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All IPCC definitions taken from Climate Change 2007: The Physical Science Basis. Working Group I Contribution to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change, Annex I, Glossary, pp. 941-954. Cambridge University Press.

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Comments 129301 to 129350:

  1. It's the sun
    "What errors have there been in the GISS record?" Had a look at October's Giss data? Trivail? I don't think so. Look up Wattsupwiththat latest post on Russian data included by GISS.
  2. CO2 lags temperature
    Has anyone discussed the possibility of bias between the two different ways of measuring CO2 and temperature as the source of the big jump near the end of the hockey stick graph? Thanks.
  3. Temp record is unreliable
    Yes, don't allow yourself to be taken in by "rhetoric" beam! In science it’s all about the evidence. I'm sure nobody would suggest that it doesn't matter if we "lose the validity of the surface temperature record". I've had a look through the thread and haven't found any post which claims that, let alone "claiming that you "Don't need" the temperature record"...that would be an odd claim indeed! Notice that in order to take action in response to real world observations we don't need "proof". Proof is a mathematical/philosophical concept. What we need is strong evidence. So the pertinent question is: "is there strong evidence that the temperature record is robust to the extent that we can reliably assess the Earth's temperature response in relation to our understanding/predictions of massive enhancement of greenhouse gas concentrations". The answer is yes I suspect we would agree for some of the reasons already outlined on this thread: (i) The record is independently assessed by three different organizations. Although there are differences in data compilation/analysis methods and some differences that relate to the nature of covering sparsely-monitored regions, the different compilations yield a consistent interpretation of the surface temperature evolution over the last 100 and a bit years. (ii) the surface record seems not to have significant contamination from the UHI since (a) a number of direct analyses indicate that the UHI isn’t significant [comparison of temperatures on windy days (with rapid excess heat dispersal) cf calm days, and other types of analysis, for example as described here: http://www.skepticalscience.com/Does-Urban-Heat-Island-effect-add-to-the-global-warming-trend.html, or in John Cooks introductory summary on this thread]; (b) one can remove all of the urban records from the analysis, and the temperature profile is pretty much unaffected; (c) those regions showing the largest warming are far, far away from urban centres and generally there is no correlation between local temperature evolution and local urban density [see for example: http://www.skepticalscience.com/urban-heat-island-effect.htm] (iii) completely independent records of the consequences of a warming Earth are consistent with the surface record [these include high latitude ice recession; independent temperature scales constructed from the record of high altitude glacier recession; tropospheric warming; enhanced tropospheric absolute humidity and so on]. So the evidence supports the interpretation that the temperature record is robust. Your point about scaling of the record with respect to the Earth’s “total existence” isn’t an important comparison with respect to the question of the consequences of massive enhancement of the atmospheric greenhouse gas concentrations at this particular time in the Earth’s long history. In any case we have a huge amount of information about temperatures in the recent and much more distant geological past. This also informs our understanding and provides strong evidence in support of the expected surface warming response to enhanced greenhouse gas concentrations. For example there is a good correlation between atmospheric CO2 concentrations and the Earth’s “temperature” in proxyCO2 and proxytemperature data stretching back right through the Phanerozoic So in general, the paleorecord reinforces the data from our contemporary temperature record and all of the vast amount of information from understanding of basic atmospheric physics, to the spectroscopy of greenhouse gases, ice core records and so on and on, that informs us on the consequences of massive enhancement of greenhouse gas concentrations. That’s not to say that there isn’t much more work to be done!
  4. Volcanoes emit more CO2 than humans
    " “The loss of ozone allowed more UV light to pass through the stratosphere at a sufficient rate to warm the lower troposphere plus 8-3/4" of the earth by 0.48 o C (1966 to 1998).” " Now spread that heat out over the top 100 m of ocean and see what happens. ( 100 m * 70 % of area + 10/4 m** / (8.75 in* 2.54 cm/in + 10/4 m** (**water depth equivalent to atmospheric heat capacity)) = 72.5 m / 2.72225 m = 26.6 0.48 deg C / 26.6 = 0.018 deg C. But the quote refers to the lower troposphere, in which case the result is less; if the lower troposphere is the air below about the 500 mb level, for example, then I get 0.48 deg C/ 48.4 = 0.0099 deg C. )
  5. Volcanoes emit more CO2 than humans
    A few of the problems with this: http://omsriram.com/GlobalWarming.htm 1. (at least one of) the IPCC figures are incorrectly interpreted - tropospheric ozone is increasing, NOT decreasing - this is also an anthropogenic effect. 2. some temperature graphs are off. 3. CO2 graph is off (though not as far off as another one I've seen). 4. The evidence really does justify a conclusion that significant CO2 increases cause significant global (tropospheric and surface) warming.
  6. Global warming stopped in 1998, 1995, 2002, 2007, 2010, ????
    Chris, I'm not sure I accept your view of solar cycle 'damping'. The annual response to orbital & axis fluctuations (which are basically the same as increasing/decreasing TSI) is quite rapid, even for large masses of water. I live on the coast and the seasonal fluctuation in sea temp is quite pronounced and predictable...peaking at around 27C and dropping to around 17C in the summer/winter cycle. These seasonal fluctuations are much greater than the solar cycle and I suspect the small warming of the solar cycle gets overshadowed somewhat rather than retarded.
  7. Models are unreliable
    Don't be silly Dan. You don't need to point out that you're parotting phrases from post to post..we can see that ourselves! The point is that your parroted phrases are illogical. The fact that insolation effects drive downtrends in temperature while CO2 levels remain high doesn't necessarily say anything about the net feedbacks to raised CO2 levels at constant insolation. This is explained in my post #64. You could look at the papers cited in that post which will enlighten you considerably about the rather straightforward phenomenon of Milankovitch-forced warming/cooling transitions. Look at the papers John Cook links to here, for example: http://www.skepticalscience.com/co2-lags-temperature.htm (Petit et al, 1999 and Shackleton, 2000 are two helpful papers.) You would also benefit from reading: Kawamura et al (2007) Northern Hemisphere forcing of climate cycles in Antarctica over the past 360,000 years. Nature 448, 912-918. Although your conundrum has been resolved by explanation several times already, here's another explanation: (i) raised CO2 levels stay raised for long periods, since CO2 is drawn out of the atmosphere rather slowly, for example in response to temperature downtrends. (ii) therefore if insolation effects (due to Milankovitch cycles) reduce critical insolation, the Earth's temperature will drop even 'though CO2 levels remain high. (iii) therefore during the ice age cycles, insolation changes that drive temperature changes will precede the CO2 responses. (iv) this doesn't mean that variation of atmospheric CO2 at constant insolation doesn't have associated positive feedbacks. All of the evidence (that we can measure in the real world, including an increase in tropospheric humidity as a feedback response to raised tropospheric warming, and reduced albedo due to surface ice recession and so on) indicates that the effects of CO2 variations are amplified by net positive feedbacks. (v) one can point out a simple analogy of the day/night cycle. Although atmospheric CO2 levels don't change overnight and remain very very high, as the sun goes down, the temperature measured at the Earth's surface drops. (vi) In other words a temperature downtrend at high/highish atmospheric CO2 levels only means that the particular driver of the temperature trend at that paticular time is variation in insolation. (vii) which we all know very well since it's rather obvious and well characterized!
  8. Volcanoes emit more CO2 than humans
    Arkadiusz Semczyszak - "The annually production anthropogenic CFC = 750,000 T pure Cl, = one week by Mount Erebus productions…, at the all a World volcanoes, have a annually production 36,000,000 T Cl" CFCs are generally very unreactive until they reach the stratosphere and are broken down by UV, releasing Cl, etc. Volcanic Cl is probably much more reactive, and more likely to be rained out before reaching the stratosphere. I don't have time to read those papers right now, but I'll just note that the stratospheric cooling associated with AGW, (and also polar stratospheric cooling associated with increasing AO, which may or may not be a seperate matter, depending...) will make polar ozone holes more likely to result from any given ozone-depleting emission. Ozone depletion itself, while warming the troposphere below, cools the stratosphere by reduced UV absorption there, and also lets more longwave radiation from the surface escape to space, reducing any tropospheric warming that would result.
  9. Temp record is unreliable
    I'm amazed at the rhetoric. If you lose the validity of the surface temperature record, your hypothesis, that warming is greater than expected, is invalidated. It is a logical fallacy to claim that it doesn't matter if one of your premises are proven false. It is impossible for the conclusion to be correct if the premises do not hold. Here in lies the crux of the problem. --------------------------------------------------------- So If I'm not mistaken this is the AGW Hypothesis: 1. The world has been warming for a century, and this warming is beyond any cyclical variation we have seen over the last 1000 or more years, and beyond the range of what we might expect from natural climate variations. 2. Almost all of the warming in the second half of the 20th century, perhaps a half a degree Celsius, is due to man-made greenhouse gases, particularly CO2 3. In the next 100 years, CO2 produced by man will cause a lot more warming, from as low as three degrees C to as high as 8 or 10 degrees C. 4. Positive feedbacks in the climate, like increased humidity, will act to triple the warming from CO2, leading to these higher forecasts and perhaps even a tipping point into climactic disaster 5. The bad effects of warming greatly outweigh the positive effects, and we are already seeing the front end of these bad effects today (polar bears dying, glaciers melting, etc) 6. These bad effects, or even a small risk of them, easily justify massive intervention today in reducing economic activity and greenhouse gas production [1] http://www.conservapedia.com/AGW_hypothesis --------------------------------------------------------- In order for this to be proven true at this point in time, the surface temperature record needs to be accurate, because the other forms of temperature data collection have not been around long enough to be relied on. We simply do not have upper atmospheric temperature measures for long enough to see any long term trends. Let alone trends that are not expected. This is also true of the surface temperature record, although it is slightly older. Let's put it into perspective, if we scaled earth's total existence in time to a period of 1 year, the 50-100 years of data collection we now have would still be a fraction of a second on that time scale. So... claiming that you "Don't need" the temperature record is simply an act of hand waving by those too stubborn to admit defeat. At least for now, there is more work to be done.
  10. Arkadiusz Semczyszak at 01:07 AM on 28 November 2008
    Volcanoes emit more CO2 than humans
    John Cook said: “There are two skeptic approachs to volcanoes: high volcanic activity causes global warming and/or low volcanic activity causes global warming” - I say: “two skeptic approachs to volcanoes”, don’t excluded… „On the contrary, relatively frequent volcanic activity in the late 20th century may have masked some of the warming caused by CO2.” - I think - it’s not “all” right… 1.In IV report IPCC, chapter 2, p. 194, is Fig. 2.18 - distinctly differ from John’s Fig whit volcanic - optical depth… 2. In this IV report on p. 195-6 is writing about “chemical destruction of stratospheric ozone”. Here is, in references, one interesting position: Tabazadeh at al, 2002… I remind You, what Tabazadeh was said then - in 2002 y: "Both the 1982 El Chichon and 1991 Mt. Pinatubo eruptions were sulfur-rich [not only S, but else Cl2 ,B(OH)3,NH3,CH4, Cl, F by metals compounds] , producing volcanic clouds that lasted a number of years in the stratosphere," "A 'volcanic ozone hole' is likely to occur over the Arctic within the next 30 years, [!!!]" “Between about 15 and 25 kilometers (9 to 16 miles) in altitude, volcanic Arctic clouds could increase springtime ozone loss over the Arctic by as much as 70 percent, according to Drdla” (http://www.spaceflightnow.com/news/n0203/05volcano/ and http://www.gsfc.nasa.gov/topstory/2002/20020304volcano.html) The annually production anthropogenic CFC = 750,000 T pure Cl, = one week by Mount Erebus productions…, at the all a World volcanoes, have a annually production 36,000,000 T Cl… Results about It , is visible here http://www.esrl.noaa.gov/gmd/dv/spo_oz/SP_Dobson_Oct15-31_2007_mod1.gif, and of stratosphere temperature in: http://www.atmosphere.mpg.de/media/archive/1385.jpg, Robert A. Ashworth in papers: CFC Destruction of Ozone - Major Cause of Recent Global Warming! (2008; http://omsriram.com/GlobalWarming.htm - all paper is very interesting) say: “The loss of ozone allowed more UV light to pass through the stratosphere at a sufficient rate to warm the lower troposphere plus 8-3/4" of the earth by 0.48 o C (1966 to 1998).” IPCC said: global anthropogenic GHG effects in this period = ~ 0,5 dg. C, Ashworth said: “anthropogenic emissions of chlorofluorocarbons”, it’s the reason it… …I say: volcanic S, Cl, F - emissions, dear Mrs. Ashworth… I propose else this image: http://www.leif.org/research/Erl70.png. It’s worth seeing.
  11. Models are unreliable
    Post #75 was a repeat of the statement in #69 that followed the statement quoted in #76. It is unclear why you did not appear to notice this before and now do not seem to be able to see the difference between the two statements.
  12. It's not bad
    Can Carbon Dioxide Be A Good Thing? Physicist Explains Benefits Of Carbon Dioxide June 1, 2007 — A physicist from Colorado State University and his colleagues from the North American Carbon Program (NACP) have discerned and confirmed the unforeseen advantages of rising carbon dioxide levels. Through the processes of photosynthesis and respiration, scientists have been able to elucidate why plants are growing more rapidly than they are dying. The NACP is employing methods, such as the use of cell phone and aircraft towers to monitor and retrieve carbon data for their continuing study.
  13. Human CO2 is a tiny % of CO2 emissions
    A thermostat 'cycles' around a predetermined temp within defined limits; design limitations normally restrict this to 2C. So, for example, a simple heating system will show a more or less sinusoidal curve around the setpoint with an offset of around 2C. This curve can be limited by the use of predictive electronics, but not completely negated. Electronic and compressed air temperature controllers modulate continuously as the detected temp fluctuates and provide closer control, BUT still show a sinusoidal fluctuation around the set point even though much lower than a conventional thermostat (industrial standards of around 0.5C). There is no equilibrium. Semantics is about the meaning of words; once you start to misuse words then communication is degraded. Better to invent a new word than to misuse an existing one..and science is historically pretty good at inventing new ones.
  14. It's the ocean
    chris Compare the charts of "hot spots" to a good map of the ocean floor such as Nat. Geo. maps. Also see post 115 in the volcano thread.
  15. It's Urban Heat Island effect
    According to WikiP the land surface area of the earth is 148,939,100 sqkm and the total area of deserts (not chocolate flavoured desserts) bigger than 50,000 sqkm amounts to 31,678,000 sqkm...about 21%. This however includes Antartica which if you remove from the list reduces the total to 17,849,000 sqkm.....more than 10% of the earth's land area and that only includes those over 50,000 sqkm. Googling 'African deserts' gives 25% of Africa is listed as desert....hardly tiny.
  16. Evaporating the water vapor argument
    Thank you, Chris. Mizimi's little docudrama is telling because its humor depends on the listener being scientifically illiterate or willing to make oneself temporarily illiterate for the sake of an ideology.
  17. Models are unreliable
    Come on Dan. You provided your own answer to that illogical mantra in your first paragraph of your post #69: [Dan ".....a temperature down trend is insufficient to prove that net positive feedback does not exist. My bad to have overlooked this before."] You were right in your post #69. Why change your mind again??
  18. It's the sun
    Not really WA What errors and corrections in the GISS record? There have been some truly trivial errors. Science doesn't proceed without errors. When these are identified they are corrected..it's not really a big deal oddly in your last paragraph, you contend that the satellite record is consistent with the hypothesis that there is no positive feedback. But in fact you are quite wrong. The satellite record is consistent with surface warming as a result of enhanced greenhouse warming of the atmosphere. The predicted enhancement of troposheric water vapour has been identified (see post #173 above). How could you have come to a completely incorrect notion of the satellite record? Probably because one or two less than honest scientists (Roy Spencer is one) have repeatedly made massively profound errors during the last nearly two decades of "analysis" of this data. And although their errors have been repeatedly corrected in the scientific literature, Spencer has taken to presenting falsehoods and misrepresentations directly to the public on dodgy website and suchlike. That's what I found astonishing about your viewpoint. On this and other threads you embrace embarrasingly erroneous nonsense (The Scotese paleotemperature/paleoCO2 sketch; a German schoolteachers pathetic misrepresentation of early CO2 measurements; hearsay notions about satellite measurements)...and yet you make dull attempts to trash the pukka science. If you have evidence that "we have ice ages with high CO2 and warm eons with low CO2", why not show us? If you've evidence that "The satellite record is to an even greater extent consistent with the hypothesis that there is no positive feeedback due to increased CO2", why not show us? If you've evidence that (the satellite record) "is also consistent with the hypothesis that human activities have no measurable effect on world temperature", why not show us? We want to see your evidence Wondering Aloud. We're skeptical of individuals that embrace errant and obvious nonsense and yet attempt to downplay pukka science. We're not concerned with proof. We're interested in the science and therefore we want to see your evidence.
  19. Wondering Aloud at 05:56 AM on 26 November 2008
    It's the sun
    Chris Re:218 This is a splinter in your neighbors eye issue if I have ever seen one. Especially in light of the errors and corrections in the GISS record. Is it your contention that it is incompetance in that case or bias? Ice core samples show that the warming happens first, our host claims a natural delay accounts for this. I think having a reversed order of cause and effect should give anyone pause, and let's not fool ourselves that is what we have there. It most certainly does not support the correlation you claim. Unless you would also contend that I ate too much junk food because I had gained weight. As to the more distant past while very uncertian I don't see how anyone could get anything like a correlation from what is there, we have ice ages with high CO2 and warm eons with low CO2. The satellite record is to an even greater extent consistent with the hypothesis that there is no positive feeedback due to increased CO2. In fact it is also consistent with the hypothesis that human activities have no measurable effect on world temperature. I think I am saying that isn't really much of a proof.
  20. Volcanoes emit more CO2 than humans
    This article Prehistoric Climate Can Help Forecast Future Changes ScienceDaily (Nov. 25, 2008, includes an interesting graphic. The "hot spot" anomalies in ocean temperatures are all very geologically active areas of volcanism/plate tectonics. While the article itself is worth reading, it's the illustration that stands out.
  21. Models are unreliable
    During the last and previous glacial periods the temperature changed from an uptrend to a down trend with the atmospheric carbon dioxide level higher during the down trend than it had been during the uptrend. That could not happen if there was significant net positive feedback and proves that significant net positive feedback does not exist. Without the imposition of substantial net positive feedback the GCMs do not predict significant global warming.
  22. Water vapor is the most powerful greenhouse gas
    Not really Mizimi: (i) The CDIAC is exactly about anthropogenic greenhouse gases. That's why they reference them with respect to pre 1750 levels (zero for the CFC's but not for CO2, methane, ozone, and nitrous oxide). (ii) both sites (EPA and CDIAC) don't include water vapour because they are considering anthropogenic greenhouse gas forcings. The EPA site has a specific section about water vapour. As they state (and we've already established this point in numerous posts above on this thread), human activities aren't believed to directly affect water vapour concentrations (it's not a forcing, it's a feedback), but the warmer atmosphere from anthropogenic greenhouse gases results in a water vapour feedback that amplifies the anthropogenic forcing from enhanced greenhouse gas concentrations. That's all very straightforward and easy to understand. (iii) Otherwise your numerology is suspect. In fact it's not possible to partition greenhouse effect contributions from the individual greenhouse gases in the manner that you have done, since the greenhouse gases don't act independently, especially when water vapour is considered. removing CO2 from the atmosphere results in a very large cooling, since a significant part of the water vapour contribution arises as a feedback to CO2-induced warming, and if you remove the CO2 you remove a lot of the water. Do you see why that makes a linear, discrete "partitioning" of the greenhouse effect to individual components inaccessible to simple-minded arithmetic? In fact this issue has been dealt with many times through the use of modelling of the effects of removing various components of the atmosphere. An early example is: Ramanathan V, Coakley JA (1978) Climate Modeling Through Radiative-Convective Models. Rev. Geophys. 16, 465-489. For example if you remove CO2 from the atmosphere the greenhouse effect is reduced by 9% and if you remove water vapour it's reduced by 36%. But if you removee CO2 and water vapour it's reduced by more than 45% (the sum of the two). Likewise if you remove everything but CO2, 26% of the longwave IR is still absorbed in the atmosphere. So if one wanted to put numbers to the contribution of CO2, it's somewhere between 9-26% of the greenhouse effect.... If you find Ramanathan and Coakley heavy going, Wikipedia has a goodish account: http://en.wikipedia.org/wiki/Greenhouse_effect#Water_vapour_effects
  23. Models are unreliable
    Re #70 I wouldn't really say that's a modelling error Quietman. Have a read of the original article in Nature Geosciences. A very small amount of carbon from inefficient burning of fossil fuels (that isn't captured in catalytic converters!), or from forest fires under oxygen-deficiency, or from people that use inefficient wood-burning stoves in the less-developed world, may be retained in the soil for long periods, and thus the amount released into the atmosphere may be reduced somewhat. Remember that no one expects the GCM models to be perfect. We know that they're not. That's not really the point of modelling. We know already from basic atmospheric physics and from numerous studies of the real world that the Earth responds to enhanced greenhouse gases with a warming somewhere of the order of 3 oC per doubling of atmospheric CO2. That's completely independent of models. The models help us to predict the spatial distribution of this warming, its effects under different emission scenarios and such like. As new information is obtained about contributions and their paramaterization, so the models are iteratively improved. So the work just published in Nature Geoscience will be explored further no doubt, and when it's sufficiently characterized/parameterized will be incorporated into the models... ..that's how science works!
  24. Models are unreliable
    Re #69 Dan O.K., so you've finally come round to the truism that a downtrend in temperature is not proof that a net positive feedback doesn't exist, after all. So everyone else but you wasn't wrong! Your bad indeed. But we got there in the end... Your second paragraph is illogical. We all know that the Earth's equilibrium temperature response has a logarithmic relationship to the atmospheric CO2 concentration. Arrhenius had worked that out already over 100 years ago. Your third and fourth paragraphs are nonsense too. Why go to a non-science magazine created with the intention (as the Editor admits) of misrepresenting the science on power industry-related matters? We've already seen (see posts #54 and #58) that "articles" in that magazine on climate-related matters are dodgy. Not surprisingly, the author of that article has got it wrong. There are lots of errors: (i) absorption of EM radiation doesn't "take place close to the surface". Photons can travel vast distances before being "absorbed". It depends on the absorbtivity/transmisivity of the medium through which the photons pass. (ii) If one considers longwave IR emitted from the Earth's surface, the wavelength/energy of the emitted wavelength has to be considered, since the absorption coefficient (k) is inversely related to the wavelength of the absorption band. The transmisivity, t, (absorbtivity = 1-transmisivity) of a column of air = t = e^(-k*p*l) where k is the absorption coefficient, p is the partial pressure and l is the path length. since the absorption coefficients for the absorption bands of the greenhouse gases are known[1], we can calculate the pathlength required to effectively absorb all of the radiation (at that energy/wavelength). For 99% absorption, the pathlength of the 4-5 micron absorption band of CO2 is 625 metres at current atmospheric CO2 concentrations and for the ~14-20 micron absorption band, CO2 at 385 ppm is still unsaturated at 7,800 metres of altitude. likewise for the 12-20 micron infrared absorption band of water at 0.4%, water vapour is still absorbing at 1,700 metres. (iii) in other words at current atmospheric greenhouse gas concentrations, the absorption bands aren't saturated, and enhancement of the concentration of greenhouse gases, particularly at higher altitudes [see (iv)], is effective in trapping more of the longwave IR emitted from the Earth's surface. (iv) In any case, the altitude of absorption of IR emitted from the Earth’s surface isn’t that important. A key element of the greenhouse effect is the altitude of emission of longwave IR into space. This has to happen for radiative balance between incoming radiation and outward radiation. You’ve actually given a clue to an important consideration unwittingly in the very first statement of your post: [Dan “bad boy” Pangbourn: “Radiated energy (from all surfaces, including earths) varies as the fourth power of absolute temperature”] Exactly so. As greenhouse gases are added to the Earth’s atmosphere, the radiation of IR into space is suppressed at any altitude (especially altitudes far from the Earth’s surface). So the radiation emitted to space from (say) 5 km is suppressed by enhanced CO2 concentrations, and so the altitude of mean radiation to space is increased. Since an increased altitude in the troposphere is at a lower temperature, the efficiency of radiation to space is decreased (as you said yourself). What’s the effect of this? The troposphere must warm in order to restore radiative balance. Since the surface and troposphere are strongly coupled, the warming of the troposphere is transmitted to the earth’s surface (and vice versa) [2]. (v) The article in the anti-science journal that you linked to makes three more errors that relate to ignoring real world measurements. These are: (i) on page 1044 your ill-informed author states: “It would be expected that more CO2 would have a greater effect on atmospheric warming at higher altitudes, but that seems not to be occurring in spite of the predictions of most GCMs”. But as we’ve seen already on this thread, the tropsopheric warming is quite consistent with GCMs (see my posts #60 and #66, where this exact issue is addressed). (ii) on page 1045 your ill-informed author states: “The GCMs take feedbacks into account, such as the supposed positive feedback from extra warming caused by the radiation by extra water vapour”. Yes, exactly. In line with the enhanced tropsopheric warming caused by enhanced [CO2], the troposphere is accumulating extra water vapour rather in line with predictions [3-7]. According to your ill-informed author this shouldn’t be happening since adding extra greenhouse gases isn’t (according to him) supposed to make the troposphere warmer! (iii) and overall your ill-informed author neglects to state that we can measure in the real world, not only the longwave radiation transmitted down to the Earth’s surface from the troposphere (which shouldn't be happening according to your ill-informed author), but the enhancement of this radiation due to the enhanced greenhouse gas concentrations of the last 30 years (which also shouldn't be happening according to yuor ill-informed author), or the reduction in this radiation outwards to space [8-12] ---------------------------------------- [1] this has been known for decades. See e.g RM Goody and GD Robinson (1951) Quart. J. Roy. Meteor. Soc. 77, 153 [2] Shine, KP (1995) Spectrochimica Acta A 51, 1393-4. [3] Santer BD et al. (2007) Identification of human-induced changes in atmospheric moisture content. Proc. Natl. Acad. Sci. USA 104, 15248-15253 [4] Soden BJ, et al (2005) The radiative signature of upper tropospheric moistening. Science 310, 841-844. [5] Buehler SA (2008) An upper tropospheric humidity data set from operational satellite microwave data. J. Geophys. Res. 113, art #D14110 [6] Brogniez H and Pierrehumbert RT (2007) Intercomparison of tropical tropospheric humidity in GCMs with AMSU-B water vapor data. Geophys. Res. Lett. 34, art #L17912 [7] Gettelman A and Fu, Q. (2008) Observed and simulated upper-tropospheric water vapor feedback. J. Climate 21, 3282-3289 [8] Harries JE et al (2001) Increases in greenhouse forcing inferred from the outgoing longwave radiation spectra of the Earth in 1970 and 1997. Nature 410, 335-337. [9] Worden HM et al. (2008) Satellite measurements of the clear-sky greenhouse effect from tropospheric ozone. Nature Geoscience 1, 305-8. [10] Philipona R et al (2004) Radiative forcing - measured at Earth's surface corroborate the increasing greenhouse effect. Geophys. Res. Lett. 31, art # L03202. [11] Wild M et al. (2008) Decadal changes in surface radiative fluxes and their role in global climate change Adv. Global Change Res. 33 , 155-167. [12] Philipona R et al (2005) Anthropogenic greenhouse forcing and strong water vapor feedback increase temperature in Europe Geophys. Res. Lett. 32, art # L19809. etc. etc. etc. etc……
  25. Water vapor is the most powerful greenhouse gas
    Try: http://yosemite.epa.gov/oar/globalwarming.nsf/UniqueKeyLookup/SHSU5BUM9T/$File/ghg_gwp.pdf which gives warming potentials; (and they acknowledge WV is a GG and address their tables to 'selected' GG's) and: http://cdiac.esd.ornl.gov/pns/current_ghg.html (which doesn't acknowledge WV...and their data is NOT just AGG's........unless you deem we are responsible for all the pre-1750 gases ???) If you check the math from table 2 in the EPA site ( which can be checked against the DOE site) CO2 accounts for ~72% of GG warming EXCLUDING WV. CH4 about 7% and N2O 19%, the rest is CFC's etc. Now factor in WV at 95% (topend) and CO2 is responsible for 72% of 5%...3.6% of the total, or 1.19C Take the lowend 90% WV and you get 7.2% of the total or 2.38C Now run the increases due to man's contributions alone and you will get the numbers I quoted in #29
  26. Misinterpreting a retraction of rising sea level predictions
    chris forget it, the damn graph was drawn backwards.
  27. Misinterpreting a retraction of rising sea level predictions
    The wording I used is misleading and I did not realize how it would be taken. The high points decline slightly but the lower end is constantly getting warmer, ie. instead of saying it's getting warmer I should have said its not getting as cold. Just follow the trend line of the coldest points to see what I meant.
  28. Water vapor is the most powerful greenhouse gas
    I have checked them out. Your numbers are nonsense and don't come from the DOE or from the IPCC. The data on Greenhouse Gas concentrations from the US government CDIAC refer to anthropogenic greenhouse gas and so don't include water vapour. Is that what you're on about? e.g. http://cdiac.esd.ornl.gov/pns/current_ghg.html But we don't really know what you're talking about unless you give us a link to the data that you cut 'n pasted those weird numbers from.
  29. Volcanoes emit more CO2 than humans
    More on Tectonic activity and poor instruments: "On May 12, 2008, at 2:28 p.m., China's Szechwan province changed forever. In the space of 90 seconds, an earthquake equivalent to 1,200 H-bombs pulverized the earth's crust for more than 280 kilometers. Entire cities disappeared and eight million homes were swallowed up. This resulted in 70,000 deaths and 20,000 missing." "According to ShaoCheng this tragedy could have been avoided. "There hasn't been one earthquake in Szechwan province for 300 years. Chinese authorities thought the fault was dead," he says. The problem is that China relied on GPS data, which showed movements of 2 mm per year in certain areas when in reality the shifts were much bigger. "GPS is high-tech, but do we really know how to interpret its data?," he questions." Ref: Can China's Future Earthquakes Be Predicted? ScienceDaily (Nov. 24, 2008)
  30. Water vapor is the most powerful greenhouse gas
    The numbers are not cut and pasted but taken from the sites mentioned. Check them out yourself. The DOE site does not include WV in their GG listing so I take that as ignoring its effect as a GG. The 95% WV quoted is the 'high' side figure from various sites; the 'low' side figure generally quoted is 90% from other sources and one can rerun the sums using the 90% if desired. The rest is simple maths. I included WV in the calcs for obvious reasons.
  31. Arctic sea ice melt - natural or man-made?
    Now I'm getting ahead of myself, but I wonder if maybe the longer-term trend in AO/NAM might be somehow related to changes in meridional momentum transport - if the residual mean meridional circulation (forced by EP fluxes) isn't changing, this doens't necessarily mean the gradient in zonal momentum that it crosses is not changing. Also - it seems odd to use this to describe a climate CHANGE - it is more obviously applicable to short term weather - but, as there is enhanced warming of the Arctic ocean and high latitudes particularly in winter relative to lower latitudes, this would tend to produce a 'thermal low' in the absence of everything else - and that would tend to pull air poleward at the surface (relative to whereever it goes otherwise) and push air equatorward at mid and high levels (relative to whereever it goes otherwise) and the coriolis effect would increase westerly winds at the surface - but while reducing them aloft; okay, that didn't work, but there could be more to it than that - maybe - I don't know...
  32. Arctic sea ice melt - natural or man-made?
    After wrapping up Rossby wave basics, I'll get back to AO/NAM (I've found one source which suggested that changes in planetary wave propagation caused by AGW could account for some of the multi-decadal trend in AO/NAM (NAM(1); however I found one paper which argues that while shorter variations of AO/NAM are linked to planetary wave flux changes, the longer-term trend doesn't seem to be so linked. (NAM(2)) Interestingly I think they focussed on a time of year when ozone depletion wouldn't be a direct factor (radiative heating/cooling), but also I'm not sure if solar changes could also be ruled out at least as far as being a direct influence via radiative heating/cooling of the polar stratosphere at the time the AO changes occur. I'm not clear on whether AGW would directly radiatively cool the lower winter polar stratosphere more than the lower winter mid-latitude stratosphere, although that seems to be the trend... Then again there's also gravity waves - did the paper include gravity waves? - no, I don't think it did... anyway, that's coming up...
  33. Arctic sea ice melt - natural or man-made?
    I've decided not to go into 'absolute momentum' unless specifically asked. The other point I was going to make was that vorticity is proportional to an angular momentum per unit mass per unit area (for circular motion at radius r, counterclockwise tangential speed v (at all points on the circle, or averaged), the angular momentum per unit mass is v*r, the circulation is v*(2*pi*r), and the area-average enclosed vorticity is the circulation divided by enclosed area, v*(2*pi*r)/(pi*r^2) = 2*v/r. Notice that v/r is the angular frequency, and the vorticity is twice the angular frequency. f is equal to twice the planetary angular frequency times the sine of the latitude, and including f, the absolute angular momentum per unit mass is v*r + 1/2*f*r^2; multiplying by 2*pi and dividing by area to get absolute vorticity, the result is 2*v/r + f, where 2*v/r is the relative vorticity. Angular momentum can also be defined for any parcel of air relative to some other parcel or point - it is then less precisely related to the vorticity in the space between. On a small scale, an intrinsic absolute angular momentum may be conserved whenever potential vorticity is conserved (when absolute vorticity is inversely proportional to an area defined by material lines), but angular momentum defined relative to any point is not necessarily conserved following the air under the same conditions. However, there is still a conservation of angular momentum that applies, where air that loses or gains this angular momentum must be exchanging angular momentum with some other air or the Earth itself. Angular momentum can be defined relative to the Earth's axis, in which case it is (per unit mass) equal to: R*cos(latitude) * [ u + OMEGA*R*cos(latitude) ] where R is the radius of the Earth (so R*cos(latitude) is the radius of a latitude circle), OMEGA is the angular frequency of Earth's rotation, u is the zonal wind (relative to the Earth) and OMEGA*R*cos(latitude) is the speed of the surface of the Earth itself in the zonal direction. Generally, on average, Westerly (eastward) angular momentum is lost from the Earth below the atmosphere by friction (and any form drag) acting on tropical trade winds, which then transport that angular momentum upward and poleward in the Hadley cell. Eddy fluxes of angular momentum transport it farther poleward and bring it downward. The Earth gets it back from friction and form drag acting on westerly winds at mid-to-high latitudes. Because the torque of the winds acting on the Earth at any one latitude belt is proportional to the wind stress times the area times the radius of the latitude circle, one or more of the following is necessary for long-term balance - stronger surface mid/high latitude westerlies than low-latitude easterlies, a greater area of mid/high latitude westerlies than low-latitude easterlies, or a greater effective drag acting on mid/high latitude westelies than low-latitude easterlies. I'm not sure if the properties of Rossby waves would tend to create the third condition if all else was equal, but the distribution of mountain ranges would have an effect. This has consequencies for how a steady-state Hadley cell would be sustained in the absence of eddies. Rather than a surface low at the equator and high at the poles with surface easterlies everywhere in between, there would be weaker polar highs or perhaps slight polar lows with midlatitude highs; the high-latitude winds would westerly with a westerly ageostrophic component (supplied from downward transport of momentum, enough to overcome friction even if around a polar low pressure) so that the coriolis force would accelerate the winds equatorward. If there were not a zero net torque, the atmosphere would continually sping up or slow down so as to change the torque until balance were achieved.
  34. Models are unreliable
    chris disregard that - I misread your statement. I was referring to the last 10 years while you referred to the entire length of the last PDO.
  35. Models are unreliable
    chris Just a small point re: "3. These (NASA GISS, Hadcrut, NOAA) show long warming trends from the mid 1970's through to the present." In reality only GISS actually shows a slight increase, the others are actually slightly negetive.
  36. Other planets are warming
    I suggest that people who think that the sun is responsible, and cite warming on other planets become familiar with the Inverse Square Law. ;)
  37. Climate change on Mars
    I suggest that people who think that the sun is responsible, and cite warming on other planets become familiar with the Inverse Square Law. ;)
  38. Models are unreliable
    Just another modelling error: Global Warming Predictions Are Overestimated, Suggests Study On Black Carbon ScienceDaily (Nov. 19, 2008) — A detailed analysis of black carbon -- the residue of burned organic matter -- in computer climate models suggests that those models may be overestimating global warming predictions.
  39. Models are unreliable
    Radiated energy (from all surfaces, including earths) varies as the fourth power of absolute temperature so a temperature down trend is insufficient to prove that net positive feedback does not exist. My bad to have overlooked this before. However, review of temperature during the last and previous glacial periods reveals that the temperature changed from an uptrend to a down trend with the atmospheric carbon dioxide level higher during the down trend than it had been during the uptrend. That could not happen if atmospheric carbon dioxide level increase was a significant driver of average global temperature increase. The present atmospheric carbon dioxide level is somewhat higher than it was during the glacial periods. As Carbon dioxide level increases, each additional increment has less influence than the previous increment. This effect is appropriately called saturation. Thus increased atmospheric carbon dioxide now is even less able to influence temperature than it was during the last glacial period when temperature increasing trend changed to a decreasing trend. The conclusion from all this is that the current rising atmospheric carbon dioxide did not have a significant influence on any temperature rise including the temperature rise from the mid 1970s until about a decade ago and will never be a significant factor in temperature increase. Contrary to Chris’ assertion which was “The major predictor of Anthropogenic Global Warming is our understanding of the greenhouse effect …” the discovery long ago that carbon dioxide and water vapor absorb certain wavelengths of infrared radiation does not mandate that human activity has caused the planet to get significantly warmer. It is pretty widely known that the infrared absorption, mainly by water vapor, helps make the planet have the nominal temperature that it does. It is less widely known that the absorption takes place close to the emitting surface (half within 24 meters as calculated from Barrett’s paper at http://www.warwickhughes.com/papers/barrett_ee05.pdf , others calculate even closer). Adding carbon dioxide to the atmosphere results in the infrared radiation being absorbed a bit closer to the emitting surface. The atoms that absorb the infrared radiation energy nearly all immediately share it by thermal conduction with the much more abundant adjacent atoms that are transparent to infrared radiation. That, for the most part, is what warms the air. The shared energy is then carried up by convection currents. Existing GCMs are unable to objectively account for this natural convection so the process is imposed on the models with a contrived parameterization. Contrary to one of many of Chris’ erroneous assertions, that I have stated that “I am right and everyone else is wrong”, I share the perception with over 31,000 other scientists and engineers at http://www.petitionproject.org/ that human release of carbon dioxide will not cause catastrophic global warming. These scientists and engineers gain nothing for this declaration while the 2500 or so alarmist climatologists must make dire predictions for the government grants to continue.
  40. Arctic sea ice melt - natural or man-made?
    "the geostrophic wind is non-divergent in isobaric (and also isentropic, I believe) coordinates - the convergent motion may be ageostrophic, and if so, the coriolis force on it is not balanced by the pressure gradient force. This means the coriolis force itself exerts a torque about a center on ageostrophic motions " ... Just to be clear, though - that was just to illustrate one major process; Solving the momentum equations for vorticity yields the more general result that absolute vorticity (RV + f) remains inversely proportional to a horizontal area or the horizontal projection of an isobaric (or isentropic) area enclosed by material lines, which shrinks or grows by horizontal convergence or divergence, respectively, when (the horizontal component of) absolute angular momentum is conserved, which is true, except for: 1. friction or mixing, 2. nonzero solenoidal term (not applicable to isobaric or isentropic coordinates), 3. nonzero tilting/twisting (horizontal variations in vertical momentum transport, which is generally small for larger scale motions and is zero for adiabatic motion in isentropic coordinates), and with the approximation that 4. the coriolis effect acting on vertical motion and causing vertical acceleration is neglible (which is true even for rapid motions in thunderstorms, because with rapid vertical motion, the air (following the air) has to start and stop within a time frame much shorter than the Earth's rotation period, given atmospheric dimensions). 5. the 'curvature terms' are neglible (which is true) - the curvature terms account for the curvature of the Earth; for x,y,z coordinates defined everywhere locally, with x being east, y being north, z being up - moving around involves accelerations of that coordinate system itself; for example, two great circle routes that are not identical inevitably intersect, so in order for two air parcels to remain on parallel trajectories for long distances, there must be some horizontal acceleration on at least one of them... etc. - but that is a small effect. Sometimes factors which absolutely must be included for understanding longer term processes, such as radiative heating and friction, can actually be ignored without losing a basic understanding of some processes that happen over short-enough periods of time.
  41. Human CO2 is a tiny % of CO2 emissions
    Not really Mizimi, Let's not get confused by semantics! Playing with words doesn't change reality. A thermostat is effectively a "dynamic equilibrium". Have a think about how a thermostat works to maintain the temperature in a room at an equilibrium temperature.
  42. Water vapor is the most powerful greenhouse gas
    Mizimi those numbers are nonsense. I don't believe they're from the IPCC reports at all. Why not simply give us the url from the site that you cut and pasted them from? And how can you say one the one hand that "they ignore WV as a GG"... ...and on the other show data that indicates that water vapour is 94.999% of the whole? ...???????
  43. It's Urban Heat Island effect
    re #13 Not really Rob. The oceans are covered rather extensively with a series of ocean surface temperature measures. Desserts don't cover 10% of the Earth's surface. At any one time a tiny proportion of the Earth's surface is covered by desserts. Even if every 280 million US citizens was holding a chocolate fudge sundae or a baked Alaska, this would cover a tiny, tiny proportion of the surface of the USA. The proportion of Africa covered by desserts is tiny, since Africans rarely eat dessert...etc...etc... The fact that Tmin is increasing faster than Tmax is what one expects from greenhouse-induced warming. Remember that the atmospheric warming due to enhanced greenhouse gases results from trapping of longwave infrared radiation emitted from the Earth's surface. While the absorption of solar radiation occurs during the day, the emission of longwave IR occurs during the day and the night. It doesn't stop when the sun stops shining. So it's not unexpected that Tmin should increase faster than Tmax...
  44. Temp record is unreliable
    ummmmm Rob.. Since I am quoting Hanson directly from one of his papers, I don't really need to tell him anything. Urban areas are generally warmer than the surrounds. Therefore one either eliminates urban areas from the record to establish the Earth's surface temperature evolution, or one corrects the data from urban stations by reference to local urban stations. However one does this (leaves out the urban stations or corrects these) the Earth's surface temperature anomaly is the pretty much the same. You would benefit from reading John Cook's article on urban heat island effect.
  45. Global warming stopped in 1998, 1995, 2002, 2007, 2010, ????
    Re #27 Not really Mizimi. Remember that the effect of a forcing (whether a warming or a cooling forcing) relates to the temperature change at equilibrium.... ...at equilibrium... Note two things about the influence of the solar cycle on the Earth's temperature response: (i) the solar cycle has a rather rapid sinusoidal variation. The entire cycle takes only 11 years to evolve from its maximum TSI to its minimum TSI and back again (ii) The Earth's surface temperature response is damped, and it comes to equilibrium much more slowly than the few years "allowed" for it to "track" the solar cycle variation. So the tracking of the Earth's temperature response to the solar cycle is continuously "frustrated" (very much like the temperature response to a thermostat). The atmosphere follows the solar cycle most faithfully. The ocean and land surface is much slower to respond. So the effects of the solar cycle is damped, and the entire effect of the solar cycle is to contribute around 0.1 oC of temperature difference at the Earth's surface, between the solar maximum and solar minimum (Tung considers that the solar cycle contribution is a bit larger...around 0.18 oC). If the solar cycle were to stop and the sun emit solar radiation equivalent to 1363.5 W/m2 for a long period (say 30 years to come close to equilibrium)...and then the sun switched to a constant TSI output equivalent to 1360.25 W/m2 for 30 years to establish the new equilibrium temperature, the temperature difference at the Earth's surface would be your 0.45-ish oC of cooling (all else being equal). ..but these temperature changes in response to forcings are equilibrium changes..
  46. It's Urban Heat Island effect
    Just had a look at the updated satellite composite at Data @ NASA GISS Surface Temperature Analysis Maps.htm (October 2008). Quite a difference to the 2005 composite,a lot more 'colder' areas, especially Antartica, Alaska, North Am,erica and Northern Europe/Greenland.
  47. Arctic sea ice melt - natural or man-made?
    clarification: turbopause ~ 100 km or around there; not to be confuse with tropopause which is 'much closer to home'.
  48. Arctic sea ice melt - natural or man-made?
    Clarification: H escape does not occur directly from all levels above the tropopause - generally it is limited to around 500 km and higher; but H atoms from (photo)dissociated molecules below will diffuse upward due to the removal at higher levels. (without removal, generally, single atoms/ions or smaller (in terms of number of atoms) molecules will diffuse downward while larger molecules/polyatomic ions will diffuse upward because chemical equilibrium by itself favors smaller molecules and single atoms/ions at lower pressures, but diffusion will occur along a non-hydrostatic gradient (above the turbopause, each chemical 'species' acts like an atmosphere unto itself in so far as pressure decline with height being related to density and gravity, density related to pressure by ideal gas law specific to each substance if the gas law is in terms of mass)...
  49. Arctic sea ice melt - natural or man-made?
    Correction: I was refering to 100 Gt (gigaton) of C (is t the correct symbol for ton? - PS I believe these are metric tons - even if they weren't, the numbers wouldn't be much different) of C, which mostly exists as CO2 in the atmosphere, of course. molar mass ratio CO2/C = ~ 44/12 = ~ 3.67 so 100 gigatons C would make 367 gigatons CO2. PS molar mass ratio (average air molecules)/C = ~ 2.42 PS back to angular momentum for me tomorrow or the next day.
  50. Arctic sea ice melt - natural or man-made?
    chris - Thanks for the clarification, I was wondering! -"There is experimental evidence that CO2 is well-mixed vertically throughout the atmosphere ('though I'd have to hunt down the relevant paper(s)). The other means that we know that CO2 is well mixed on annual timescales is that there are is a large number of measuring stations scattered around the remote and isolated regions"... Actually I would like to know more about that - just how close to the surface does one have to get before one finds a diurnal variation of x% or a spatial variation of y ppm/km, etc. (The annual fluxes between the atmosphere and 1.land biota (and soil), 2.the ocean - are about 100 Gigatons and 90 Gigatons, respectively - each to and from, thus no net change, except for an imbalance most likely induced by anthropogenic emissions that removes CO2 from the air (unfortunately not all, nor guaranteed to continue as it has been - biological uptake limited/influenced by climate, attainable tree heights,etc, evolved plant cabilities, ecological interactions (and soil responses), etc, oceanic uptake limited by exchange with the deeper ocean, chemistry, etc - not as simple as just dissolving a gas in water) - and except for geologic emissions, chemical weathering, and organic burial, which are all very small in comparison. Some (most??)of the oceanic fluxes are associated with CO2 release from warmer ocean surfaces and CO2 uptake by colder ocean surfaces. Of course, the seasonal cycle in atmospheric CO2 is, I think, either mostly or entirely due to different seasonal cycles in land biota CO2 uptake and CO2 release. Adding or taking up 1 gigaton of CO2 is about 0.47 ppm change in atmospheric concentration; since the annual variation is quite a bit smaller than 50 ppm we know much of those natural fluxes are going both ways at the same time, at least if averaged over days. If the 100 gigaton addition or removal by land biota occured completely without the other, were concentrated over 10% of the surface (~1/3 land area - that might actually be about true?), and concentrated to 1/3 of the year, then a change per day of 0.4 ppm would occur if the air were stagnant horizontally; 4 ppm per day if only mixed vertically in the bottom 100 mb of air and stagnant horizontally... ) I had found a website showing the CO2 records of the last few-several decades from - I think - 8 stations(including Mauna Loa, and a few from the Southern Hemisphere). I copied and pasted some of graphs into Microsoft Paint files and overlaid them and indeed they match up very well in annual averages. It's also interesting to sea the seasonal cycles, which not surprisingly are largest in northern high latitudes. I'll post that website here if I find it again (it may have been from CDIAC). -"I guess the fact that so much of the earth's hydrogen is "locked up" in water helps to limit its loss" True; I've read that, due to lack of atmospheric oxygen, in the Archean eon, atmospheric CH4 could have built up to levels far beyond what we know; and not condensing befor reaching the tropopause, would have greatly enhanced total H content above that point, thus greatly enhancing H escape to space and - being as (after some evolution of life) most CH4 would have biogenic, and produced from photosynthetic C fixation which split H2O - methanogens and cyanobacteria together thus allowing a net reaction H2O _ 2H + O, O accumulating as H escapes to space. Of course O gets sequestered by ferrous iron in rocks (serpentinization, etc.) and the ocean (BIFs) before finally building up in the atmosphere - and then there is some evidence that over the middle of the Proterozoic, only the upper ocean was oxydized; the oxic atmospheric conditions, etc, affecting the sulfur cycle (I don't know or recall the details of that) so that the deeper ocean water turned sulfidic for several hundred million years before finally turning oxic.... (in case your interested:) 1. "Biogenic Methane, Hydrogen Escape, and the Irreversible Oxidation of Early Earth David C. Catling,12* Kevin J. Zahnle,1 Christopher P. McKay1" http://www.sciencemag.org/cgi/content/abstract/293/5531/839 2. "Proterozoic Ocean Chemistry and Evolution: A Bioinorganic Bridge? A. D. Anbar,1* A. H. Knoll2" http://www.sciencemag.org/cgi/content/abstract/297/5584/1137?ck=nck It's been awhile but I had read the whole of each of those; I've just found some interesting related material: "Molybdenum Isotope Evidence for Widespread Anoxia in Mid-Proterozoic Oceans G. L. Arnold,1* A. D. Anbar,1,2 J. Barling,1 T. W. Lyons3 " http://www.sciencemag.org/cgi/content/abstract/304/5667/87 "Did the Proterozoic 'Canfield Ocean' cause a laughing gas greenhouse? R. BUICK Department of Earth & Space Sciences and Astrobiology Program, University of Washington, Seattle WA 98195-1310, USA" http://www3.interscience.wiley.com/journal/118516679/abstract "Constraints on the Archaean Environment" "Carbon dioxide cycling through the mantle and implications for the climate of ancient Earth Kevin Zahnle1 & Norman H. Sleep2" http://sp.lyellcollection.org/cgi/content/abstract/199/1/231 --- Philippe Chantreau -"I probably have a lot less disposable time than Chris or Patrick for blogging, so I may or may not get to take a look at the papers you link." I haven't looked at any of those papers yet, either - so I've been grateful someone else did!

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