How Gorebal Warming Could Transform Earth Into Venus…

Guest ridicule by David Middleton

Anthony covered this story a couple of days ago: MIT: Climate tipping point busted – globe needs to reach 152°F before runaway greenhouse effect kicks in.

When I saw this headline on Real Clear Science, I assumed it had to be about some other study…

How Earth Could Eventually Become Venus – Alan Duffy, Cosmos Magazine

But… No… It was an article about the same MIT study…

NEWS CLIMATE 26 SEPTEMBER 2018

A warming Earth might eventually copy the greenhouse effect of Venus

Modelling finds the precious equilibrium between temperature and radiation breaks down beyond a certain point, spelling big trouble. Alan Duffy reports.

 

Climate models show a warming Earth radiates more heat into space, but when pushed too far, and this release valve shuts down, temperatures skyrocket to potentially Venusian levels.

[…]

Now, climate models published in the journal Proceedings of the National Academy of Science, calculated by researchers at the Massachusetts Institute of Technology’s Department of Earth, Atmospheric and Planetary Sciences (EAPS), have revealed why this linear relation holds – and when it may break down to the detriment of all life.

[…]

Confident in their model, the EAPS team then cranked up the surface to ever hotter temperatures, finding that the simple linear relation broke down at 300 °K (27 °C). Above this threshold, the increasing temperature of the surface didn’t lead to a similar increase in the amount of heat escaping, thus trapping more heat.

The rising surface temperature led to more water in the atmosphere, which in turn trapped the heat, causing ever higher temperatures, resulting in a runaway greenhouse effect. This process is believed to have occurred on Earth’s twin, the planet Venus.

[…]

Koll calculated that for Earth the runaway temperature threshold was at 340 °K (67 °C) – thankfully far beyond the current average surface temperature of about 285 °K (12 °C).

Such dramatic temperature rises could only be possible through cataclysmic events, such as increasing solar outputs over billions of years of the sun’s evolution. The EAPS work suggests that the more modest, yet still dangerous, climate change-inducing temperature rises the existing model predicts for Earth will see the linear relation hold true.

So, while Earth won’t go the way of Venus any time soon, a warming planet still means a hotter world despite the increasing heat escaping into space.

ALAN DUFFY is an astrophysicist at Swinburne University of Technology, Melbourne. Twitter | @astroduff

Cosmos

 

67 °C = 153 °F

27 °C = 81 °F

When was Earth’s average surface temperature 67 °C (153 °F) or above?

During the time known as the Hadean (yes, because it was like Hades), Earth’s collisions with other large planetesimals in our young solar system—including a Mars-sized one whose impact with Earth is thought to have created the Moon—would have melted and vaporized most rock at the surface. Because no rocks on Earth have survived from so long ago, scientists have estimated early Earth conditions based on observations of the Moon and on astronomical models. Following the collision that spawned the Moon, the planet was estimated to have been around 2,300 Kelvin (3,680°F).

Even after collisions stopped, and the planet had tens of millions of years to cool, surface temperatures were likely more than 400° Fahrenheit. Zircon crystals from Australia, only about 150 million years younger than the Earth itself, hint that our planet may have cooled faster than scientists previously thought. Still, in its infancy, Earth would have experienced temperatures far higher than we humans could possibly survive.

But suppose we exclude the violent and scorching years when Earth first formed. When else has Earth’s surface sweltered?

Climate-Dot-Gov

The Hadean Eon was from 4.6 to about 4.0 billion years ago and “our planet may have cooled faster than scientists previously thought”.

When was Earth’s average surface temperature 27 °C (81 °F) or above?

Not during the Cenozoic Era…

During the PETM, the global mean temperature appears to have risen by as much as 5-8°C (9-14°F) to an average temperature as high as 73°F. (Again, today’s global average is shy of 60°F.)

Climate-Dot-Gov

Cenozoic temperature change. (Zachos et al., 2001)

Even if CO2 played a role in the warmth of the Paleocene-Eocene, it has no relevance to the notion that a “warming Earth might eventually copy the greenhouse effect of Venus.”

Cenozoic CO2 atmospheric mixing ratio and seawater partial pressure.  Notice the huge difference between atmospheric CO2 and pCO2.  Also notice that pCO2 was higher before and after the PETM and that stomata data indicate that CO2 was about what it is today, apart from a short duration spike to about 800 ppmv 55.2 Mya.  Talk about settled science!

Even with CO2 levels far higher than the Paleocene-Eocene, a “warming Earth” has never indicated that it “might eventually copy the greenhouse effect of Venus.”

Phanerozoic CO2 vs temperature. Unlabeled x-axis is in millions of years before present. Berner & Kothavala, 2001 and  Royer et al., 2004.

The Phanerozoic Eon appears to have a equilibrium climate sensitivity of about 1.28 °C per doubling of atmospheric CO2.   It would require over nine doublings of atmospheric CO2 just to raise the Earth’s average surface temperature from 15 to 27 °C.  You can’t even get there with RCP8.5.

A “warming Earth” can’t “eventually copy the greenhouse effect of Venus.”  Only a warming Sun or some other astrophysical/geophysical catastrophe could accomplish this task.  Dr. Duffy alludes to this near the end of the article.  However the headline and intimation that a “warming Earth might eventually copy the greenhouse effect of Venus” are grossly irresponsible. Allan Duffy is supposedly an astrophysicist/astronomer, who has won awards for science communication.

References

Berner, R.A. and Z. Kothavala, 2001. GEOCARB III: A Revised Model of Atmospheric CO2 over Phanerozoic Time, American Journal of Science, v.301, pp.182-204, February 2001.

Pagani, M., J.C. Zachos, K.H. Freeman, B. Tipple, and S. Bohaty. 2005. Marked Decline in Atmospheric Carbon Dioxide Concentrations During the Paleogene. Science, Vol. 309, pp. 600-603, 22 July 2005.

Pearson, P. N. and Palmer, M. R.: Atmospheric carbon dioxide concentrations over the past 60 million years, Nature, 406, 695–699,https://doi.org/10.1038/35021000, 2000.

Royer, et al., 2001. Paleobotanical Evidence for Near Present-Day Levels of Atmospheric CO2 During Part of the Tertiary. Science 22 June 2001: 2310-2313. DOI:10.112

Royer, D. L., R. A. Berner, I. P. Montanez, N. J. Tabor and D. J. Beerling. CO2 as a primary driver of Phanerozoic climate.  GSA Today, Vol. 14, No. 3. (2004), pp. 4-10

Tripati, A.K., C.D. Roberts, and R.A. Eagle. 2009.  Coupling of CO2 and Ice Sheet Stability Over Major Climate Transitions of the Last 20 Million Years.  Science, Vol. 326, pp. 1394 1397, 4 December 2009.  DOI: 10.1126/science.1178296

Zachos, J. C., Pagani, M., Sloan, L. C., Thomas, E. & Billups, K. Trends, rhythms, and aberrations in global climate 65 Ma to present. Science 292, 686–-693 (2001).

Featured Image

Maat Mons, Venus https://www.jpl.nasa.gov/spaceimages/details.php?id=PIA00254

 

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86 thoughts on “How Gorebal Warming Could Transform Earth Into Venus…

  1. They are the very definition of a criminal gang.

    Here’s one I found earlier …

    “”

    Peter Wadhams first became aware of Isaac’s 1940s proposal while working at Scripps at the start of his career. “Prince Faisal then cottoned onto this idea, and asked ‘can we tow icebergs to Saudi Arabia?’ Of course, the obvious answer is ‘no’ because you’ve got to get them across the equator and they melt, but nobody told him that because he had a lot of money to put in, and he funded a lot of research.”

    Not petty larceny. Federal sized crime is their forte.

    • well, if you start out with a big enough iceberg and can get it moving at fast enough speed you just might get a few ice cubes to Saudi Arabia, but all the energy required to transport it there before all the ice melted away would have been better spent running AC units and refrigerators in Saudi instead.

  2. When will Earth become like Venus?
    … not for a very very looooooooong time… when the sun begins to burn out and swell.

      • David

        What that paper does get right is they invoke water vapour, not CO2, as a potential absorber responsible for a runaway greenhouse on Venus (and Earth). If you check the CO2 absorption bands, you see that CO2 cannot have produced the current Venus surface temperature (to do that by atmospheric processes (rather than geophysical processes) you need to invoke absorption by volcanic gases and/or water vapour). On the other hand, it is correct that CO2 is presently preventing Venus from getting any cooler because the current Venus surface temperature is sitting just above one of the few CO2 IR absorption bands. So you can’t use CO2 to explain how Venus got this hot but CO2 explains why Venus isn’t cooling significantly today (well, CO2 or the possibility that Venus is still volcanically active today).

    • Temperature on Venus has nothing to do with greenhouse warming and everything to do with self-compression in a 96% CO2 atmosphere which is nearly 100 times as dense as Earth’s. By Gay-Lussac’s law, if that atmosphere were confined at it’s top, it would have a surface temperature almost 5 times that of Sun’s. The fact that it’s not so confined, and that atmospheric gases can rise and cool vertically by convection gives it the surface temperature it now has. More on this at: https://www.amazon.com/dp/1520538456
      I discuss why CO2 isn’t an effective greenhouse gas in Earth’s atmosphere at: https://www.asianacademicresearch.org/2018_paper/september_md_2018/3.pdf

  3. From the files of Captain Obvious:
    “a warming planet still means a hotter world”
    {facepalm}
    And a cooling planet means a colder world.

    • From the paper linked by Andre:-

      This scenario for resurfacing Venus has many attractive features. The main difference that has resulted in such radically different present conditions on Earth and Venus might be as simple as the accident that Venus rotates in a retrograde sense and Earth in a prograde sense. Where does all the energy come from that is required to resurface Venus? Could it really come just from a rearrangement of the heat already in the interior? In our scenario, the energy that is required to resurface the planet is drawn from the kinetic energy of rotation of the planet. Though not infinite, the rotational kinetic energy is a very large reservoir (about 2.5 x 10^29 J). There is plenty of available energy. The energy that is dissipated during resonance passage (as much as 2 x 10^27 J) seems to be sufficient to initiate the resurfacing of Venus. Preliminary mantle convection simulations (B. Hager 2001, private communication) have produced encouraging results concerning resurfacing, given the amount of resonant heating we have estimated here. Venus must slow down to the present slow rate of rotation in the billion or so years since resurfacing. A number of possible braking mechanisms were presented. Further study is required.

      Wow! Anyone want to guess when the Earth is going to start having retrograde rotation?

      • Calm down Philip, relax, everything is under control. We have a moon. Venus does not. That’s the difference. The moon makes sure that the frequency of the obliquity (Milankovitch cycle) is much slower than the precession cycle. This prevents Earth from entering the “chaotic zone”, where interference/resonance between precession and obliquity causes extreme excursions of the planets spin axis of mantle and of the core.

        As long as we have the moon it won’t happen.

        On the chaotic zone see: http://www.scholarpedia.org/article/Stability_of_the_solar_system

        • Thanks andré
          I was getting worried about all those windmills slowing us down and leading to planetary heat death.

  4. The Sun is going to have to get a whole lot hotter than usual for us to get to that temperature. Hell, by the time that happen, Global Warming won’t be a concern, Earth being inside of the Chromosphere is a bigger problem.

  5. I thought pressure had more to do with a planets heat. Example , both Mars and Venus have similar atmospheric composition of CO2 at about 95% and N2 at about 3% however the temperature is vastly different at approximately 460C for Venus and -60c for Mars. The pressure difference is even bigger at 9300kPa for Venus and 0.64kPa for Mars. (or thereabouts). Earth with N2 at 78% and O2 at 21% and an atmospheric pressure of 101kPa is a long way from either of these worlds. As a layperson I find this hypothesis of the atmosphere of the Earth becoming similar to that of Venus quite a stretch of imagination. I would be interested in any evidence that the planet Venus is a “Twin” of the Earth – without using fanciful evidence such as it probably is!

    • Tony Heller has a You Tube video basically stating Ancient Scouse’s post. Atmospheric temperature is highly dependent on pressure and not necessarily composition.

      • Temperature is only pressure dependent in the atmosphere when there is convective mixing (see the stratosphere? temperature DECREASES with pressure over a factor of 100x change in pressure), and convective mixing depends upon the greenhouse effect to destabilize the tropospheric lapse rate. And even in that case, pressure (in a convecting atmosphere) only tells you what the lapse rate is… not what the temperature is. Temperature is a function of energy gain and energy loss, not pressure. The empirical correlation to pressure is because pressure is a measure of how much atmosphere (and thus greenhouse gases) is above.

        • Umm, are you throwing out the combined gas laws which have been empirically verified as showing Temperature IS pressure dependent?

          • Richard Patton,

            The combined gas laws do not show this empirically or even theoretically. What they do show, both empirically and theoretically, is that the pressure, temperature and volume of a given quantity of gas are interdependent according to the formula:

            PV/T = R

            where P = Pressure,
            V = Volume,
            T = Temperature,
            and R = a constant specific to the gas in question.

            (See: https://en.wikipedia.org/wiki/Gas_laws#Combined_and_ideal_gas_laws for derivation.)

          • No Richard Patton, Dr. Spencer is not saying that at all.

            Temperature is determined by the energy balance. The ideal gas law tells you how big the volume will be for a given number of moles at that temperature. Atmospheric pressure (at the surface) is just the total mass of the atmosphere divided by the surface area of the planet.

            If you doubt this, then please answer this question:

            Imagine that Venus is flung out of orbit into interstellar space by a passing black hole (or by a unicorn, let’s not waste time arguing how it could or couldn’t happen). What would you estimate would be its atmospheric pressure, volume, mass, and temperature after two million years?

            Please reconcile your answer with the following facts:

            Approximate temperature of interstellar space: 3K
            Freezing points:
            H2O: 273K
            CO2: 195K
            CH3: 91K
            Ar: 84K
            N2: 63K
            O2: 54K
            H2: 14K

            The answers are approximately 0, 0, 0, 3K

            Next thought experiment:
            Move the earth inside the orbit of Mercury. Ignore the fact that solar wind will strip away the atmosphere eventually. What will be the approximate mass of the oceans and the mass of the atmosphere if the current mass of the ocean is Mo and the current mass of the atmosphere is Ma?

            The answers are 0, (Ma + Mo)

            If all of the water on earth vaporizes, what will the pressure be at the surface? Was it the pressure that created the temperature or the temperature that created the pressure?

          • Back of the envelope calculations.

            Area = length x breadth ( l x b) …. [1]
            Load = Mass x gravity (M x g) …. [2]
            Volume = length x breadth x height ( l x b x h) …. [3]

            Pressure = Load / Area = [2] / [1]
            or Pressure = (M x g / l x b)

            PV = Pressure x Volume

            substituting PV = (Load / Area) x (Volume)
            & thus PV = (Mass x gravity / l x b ) x (l x b x h)
            simplify PV = Mass x gravity x height
            or PV = Mgh

            Given that PV = nRT (The Ideal Gas Law)
            & PV= Mgh
            then nRT = Mgh
            T = Mgh/nR

            Temperature of a gas is therefore a function of planetary mass, gravity & altitude (height).
            Thus the atmosphere of a massive gaseous planet located in interstellar space would still have an atmospheric temperature above zero Kelvin.
            External energy is not required, but is obviously an temperature influencing factor in a solar system!

          • @KAT
            You need another envelope for calculations.

            Where you and countless others go wrong is that you imagine that the atmospheric mass and volume is a constant.

            Take it step by step. Right now Venus receives a large amount of energy from the sun and approximately the same amount leaves the planet (reflected, radiated to 3K space). Otherwise the net absorption would be raising the temperature continuously.

            The flying unicorn farts blow Venus out of orbit. Now initially the heat radiated to 3K space is unchanged, but virtually all energy input stops. Temperature begins to drop due to the imbalance. Still far above 273K, so there is no change in atmospheric mass. (Nothing condenses out yet, so no change in pressure). T has dropped, but n, and P are unchanged. Only V remains. V = nRT/P. The atmosphere begins to shrink.

            After a long intermission, temperature has dropped and volume has shrunken down until CO2 begins to precipitate out of the atmosphere. Now n, the number of moles of gas, is also dropping. The mass of the atmosphere is dropping, so pressure at the surface starts to drop. While CO2 gas and liquid coexist, surface temperature will remain constant. Volume continues to shrink, to satisfy the ideal gas law. In this period, the heat being lost to space is coming from the latent heat of vaporization released from condensation of CO2 gas.

            (I am glossing over the question of phase changes depending on pressure. At Venus pressure it should go from gas to liquid, then reach the triple point and ultimately all go to solid).

            At a certain point all of the CO2 on Venus has gone to the solid state. So now the mass of the atmosphere has dropped by well over 95%. Pressure has dropped below that of earth. Volume has shrunken dramatically. Temperature resumes its decline now that latent heat is no longer being liberated.

            Temperatures continue to cool until the nearly pure Nitrogen atmosphere begins to condense out. Same scenario plays out as with CO2. Temperature pauses until the latent heat has been all released. Volume approaches zero now. The number of moles approaches zero. The atmospheric mass approaches zero. The pressure approaches the vacuum of space.

            Finally, all of the nitrogen freezes solid. Temperatue continues to fall from the now greatly reduced radiation heat loss. Eventually the frozen surface reaches approximately 3K.

            (I glossed over internal heat so to make it easier lets say 2 billion years instead of my original 2 million).

          • @Rich
            In my original post I wrote……….
            Thus the atmosphere of a MASSIVE GASEOUS planet located in interstellar space would still have an atmospheric temperature above zero Kelvin.

            Venus is a small rocky planet with a relatively weak gravitation field. It’s atmosphere does not have the correct gas composition to remain in a gaseous state at extremely low temperatures. The component gases of the atmosphere would eventually change from the gaseous to the solid state depending on the properties of each particular gas.
            Venus would eventually lose all of it’s temperature in interstellar space in the manner that you correctly describe.
            On the other hand, Jupiter is an example of a massive gaseous plant that would retain it’s core temperature in interstellar space. The gravitational field is so powerful that the planet retains light gases such as helium and hydrogen, that have extremely low critical temperatures. The properties of these two gases are crucial.

            “Unlike any other element, helium will remain liquid down to absolute zero at normal pressures. This is a direct effect of quantum mechanics: specifically, the zero point energy of the system is too high to allow freezing.
            Solid helium requires a temperature of 1-1.5 K (about −272 °C or −457 °F) at about 25 bar (2.5 MPa) of pressure.”

            https://en.wikipedia.org/wiki/Helium

          • @KAT
            I guess this thread is getting pretty old. But one last comment from me.

            The key point that I thought I was disputing with you was the idea that the surface temperature is somehow determined by the surface pressure.

            Helium can’t freeze because the background radiation is at 3K currently. Hydrogen could freeze. The gas giants in a solar system still receive sufficient solar energy that they don’t precipitate their hydrogen. Also they can be heated by tidal forces of their moons and other bodies converting their kinetic energy to heat and slowing their rotation and degrading their orbits.

            If isolated in interstellar space, eventually Jupiter or Saturn would shrink down to a 3K frozen hydrogen planet with a helium ocean and thin helium atmosphere.

            If you don’t dispute that then I was mistaken that you are one of the people who believe that static pressure creates heat and determines temperature.

            Summarizing my case:
            The energy balance determines temperature T. Pressure P depends on the mass of the atmosphere over the surface area of the planet, which also determines the number of moles n. At a particular T, the composition is fixed, so P and n are constants. R is a universal gas constant independent of the gas composition or gravitational field. Thus when the independent variable T changes, the dependent variable V must obey the ideal gas law PV=nRT => V=nRT/P. The atmosphere puffs out when heated and shrinks down when cooled. The application to Venus is that it has the temperature it has because of the energy balance acting on the quantity and composition of atmosphere that it has, not because that quantity generates a pressure.

        • Roy W Spencer

          “…convective mixing depends upon the greenhouse effect to destabilize the tropospheric lapse rate…”

          An atmosphere without GHG’s at all will be heated by the surface during the daytime and not at night, inducing convective vertical mixing. I realise that the convective heat transfer from the surface to the atmosphere has been ignored by basically everyone including Monckton and G Schmidt, but Prof Adrian Bejan did not, nor do I.

          There is no absolute requirement for GHG’s to be present in order to have vertical convection in a real atmosphere. A Lava Lamp has vertical convection without any GHG’s. Air is a fluid and will respond the same way. Thermal convection in a pot of water before bubbles appear is another example of a fluid being driven by convective heat transfer, not radiative interception. The same buoyancy effect drives a thermosiphon.

          If the air were cleared of all GHG’s, the current incident radiation absorption will approximately double. There would be lots of energy delivered to the surface air to drive convection. However in that condition, there would be no way for the atmosphere to cool radiatively so the temperature would continue to rise. Absent GHG’s, thermal equilibrium would only be reached when the atmosphere would be far hotter than it is now. The corollary is that as GHG’s tend to zero concentration, the temperature of the atmosphere would rise rapidly, driven by surface heating and convective heat transfer, with virtually no cooling mechanism (save re-convection to the surface at night, a weak mechanism opposed by the buoyancy effect, enhanced by convective mixing).

          • An atmosphere…,,, I realise that the convective heat transfer…. but Prof Adrian Bejan did not, nor do I. That is why Yuma daytime high temps are 15 degrees warmer than Shreveport but their nighttime low temps are about the same.

        • @Rich

          Nope.
          The mass of gas in the above formula refers to a column of gas standing on an unspecified area.
          The volume of the gas is not relevant except insofar as it does not determine the height which is the main variable.
          The temperature of the gas varies in accordance with the height.

          An similar example would be the hydrostatic formula: P = density x g x h

          If a hosepipe of section 25 square mm filled with water were to be held at a certain height (say 50m) above ground level as compared to a huge pipe column of 3 square metres cross section; the pressure would be determined by the height in both cases. The changes in volume & mass are not relevant to the calculation.

          • @KAT
            It is of course correct that there is a lapse rate since the top of atmosphere is exposed to 3K and the surface is currently 462C. There is also a pressure gradient that goes from zero at TOA to the average pressure at the surface. So what? To use the ideal gas law as an approximation in this case, you will have to use average P and T over the entire atmosphere. It’s also true that Venus’ atmosphere doesn’t really obey the ideal gas law at any altitude, but as an approximation it’s close enough. If you cover the whole surface with your “hosepipes” and add them all up you will get the total mass of the atmosphere, and each of them will probably show a little variation in pressure, just as we experience on earth. And temperature will also vary, independent of pressure, just as on earth.

            How can you say that volume doesn’t enter into it when the ideal gas law is PV=nRT?

            You want to look at all the little details that have been simplified, go right ahead, but let me get this straight. You seriously want to contend that Venus would stay at 462C for two billion years if it were transported to interstellar space and was only receiving faint starlight? That’s pretty magical. How does the insulation work?

  6. I am surprised you all are missing a rather obvious conclusion from this study, there is indeed one way the Earth’s temperature could rise this high, based on the historical record. If Thanos decides to wreak his vengeance upon us and bombards the earth with planetoids until the entire surface become molten, then the planet would definitely cross the threshold and become like Venus. it’s obvious, isn’t it?

    • wws

      If Thanos decides to wreak his vengeance upon us and bombards the earth with planetoids until the entire surface become molten, then the planet would definitely cross the threshold and become like Venus.

      After which, in short order (geologically speaking) the earth would promptly cool back down to near-today’s global average temperature, pressure, and humidity. With many fewer liberals in their protected academia jobs.

  7. “It would require over nine doublings of atmospheric CO2 just to raise the Earth’s average surface temperature from 15 to 27 °C. ”

    Nine doublings mean that the atmosphere would be about 20% CO2. Even though humans are remarkably tolerant of high CO2 levels that is well above lethal level, so the temperature would the least of our problems.

    • The Submarine Service found that 1/10 of that would make some folk ill. Back in the balmy olden-times of above deck ambient 372pmmv. Ahhh, I remember it well.

      https://www.nap.edu/read/11170/chapter/5#51

      “CO2 exposures as low as 7,000 ppm can lower blood pH by up to 0.05 units, but even at high exposures, renal compensation seems to occur in healthy subjects. In a 30-day exposure to CO2 at 20,000 ppm, there was an average pH change of only 0.01 units (Guillerm and Radziszewski 1979). Compensation occurs over a variable period of time, but effects of lowered pH on clinical status or performance have not been reported either experimentally or operationally (Schaefer et al. 1964a).”

      Some folk get headaches and ask to never go back in a sub. Most don’t. To be sure, they are ‘fit’, youngish folk and ambient CO2 ‘only’ approaches @0.7% during tours.

      ” … Bless those who serve beneath the deep,
      Through lonely hours their vigil keep …”

      • I was an Atmosphere Control Technician on a fast attack nuclear sub. We had the CO2 level alarm set to 8,000 PPM (1980 time frame). If the alarm was going off, I’d have to explain to the Captain, the XO, and the Engineer why I allowed it to get that high. Scrubbers broken?

      • Before you get that far it will change from a log dependence to square root so it won’t need such a large change in concentration.

  8. Doesn’t Venus have something like 90 times the atmospheric pressure of Earth? And doesn’t PV=nRT on both planets? We need a lot more hot air if we’re going to get Venusian temperatures.

    • Any time I hear of Venus, I always want to say : “Have any of you idiots ever heard about spectral line broadening due to pressure?” Shucks, that is why you can have the weighting function on the AMSU that you do. Then again, trying to get these idjits to understand that greenhouses stay warm because of something other than the “greenhouse effect” is lost on them too. Getting them to understand that it really the “parked car effect” usually does not work. Bah!

    • you have that exactly backwards. We need a lot more heat going into the atmosphere to vaporize the oceans before we would reach pressures like on Venus.

  9. It’s my understanding that a lot of the early high concentration of CO2 over geological time got turned into shells of marine creatures. Without life, could Earth have become Venus?

    • All we would need is for the atmosphere to somehow increase its mass so that its pressure is about 100 times what it is now and move the planet 25% closer to the sun, like Venus is.

      • Jim, you’ll need to slow it down… and actually reverse it. Venus rotates in retrograde. But, its days are also 243 earth days long. High noon lasts about a week! Should make day time temperatures rather balmy.

        • The important point is how slow it rotates. I know it is retrograde but don’t understand how that would make a difference in temperature.

  10. ‘So, while Earth won’t go the way of Venus any time soon, a warming planet still means a hotter world despite the increasing heat escaping into space.”
    —————————————–

    To me the simple above statement means that these guys at last have to consider seriously that an increase in RF, at some given point, and above it,
    actually may result in a considerable atmospheric heat content loss to space, aka cooling.

    Where the contemplation of a “hotter world” still in the cards, only due to same circular reasoning, as always before, solely based basically in the same faulty understanding and mechanisms that support AGW, as the main mean of an explanation attempted by these Phd’s.
    Very wrong indeed.

    Unless, at least the approach consist within the clause of the radiation imbalance, or as maybe the dear Lord Moncton may put it, “the sun shine”, these guys be barking in the wrong tree, regardless of how eloquent or intelligible it may sound.

    RF going up still, when no any thermal expansion of atmosphere, then the only expected outcome is “heat escaping into space”, or heat released into space in a manner of a negative energy balance of the atmosphere and the earth system, aka cooling.

    As per my understanding that has started at the point when 380 ppm reached, and it will keep going that way increasing for as long as ppms go up, when with no any further thermal expansion of atmosphere, aka as a in condition of hiatus, or cooling.

    A proper “heat loss content into space”, due to RF increase can not be explanatory attempted by the old faulty ways of AGW climatology content,,,really silly..

    I really do miss a lot the edit button.

    cheers

  11. “nine doublings of atmospheric CO2 just to raise the Earth’s average surface temperature from 15 to 27 °C. You can’t even get there with RCP8.5.” I’m not a scientist, but isn’t CO2 effect on temperature logarithmic? 204,000 PPM sending the temperature up 12 degrees C? May it does?

  12. There is no way to compute such a thing because you have to assume how precipitation systems would change to remove the extra water vapor (our main greenhouse gas). They probably assumed constant RH throughout the troposphere, which would lead to astoundingly high water vapor contents at very high temperatures. There is no reason to do such a study, other than to create sci fi-based alarm.

    • Roy is right. They do assume the RH remains constant – something proposed many times but contradicted by NASA measurements – see Miskolczi 2011, 2012 for the details.

      I read the paper and one has to understand what “effect” they are investigating. It is limited to the behaviour of the GHG’s in the absence of any cloud behaviours and not considering heat going from the surface to the atmosphere by convective heat transfer. It is purely about the radiative effects across temperatures using line-by-line analysis method.

      They confirm that the way General Circulation Models treat GHG radiative effects is correct. I don’t think anyone was disputing that. The criticisms of GCM’s are about the poor job they do predicting temperature even a few years out, and that they do not capture the behaviour of clouds or surface heating well. I believe these two latter failures explain the former.

      The paper reports some surprising things but not that GCM’s work. It is akin to a mechanic checking a car over and reporting that the gearbox ratios are what they were though to be. That may be true but it doesn’t tell you anything about how the car performs.

  13. Can some one take it to heart, and explain to me what actually does this
    “the increasing heat escaping into space”
    mean!

    My English most probably fails me completely with this one.
    The only thing I can make out of it is like in the lines of, really stupid or stupid in steroids.

    How can there be increased heat when in the same time it is lost or escapes???

    Some thing I must be missing here!!!

    cheers

    • Whiten,
      It seems that your concern is that the earth can’t become hotter if it is losing more heat. But that is a fallacy. Consider an analogy to a tank of water with a small hole near the bottom, being filled from the top by a large pipe. Turning on the feed from the pipe into the tank (analogous to an increase in input energy), the water level can rise in the tank (analogous to a rise in the temperature). At the same time, the amount of water leaking from the hole can increase (analogous to the increasing heat escaping into space). In fact, the amount of water that leaks MUST be greater as the water level increases, because the pressure at the hole increases. The same is true for heat. If the surface temperature rises due to an increase in incoming energy, the amount of heat radiated away must increase because the driving force (delta T) has increased (analogous to the water pressure). Radiative heat loss will be proportional to the fourth power of temperature.

  14. Let us never forget that planet Earth is a water planet, that 70 % of Oceans makes all the difference. The Oceans are the flywheels of the climate, smoothing it all out, bar of course the local variations.

    We are lucky to be in the Goldylocks zone weather wise.

    MJE

  15. “Confident in their model, the EAPS team then cranked up the surface to ever hotter temperatures, finding that the simple linear relation broke down at 300 °K (27 °C). Above this threshold, the increasing temperature of the surface didn’t lead to a similar increase in the amount of heat escaping, thus trapping more heat.”

    *At what point above that threshold I wonder. Also, with all of the water up there as clouds and vapor, how did they manage to heat the surface, with a cigarette lighter? 😉

    “The rising surface temperature led to more water in the atmosphere, which in turn trapped the heat, causing ever higher temperatures, resulting in a runaway greenhouse effect. This process is believed to have occurred on Earth’s twin, the planet Venus.”

    I wonder how fast they turned up the heat. This Venus crap just won’t go away. There is no evidence Venus ever had a hydrological cycle, some evidence it did not form in this solar system and it has an atmosphere that acts more like a comet coma than our own atmosphere, and of course it’s closer to the sun.

    Comparisons to Venus are like much other nonsense in “climate science” where one must disregard all other factors in order to come to a conclusion. In this case, billions of years of geological evolution, of both earth and Venus.. is ignored, it all “must be CO2”.

    My brain hurts reading this rubbish

    • That was the point of Anthony’s original posr on this.

      A skeptic views this as the “tipping point” being way beyond science fiction.

      An alarmist views it as the “tipping point” toward Venus.

      “Same as it ever was.”

  16. frankclimate, given the hypothetical atmospheric structure and relative humidity scenario/s used in the paper, what are the actual meaningful conclusions ?

    i see they claim increased confidence in the robustness of clear sky feedbacks in global climate models despite their acknowledgement that clear sky feedbacks in gcm’s roughly double earths climate sensitivity and the magnitude of these feedbacks is consistent across models. they then go on to say this agreement is not obvious as gcm’s exhibit various temperature and relative humidity biases and differ from satellite data as well as other gcm’s !

    this supposedly means because linear olr requires a constant feedback the magnitude of the net clear sky longwave feedback in gcm’s is insensitive to moderate biases. to me this implies the possibility of the right result for the wrong reasons.

    the core for me is : this logic no longer holds under hot conditions (surprise surprise) , fig 2 that you highlight is used to demonstrate that above around 300k the linearity breaks down. they say such conditions would have been widespread during past warm periods such as the eocene hothouse period (and now the money shot) could occur regionally under strong global warming.

    i assume as 300k and above temperatures are nothing out of the ordinary they have already tested their proposals by measurement somewhere in the tropics ? or would that be impossible due to the fact that a stationary column of atmosphere, stationary oceans, constrained trop and strat temps etc etc do not exist anywhere on earth ?

    they then go on to state that model biases under such conditions will amplify making it difficult to accurately simulate past climates or to constrain the worst case outcomes of future (modeled) warming.

    that reads to me as getting an excuse in early should there ever be any auditing (there should be) of climate models by competent modelers outside the climatosphere or someone forces them to publish the results of long model runs that show past and future scenarios beyond the bounds of reality outside of the short period around the present time where they are only considerably wrong.

  17. bit: I agree mostly with your opinion.
    In CMIP5 one gets increasing ECS ( lower lambda) with strongly increasing GMST, well below the 26°C threshold. This is not justified… They also state, that “patterns” with diverging ECS could only arise from cloud-surface albedo- and rel. humidity changes. NOT from the forcing.
    re: 26 °C: I interpret it as a measure for GMST. Only local areas with such a high Tmean ( during day time?) seems to me to have too less regards for the issue of the paper.

    • There are large areas with Mean Annual Temperatures over 27 C, even large areas where the mean monthly temperature of every month is over 27 C, much of the Western Pacific for example. And not a sign of any runaway greenhouse.

      • That’s why I would think that they mean the GMST ( today about 15 °C) and NOT some locations where the T’s are above the 27°C theshold.

        • i see your point frank, but they explicitly make the claim ” such conditions would have been widespread during past warm climates such as the eocene hothouse and could occur regionally under strong global warming “.

          • bit: yes, a more uncertain wording. What means “widespread”? The SST in the tropics are now at 26…27 °C ( see HadISST1) and during ElNinos well above 27°C. As we can formulate the question it’s clear that there was no “Venus-train”. I would think they mean GMST…

  18. The oceans would have to boil first.
    And there is ‘zero point zero’ evidence that Venus ever had oceans.

  19. That model is fatally flawed. Cannot work for Earth even if not buggy (can work very approximately for Mars, for reasons I won’t detail here). Because they used that lunacy as an aggressive propaganda on Facebook, I decided to look briefly into the code. Not surprisingly, I quickly found that it has ugly bugs. Here is one I signaled (was already acknowledged and fixed): https://github.com/ddbkoll/PyRADS/issues/2 They used for CO2 spectrum the spectrum of H2O!
    They also already acknowledged another issue with spectral lines broadening…

    Very shortly, that piece of garbage is garbage. Not only it’s buggy, but a 1D model for Earth (that cannot simulate correctly convection + latent heats, for example, which are paramount important for energy transport from surface) cannot work. It’s very easy to comprehend why, even only thinking of horizontal energy transport, which is definitively not negligible on Earth.

  20. If, as many seem to be stating unequivocally, atmospheric pressure due to gravitational compression of gases cannot explain temperatures at the surface or deep in the atmospheres of the “gas giants” then just how do these same people reconcile the data readily available such as this from NASA :

    “The temperature in the clouds of Jupiter is about minus 145 degrees Celsius (minus 234 degrees Fahrenheit). The temperature near the planet’s center is much, much hotter. The core temperature may be about 24,000 degrees Celsius (43,000 degrees Fahrenheit). That’s hotter than the surface of the sun!”

    https://www.nasa.gov/audience/forstudents/5-8/features/nasa-knows/what-is-jupiter-58.html

    Or this:-

    “At the point where atmospheric pressure is ten times what it is on Earth, the temperature reaches 21°C, what we Earthlings consider a comfortable “room temperature”. At the core of the planet, the temperature is much higher, reaching as much as 35,700°C – hotter than even the surface of the Sun.”

    “And much like Jupiter, the temperature in the upper atmosphere of Saturn is cold, but increases closer to the center of the planet. At the core of the planet, temperatures are believed to reach as high as 11,700 °C.”

    “Much like the other gas giants in our Solar System, the core of Uranus gives off far more heat than is absorbed from the Sun. However, with a core temperature of approximately 4,737 °C, Uranus’ interior gives of only one-fifth the heat that Jupiter’s does and less than half that of Saturn.”

    “With temperatures dropping to -218°C in Neptune’s upper atmosphere, the planet is one of the coldest in our Solar System. And like all of the gas giants, Neptune has a much hotter core, which is around 7,000°C.”

    https://www.universetoday.com/35664/temperature-of-the-planets/

    There is ZERO chance of ANY Greenhouse Effect on any of these planets. How could 50.5 W/m2 solar radiation at Jupiter EVER explain the temperatures postulated ??

    Surely NASA wouldn’t lie ?

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