Retro 3D climate model applied to faint young sun paradox

faint_sun1From the AGU weekly highlights:

Evaluating solutions to the faint young Sun problem

During the Archean eon, between about 3.8 billion years ago and 2.5 billion years ago, the Sun was about 20 to 25 percent fainter than it is today. With less sunlight to warm the Earth, the oceans should have been frozen over, but geological evidence suggests that this was not the case.

Some proposed solutions to this problem, known as the faint young Sun problem, include an atmospheric composition with higher concentrations of greenhouse gases, higher atmospheric pressure, increased cloud droplet size, and changes in land distribution and Earth’s rotation rate.

Charnay et al. used a three-dimensional global climate model coupled to a dynamic ocean model to examine these possible solutions.

They find that an atmosphere that had 100 millibars of carbon dioxide and 2 millibars of methane 3.8 billion years ago, and 10 millibars of carbon dioxide and 2 millibars of methane 2.5 billion years ago—levels corresponding to 25 to 250 times the present level of carbon dioxide and 1000 times the present level of methane—would have made it possible for Earth to have had a temperate climate with a mean surface temperature between 10 and 20 degrees Celsius (50 and 68 degrees Fahrenheit), close to the current climate.

The authors suggest that these levels of greenhouse gases are consistent with geological data, making such an atmospheric composition a viable solution to the faint young Sun problem. Cloud feedbacks were also shown to prevent a full snowball Earth from developing during that time period. The authors find that some of the other potential solutions could have produced some warming during the Archean, but none individually produced enough warming to avoid widespread glaciation.

Source: Journal of Geophysical Research-Atmospheres, doi:10.1002/jgrd.50808, 2013 http://onlinelibrary.wiley.com/doi/10.1002/jgrd.50808/abstract

 

Exploring the faint young Sun problem and the possible climates of the Archean Earth with a 3-D GCM

[1] Different solutions have been proposed to solve the “faint young Sun problem,” defined by the fact that the Earth was not fully frozen during the Archean despite the fainter Sun. Most previous studies were performed with simple 1-D radiative convective models and did not account well for the clouds and ice-albedo feedback or the atmospheric and oceanic transport of energy. We apply a global climate model (GCM) to test the different solutions to the faint young Sun problem. We explore the effect of greenhouse gases (CO2 and CH4), atmospheric pressure, cloud droplet size, land distribution, and Earth’s rotation rate. We show that neglecting organic haze, 100 mbar of CO2 with 2 mbar of CH4 at 3.8 Ga and 10 mbar of CO2 with 2 mbar of CH4 at 2.5 Ga allow a temperate climate (mean surface temperature between 10°C and 20°C). Such amounts of greenhouse gases remain consistent with the geological data. Removing continents produces a warming lower than +4°C. The effect of rotation rate is even more limited. Larger droplets (radii of 17 μm versus 12 μm) and a doubling of the atmospheric pressure produce a similar warming of around +7°C. In our model, ice-free water belts can be maintained up to 25°N/S with less than 1 mbar of CO2 and no methane. An interesting cloud feedback appears above cold oceans, stopping the glaciation. Such a resistance against full glaciation tends to strongly mitigate the faint young Sun problem.

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96 Responses to Retro 3D climate model applied to faint young sun paradox

  1. GlynnMhor says:

    “Cloud feedbacks were also shown to prevent a full snowball Earth…”

    What assumptions were used for the cloud feedbacks, given that there is doubt as to the magnitude and even the sign of cloud effects?

  2. phlogiston says:

    Yet another climate model study in which the conclusion of the study is one of the model inputs.

  3. michael hart says:

    I wonder how they modeled the effect of life on the carbon cycle 3.8 Billion years ago?
    Nexxxt.

  4. More meaningless talk to try to promote their soon to be obsolete AGW theroy.

  5. thomasinga says:

    Amazing that nobody is considering planetary migration as a factor, which could greatly vary the amount of radiation receives from even an cooler sun. Gravitational forces from other planets, even ones not currently counted in our existing solar system, could migrate the earth’s orbit by a very large degree. Consider the moon, at it’s formation ~4 billion years ago, it was 80-90% closer than its current oribt. Tidal forces alone likely were the sole cause of this migration. Not a stretch to think that that Earth was much closer to the sun in its early history.

  6. F. Ross says:

    Interesting study. Sounds plausible.

    In a lighter vein … um
    …the study results are due to humans back then, right? Right?

  7. shenanigans24 says:

    Isn’t this just backcasting using a model that has already shown no ability to forecast? If the model is told CO2 drives the temperature with steady solar input, and we reduce the solar input then the model would have to react by increasing the CO2 to get the temperature wouldn’t it? Seems all this would say is the model behaves the way we told it to.

    It’s like saying raindances bring rain, so by extrapolating the number of raindancers from the last rain shower we can prove the flood 100 years ago was caused by 1,000 raindancers. The rain dancing calculation is meaningless unless you have first proved raindancing causes rain. The CO2 calculation would seem the same until you can figure out what CO2 is doing to the temperature right now, which clearly nobody can.

    I don’t know, maybe I’m way off. It just seems all these super hindcasting, forecasting results are nothing but mathematical masturbation. At some point you”re going to have to figure out what actually moves these temperatures, and models are not a shortcut for hardwork and patience.

  8. milodonharlani says:

    Their assumptions aren’t consistent with geologic data. Archean rocks show CO2 levels at most fifty times “pre-industrial” concentration. Some banded iron formations imply that the Archean atmosphere might have contained no more than about 900 ppm, just three times the presumed pre-industrial level.

    Maybe their study addresses this conundrum. In any case, models whether 3D or 1D can’t be convincing.

  9. And then the sun grew brighter/stronger(near present levels) and in the Jurassic period some 170 million years ago when CO2 concentrations were near 2000 ppm why did the temperatures not have a run away rise to the upside and keep going? That is what AGW theory would suggest today if CO2 concentrations were to go to 2000 ppm ,let alone the 400 ppm they are making such a big deal over..

    I wonder what their explanation would be for that? My answer is no explanation becaue the greenhouse gas/climate correlation does not work the way they are trying to convey.

  10. bubbagyro says:

    Radioisotope decay…

  11. Latitude says:

    The authors suggest that these levels of greenhouse gases…

    I thought it was logarithmic

  12. phodges says:

    The orbit of the Earth was probably also different at the time.

    This is something that is always neglected at the geologic timescale.

    http://en.wikipedia.org/wiki/Stability_of_the_Solar_System

  13. phodges says:

    Fairly recent summary:

    http://arxiv.org/abs/1209.5996

    Is the Solar System Stable ?
    Jacques Laskar
    (Submitted on 26 Sep 2012)

    Since the formulation of the problem by Newton, and during three centuries, astronomers and mathematicians have sought to demonstrate the stability of the Solar System. Thanks to the numerical experiments of the last two decades, we know now that the motion of the planets in the Solar System is chaotic, which prohibits any accurate prediction of their trajectories beyond a few tens of millions of years. The recent simulations even show that planetary collisions or ejections are possible on a period of less than 5 billion years, before the end of the life of the Sun.

    Comments: 28 pages, 6 figures. Text of the Lecture given in the Poincar\’e S\’eminar, Paris, on June 2010, submitted
    Subjects: Earth and Planetary Astrophysics (astro-ph.EP); Mathematical Physics (math-ph); Chaotic Dynamics (nlin.CD)
    Cite as: arXiv:1209.5996 [astro-ph.EP]
    (or arXiv:1209.5996v1 [astro-ph.EP] for this version)
    Submission history
    From: Jacques Laskar [view email]
    [v1] Wed, 26 Sep 2012 16:34:34 GMT (1486kb,D)

  14. MattS says:

    Latitude,

    “I thought it was logarithmic”

    Yes it is, but the authors are talking about a 1 to 2 order of magnitude increase from current CO2 levels. That is going to make a noticeable difference even if the effect is logarithmic.

  15. milodonharlani says:

    Salvatore Del Prete says:
    September 24, 2013 at 11:41 am

    The Middle & Late Jurassic & Early Cretaceous are among the epochs most destructive to the CACA hypothesis.

    http://www.geocraft.com/WVFossils/Carboniferous_climate.html

    Paleo proxy data suggest that during the MJ, CO2 rose rapidly without affecting temperature, but just when the gas peaked in the LJ, temperature fell precipitously (possibly promoting the proliferation of feathered dinosaurs). Carbon dioxide dropped slowly & slightly during the LJ & EK, continuing to fall while temperature was rising toward its mid-Cretaceous high.

    Other mid-Mesozoic CO2 reconstructions are even worse for the CACA case, when correlated with temperature.

  16. Bill Illis says:

    “… In our model, ice-free water belts can be maintained up to 25°N/S with less than 1 mbar of CO2 and no methane. An interesting cloud feedback appears above cold oceans, stopping the glaciation. Such a resistance against full glaciation tends to strongly mitigate the faint young Sun problem.”

    I believe that says “less than 1000 ppm CO2 and no methane, cloud feedback stopped the glaciation at the tropics.”

    In any event, a 25% less luminous Sun is entirely offset with a reduction in Albedo from today’s 30% to 5% at that period, (an unlikely number but any reduction would help).

  17. Exactly, they are so full of it. Excellent link milodonharlani.

  18. Barry Cullen says:

    Reading the replies to a recent Willis Post I came to the realization how the earth maintained >273k temperature ca. 2.5 Byrs ago. Since the earth was receiving significantly less TSI, gravity was unchanged, and the atmospheric pressure had dropped to somewhere in the range of 50 – 100 bar by bleeding off into space then, any storms topped out at much lower elevations resulting in radiating significantly less energy back into space. With a higher pressure the adiabatic lapse rate had to be significantly greater than 10k/1000 M.

    BTW – based on the present rate of atmosphere loss on Mars the atmospheric pressure had to be similar to Earth’s shortly after formation. That is 200 – 250 bar.

  19. milodonharlani says:

    phodges says:
    September 24, 2013 at 11:50 am

    Same goes for climatic effects of Earth’s rotation rate & the proximity of the Moon.

    There have also been studies of the effects on life forms or lack thereof on the composition of the atmosphere & cloudiness.

    The causes of the paradox may be many, but IMO among them are atmospheric density & composition, even without considering CO2 & CH4. Science cannot say with any precision how long it took H2 to escape to space or be consumed by organisms. If it lingered well into the Archean to any meaningful degree, then an atmosphere with twice as much N2 as now (ie, about twice as dense as at present) could produce ammonia & other hydrogen-nitrogen compounds, however short-lived, that would act as GHGs. The recent fossil raindrop study suggests that the Archean atmosphere was no more than about twice as dense as now.

  20. GH05T says:

    I love it when they use one faith-based theory to prove another. If the empirical evidence doesn’t support the Faint Young Sun theory, maybe the theory of stellar evolution is flawed. It’s not like anyone has ever seen one kind of star turn into a different type of star over the course of billions of years. We just observed different types of stars and imparted our own human need for order and categorization upon them.

    Of course Stellar evolution may be correct and it’s the geological evidence that’s being misinterpreted. Maybe the calculation for the age of the strata is flawed. So much of what gets called science these days is nothing more than assumption stacked on assumption.

  21. Paul says:

    They forgot to mention that the earth was probably much more volcanic and with a hotter more radioactive core. Undersea volcanoes released enough heat to keep the seas much warmer making the atmosphere hot and humid. The atmosphere being much thicker would trap in the heat much better than the thin of atmosphere today. That is why carbon dioxide makes no difference to climate now. If you have a thick duvet on your bed in winter you will be cosy and warm but if you have a thin sheet you will be cold. Over billions of years the solar wind has stripped away some of earths atmosphere making it easier for heat to escape.

  22. JimS says:

    I can understand what a problem a dimmer Sun would mean. It seems that the Sun smartened up fast enough.

  23. Carrick says:

    Of course this is a model result, and may be false:

    During the Archean eon, between about 3.8 billion years ago and 2.5 billion years ago, the Sun was about 20 to 25 percent fainter than it is today.

    I don’t personally view evolutionary stellar models as being particularly more robust than climate models. One of the big unknowns is the rotational profile of the interior of the Sun. If you assume a constant rotation with depth, it is true this leads to the result that the Sun was about 25% less luminous 4-billion years ago, and then to an apparent paradox between observed Earth climate and solar luminosity.

    If you assume a more rapid rotation of the interior, this leads to a much “flatter” luminosity curve with time than in a standard slowly rotating star. (See Tassoul’s excellent book on stellar rotation for an overview of this.)

  24. Latitude says:

    MattS says:
    September 24, 2013 at 11:53 am
    Yes it is, but the authors are talking about a 1 to 2 order of magnitude increase from current CO2 levels. That is going to make a noticeable difference even if the effect is logarithmic.
    ==================
    It shouldn’t….once the bands are saturated…party’s over

  25. Spartacus says:

    For a geologist, this is almost a non-sense discussion. The earth’s crust was not even completely formed and it was thinner than today, granites were very scarce. Basalt and other basic rocks were dominant. The Earth behaved, until the end of the Archean, as a giant heat ball. Even the oceans were not as we know them today but a “soup” (heat ocean), were the life took the first steps. Not even massive continents, as we have today, existed. Oceans covered almost the majority of the earth’s surface, allowing a very good resilience to any temperature drop. It would be better if the authors of these alike articles could read a little about the work of geologists that study this period.

  26. phlogiston says:

    I go with negative feedbacks based on water and life and Lovelock’s daisyworld.

  27. Billy Liar says:

    Now they’ve explained the Archean period for earth perhaps they could go on to explain why Mars had oceans 3.8Bn years ago too.

  28. Bryan A says:

    @Salvatore Del Prete says:
    September 24, 2013 at 11:41 am

    During the time period of approx. 170my ago (Jurassic) Continental Drift was in full swing. The area that is now at the bottom of the Atlantic Ocean, The Volcanic Rift zone where the plates are spreading, was a heavily volcanically active zone and was largely responsible for the majority of the atmospheric CO2 concentration at the time. But the Mid Atlantic Rift Zone, prior to being submerged beneath the ocean was a volcanic ridge. In addition to CO2, there was other gasses like SO2, and various particulate matter like Ash clouds that would have acted as a negative feedback thereby moderating the effect of the volcanic CO2 and Mega Fauna induced CH4.

  29. mkelly says:

    If CH4 is a fossil fuel as they claim where did it come from way back then. Not many things around to make fossil fuel out of.

  30. milodonharlani says:

    Spartacus says:
    September 24, 2013 at 12:29 pm

    Excellent points. Sagan missed a lot by not studying other sciences, as shown by the errors in his TV show. His first wife was even a biologist.

    Even had Archean global average temperature been zero degrees C, much of the nearly worldwide ocean would have remained ice-free.

  31. george e. smith says:

    Excuse me sir, but if the oceans are looking like they want to freeze, don’t you have a sky with basically no clouds in it, so you would have a whole lot more of the incident solar energy, not being scattered or absorbed by clouds and water vapor.

  32. Outrageous Ampersand says:

    It’s all about erosion. The atmosphere has been eroding away for eons by the solar wind.

    As the sun got brighter, the solar wind became more forceful, and eroded the atmosphere faster. This thinner atmosphere held less heat, and thus the increased radiation didn’t heat the planet much.

  33. jono1066 says:

    Just create and filmed a mini solar system using electrostatically charged polystyrene granules and a fast rotating conducting core in my workshop, clearly showing eleptical orbits… anyone got a computer model so I can prove its real….

  34. jono1066 says:

    thats “just created” (past tense)
    sorry

  35. Here is an interesting graphic for the percent composition of the earth’s atmosphere over 4.6 billion years.

    http://www.scientificpsychic.com/etc/timeline/atmosphere-composition.html

    I’m not sure i believe it entirely…. the overlap of H20 and CO2 does not leave room for the N2 at 3.8 Billion years. It also does not indicate the surface pressure and changes to it. But it is a generally well done graphic.

  36. Billy Liar says:

    mkelly says:
    September 24, 2013 at 12:38 pm

    If CH4 is a fossil fuel as they claim where did it come from way back then. Not many things around to make fossil fuel out of.

    On Mars, Curiosity (the rover) is looking for CH4 because ‘it is the signature of life’. WUWT?

    http://www.space.com/18333-mars-rover-curiosity-methane-measurements.html

  37. DirkH says:

    Yeah, use models that failed right after their invention in explaining today’s climate within a decade and use them to examine millions of years.

    It’s the easy way to get the taxpayer’s dough. You can do it too!

  38. mkelly says:

    Billy Liar says:

    September 24, 2013 at 1:14 pm
    On Mars, Curiosity (the rover) is looking for CH4 because ‘it is the signature of life’. WUWT?

    The problem with that idea is Titan. Where did it get life to make methane?

  39. milodonharlani says:

    mkelly says:
    September 24, 2013 at 1:31 pm

    Methane can be produced both abiotically & biotically, but on Earth, it’s mainly biological.

    This prediction of methane loss on Titan is based upon a model, but with some observational data & basic chemistry behind it:

    http://www.jpl.nasa.gov/news/news.php?release=2013-136

  40. mkelly says:

    milodonharlani says:

    September 24, 2013 at 1:41 pm

    mkelly says:
    September 24, 2013 at 1:31 pm

    Methane can be produced both abiotically & biotically, but on Earth, it’s mainly biological.

    Yes I know. But you cannot claim you found proof of life on Mars just by finding CH4.

  41. Berényi Péter says:

    Do we know salinity of Archean seas? At 350 PSU (ten times more saline than present day oceans, equal to salinity of Dead Sea) freezing point is -35°C.

    The process regulating salinity of seawater is not well understood. Amount of salts carried by rivers to sea is enough to reach 35 PSU (current average) in 10 million years (a small fraction of geologic time). In the Archean this process might have been dominated by deep ocean vents, sped up by a much higher geothermal gradient. At the same time there were less chance to form closed basins where salts are removed by evaporation/sedimentation, because less continental crust was available.

    Anyway, it is possible to have liquid water well below 0°C.

  42. MarkW says:

    The sun is currently shrinking by millions of tons a day, both in the form of the solar wind and from fusing hydrogen into helium. As the sun grew lighter, the orbits of the planets expanded.
    Doubt this will account for all of the difference, but it will handle some of it.

  43. kadaka (KD Knoebel) says:

    Compare to what is said about the Oxygen Crisis, aka the Great Oxygenation Event of 2.4 billion years ago:

    Either way, the oxygen did eventually accumulate in the atmosphere, with two major consequences. First, it oxidized atmospheric methane (a strong greenhouse gas) to carbon dioxide (a weaker one) and water, triggering the Huronian glaciation. The latter may have been a full-blown, and possibly the longest ever, snowball Earth episode, lasting 300–400 million years.[7][8]

    Above from the press release:

    They find that an atmosphere that had 100 millibars of carbon dioxide and 2 millibars of methane 3.8 billion years ago, and 10 millibars of carbon dioxide and 2 millibars of methane 2.5 billion years ago—levels corresponding to 25 to 250 times the present level of carbon dioxide and 1000 times the present level of methane…

    Five times more partial pressure of CO₂ than CH₄, and it was the methane keeping the planet warm. Once the methane went away in the Oxygen Crisis, the Earth’s surface cooled to deep glaciation.

    Conclusion: Carbon Dioxide is WEAK. At 25 times current concentrations it was insufficient to keep the planet warm. With mounting evidence the logarithmic greenhouse effect of CO₂ is saturated at current levels, we can clearly see the further expected increases are nothing to fear.

    But as the planet is cooling and this interglacial altogether has been cooling as we slide back to planetary glaciation, we could use more methane. I’ll do my part to increase demand for cow-derived products. We also need more termites. We’ll let them eat The House That Gore Built.

  44. Duster says:

    mkelly says:
    September 24, 2013 at 12:38 pm

    If CH4 is a fossil fuel as they claim where did it come from way back then. Not many things around to make fossil fuel out of.

    Methane occurs on all the outer gaseous planets, in traces on Mars, and in gaseous nebulae in deep, interstellar space as well . It is not necessarily a “fossil fuel” in the proper sense of the word “fossil.” Here on earth it can be, and mostly is. However during the era of planetary condensation, vast volumes of methane would have been pulled in, and that is one of the empirical realities that has been used to brace the argument for so-called “abiotic” oil. Merely because a molecule is an “organic” compound does not mean it was ever part of a living organism.

    Probably more important to climate is the observation made by Phodges that the solar system is chaotic. The Lyupanov Time for the solar system is uncertain – the estimate I’ve read places it with two orders of magnitude. The important point though is that over at least a few tens of millions of years it simply is no longer possible to be certain about things like when the seasons occurred, or even if there were seasons. I have a geology text that states that there is no evidence of seasons during the paleo- and mesozoic. You don’t necessarily have to take that as a fact, but it does mean that even the origins of seasons is not fully understood – we know why but not when. That could very well account for things like dinosaurs within less than 10 degrees of the north pole, which leaves you wondering about whether plate tectonics may have a very long term effect on seasons by redistributing and creating continental mass and affecting the efficient redistribution of ocean water around the globe.

    There’s a whole lot we don’t know, and models which simply use a random number generator to simulate our ignorance really can’t inform of us of anything.

  45. Bryan A says:

    mkelly says:
    September 24, 2013 at 12:38 pm
    If CH4 is a fossil fuel as they claim where did it come from way back then. Not many things around to make fossil fuel out of.

    CH4 or Methane is a byproduct of digestion and given the size of the animals of the time, there were probably remarkable amounts of Gut Gasses. Not to mention the massive ammounts of off gassing from Dino Droppings

  46. tty says:

    It is hard to see how such a high concentration of CH4 could be maintained for such a long time. Even in an anoxic atmosphere surprisingly large quantities of H2O2 are formed photochemically and would oxidize the CH4, It would an enormous biological production to maintain it.

  47. kadaka (KD Knoebel) says:

    From MarkW on September 24, 2013 at 1:56 pm:

    The sun is currently shrinking by millions of tons a day, both in the form of the solar wind and from fusing hydrogen into helium. As the sun grew lighter, the orbits of the planets expanded.

    The mass of the Sun is 1.989×10^30 kilograms. It is 99.86% of the total mass of the solar system.

    In the core, the Sun is fusing 620 million metric tons (6.2 x 10^11 kg) of hydrogen every second. The resulting elements however are staying around the core thus the Sun is not shrinking by that much mass per second.

    The solar wind accounts for a mass loss of about 4 to 6 billion metric tons per hour. While this may sound impressive, only about 0.01% of the Sun’s total mass has been lost in total this way.

    The fusing does not reduce the Sun’s mass, save the tiny bit released as energy by current exothermic fusion processes. The solar wind does not noticeably reduce the Sun’s mass.

    In all but the most technical senses, the Sun is not shrinking, it has not gotten lighter.

  48. klem says:

    “Radioisotope decay…”

    Exactly, the earth probably stayed warm because it produced it’s own heat.

  49. Brad Weaver says:

    Are you guys kidding me? Modeling something that MIGHT have happened 3.8 BILLION YEARS AGO???
    What a waste of carbon (air breathers) and electrons (computer modeling)…

    1.75 BILLION YEARS (latest estimated time left for life on Earth) from now, is someone going to say how accurate the warmistas were?

    What is our “time-span” concern for the future? 500, or a thousand years? At what point do they call it quits and take a break?
    Hasn’t humanity adjusted to its climatic environment, moving as needed, adapting to new foods and shelter, etc?

    All this time and effort for some mystical “solution” that won’t alter climate change, and could get wiped out in the span of a few days by a large asteroid the size of a small building….very sad.

  50. markx says:

    Given that the moon was supposedly created by a massive planetary collision I’d be very surprised if this had not force an orbital change upon the earth.

    Further, as is mentioned above in comments, a partially formed, mobile crust would have released large amounts of internal heat.

    Working on this problem with a climate model would appear to be terribly limiting.

  51. Steve C says:

    If the sun was “25% fainter”, then presumably the ancient earth would have received about 1020 watts per square metre, rather than the current 1360. Thus the equilibrium black body temperature at the subsolar point (ignoring atmospheric transmission effects) would have been around 93°C, rather than 120° as at present. Either of these rates of energy input is easily sufficient to ensure that the earth’s water thermostat (­© Willis) controls the overall temperature in the long term. What’s the problem, or have I missed something centrally important here?

  52. bit chilly says:

    they used a climate model ?why ? would have been a lot quicker and less expensive to use a pack of tarot cards.the results would be at least as robust as those from the climate model.

  53. Alan Robertson says:

    What happened to the turtles? I liked them better than the models, all the way down.

  54. DocMartyn says:

    At the time the oceans were acidic, anaerobic and contained huge levels of dissolved transition metal salts. Many of these, like iron, nickel, cobalt, copper and manganese are colored and the oceans would have been dark brown and not blue. The difference in albedo would be substantial and the very top few centimeters of the oceans would absorb most of the incoming solar energy..
    The land would have consisted of dark sulphides and not the lighter oxides.
    The land and ocean albedos would have been quite different from now.

  55. Nir Shaviv has a partial explanation based upon cosmic rays. He wrote:

    The sun, like other stars of its type, is slowly increasing its energy output as it converts its Hydrogen into Helium. 4.5 Billion years ago, the sun was 30% fainter than it is today and Earth should have been frozen solid, but it wasn’t. This problem was coined as the “Faint Sun Paradox” by Carl Sagan.

    If the Cosmic Ray Flux climate link is real, it significantly extenuates this discrepancy. This is because the young sun, which was rotating much faster, necessarily had a much stronger solar wind. This implies that less cosmic rays from the galaxy could have reached Earth because cosmic rays lose energy in the solar wind as they propagate from the interstellar medium to Earth. Since less cosmic rays implies a higher temperature, this effect will tend to compensate for the fainter sun.

    Plugging in the numbers reveals that about 2/3’s of the temperature increase required to warm the young Earth to above today’s temperature, can be explained with this effect. The remaining 1/3 or so, can be explained with moderate amounts of greenhouse gases, such as 0.01 bar of CO2 (amounts which are consistent with geological constraints), or some NH3 or CH4.

    See: http://www.sciencebits.com/ice-ages

  56. Too many differences from the present for this thread to have any point other a bit of fun.

  57. OssQss says:

    Sorry, we cannot mimic the climate of the last 10 years with GCM’s. How could we possibly use them to mimic a different planet , which Earth was, 3 billion years ago?

    Can I get a refund!

  58. milodonharlani says:

    mkelly says:
    September 24, 2013 at 1:44 pm

    No, methane alone wouldn’t confirm the existence of life on Mars, but it would tend to support the hypothesis.

    Duster says:
    September 24, 2013 at 2:05 pm

    There is evidence of seasons in both the Paleozoic & Mesozoic Eras. Dinosaurs, crocodilians & even amphibians near the Poles is evidence of a warmer, more equable climate, not a falsification of seasonality. By equable in this case is meant a less steep gradient in temperature from the Equator to the Poles.

    BTW, GCMs cannot reproduce Cretaceous climate without assuming preposterously high ECS, even with the much higher CO2 levels of the Period. A proposed fix is less cloudiness due to less biological productivity in the then very warm tropical oceans, which of course the models can’t handle.

  59. milodonharlani says:

    PS: Which is not to say that it didn’t get cold at the Poles in the Mesozoic. It did, naturally, with dark winters then as now. But dinosaurs & crocodilians (archosaurs) have four-chambered hearts (down-rated with a hole for modern, aquatic crocs), while the amphibians hibernated.

  60. jjfox says:

    The “faint sun paradox” is a farce.

    Three point eight to 2.5 billion years ago planet Earth was releasing far greater amounts of the heat of formation than it does today.

    In addition to this, the amounts of radioactively-generated heat in the core were also much greater.

    This is the reason why the ocean was warm and liquid; the ocean was being heated from the top down by a fainter sun than we have today, and it was also being heated from the bottom up by a much hotter planet.

    The situation didn’t have anything to do with an imaginary “greenhouse effect” that definitely does not exist or any of the other suggestions.

    As an aside, the thermal structure of the ocean was also much different back then, being coolest in the mid-depths and warmer both above and below.

    Planet Earth was a much different place back then.

  61. Crispin in Waterloo but really in Jakarta says:

    @GlynnMhor says:

    >What assumptions were used for the cloud feedbacks, given that there is doubt as to the magnitude and even the sign of cloud effects?

    Well, I had a similar question right off the bat: What forcing value was used to calculate how much CO2 was needed to get that equilibrium temperature? Was it 0.8? 1.0? 3.2?

  62. Carla says:

    “””Evaluating solutions to the faint young Sun problem

    During the Archean eon, between about 3.8 billion years ago and 2.5 billion years ago, the Sun was about 20 to 25 percent fainter than it is today. With less sunlight to warm the Earth, the oceans should have been frozen over, but geological evidence suggests that this was not the case.”””

    FWIW
    Where was the faint sun located?

    Near its own star forming region or near another?

    The higher energetic level of GCR and Dust.
    Like GCR at the Peta and Giga and Mega electron volt range of energy might also ionize some Earthly atmospheric gaseous.
    Not to mention what it would do to the inner solar system.

  63. ROM says:

    It would appear from the collective wisdom of the WUWT commenters here that it does not need a Green House Gas explanation from another highly suspect climate model to solve the Faint Sun Paradox and the failure of the global oceans to freeze over due to Solar radiation levels being some 20% to 25% lower during the later Archean period.

    There is a whole gamut of explanations for solving the Faint Sun Paradox, none of which are likely to be the sole explanation but most or all of which operated collectively to negate and counter the lack of or lower solar radiation of the late Archean period and which led to an Earth temperature that maintained water as a fluid and therefore created the conditions for life to evolve and exist..

    I just collected a few of the comments from the above WUWT posts that provide the various and alternative reasons as explanations for solving the FSP.. Other commenters have made very similar points to those quoted.

    Carrick 12.26 pm
    Sun’s interior rotation rates more rapid leading to a flatter lumnosity curve during this era.

    Thomasinga 11.30 am and a number of other commenters
    Gravitational force heating due to ;

    Earth’s orbit more elliptical and elongated.
    Earth’s orbit much closer to the Sun
    Moon’s orbit close into Earth and far more elliptical and elongated
    Planetary orbits more elongated and probably swinging in much closer to Earth at various points in their various orbits around the Sun

    Therefore planetary orbits being far more elliptical and elongated led to high variations in gravitational tidal forces acting on the Earth leading to heating of the Earth’s interior..

    Jupiter’s “Io” moon with it’s numerous volcanoes is the classic present example of gravitational tidal forces from both Jupiter’s mass and the mases of Jupiter’s other moons all creating strong gravitationally induced tidal forces on Io leading to interior heating of that planet and the presence of a number of volcanoes on Io.

    Earth’s mantle was far thinner and far more plastic allowing much greater tectonic movement due to gravitationally induced tidal forces from other planets, the Moon and the Sun and planets.

    bubbagyro 11.46am

    Radioactive isotope decay.
    Radioactive isotopes 3.8 billion years ago were obviously in much higher concentrations than today.
    The 2 billion year old OKLA fossil fission reactors in Gabon are the only surviving remnants of what could have been a number of these natural nuclear fission reactors existent in early Earth that ran on the concentrations of radio active isotopes for some hundreds of millions or a couple of billion years during Earth’s early eras whenever local climatic conditions [ rainfall ] were suitable.

    http://oklo.curtin.edu.au/

    And it is of interest to quote Wiki here;

    The Archean is one of the four principal eons of Earth history. When the Archean began, the Earth’s heat flow was nearly three times as high as it is today, and it was still twice the current level at the transition from the Archean to the Proterozoic (2,500 Ma). The extra heat was the result of a mix of remnant heat from planetary accretion, heat from the formation of the Earth’s core, and heat produced by radioactive elements.

    Barry Cullen; 12.09 pm

    Atmospheric density much higher and therefore a different adiabatic lapse rate and consequent lower storm heights leading to considerably less energy being radiated back into space than presently theerby countering the reduced radiation emissions from the Sun.
    Raindrop studies support the Archean higher density atmosphere hypothesis.

    It seems that one does not have to rely on some unproven climate modeled green house effect to account for and solve the Faint Sun Paradox..
    All the above explanations of course are unproven and just hypothesis as is the climate modeled green house effect.
    But all the above hypothesis are an equal and I suspect, a much more acceptable explanation for explaining and solving the Faint Sun Paradox than any climate modeled green house effect which at best might have been a minor contributor compared to gravitation tidal forces and the isotope decay contribution to the warming of the Earth during the long Archean era.

  64. Michael Cook says:

    I vote for the gravitational force heating due to a nearer moon and more elliptical orbit of Earth and moon around the sun. We can affirm today that this is a significant factor just by observing Saturn’s inner moon temps. These moons are a long, long way from Old Sol, which is small indeed in their sky.

  65. Pamela Gray says:

    Now wait a minute. Do we know how much “organic haze” there was? Was this volcanic ash? Dust? Smoke from fires? This kind of atmospheric stuff cannot be ignored, especially if it is nonstop. If the Sun were fainter, any amount of haze would prevent much needed warmth from getting into the oceans around the equatorial belt.

    So it appears to me they ignored a most important factor. Why?

  66. Bill Illis says:

    The faint young sun appears to be a real problem.

    But life did evolve 4.0 to 3.6 billion years ago and there really was a great oxidization event starting at 2.6 billion years ago lasting to 1.0 billion years ago and there really was at least 4 large snowball Earth episodes starting at 2.4 billion years ago and complex lifeforms really did start appearing about 620 million years ago.

    And we are most certainly here 4.45 billion years after the Earth formed so the faint young sun is not so much a paradox, but something that was overcome (either easily or just barely but it was nevertheless).

    If we could trust the climate models to accurately represent the climate then we would have to rely on the scenarios they present. But we can’t. We must rely on what really happened and what really is happening today.

  67. RoHa says:

    @shenanigans24

    Rain-dance denier.

  68. RoHa says:

    But there is no real problem about why the Earth was warm during the Achaean era. We know that both the Achaeans and the Trojans burnt their dead during the ten-year long war, so we know that huge amounts of CO2 would have been produced to keep the Earth warm.

  69. Steven Mosher says:

    and if the models could not explain the paradox folks would of course reject them.

    Absent a different explanation ( in numbers not in words ) one is left with the conclusion that the paradox is solvable under certain assumptions. The presence of a good explanation does not rule out the possibility of a better explanation. The course of science is for other people to know offer better solutions.

  70. wayne says:

    I feel their statement “Larger droplets (radii of 17 μm versus 12 μm) and a doubling of the atmospheric pressure produce a similar warming of around +7°C.” is way, way off in the case of pressure, about one magnitude to low. Both Earth’s atmosphere and Venus’s are only 6.7 times of doubling in pressure terms (mass) and both are totally opaque (so very near to totally) to both water vapors and carbondioxide’s lines from the surface upward and bands. I need to revisit the Beer-Lambert law and optical depth in releation to what they are claiming of both incoming solar radiation absorbed by the atmosphere itself or reflected and the outgoing infrared from the surface. Wish I could see their calculation or logic explaining how they came up with this +7°C figure for a pressure doubling.

  71. TimTheToolMan says:

    Mosher writes “The course of science is for other people to know offer better solutions.”

    There is so very much about the distant past that we dont and cant ever know. This study is based on assumption after assumption. At some point one leaves the realm of science and it becomes something else.

  72. george e. smith says:

    “””””……MattS says:

    September 24, 2013 at 11:53 am

    Latitude,

    “I thought it was logarithmic”

    Yes it is, but the authors are talking about a 1 to 2 order of magnitude increase from current CO2 levels. That is going to make a noticeable difference even if the effect is logarithmic……..””””””

    I wish people would stop saying “it” is logarithmic.

    The problem with that is it doesn’t make any difference whether you take the logarithm of the CO2 data or whether you take the logarithm of the Temperature data; or for that matter if you do both; or if you do neither. The resulting plots are equally uncertain.

    Please look up the power series for Ln(1+x). or e^x for small x .

    And don’t give me any Beer’s Law claim of a theoretical foundation. Beer’s law is a law for ABSORPTION of radiant energy, as a function of absorbing species concentration.

    It is NOT a law for TRANSMISSION of radiant energy as a function of absorbing species concentration.

    Beer’s law ASSUMES that absorbed radiant energy stays dead.

    Absorbed radiant energy NEVER STAYS DEAD; it is re-emitted at some other (longer) wavelength, and gets transmitted anyway.

  73. wayne says:

    “Beer’s law is a law for ABSORPTION of radiant energy, as a function of absorbing species concentration.”
    and
    “And don’t give me any Beer’s Law claim of a theoretical foundation. Beer’s law is a law for ABSORPTION of radiant energy, as a function of absorbing species concentration.”

    Whew… if you are saying that the absorbance becomes linear with the concentration, true, opaque is total absorption. But the transimttance is dependent on the concentration times length of path through the media (exponentially), the optical mass that hinders passage that can be via scattering, refection or absorption, the tau.s in I = I0 * exp(-m(τa + τb + τc + … )). Am I not right? Seems something hit a raw nerve with you George since I think I was the only commenter above that even mentioning it, be assured if I do use that law, and I will, I will be careful to do so properly. If you are saying it can be misused or misinterpreted easily, I agree. But come on, the ratio of the intensities are the transmissivity and it is embedded in the definition of the law. Or have I misstated something, used a wrong word above. I usually speak here loosely and don’t take the time to check that every single term is perfect. Or, am I missing something you are trying to say?

  74. Mark says:

    Maybe there’s a fundamental problem with the understanding of the sun, and maybe that explains why scientists are surprised at every new thing the discover about the sun.

    Here’s an alternative:

    http://www.holoscience.com/wp/sciences-looming-tipping-point/

  75. richard verney says:

    thomasinga says:

    September 24, 2013 at 11:30 am
    //////////////////
    I agree that there is every reason to suspect that orbits were different in the very early years of the solar system, if only because the mass of the sun was greater and therefore exerted a greater gravitational pull.

    Further, the earth’s rotation was considerably quicker, if I recall correctly a day lasted somewhere between 4 to 7 hours, ie., the speed of rotation was 4 or more times quicker. This has a significant impact on how much warmth is retained since the times between receiving full incoming sloar irradiance is shorter and the time for heat to be lost (night) is much shorter. This is particularly material with respect to heating the oceans and heat retatined by the oceans given their latent heat capacity.

    Further, I understand that the solar spectrum was different in the early yearsof the solar system. I understand that it consisted of a greater proportion of high energy photons. Now I am aware that some consider that TSI as a whole is the only factor, but that has yet to be established. The different spectrum of the sun in the early period may be significant. I am not saying that it is, just may be and that it is a factor that should be thrown into the mix.

    Finally, when you see such studies posturing upon the freezing of the oceans, one never sees calculations as to how much energy is required to keep the tropical ocean liquid. This is relevant since even if there is enough incoming solar energy sufficient just to keep some relatively small proporation of the tropical ocean liquid, the water cycle begins and hence the atmosphere contains water vapour which in itself is a GHG and which accordingly would ‘theoretically’ lead to some warming thereby encouraging a wider region of the tropical ocean to become liquid thereupon releasing yet more water vapour leading to yet more warming leading to even more of the tropical ocean being liquid leading to yet more…..etc. etc. there may be no need for any role to be played by CO2. That said, of course, at some stage there must have been very high levels of CO2 which subsequently has become sequested particularly in carbonated rocks. But given this, and given the claimed warming effect of CO2why was there not runaway greenhouse warming?

    There is much that we do not understand but I doubt that computer models will help solve matters since they do no more than tell you the conclusions of the assumptions fed into them and if you know the assumptions made, you already all but know the conclusion that will be drawn from those assumptions without the aid of a computer model to tell you.

    PS. Have we not seen this study before. I recall having seen a post a few months back on this 9or similar) computer model led study.

  76. richard verney says:

    Michael Cook says:

    September 24, 2013 at 6:04 pm
    /////////////////////

    Look at Io.

    it is the most geologically active body in the solar system. all due to gravitational pull (its position b’twix jupiter and the other Galilaen moons).

    Personally I consider that there may be a failure to appreciate how much work/energy is involved in moving the tides and the atmospheric bulge. People argue that whilst pressure leads to heat that that heat dissipates over time when the pressure remains constant. But on Earth, the pressure is not really constant since the atmosphere is continually bulging being displaced by the tides from below and being pulled by gravity by the moon and sun above. Further even the distribution of pressure is in constant flux. I do not know to what extent this is relevant but is in my opinion a factor to be evaluated and not dismissed out of hand.

    It is well known that slight flexing of the side wall of a tyre will maintain temperature in the tyre. This is seen all the time in racing, and is why car lining up to the grid swerve right and left etc to built up/retain temperature in the tyre which temperature is then retained during the race by way the tyre side wall flexes during the course of the race itself. You do not need much movement (the pressure in the tyre does not vary greatly between that when on the straights and that when the car is cornering) to retain temperature which was put in the tyre when it was first filled up with air.

  77. RACookPE1978 says:

    Does not the earth’s crust itself (not just the water above the crust) move up and down about 12 inches as the moon goes overhead each day?

  78. Jon says:

    Religion, idology and their Policy based science claims likes to stay in areas where there is a low degree of scientific knowledge or high degree of uncertainty?

    Mars does not have a magnetic field so the Sun removed Mars atmosphere and water much quicker.

  79. Larry Kirk says:

    .

    As I did mention once before, and as Paul and Spartacus point out again above, to a geologist this is silly, pointless controversy about nothing. It is founded on the incorrect assumption that everything at the Earth’s surface, apart from the incoming the energy of the sun, was the same as today 2-3 billion years ago, when in fact nothing could be further form the truth.

    The geothermal gradient was much higher during the Archaean. What that means is that the rate of temperature increase with depth as you go down through the Earth’s then much thinner crust would have been much higher. As a result, the heat flow from the core up through the immature mantle and the crust would have been much greater, and much of this heat flow would have come up into the overlying oceans.

    The Archaean rocks that we find preserved at the surface today in the world’s continental greenstone belts are dominantly volcanic rocks, and volcanic rocks of the type that you nowadays only find in areas of thin, high heat flow oceanic crust: mafic volcanics, basaltic and ultramafic lava flows, basaltic pillow lavas (extruded under water), etc., and these rocks are also full of the sort of hydrothermal mineral deposits that you nowadays find restricted to the thinnest areas of modern oceanic crust, now found at mid ocean ridges.

    The Archaean crust was thin, hot, intensely volcanic, with a very high heat flow and widespread hydrothermal venting. Current best guesses as to the likely emergence and continuation of life in this environment is as ‘extremophile’ organisms, inhabiting vesicular cavities in the sulphidic ‘chimneys’ and porous eruptive rocks around subsea hydrothermal vents, where they initially obtained energy not from respiration or photosynthesis, but directly from the chemical potentials present in this sort of environment.

    What was happening at the overlying ocean surface, or in the thick, and to most of present day life highly toxic atmosphere above that was probably of little concern to these early forms of life.

    (As it may also be to the possible current inhabitants of ice-encased celestial bodies such as Saturn’s moon Enceladus)

  80. Adam says:

    “During the Archean eon, between about 3.8 billion years ago and 2.5 billion years ago, the Sun was about 20 to 25 percent fainter than it is today. “.

    Wow. Gotta laugh at that one! So we know this for sure, do we? Did somebody measure that billions of years ago?

    Answer: No. We do not. It is a *theory* of the evolution of stars. The sentence should read:

    “One theory predicts that during the Archean eon, between about 3.8 billion years ago and 2.5 billion years ago, the Sun may have been about 20 to 25 percent fainter than it is today… this is presents a paradox because…”

  81. Bill Illis says:

    What is the freezing point of water that has salts, iron and manganese dissolved in it?

    The freezing point of salty water is -1.6C to -2.0C (depending on the salt concentration).

    But what about when iron is also dissolved in it as well and there is no oxygen available to pull the iron out?

    Do the properties of the oceans change as well with vast quantities of iron dissolved it. I know it becomes more green and much more dense, but what about other changes.

    I note, the first evidence of large glaciation (which turned into a large snowball event) is at 2.4 billion years ago, just the oxygen rose to high enough level to start pulling most of the iron out of the early Earth ocean. Before that, there is no evidence of glaciation on land.

  82. Phil. says:

    MattS says:
    September 24, 2013 at 11:53 am
    Latitude,

    “I thought it was logarithmic”

    Yes it is, but the authors are talking about a 1 to 2 order of magnitude increase from current CO2 levels. That is going to make a noticeable difference even if the effect is logarithmic.

    At those concentrations the dependence on concentration would be square-root not log.

  83. tadchem says:

    The Standard Solar Model (SSM) is the origin of the ‘faint young sun’. It is also a purely computational model. Feynman would have advised us to re-examine our models when they don’t agree with the measurements.

  84. Jim G says:

    thomasinga says:
    September 24, 2013 at 11:30 am
    “Amazing that nobody is considering planetary migration as a factor, which could greatly vary the amount of radiation receives from even an cooler sun. Gravitational forces from other planets, even ones not currently counted in our existing solar system, could migrate the earth’s orbit by a very large degree. Consider the moon, at it’s formation ~4 billion years ago, it was 80-90% closer than its current oribt. Tidal forces alone likely were the sole cause of this migration. Not a stretch to think that that Earth was much closer to the sun in its early history.”

    This post notes an excellent sampling of many of the exogenous variables, other than GHG’s, which could explain the weak sun/warm earth issue. Per your comment, it is also not a stretch to consider tidal forces upon the earth’s core and huge ocean tides due to the much closer moon causing internal heating as well as continuous roiling of the waters keeping them from freezing. Fun to think about all the possibilities as long as they are not taken as dogma. Just too many possibilities and questionable paleo data.

  85. Jim G says:

    Leif,

    Where are you? Thoughts on the “faint young sun” theory?

  86. milodonharlani says:

    Salvatore Del Prete says:
    September 24, 2013 at 12:02 pm

    Just as the anti-scientists have tried to get rid of the Medieval & prior Holocene warm periods, now they’re trying to get rid of the Jurassic-Cretaceous cold epochs:

    http://www.nature.com/srep/2013/130313/srep01438/full/srep01438.html

    Few are the earth & life science disciplines that have not been corrupted by the baleful influence of the corrosive CACA scam.

  87. Re: Titan
    Here is an interesting chart of Temperature Profiles (polytropic or adiabatic) for all planets + Titan – Venus.
    At the bottom of The Oil Conundrum, March 17, 2013.
    It says it is from Class 14 – Earth, Venus, Mars – 4 of Planetary Atmospheres ASTR3720
    Spring 2005 Fran Bagenal

  88. milodonharlani says:

    Astrobiologists have hypothesized three possible kinds of life on Titan, although NASA nixed a proposal to send a probe to test the first one (or two, depending upon thickness of rock-hard water ice crust above presumed ocean):

    1) Strange life based upon liquid hydrocarbons rather than water;

    2) More Earth-like life based upon water around seafloor hydrothermal vents, &

    3) Earth-like life based upon surface water billions of years in the future, after the Sun goes red giant.

  89. cba says:

    Personally, I don’t see that much problem. A 25% weaker Sun means more like 1000 W/m^2 TOA incoming which averages out to be around 250 W/m^2. At present, after albedo is accounted for, we have around 239 W/m^2. Water (oceans) have rather low albedo, rock has moderately low albedo – like Moon & Mars so having an albedo of around 10% assuming little to no clouds is possibly even overly generous. Having similar temperatures and outgoing absorption not all that different from today with the lower albedo due to less cloud cover would give us similar temperatures. Granted this post doesn’t rise to the level of a back of the envelope calculation but I just don’t see it obviously demanding serious variations in atmospheric ghg concentrations or in temperatures.

  90. Marlow Metcalf says:

    Regarding cosmic rays, where in the galaxy was the sun 2.5 to 3.8 billion years ago. If it orbits the galaxy every 224 to 251 million years then it was in and out of the spiral arms a lot. The cosmic radiation would vary a lot. So clouds would vary a lot or would the fast spinning sun with it’s high solar wind output make being in or out of a spiral arm not matter.

  91. Leo G says:

    During the Archean eon, between about 3.8 billion years ago and 2.5 billion years ago, the Sun was about 20 to 25 percent fainter than it is today. With less sunlight to warm the Earth, the oceans should have been frozen over, but geological evidence suggests that this was not the case.

    Could this be evidence that the metric expansion of space is felt at small scales?

  92. phlogiston says:

    The Charnay hypothesis fighting to defend CACA orthodoxy, and also most of the alternative hypotheses presented in the thread take the following form:

    the sun’s heat input steadily increased over the last 4 billion years
    BUT
    as it happens
    oddly and coincidentally
    my favourite climate river: [insert CO2 / moon orbit / earth orbit / thin basalt crust / atmosphere blown away by solar wind / etc etc... ]
    JUST
    happened to change steadily in such a way as to
    EXACTLY
    counteract the increase in solar input
    SO THAT
    the earth’s temperature varied by a small fraction of the 25% solar input change
    DUDE
    thats a coincidence
    IS THERE A GOD!!

    Sorry but no. All these fail Occam’s razor. A far less tortuous and more likely explanation is regulation arising from nonlinear dynamics, Lyapunov stability of a nonlinear system. The main players are life and water. This is the essence of Lovelock’s Daisyworld.

  93. phlogiston says:

    milodonharlani says:
    September 25, 2013 at 10:25 am
    Salvatore Del Prete says:
    September 24, 2013 at 12:02 pm

    Just as the anti-scientists have tried to get rid of the Medieval & prior Holocene warm periods, now they’re trying to get rid of the Jurassic-Cretaceous cold epochs:

    http://www.nature.com/srep/2013/130313/srep01438/full/srep01438.html

    Few are the earth & life science disciplines that have not been corrupted by the baleful influence of the corrosive CACA scam.

    Yes, this is sinister indeed. “CO2 uber alles” from the very first to the last word of the paper.

  94. george e. smith says:

    “”””””…..wayne says:

    September 24, 2013 at 10:40 pm

    “Beer’s law is a law for ABSORPTION of radiant energy, as a function of absorbing species concentration.”
    and
    “And don’t give me any Beer’s Law claim of a theoretical foundation. Beer’s law is a law for ABSORPTION of radiant energy, as a function of absorbing species concentration.”

    Whew… if you are saying that the absorbance becomes linear with the concentration, true, opaque is total absorption. But the transimttance is dependent on the concentration times length of path through the media (exponentially), the optical mass that hinders passage that can be via scattering, refection or absorption, the tau.s in I = I0 * exp(-m(τa + τb + τc + … )). Am I not right?

    The story of my life. No matter how many words, I write to explain some simple concept, it’s still not enough to convey the idea to some people.

    Item 1/ We are talking about optical absorption in optically homogeneous media.
    Ergo, there are NO scattering processes. CO2 molecules in the atmosphere ABSORB EM radiation; they do not SCATTER it.

    Beer’s law, which strictly speaking applies to optical absorption in dilute solutions of absorbing species in a non absorbing liquid, as a function of the molar concentration of the absorbing species.

    All that matters is the no of molecules of the absorbing species in the optical path of the ray. You can have them all in a thin layer of high density of the absorber, or a longer path of lower density.

    What is meant by “absorbing species concentration” in my post that you quoted from, is simply that number of molecules in the path. So you can have a variable path length at a fixed molar fraction or a fixed path length and a variable molar fraction. What matters, is that each molecule in the path has some finite probability of absorbing a photon or not.

    If 1 mm length absorbs 90% of the photons, the next mm will absorb 90% of the remainder of the input stream of photons.

    So for example, if our input radiation is say a 441.6 nm HeCd blue laser, we will have blue 441.6 photons constantly being peeled off by absorbing molecules in their path; for example perhaps by a Cerium ion in a YAG crystal. The remaining 441.6 nm photons follows the normal exponential decay curve, much the same as the decay of radioactive isotopes.

    The ASSUMPTION in all of these examples is that “The fraction of input photons TRANSMITTED” is simply 1 – “the fraction of input photons ABSORBED.” That is the Beer’s law assumption, and it is followed in many non scattering optically homogenious absorption situations.

    So what is the problem ? The problem is:- The same is NOT TRUE for the TRANSMITTED ENERGY.”

    Beer’s law naively assumes that the absorbed energy disappears, in direct conflict with the first law of thermodynamics. Energy is neither created nor destroyed. Those absorbed 441.6 nm blue photons refuse to stay DEAD ! They are re-incarnated , perhaps as yellow photons at say 580 nm wavelength, or red ones at 650 nm; they might even be re-emitted at a wavelength of 10 microns, in the infra-red, due perhaps to heating of the specimen by all that absorbed energy.

    Now of course, it is assumed that the incoming photons are in a directed beam. The re-incarnated photons, at some longer wavelengths, are of course emitted isotropically; they go in every direction but they do go on living.

    Same thing is true in the atmosphere, the photons absorbed by CO2 do not stay dead, so the energy transmission doe not obey Beer’s law. There simply is no basis, either theoretical of experimental for presuming that the atmosphere retains radiant energy as a logarithmic function of the molar abundance of CO2 or other GHG molecular species; or that the Temperature follows such a law. The available data is not statistically different from a simple linear relationship, nor is it dependent on any time offset between the two data sets (Temperature and CO2 abundance.)

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