mentors for any rulings. This is just my own understanding of the rules we've been given.

    Cheers -- sylas
     
  19. Sep 12, 2009 #18

    Evo

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    Roger has been told that his post with his own figures are not acceptable. He can cite data from mainstream scientific sources, such as temperature recordings, greenhouse gasses verified in reputable scientific journals, etc.. and then discuss them.

    If he wants to discuss anything, he'll need to cite sources. So his post has been closed, the entire thread does not need to be closed.
     
  20. Sep 13, 2009 #19

    sylas

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    This thread was started and finished back in February 2007. The answer to the question of the thread is that the IPCC 4th assessment report is available at IPCC Fourth Assessment Report: Climate Change 2007 (AR4).

    The thread has been reopened in Sept 2009 by Roger Taguchi, with a post containing claims about the science of climate that conflict with conventional physics applied by scientists working on climate. I have also seen the unpublished article where Roger has written up this in more detail.

    I did want to defer making a detailed response until it was clear whether or not the new post would remain in the thread. I'm happy now to go ahead with an explanation of why it is incorrect, properly sourced to appropriate references.

    Climate sensitivity

    Roger has confused the notion of climate sensitivity with the notion of Plank response. Neither value is known with three figures of accuracy.

    The concept of Planck response is explained, with references, in a number of recent discussions. See, for example, [post=2199572]msg #69[/post] of thread "Physics of Global Warming", and following; [post=2225918]msg #47[/post] of "Ocean Heat Storage", and [post=2309961]msg #147[/post] of "Need Help: Can You Model CO2 as a Greenhouse Gas (Or is This Just Wishful Thinking?)" and following.

    In brief, the Planck response is the temperature change you should expect per unit forcing, if nothing at all changes about the Earth other than temperatures. The climate sensitivity is the temperature change you should expect as other aspects of the Earth come in to equilibrium with the new temperature, such as humidity, surface cover, lapse rate, cloud cover, and so on.

    The calculation Roger uses is for Planck response. Furthermore, it is a bit too low. Here's a very useful and widely cited reference on climate feedbacks, which includes some helpful definitions and explanations of the terms being used (link to 3.2Mb pdf):

    Here's an extract from Appendix A, on definitions (page 3475)
    The Planck feedback parameter λP is negative (an increase in temperature enhances the LW emission to space and thus reduces R) and its typical value for the earth’s atmosphere, estimated from GCM calculationsA1 (Colman 2003; Soden and Held 2006), is about -3.2 W m-2K-1 (a value of -3.8 W m-2K-1 is obtained by defining λP simply as -4σT3, by equating the global mean OLR to σT4 and by assuming an emission temperature of 255 K).

    This reference is using the inverted value (forcing per unit temperature), but it corresponds to 0.31 K/(W/m2). The simplistic method Bony et al describe gives 0.26 K/(W/m2), close to Roger's value.

    Roger speaks of 0.8 as the "generally accepted value", and this is a reference to climate sensitivity. There is no "generally accepted value"; climate sensitivity is one of the great unknowns in climate science and there are many different values proposed, with large associated uncertainties. However, for the most part the empirical and theoretical estimates tend to fall in a range about 50% either side of 0.8; with a couple of odd exceptions. The IPCC summarizes the range of credible values as being from about 0.5 to about 1.2. The paper by Bony et al (2006) cited above is a review article, which is focused upon the feedbacks that amplify Planck response to give sensitivity. The paper does not give sensitivity explicitly, though it can be inferred from the feedback numbers provided, to be in the range about 0.61 to 1.14. (See also the reference in that paper to Soden and Held, 2006).

    The thread [thread=334005]A low likelihood for high climate sensitivity[/thread] also considers the range of likely values for sensitivity, and how they are estimated. Note that sensitivity is sometimes given in terms of 2xCO2 rather than W/m2 for the forcing unit. There are references in that thread to recent papers on estimation and constraints for climate sensitivity.

    Beer's law and the effect of doubled concentrations

    The conventional physics of radiation transfer in the atmosphere is of course fully consistent with the Beer-Lambert law, as is the inference of substantial forcings for successive doublings of CO2. In thinking there is some conflict, Roger is, I suspect, mixing up the effect on a single frequency of light with the effect on the whole spectrum. In any case, his statements quoted above are incorrect.

    The Beer-Lampert law, or Beer's Law, indicates that the proportion of light at a given frequency which is transmitted is a negative exponential function of the density of absorbing gas in the atmosphere. Let I be the intensity of incident light, and T be the intensity of transmitted light. Let l be the path length, N be the number density, and σ be the absorption cross section. Then Beer's law in a gas can be expressed:
    [tex]\frac{T}{I} = e^{- \sigma l N}[/tex]​
    This law does not consider re-radiation within the gas, and more importantly, it applies for a single frequency of light and the absorption cross section associated with that frequency. The simple consequence is that if the density of a gas is doubled, the proportion of light transmitted is squared (and hence reduced, since a proportion is in the range 0 to 1). However, this applies for each frequency individually; and does not carry across to the whole spectrum.

    For example, suppose that a gas absorbs in three distinct bands. In the weak absorption band, there is 99% transmission. In the strong absorption band there is 1% transmission. And in the partial absorption band there is 50% transmission. When you double the density of the absorbing gas, these numbers become 98%, 0.01% and 25% respectively, by application of Beer's law. Now if the incoming light is equally intense in all bands, then the transmitted fraction is originally 50%, and after doubling it becomes 41%. All consistent with Beer's law. The great majority of the additional absorption occurs not in the weak or strong absorption bands, but in the partial band, where the derivative of absorption with density is greatest.

    The actual absorption spectrum of a gas is much more complex than the simple three band case I've given as an example here, but the same principle holds in general. The major effect of doubling concentrations of a greenhouse gas (one that absorbs thermal radiation) is to increase absorption in the "shoulders", or "wings", of the main absorption band. This is a basic detail of the transmission of light in a gas which should be covered in any decent undergraduate text.

    CO2 absorbs strongly at around 12 microns. Hence pretty much all of that frequency is absorbed. Further doublings of CO2 have negligible further effect on the absorption in the middle of that band. However, the width of the saturated band increases, as more and more frequencies move from being minimally absorbed to mostly absorbed; and the net effect of this is the basis for the logarithmic relation between density of a greenhouse gas, and temperature impact.

    My reference for this effect is the online textbook Principles of Planetary Climate, by Raymond Pierrehumbert at the Uni of Chicago. Beer's Law is discussed on page 155. Here's an extract, including figure 4.12, from page 186, which explains the effect of increasing concentrations of a greenhouse gas, using CO2 as the example.

    [​IMG]
    Figure 4.12: Lower panel: The absorption coefficient for CO2 at 1 bar and 300K, in the wavenumber range of interest for Earthlike and Marslike planets. The horizontal lines show the wavenumber range within which the optical thickness exceeds unity for CO2 paths of 1/10 , 1 and 1000 kg/m2. Upper panel: The corresponding OLR for the three path values, computed for the same temperature profiles as in Figure 4.5. The OLR has been averaged over bands of width 10 cm−1.​

    Figure 4.12 explains why the OLR reduction is approximately logarithmic in greenhouse gas concentration for CO2 and similar greenhouse gases. The key thing to note is that the absorption coefficient in the principal band centered on 675cm−1 decays exponentially with distance from the center. Hence, as the CO2 path is increased by a factor of 10, from 1/10 to 1 kg/m2, the width of the ditch within which the radiating temperature is reduced to cold stratospheric values increases only like the logarithm of the ratio of paths. This is true for paths as small as .01 kg/m2 and as large as 100kg/m2. However, when the path gets as large as 1000kg/m2, the weak absorption bands on the shoulder, near 950 and 1050 cm−1 start to become important, and enhance the optical thickness beyond what one would expect on the basis of the central absorption peak. 1000 kg/m2 corresponds to a partial pressure of CO2 of about 100mb for Earth’s gravity, or equivalently a molar mixing ratio of about 10 % for Earth’s current surface pressure. This is far in excess of any CO2 concentration on Earth likely to have been attained in the past 300 million years [...]. Many greenhouse gases also have a central absorption peak with exponential skirts, and these will also exhibit a nearly logarithmic dependence of OLR on the concentration of the corresponding greenhouse gas.

    You can also see [post=2171458]msg #7[/post] of thread "Rising Carbon Dioxide Levels Don’t Increase Earth’s Temperature" for two spectra obtained from the MODTRAN calculator which shows clearly the effect of additional absorption in the wings of the main absorption band when concentrations are doubled.

    Water vapour in the atmosphere

    Water vapour is indeed the strongest greenhouse gas in the atmosphere. The interactions of gases is not simple, but in general I would say water is at least twice as important as carbon dioxide for the Earth's greenhouse effect. 1.5 times seems an underestimate of its importance.

    The major point about water vapour is that it cycles through the atmosphere so quickly. Enormous volumes of water evaporate into the atmosphere and precipitate out again every day. The total water content is determined largely by temperature. As temperature rises, you get more water vapour (higher specific humidity), as relative humidity remains about the same or even reduces a bit. If you add a lot of water into the atmosphere, it rains out again in very short order, to restore the natural equilibrium for humidity.

    Hence human emissions of water into the atmosphere don't have much effect on the total water vapour content. The best way to have a significant effect on water vapour is to somehow raise temperatures. This is why water vapour is treated as a "feedback", and carbon dioxide as a "forcing". Added carbon dioxide remains in the atmosphere a long time, and contributes to a stronger greenhouse effect and higher temperatures. This tends to raise specific humidity, which increases water in the atmosphere as well, and that makes the greenhouse effect stronger again. There are many complexities with the feedbacks, discussed in the reference Bony et al (2006) cited above. The point is that it is a feedback, because humidity is so strongly influenced by temperature, rather than by anthropogenic emissions.

    Roger speaks above of "efforts to mitigate climate change by reducing human-produced water vapour". There are no such efforts. It would be a waste of time, because human produced water vapour has so little effect.

    References. The various kinds of feedback that are involved with water vapour are discussed in Bony et al (2006). The relation of water vapour and temperature on Earth is discussed on page 101 of Principles of Planetary Climate, and also page 208 and following. Here is an extract from page 209:
    On a planet without a substantial condensed water reservoir, water vapor could be a wellmixed noncondensing greenhouse gas much like CO2 on modern or early Earth. In most known cases of interest, though, atmospheric water vapor is in equilibrium with a reservoir -- an ocean or glacier -- which fills the atmosphere to the point that the atmospheric water vapor content is limited by the saturation vapor pressure.

    Conclusion

    There are plenty of open questions in climate science, and room for reasonable skepticism about some of the conclusions that are reported. However, the various sides of real scientific questions all work from a common underlying physical foundation. In my opinion, the post to which I am responding is not so much skepticism as basic error and misunderstanding of foundational material from which all the many genuinely open questions should be examined. I am not in any personal doubt about this myself; but I don't demand agreement from everyone. I have tried to give the explanation in some detail, with appropriate references, and am happy to let it stand as a response for readers to consider.

    Cheers -- sylas

    PS. Evo, thanks for your work on this. I hope this is okay. If there are still problems, let me know. I was not able to PM you; your box is full. Feel free to delete this postscript if you see it.
     
    Last edited: Sep 14, 2009
  21. Sep 13, 2009 #20
    Let's have a look at this:

    Now, repeating my remark,

    Did somebody do the paperwork here, how high is the energy bill? And is global warming paying for that? For getting all that extra water in the atmosphere?
     
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