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Global warming and the sciencific method

  1. Sep 28, 2004 #1
    As I see a new brave offensive against those devious satanic gasses and obviously, weather of mass destruction is about to destroy the world. So, perhaps it's time to review the science behind greenhouse warming.

    How about using the scientific method this time.

    It seems to be getting warmer, Glaciers are melting, earthquakes in Alaska, etc. whatever.

    Well we know the greenhouse gas effect and we know that CO2 is rising. So could the increase of CO2 be the cause?

    So if increase of GHG is causing the warming. More GHG is more warming so we can model several scenarios leading to a prediction of the temperature in the future. Here is one.

    The complete story here

    And indeed we have covered a few more years since 1998 and we know the outcome.

    If we merge the two (red dots and the boldface trendline) we will find that we rougly have approached scenario C instead of A or B.

    But did CO2 stopped increasing in 2000 and did we have large volcano eruptions?

    Prediction failed

    (or at least increasingly inaccurate)

    What now?
     
    Last edited: Sep 28, 2004
  2. jcsd
  3. Sep 28, 2004 #2
    So their prediction is inaccurate if we assume that actual greenhouse gas emmisions have been different than their predicted emissions in scenario C. Could you help me find some actual estimates of emmited gases, so I can compare them with Table 3 in the text? Since my knowledge of the subject is limited, I'm afraid of guessing at what emmissions were.

    Also, I'm not convinced the actual data approximates scenario C. Looking at the merged chart I see a great deal of extremely wide variation in temperature over the past 4 years. I think it is safe to rule out scenario A, but what technique is being used to rule out B? Root mean square or something of the sort?
     
  4. Sep 29, 2004 #3
    Well Emision data are perhaps less relevant than the accumulation of CO2 in the atmosphere.

    http://www.grida.no/db/maps/prod/level3/id_1463.htm

    The most recent data:

    http://www.usatoday.com/weather/news/2004-03-21-co2-buildup_x.htm

    The temp data of the other graph are the monthly GHCN Land/Sea Global temp anomalies from Jan 1997 to June 2004.

    So, the CO2 concentration is steadily rising but the temperature is not. Scenario B assumes CO2 rising but warming tempered by an odd major volcanic eruption. However, there wasn't any real big one after the eruption of Mt. Pinatubo
    in June 1991.
     
  5. Sep 29, 2004 #4
    So the CO2 is rising, but the article you linked suggested it is rising at less than 1% per year, which is lower than their scenario B. We also don't know if the CH4 and NO2 values were similar to their assumption.

    It seems to me circumstances simply differed too much from their models to say for sure whether the models worked or not. It also bothers me how much the recent temperature data varies; I see a dark black line meant to suggest that is an average, but eyeballing it doesen't look like an average to me. A least square formulation seems the only acceptable way of picking which scenario it is actually approaching.

    Murky business indeed.
     
  6. Sep 29, 2004 #5
    The trendline was just calculated by Excel. No doubt, RMS methods.
     
  7. Sep 29, 2004 #6
    This will be slightly off topic, but I wonder if you wouldn't mind clarifying your stance on this particular issue for me Andre. I'm sure you've been more than clear in the past, but I'm relatively new to this forum. This topic seems to come up regularly and is of great debate in the US at this time.

    1) Your stance seems to be not necessarily that global warming isn't happening, but that there is not evidence that humans are causing global warming, and that much evidence presented is based on mediocre science at best. Would you say this is a fair description?

    2) Would you clarify whether you think greenhouse gases can warm the earth? Do you believe that global warming via greenhouse gases is faulty in theory? Is it that you believe that there are CO2 sinks we aren't aware of? At what point do you begin to really dissagree with the argument that humans are warming the earth?

    I have more questions but those are the big ones. THank you for your time.
     
  8. Sep 29, 2004 #7
    1. There is no doubt that on a global scale it's warmer than 15 years ago. But climate has changed a lot constantly, ever since the world came into existence.

    2. Most certainly greenhouse gasses (GHG) cause the world to be warmer than without. But the relationship is very complicated. The general feeling is that greenhouse gas warming is proportional to the amount of greenhouse gas. No dice however. The bandwith in the EM spectrum at which a greenhouse gas is active is quickly saturated and there is very little difference in GHG effect between 200 part per million (ppm) in the ice age, 280ppm (pre industrial) or 379ppm (last week) or even 1000ppm. It's the first 10ppm that counts. That's why methane is such a powerfull greenhouse gas, because the differnce between 1ppm or 4ppm is major GHG.

    Back soon.
     
  9. Sep 29, 2004 #8
    Thank you very much for your reply. That note about the bandwidth being saturated is an interesting one, and as a physicist I believe the theory would be accessible to me. Do you have a suggestion on where to start looking to learn more about it?
     
  10. Sep 29, 2004 #9
    My pleasure.

    These page may help.

    http://www.heliosat3.de/e-learning/radiative-transfer/rt1/AT622_section1.pdf

    and so on, especially

    http://www.heliosat3.de/e-learning/radiative-transfer/rt1/AT622_section10.pdf

    Good to have a physicist interested in this. I have never succeeded in finding somebody who would listen to and understand my ideas of how signal analysis in paleo proxies could shed more light on cause and effect, assuming the oceans as a linear higher order open loop system. Paleo climate could have been totally different than the present paradigms assume, those that lead to the global warming ..err..idea.
     
  11. Sep 30, 2004 #10
    This may sum it up a little bit.

    Of course, climatologists know this. The quick and dirty approach is that the greenhouse gas effect increases about one degree with every doubling of the concentration. So looking at about 280 ppm in 1850 and a lineair trend of about 1,1 ppm a year and being at 380ppm right now, it will be some 164 more years before reaching 560ppm, the double value of 1850. So it would be the year 2168 before it could be one degree warmer than in 1850. Clearly, things are totally different.

    This is why the positive feedback has been invented.
     
  12. Sep 30, 2004 #11
    That (http://geosci.uchicago.edu/~archer/PS134/LabManual/lab.modtran.html ) is an excellent site, Andre. Succinct, but scientifically detailed. AND they let you play around with that model all you want. I'm definitely saving this one.
    I ran a test of CH4 increases similar to the test they ran for CO2. It shows that an increase in CH4 from 1.7ppm (which I assume is close to the current real value since it is the default for this model) to 10ppm would result in a 0.6% decrease of the energy emitted. According to the website's modeling, an increase of CO2 from 330ppm to 1000ppm would result in a 1.5% decrease of the energy emitted. Additionally, CO2 must increase to 585ppm (from 360ppm) to incur a 0.6% decrease; CH4 must increase to 55ppm from 1.7ppm to incur a 1.5% decrease. Furthermore, the increase from 280ppm CO2 to 360ppm incurs about 0.3% decrease in energy emitted. That is the approximate change in atmospheric CO2 in the past 250 years.
    This shows that CH4 concentrations are much more sensitive in absolute measures (ppm) than CO2, considering their current atmospheric concentrations. So an increase of 8ppm of CH4 is approximately equal to an increase of 225ppm of CO2 from current values. But the likelihood of CH4 increasing to that degree seems less than that of CO2 increasing to that degree.
    I know how Andre has some disagreements about ice cores, but http://cdiac.esd.ornl.gov/trends/co2/siple-gr.htm and http://cdiac.esd.ornl.gov/trends/co2/graphics/lawdome.gif show very clearly that CO2 has not risen linearly over the past 250 years. I'm not saying CO2 is going to continue to increase so dramatically, but it is careless to assume it will rise at the same approximate rate that it has for the past 50 or 100 years. The rise in CO2 is hard to dissociate from man's use of fossil fuels and destruction of forests. Assuming that is the main component in the recent rise in CO2, we can expect accelerated increases of CO2 as China, India, and other undeveloped nations bring electricity and manufacturing online on the large scale in the next 50 years IF we allow the 'business as usual' approach to these industries. In short, CO2 is going to continue to rise at rates greater than today's if nothing is done to prevent that.
    I am not nearly as familiar with the CH4 cycle as the CO2 cycle, so I can't really say how it is changing or will change. But the fact that it is currently in the low single digits (if you can point me toward an exact number, anyone, please do) implies that there is currently not a enormous imbalance in production vs consumption. I know livestock (particularly cattle) are blamed for huge quantities of CH4 entering the atmosphere, so the increase in the past couple decades of cattle production may be driving up CH4. Mainly, I'd argue that CH4 will not increase 8ppm by the hand of man any time soon is because it doesn't appear to currently be increasing and since we know it is harmful the world's nations will avoid starting anything that would increase it greatly. This is not the case with CO2 because it is already increasing dramatically and the fossil fuel use that is driving it is the workhorse of every great nation's economy.


    Seperately, if anyone can point me to information and calculations on the connection between non-emitted IR energy and 'global temperature' I'd appreciate it (i.e. how does the IR energy retained in earth's atmosphere affect the temperature?)
     
  13. Oct 1, 2004 #12
    You may be refering to the Stefan Boltzmann law.

    Here is an example of the calculation of the effect of doubling CO2 leading to about 0,7 degrees.

    However, the presumption of Stefan Boltzman is an ideal black body, so the figure needs to be corrected slightly. One degree seems to be a very generous estimate.

    Well, that's an interesting one. Giving the erratic behavior of oceanic clathrate, that can explode into enormous quantities of CH4. Obviously this can lead to enhanced greenhouse gas effect - given the formerly indicated sensitivity. However oxydation of CH4 in the atmosphere is rather quick, giving a useful life time of only about a decade. More info

    So CH4 will not normally reach significantly higher quantities, unless we have a fast and enormous source like destabilizating oceanic clathrate. This may have happened 55 million years ago during the Paleocene thermal maximum
     
  14. Oct 1, 2004 #13
    Now despite the marginal effect of increasing CO2, I seem to observe a general counter-intuitive reaction. All the eyes are set on Kyoto and the Russians, leading us to an economical collapse without any benefit.

    Why do we still think that more CO2 is increasing heat rapidly? Some 2,8 to 4 degrees as far as I remember instead of <<1 degree in 2100 AD?

    The first reason are the ice cores indeed. There is an overwhelming correllation between alleged temperature indicators and greenhouse gasses. And of course "post hoc, ergo propter hoc". So the first idea was that the interglacials between ice ages are caused by initial warming due to increasing CO2 and CH4 (from the yet to be found swamps). This causes some ice to melt, this causes a decrease in reflection of sunlight, which causes more warmth to devellop, which melts more ice, etc, etc. (the positive feedback). The Milankovitch cycles also may have triggered these events. Also increasing temperatures induces more moisture in the air and hence more greenhouse gasses. Water works on a much broader bandwith than CO2 and CH4, and hence is a much powerfull greenhouse gas. Anyway, the ice cores seem to tell us that CO2 is causing the warming.

    Secondly, the Eocene thermal maximum also shows high temperatures and high CO2 rates. So apparantly another indicator of CO2 causing warming.

    Finally and most obviously, we have planet Venus, with the dense carbon dioxide atmosphere (92,000 Hpa). So it must be an extreme greenhouse gas effect that causes the high temperatures of the planet (482 degrees Celsius)

    All pretty simple, where it is warm, there is carbon dioxide so why doubt that more GHG= more heat?

    I think we can more or less debunk all three of those, but it requires rather controversial hypotheses to replace them.
     
  15. Oct 2, 2004 #14
    I'd like to continue with those three factors in reverse order, that way we end up finishing the other adjacent thread, "climate and clathrate".

    So Venus first.

    Venus is a mysterous playing ground for three differend specialism. The Astro-physicists gaze at it's strange retrograde spinning. The geologists wonder about the enigmatic highly volcanic past and it's mysterious tectonics, while the climatologists speculate about which greenhouse gas effects may have caused the extreme high temperatures in the extremely dense atmosphere.

    Since the specialists are burried in their pet areas of interests, it probably takes a jack of all trades to remain looking at the general picture and to come up with an idea in an attempt to explain all those features simultaneously. Here is that particular thread. Recommended :smile:

    Last update:

    A lot of new evidence has been uncovered. For instance studies now indicate that the geology of Venus assumes temperatures up to at least 1050K in the past (777 degrees C). Hence Venus is cooling, hence there can not be a thermal Greenhouse gas runaway mechanism in whatever form.

    The current explanation is extreme radiogenic heat. Yet, the chemistry of the surface does not suggest an abundance of radioactive material. The analyzed basalts for instance are more depleted of Potassium than the Earths basalts, whilst radioactive Potassium40 (40K) is supposed to be prime candidate for the principal heat source of planets cores.

    BTW. The concept paper is ready (35 pages) except for filling in all the references. I tried a few Venus specialists but all remained silent when I mentioned big brakes. So anyone can help me to genuine peer reviewers?

    Bottom line: despite the favorable conditions for greenhouse gas effect, it still may not be the cause for the extreme heat of Venus.
     
    Last edited: Oct 2, 2004
  16. Oct 3, 2004 #15
    Sure I can recommend one at my university.
     
  17. Oct 3, 2004 #16
    Make that 2 and maybe more. Check your PM's.
     
  18. Oct 4, 2004 #17
    This thread continues to be very interesting, thanks Andre.
     
  19. Oct 6, 2004 #18
    Sorry for the delay but things are getting a bit more complicated now and I have to figur out how to bring it, given the limited time.

    Anyway, we were discussing the role of greenhouse gasses in warming and we have seen the roughly logaritmic relationship between the concentration of GHG and the temperature. So to enforce the global warming hype, the alarmists have invented "positive feedback" factors that allegedly caused an much higher temperature response. Such is claimed for Venus, the Eocene Thermal Maximum and the Pleistocene ice ages. We have seen that Venus might have got it heat from a totally different source, which does not support the two main Greenhouse Gas hypotheses for Venus.

    Next in line is the Eocene Thermal Maximum. Several studies have made the clathrate burst scenario very likely. Here more info looking through the eyes of the alarmists.

    So, the next step is a glance at the mechanics of such a huge clathrate destabilisation event. Of course when big amount of Methane and Carbon Dioxide enter the atmosphere, inevitably the climate must react according to the previously discussed relations. However I'll try to reason that atmosphere and climates reaction was stable, without positive feedback factors. And again, without positive feedback, there can not be catastrophic global warming.

    The complication now it that we need some understanding of how palaeo temperatures are connected to stable isotope ratios. The thread Climate and Clathrate gives some basic ideas about the isotopes of the ice cores. But for the Eocene we have only the isotopes of the plantonic and benthic foraminifera in ocean sediment cores.

    And that is much more complicated than the ice cores. Especially when given that salinity and acidity influence the isotope ratio, what has previously only been translated to temperature.

    That's for the next time. And we're now merging the climate and clathrate thread.
     
    Last edited: Oct 6, 2004
  20. Oct 7, 2004 #19
    Before the discussion we need the facts and the assumptions about the Paleocene - Eocene Thermal Maximum (PETM).

    Here are a few sources:

    http://encyclopedia.thefreedictionary.com/Paleocene-Eocene Thermal Maximum
    http://eprints.soton.ac.uk/231/01/BICE_&_MAROTZKE_paper_paleoce_figures.pdf

    What I intend us (as this is a dialogue thread) to do is:
    - Assess the actual temperature increase of the oceans, considering all the processes.
    - Assess the required global air temperature to attain those sea temperatures
    - Estimate the average concentrations of CO2 and CH4 in the amosphere as a result of the Clathrate destabilisation.
    - Assess the re-radiation absorption of that atmosphere using the MODTRAN3 model and estimate the resultant temperature increase
    - Assess the difference between the required temperature for the warming oceans and the temperature increase due to greenhouse gas effect.

    If those match or the GHG temp is more than required, we could say that we did not need positive feedback effect, which would not support the current greenhouse hype.

    If we cannot explain the warming of the oceans with MODTRAN3 warming results, then we need more positive feedback and the Global warming idea would be fortified.

    I admit that I have already made some very rough estimates that suggests that the first possibility may have a good chance but any thought counts of course.
     
    Last edited: Oct 7, 2004
  21. Oct 8, 2004 #20
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