the Air Vent

Because the world needs another opinion

Some comments on AGW

Posted by Jeff Id on October 23, 2009

My computer has a virus so I can’t do much of anything.  Sorry for not interacting much on the threads.   I’m working on repair and will probably be back up tomorrow.  In the meantime Dr. Weinstein has a few thoughts on conclusions in AGW he wanted to share.

———————————————

Leonard Weinstein, ScD

October 23, 2009

The “Positive Feedback” issue:

A write-up at http://chriscolose.wordpress.com/2009/10/08/re-visiting-cff/ reviews the climate forcing/feedback concepts. The basic review of the direct effect of CO2 seems very reasonable, and concludes that a doubling of CO2 would give a temperature rise of about 10C if there were no feedback. The write-up then states that best evidence, as stated in the IPCC 2007 report, indicated that the actual effect would be 20C to 4.50C per doubling of CO2 rather than 10C, due to positive feedback effects. The paper then shows a figure with several model calculations of possible contributions from all expected main sources of the feedback. All of the expected terms except water vapor are relative small and may even result in a slightly negative feedback. However, the contribution due to expected increased absolute water vapor content at higher altitudes is calculated to give a feedback multiplier about 2, and is by far the dominate term in the expected feedback. However, the absolute water vapor content as a function of altitude and date has been measured, and is shown in http://junkscience.com/Greenhouse/moisture.html. The data, which was obtained from ESRL, is shown for near ground level to 30,000 ft altitude. It should be pointed out that the higher altitudes are where the feedback is supposed to occur. The only conclusion seen for data from 1948 to 2008 is that the absolute level is slightly dropping except very near the ground. This is the opposite of what is needed for positive feedback, and in fact shows that a slight negative feedback should exist for that time period due to water vapor.

Residence time of CO2:


The monthly CO2 readings obtained at Mauna Loa (http://www.esrl.noaa.gov/gmd/ccgg/trends/) and other sites vary in a yearly cycle, which is superimposed on a continual rising average. The maximum drop rate within the cycles occurs in the northern hemisphere fall season. The average maximum drop rate is about 2.3 ppm per month at a level of about 386 ppm. This implies a maximum drop rate time constant of 168 months or 14 years. However, natural and continually increasing anthropogenic CO2 production did not stop during that time. The probable cause of the drop is the greater solubility of CO2 in cooling water due to dropping temperatures. A similar maximum rise rate of CO2 is found in spring as northern oceans warm. Since the majority of land and human activity are in the northern hemisphere, the unbalanced global land and activity location may cause the change since atmospheric mixing with the southern hemisphere has a lag time of at least several months to over a year. If the total anthropogenic emitted level were to totally stop, the ocean absorption time constant would almost surely be even shorter due to the larger drop. Since the upper layer of the ocean mixes well to a depth of several hundred feet within a few weeks, and the northern latitudes portion of this surface layer (the part that dissolves the most CO2) is in fact removed to a large depth by the surface and thermohaline currents within a few months, the excess trapped surface CO2 would thus be removed in a time constant even shorter than the ocean absorption time constant. This indicated that the residence time of CO2 in the atmosphere is almost surely much shorter than 100 years as claimed by AGW supporters. A probable mechanism for the fairly rapid removal of CO2 from the atmosphere would be by dissolving in raindrops, which then drop into the oceans.  One time constant drop of CO2 would lower the excess atmospheric level by over 60%, and each additional time constant would drop it over 60% of the remainder. The literature is full of references that indicate the atmospheric residence time constant for CO2 is close to 10 years, which is in reasonable agreement with this observed variation. The question arises, where do CAGW supporters get a value of 100 years?

Local vs. average temperatures:

Using worldwide temperature averages as a function of time may miss an important fact. Since the timing of the relative peaks and dips in regional temperatures are at least somewhat random in when they appear, they sometimes overlap and sometimes are out of phase, This results in variations of the average global temperature but this is not necessarily due to drivers such as Solar variations, or changes in CO2 levels. It is more likely that it is a combination of long period ocean current lag and natural chaotic effects that occur in such a complex nonlinear system. For example, the Sargasso Sea, Greenland, and Antarctic temperature variations (and many other regional areas) all occurred with similar rates and maximum amplitude of variation over all reasonably long-term time scales. However, the peaks and dips of the three regions mentioned did not always exactly line up. However, the overlap corresponding to the Medieval Climate Optimum is at least northern hemisphere wide, and seems to have occurred even in parts of the southern hemisphere also. The Little Ice Age and recent warming appear to be very much worldwide events. Claims that the poles heat (and cool) faster than the rest of the world average may be true, but so do many other regions. It may only imply that a selected but limited size region is more correlated in change than the sum of regions over the entire Earth. Europe and Northern US both had unusual large temperature swings in the not too distant past that lasted several years to decades, but they sometimes occurred at slightly different times. If the amplitude of the swings at the poles loses their unique speed of change feature, this minimizes the impact of another common assumption that something has to be causing the global warming. It is reasonable that if a forcing such as a large Solar effect or large CO2 change occurred, the poles would heat faster than typical other locations, but this does not seem to be the present case. In fact the Arctic heated about as fast and reached similar peak values in 1912 to 1942 as 1972 to 2002 (it doesn’t matter which was slightly larger, they were close). The earlier period is not thought to be anything but natural variation. The Antarctic has heated only a small amount over the time it has been monitored, and recent decades may even have net cooling, or at most small net warming.

Conclusion:

The hypothesis for an anthropogenic caused temperature rise of 20C to 60C by 2100 and more rise beyond that time is running out of any positive arguments. I would like to see any falsifiable claims that support that hypothesis, and that can be examined in a reasonable time period.



22 Responses to “Some comments on AGW”

  1. ThomasL said

    Dude, your computer is like 4 minutes old. What did you do? :)

    http://www.microsoft.com/security_essentials/

  2. Gary P said

    The link below goes to a chart from c3headlines.typepad.com. You mentioned that the IPCC estimate of CO2 residence time is much larger than from other estimates. This chart will hammer home the message that the IPCC is making stuff up.

    http://tinyurl.com/CO2residenc

    Their models are not just garbage processors, the climate models are garbage.
    h/t Jennifer Marohasy.

  3. Jason said

    If the humidity data given at the Junk Science link were correct, Weinstein would have a point. However, there numerous reasons to belive that this data is incorrect.

    By choosing a single data source, not mentioning the serious issues with it, and pretending that alternative data sources don’t exist Weinstein is acting like Michael Mann.

    Resolving the actual historical change in water vapor in the upper atmosphere is of great importance, but this sort of misdirection hardly helps.

  4. lweinstein said

    Jason,

    The data is from the NOAA ESRL site. Please tell me of a better source. I went to the ESRL site to verify it. The reference site I quoted only put the selected plots in a compact form. If you disagree with NOAA tell me why.

  5. lweinstein said

    Jason,
    Go to the site below and enter required choices. You will see the data.

    http://www.esrl.noaa.gov/psd/cgi-bin/data/timeseries/timeseries1.pl

  6. “The question arises, where do CAGW supporters get a value of 100 years?”

    The excessive residence half-life used by the IPCC is nothing more than a means of creating an accumulation of anthropogenic CO2 required to support the AGW assertion. In fact more or less any positive increasing dataset can be taken and fed through the process to result in a close match to the CO2 record. In some ways, it is analogous to the infamous ‘hockey stick’ routine.

    Anyway, I have put an example on my website, here: http://homepage.ntlworld.com/jdrake/Questioning_Climate/_sgg/mdm3_1.htm
    It is named “Is the MetOffice to Blame for the Rising CO2 Levels?”

  7. j ferguson said

    Jason said: “If the humidity data given at the Junk Science link were correct, Weinstein would have a point. However, there (are?) numerous reasons to belive that this data is incorrect.”

    Jason, tell us some of the “numerous reasons”. Hit and run isn’t a helpful response to Dr. Weinstein’s concise notes.

  8. Jason said

    I apologize for not being more polite.

    Nonetheless, this was previously discussed at CA in the context of the Paltridge submission (http://www.climateaudit.org/?p=5416). There are quite a number of reasons to disbelieve the NCEP Reanalysis, and quite a number of alternative sources of the data that appear to support the mainstream view (In my opinion, none of the data sources are of sufficiently high quality to resolve the issue either way).

    Dessler and Sherwood had an article about this in Science mag (http://geotest.tamu.edu/userfiles/216/dessler09.pdf) which is biased in the other direction. I believe that they have a comprehensive review paper in progress which will become the authoritative reference for this issue [I think Sherwood promised to cite Paltridge here, as he should].

    This appears to be a prepublication (http://web.science.unsw.edu.au/~stevensherwood/H2O_review_2.2.pdf). Paltridge (i.e. your data) is addressed on page 46.

    My main problem with the original article is that it gives the impression that the data clearly indicates that the models are wrong about humidity. This is absolutely not the case. At best, you can claim that this data source seems to disagree with the consensus. And good explanations have been provided to explain why it might be your data that is in error.

  9. Curt said

    You MUST distinguish between the time constant for a particular molecule of CO2 to stay in the atmosphere, and the time constant for a concentration of CO2 to be maintained in the atmosphere. (Freeman Dyson calls these the times with and without replacement.) These two times are very independent of each other, and must be deduced with different types of evidence.

    The residence time constant for an individual CO2 molecule is very well understood, mainly because we have been able to observe the decline in 14C levels since the pulse from atmospheric nuclear testing in the mid-20th century. These estimates generally come in under 10 years residence for the “average” molecule of CO2, quite tightly clustered, and not very controversial. (This time constant must be as short or shorter than that implied by the negative slope of the annual sawtooth wave in CO2 concentration.

    However, this says nothing about the time constant for levels of CO2 in the atmosphere, which is the number that is (at least potentially) for climatological purposes. This time constant is best thought of as the characteristic decay time in concentration after a sudden (impulse) addition of CO2 to a system that had been reasonably close to equilibrium. A moment’s thought will tell you that this number must be longer than that for individual atoms.

    How much longer is a big question, though, and there is a wide range of estimates for this. We have no evidence as strong as the 14C decay for this value. I haven’t looked at this question in a while, but I recall a lot of estimates in the 25 – 50 year range. The IPCC’s estimate of a 100-year time period is definitely on the high side of these estimates, but not ridiculously so.

  10. lweinstein said

    Curt,
    The same argument can be said for water vapor. The atmosphere does not care where gas molecules came from, and only the local average concentrations, not residence time, affects the long wave absorption. However, to specifically respond, the fact that part of the removed CO2 (with an initial time constant less than 10 years) partially returns back to the atmosphere then makes this returning part due to natural exchanges (from decaying plants, surface ocean evaporation before the CO2 that entered could be permanently removed), not part of the new human continuing input. Thus the fact that it reenters the atmosphere and delays final permanent removal (with a time constant of 100 years) (i.e., thermohaline to deep ocean, calcium carbonate dropping to the sea floor, or accumulating biomass) is NOT a sign that human activity is the cause.

  11. lweinstein said

    Jason,

    If you look at:

    http://www.ssmi.com/msu/msu_data_description.html#msu_amsu_time_series

    and look at Ch. TTS, you see a temperature cooling in the range of 5 to 15 km height (where the issue is) for the entire period of operation. If either the relative humidity were constant, or if the air were saturated, the absolute water vapor content would have to have dropped. This drop agrees with the NCEP measurements. I think this puts the claims that the issue is not settled to rest. Please explain how this is not so.

  12. lweinstein said

    Curt,

    I was not stating that human activity has not contributed to the rising CO2 level, only that the model assumptions of 100 year residence has no specific basis. I know of no study that showed the time constant of the residence replacement level would be 5 to 10 times the non-replacement level. I agree they could be different, but in fact, from my above comments, I expect a particular molecule (thus isotope) to be recycled naturally. From the residency of Carbon isotopes after nuclear tests, the residence time was actually short, so I expect the replacement level to also be short (<10 years TC).

  13. Jason said

    Lweinstein,

    Saying that this “puts the claims that the issue is not settled to rest” is patently absurd. As my previous references show, numerous data sets disagree with the analysis. Multiple papers are currently in press which reach the opposite conclusion.

    In fact, there should be absolutely no doubt that most people actively researching this issue and publishing papers believe that the issue is on the verge of being settled in the opposite direction. The review paper will provide you with ample references.

    Even if the issue of the big red dog (i.e. the predicted enhanced temperature change in the upper tropical troposphere) was settled, it would not be a sufficient basis on which to conclude that this one data series is correct and the others are incorrect.

    Multiple theories have been advanced by Lindzen and others that could explain the absence of the big red dog by alternative means.

    More importantly, the absence of the big red dog has NOT been established. I look forward to McIntyre’s paper debunking Santer et al 2008. But I certainly do not expect it to “settle” the issue.

    In my opinion, neither temperature nor humidity trends in this part of the atmosphere are well understood. The presence of contradictory analyses testifies to this uncertainty.

    Without a doubt, the issue most likely to poke a hole in the AGW consensus, but it is grossly premature to claim that this has already happened.

  14. Geoff Sherrington said

    There are many regions of the world where the temperature showed quite high in year 1998. I’m in the process of subtracting year 1997 (an more normal year) month by month from the 1998 months. to see if the hot period was narrow or broad, whether it was at the same month(s) all over the world and hopefully what caused it.

    If it was a global irradiance effect from GHG, then it should not have dropped because the GHG did not. If it was an anomaly like a warm water upwelling, then it should be possible to find the locus.

    In either case, because we measure air temperature a few feet above the ground, the anomaly could well involve mixing. It might show how fast mixing moves a thermal shock around the globe.

    Anyone who wiahes to choose any stations at all and subtract 1997 from 1998 by month, then send me the data, would be a friend indeed. Here’s a table for example from Meekatharra in the middle of nowhere in West Australia. It makes a plot that raises more questions than it answers, but that’s how science advances.

    MONTH DIFFERENCE DEG C (Tmax THEN Tmin)
    JAN 3.374 1.91
    FEB 6.24 2.45
    MAR 0.02 0.89
    APR -0.24 0.54
    MAY 5.47 3.31
    JUN -0.65 0.62
    JUL -1.98 0.99
    AUG 3.1 1.67
    SEP -0.93 -0.27
    OCT -0.77 -0.32
    NOV 1.98 2.95
    DEC -4.49 -2.32

    Sine curves, anyone?

    It’s not a particulatly elegant approach, but it should give a good lead to the next step. Please, I need as many stations as I can get, but don’t break your computer to compile them. Choose at random, give lat, long and alt. email sherro1 at optusnet dot com dot au Thank you.

  15. lweinstein said

    Jason,

    I look at TTS and see a temperature drop. All other arguments look at data error sources and some selected special cases and wave their hands that nothing is proved and it is possible the water vapor is higher. Are you saying that both cooling indicated by by the best satellite data and lower absolute water content by direct measurements are wrong because data uncertainty allows possible variation the other way? The ground based temperature measurements are typically accurate to 1 to 2 degrees or more and have very large “corrections” for heat island and other effects. Yet claims of final accuracy are made to 0.01 degrees. Ocean level is measured to 10’s of cm, but corrections are used and claims are made that changes of 0.1 mm are detected. Yet measurements are made by satellite and radiosonde and you don’t accept the measurements. Why the selective rejection. I am sure the temperature and water vapor increased at altitude at some times. There is some mixing. Finding some data is not the issue, it is the long time average, and the only data that comes close is the data I mentioned.

  16. lweinstein said

    Jason,

    I read the first two of your URL’s, but the third is not on line. The assumption of constant relative humidity seems to be just that, an assumption used by all of the modelers, but with no real data support. I would appreciate if you could send me the copy of the third paper. I am at

  17. lweinstein said

    Jason,

    My e-mail address did not go through. If you have another way to get the third paper on line please do.

  18. TerryMN said

    Re: 17 –

    There is an extraneous right paren at the end of the URL for the third paper. Remove it and the link works.

  19. Wayne said

    C14 has a residence time of around 16 years, C12/13 has a residence time of about 5 years.

    The study is recent and references to thestudy was posted on CO2 science in the last few days.

    http://www.co2science.org/articles/V12/N31/EDIT.php

  20. Jason said

    LWeinstein:

    Your comment in #16: “The assumption of constant relative humidity seems to be just that, an assumption used by all of the modelers, but with no real data support” was my original interpretation.

    After some personal investigation, this remains the case. The scientific community seems to find the satellite data much more persuasive than I do. I tried digging into the derivation of the satellite data, and decided that it depends on too many assumptions and calibrations to be convincing.

    BUT the same can most certainly be said of the NCEP reanalysis. We should apply the same skeptical standards to all sources. In my opinion, none of the humidity data is particularly convincing. You are welcome to reach a different conclusion. But when a majority of data sources and papers disagree with you, it seems a little silly to call that conclusion settled. Settling the issue, almost by definition, requires convincing a substantial portion of the scientists who are actively studying the issue.

    As far as TTS, I don’t want to have to argue the Santer ’08 version of things. I simply point out that people are actively publishing papers that claim that TTS is following the model predictions. It is therefore premature to suggest that this issue is settled either. [I actually _do_ agree with you and McIntyre on this one. Santer et al have a losing case. My only dispute is the notion that this has already been settled. I think that there is a very serious inconsistency between this data and the models, hence my interest in the humidity issue]

    Here is the review paper without the trailing parenthesis:

    http://go2.wordpress.com/?id=725X1342&site=noconsensus.wordpress.com&url=http%3A%2F%2Fweb.science.unsw.edu.au%2F~stevensherwood%2FH2O_review_2.2.pdf

    I haven’t had a chance to read it yet.

  21. lweinstein said

    Jason,

    I read the paper. It is long and covers a lot of references. I agree based on the discussion that the subject is not as settled as much as I thought. However, keep in mind that the hypothesis has to be supported to stand up (not just shown to be uncertain). It is not necessary to falsify every claim, only one to require modification or rejection of a hypothesis. In the end, the fact that SST has not risen for several years (so there is nothing in the pipeline), and the temperature has slightly dropped the last few years, all while CO2 still rises is the strongest argument for questioning AGW. The second and third comments I made also still stand. I do appreciate the fact that you made honest arguments rather than just throwing stones as many in the AGW (and more than a few in the other camp) do. I tried to get into several of the AGW blogs with honest questions and never was admitted.

  22. Jeff Id said

    #21, Thanks for the post Dr. I much prefer an open moderation to allow real questions. It’s only the troll (you’re never right) behavior that drives me nuts in this kind of format.

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