Why Dessler et al.’s critique of energy-budget climate sensitivity estimation is mistaken

By Nic Lewis

Plain language summary

  • A new paper by Andrew Dessler et al. claims, based on 100 simulations of the historical period (1850 to date) by the MPI‑ESM1.1 climate model, that estimates of climate sensitivity using the energy-budget method can vary widely due to internal climate system variability.
  • I calculated what effect the uncertainty implied by the internal variability affecting the MPI‑ESM1.1 simulations had on the distribution of the primary climate sensitivity estimate in the recent Lewis & Curry energy-budget paper.
  • The result was a marginal narrowing of the Lewis & Curry sensitivity estimate. This is because the allowance for internal variability by Lewis & Curry is larger than internal variability in MPI‑ESM1.1.
  • Since historical period energy-budget sensitivity estimates are much more  imprecise for other reasons, internal variability contributes little to their total uncertainty; it is an unimportant factor.
  • Nothing in the new Dessler et al. paper indicates that the Lewis & Curry energy-budget climate sensitivity estimates are likely to be biased low.

Introduction

Climate scientist Andrew Dessler has two interlinked short papers on climate sensitivity estimation out, one as an unpublished non-peer reviewed preprint. I focus here on the published study (hereafter Dessler18).[1]

The abstract reads:

Our climate is constrained by the balance between solar energy absorbed by the Earth and terrestrial energy radiated to space. This energy balance has been widely used to infer equilibrium climate sensitivity (ECS) from observations of 20th-century warming. Such estimates yield lower values than other methods and these have been influential in pushing down the consensus ECS range in recent assessments. Here we test the method using a 100- member ensemble of the MPI-ESM1.1 climate model simulations of the period 1850-2005 with known forcing. We calculate ECS in each ensemble member using energy balance, yielding values ranging from 2.1 to 3.9 K.[2]The spread in the ensemble is related to the central hypothesis in the energy budget framework: that global average surface temperature anomalies are indicative of anomalies in outgoing energy (either of terrestrial origin or reflected solar energy). We find that assumption is not well supported over the historical temperature record in the model ensemble or more recent satellite observations. We find that framing energy balance in terms of 500-hPa tropical temperature better describes the planet’s energy balance.

Of direct relevance to the new Lewis and Curry paper (hereafter LC18)[1]</sup3, Dessler18 states:

With respect to precision of the estimates, our analysis shows that λand ECS estimated from the historical record can vary widely simply due to internal variability.

Andrew Dessler has been using the Dessler18 results to criticise energy budget ECS estimates, such as that in LC18. He tweeted:

New Lewis and Curry paper is out! Unfortunately for them, it’s already shown to be wrong! Our recent paper showed that the methodology produces answers that can deviate significantly from reality.[4]

In reality, the LC18 results are untouched by the Dessler18 findings, as I shall show.

More here at Judith Curry’s

The paper:

Dessler, A.E., P.M. Forster, 2018. An estimate of equilibrium climate sensitivity from interannual variability. Preprint of submitted manuscript.

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34 thoughts on “Why Dessler et al.’s critique of energy-budget climate sensitivity estimation is mistaken

  1. Delighted that my near neighbor Nic Lewis has produced such an excellent new paper, and that he is so easily able to dismiss the inevitable attack on it by Dessler et al. Whichever way one stacks it, equilibrium sensitivity in published papers has been declining over the past two decades, not least thanks to the determined work by Lews & Curry both in their 2015 paper and in their recent revision.

  2. Since historical period energy-budget sensitivity estimates are much more imprecise for other reasons, internal variability contributes little to their total uncertainty.
    =========
    This may be false. No one knows what the internal variability of the climate system is because no one knows how far the climate system was from equilibrium in 1850. The models assume the climate was in equilibrium in 1850 and this may well have led to the incorrect assumption that internal variability is low.

    • However the IMPORTANT point is that whatever the climate sensitivity or internal variability was in 1850, it didnt have very much to do with CO2. The argument that CO2 affects climate/temperature depends upon differences in CO2 levels. Clmate sensitivity by its very defintion depends on CO2 levels. Even if we accept the definition of climate sensitivity as it stands (the science on this is even not settled but never mind), then that presupposes that mankind has only affected it to any significant degree by 1950 a full century after 1850. If the researchers used a flawed computer model (any climate computer model is uselessly flawed) to output sensitivity results then any conclusion that they draw upon based on those outputs are no better than throwing darts at a dartboard. This whole exercise is so far away from science that I am embarrassed to even be discussing it.

  3. May I suggest here that one of the reasons there is such variability in these estimates is the the process whereby large energy transfers take place physically up through the atmosphere by means of the Rankine Cycle and I suspect that these transfers are not taken into account in the radiation budgets and calculations.
    The process itself is, in fact, self regulating and reacts to any variations in enthalpy input by accelerating the process. In essence it is the prime reactive process to any purported increase in radiative imbalanc and could be well considered as the basic negative feedback mechanism.
    Those in the steam gleneration area will be acquainted with the the fundamentals of this and would realise that it is gravity that ultimately controls the whole process.
    Radiation calculations on their own are not suitable to determine overall climate sensitivity within the atmosphere.

    • “Radiation calculations on their own are not suitable to determine overall climate sensitivity within the atmosphere”
      I start with the null hypothesis.. it has NO effect on the earths mean temperature. So far, I have only found the gravity thermal effect that can refute that. I invite posters to provide empirical evidence proving more. BTW, where is the upper Troposphere’s hot spot?

      • Weather is the atmosphere performing work. The primary driver of weather is the warming of the ocean waters by the sun. The evaporation of warm water. Warm moist air rising as much as 15Km. Water condensing out of the gas phase and falling back to the earth. Cold air now sinking creating Hadley cells.

      • Yes indeed Keith. It takes a lot of energy to pump all that water up into the clouds; but as it all comes back down again it is a zero sum situation.
        However where gravity has a major influence is its control of the pressure and via this the temperature at which evaporation or condensation takes place based on the vapour pressure of water and its Partial Pressure.
        Thus gravity essentially determines the equilibrium global temperature and the climate hunts about this irrespective of minor changes in insulation; but of course,with leads and lags involved which could be described as weather.

  4. The missing ECS is going the same place as the missing heat: in the deep oceans. By remarkable coincidence, that is where the space aliens also are hiding, as they bide their time, waiting to attack. When they do, along with the missing heat, ECS, and everything else missing from climate “science”, boy are we in trouble.

    • We will fight them with a CO2 screen. It works something like a smokescreen. Our enemies will be so confused that they will surrender shouting CO2 FOREVER!!!!!!!!!!!!!!!!!!!!!!!!! We need more CO2 NOT less

  5. S-B & GHG & LWIR & RGHE & CAGW
    Introduction
    The absolute foundation bedrock, cornerstone and keystone of man-caused climate change is the unassailable & sacrosanct radiative greenhouse theory (RGHE). This theory claims that there are GHGs (greenhouse gases) inside the atmosphere that “trap” and recirculate long wave infra-red (LWIR) heat warming the surface similar to a greenhouse. (Much disputed analogy, btw.) Mankind’s fossil fueled production of GHG carbon dioxide, a distant second to water vapor, leads to increased and catastrophic anthropogenic global warming (CAGW). This GHG energy loop is exemplified by the Kiehl-Trenberth power flux balance diagram (Figure 10 Trenberth et al 2011jcli24) and numerous clones.
    As noted in my WriterBeat papers this diagram and GHG energy loop have numerous thermodynamic issues: 1) energy out of nowhere, 2) energy from cold to hot without added work, 3) a 100 % perpetual energy loop with no losses.
    All of this is driven by the Stefan-Boltzmann radiative heat equation that relates the temperature of a surface to its radiative energy flow. Any surface above 0 K temperature will emit infrared radiation. There is much handwaviium over this equation, but the following is rather basic, HS algebra level.
    The following discussion deals with the origin and substance of the GHG energy loop.
    S-B Equation
    OK, first let’s write the Stefan-Boltzmann equation like we know what we are doing.
    3.6 kJ/h = W = σ * ε * A * T^4
    (kJ=kiloJoules, h=metric hours, W=watts, σ=S-B constant, ε=emissivity, ratio of actual radiation/ideal BB radiation, A = area, m^2, T=absolute degrees Kelvin)
    Remember, to preserve an equation’s balance an operation done to one side must be done to the other OR what is done to one side must be undone on the same side. Inserting a term = 1.0 does not alter the balance.
    Say the emissivity is 0.7. We can’t just stick 0.7 in for ε. Inserting any value other than 1.0 unbalances the equation. But 1.0 can take many forms: 0.9/0.9 or 0.7/0.7 or 0.4/0.4 or 0.2/0.2.
    Consider the more popular form using W/A, W/m^2 or power flux.
    W/A = σ * 0.7/0.7 * T^4
    Now, what to do with the 0.7 in the denominator?
    If we know the power flux as was actually measured in my modest experiment
    (see https://www.linkedin.com/feed/update/urn:li:activity:6394226874976919552):
    125 W/8.95E-3 m^2 = 1.4 E+4 W/m^2 = σ * 0.7 * T^4 / 0.7 and T increases.
    But if we know T as in the case of the earth, e.g. K-T power flux balance uses 289 K:
    W/A * 0.7 = σ * 0.7 * 289 K^4 and the power flux decreases, e.g. from 289 K, 1.0 ε, 396 W/m^2 to 289 K, 0.16 ε, 63 W/m^2.
    And ——- the LWIR GHG net 333 W/m^2 energy loop simply vanishes back into the thin air from whence it came.
    Emissivity & the Heat Balance
    Emissivity is defined as the amount of radiative heat leaving a surface to the theoretical maximum or BB radiation at the surface temperature. The heat balance defines what enters and leaves a system, i.e.
    W/m^2 = radiative + conductive + convective + latent
    Emissivity = radiative / W/m^2 = radiative / (radiative + conductive + convective + latent)
    In a vacuum (conductive + convective + latent) = 0 and emissivity equals 1.0.
    In open air full of molecules other transfer modes reduce radiation’s share and emissivity, e.g.:
    conduction = 15%, convection =35%, latent = 30%, radiation & emissivity = 20%
    The Instruments & Measurements
    But wait, you say, upwelling LWIR power flux is actually measured.
    Well, no it’s not.
    IR instruments, e.g. pyrheliometers, radiometers, etc. don’t directly measure power flux. They measure a relative temperature compared to heated/chilled/reference thermistors or thermopiles and INFER a power flux using that comparative temperature and ASSUMING an emissivity of 1.0.
    The Apogee instrument instruction book actually warns the owner/operator about this potential error noting that ground/surface ε can be less than 1.0.
    That this warning went unheeded explains why SURFRAD upwelling LWIR with an assumed and uncorrected ε of 1.0 measures TWICE as much upwelling LWIR as incoming ISR, a rather egregious breach of energy conservation.
    This also explains why USCRN data shows that the IR (SUR_TEMP) parallels the 1.5 m air temperature, (T_HR_AVG) and not the actual ground (SOIL_TEMP_5). The actual ground is warmer than the air temperature with few exceptions, contradicting the RGHE notion that the air warms the ground.
    Conclusion
    So, the 396 W/m^2 upwelling LWIR and net 333 W/m^2 GHG energy loop of RGHE and the K-T diagram and RGHE claim that the air warms the ground are all illusions due to misunderstood instruments.
    No GHG energy loop = No RGHE theory = No man-caused climate change.

    • nickreality65,
      If one has a valid, balanced equation and wishes to manipulate the equation, it is true that whatever one does to one side of the equation must be done to the other side to maintain balance. However, substituting a known (or assumed) value for one of the symbolic variables does NOT require adding that value to the other side of the equation! That is elementary algebra.

      • I did not do any addition.
        I cross multiplied opposite side W/m^2 with the denominator.
        Believe that is quite allowable.
        And undid the same side temperature w/ straight division.
        Is that all?

    • Emissivity appears on both sides of the SB equation because emissivity equals absorptivity (Kirchhoff’s law). This is a special case when the body is in thermal equilibrium. Absorbed incident radiation equals emission of radiation. When measuring only the emission, the emissivity does not appear on the left side of the SB equation (power flux side)

    • “the Kiehl-Trenberth power flux balance diagram (Figure 10 Trenberth et al 2011jcli24) and numerous clones.”
      And it is wildly unphysical.
      It is literally a flat earth which has a tiny fraction of the oceans that real earth does. It does not account for the real driver of the weather which is the warming of ocean water by the sun. It does not account for the enthalpy of the oceans which is 3 orders of magnitude greater than the atmosphere’s.
      It does not account for the 12 hours of darkness the spinning earth produces every day, so that energy can radiate into inter galactic space which has a temperature of 2.3K.
      It does not account for the expansion of warm gases which creates larger radiative surfaces. And on and on.
      The claim that the models represent all known physics is simply wrong.

      • If it does not account for Earth’s spin, the flux would be around 1,000 W/m^2 rather than 342
        Power flux is computed per Earth’s surface area. Earth’s radius = 6371 km. TOA = 10 km
        6371^2 / (6371 + 10)^2 = 1.003 or 0.3% error
        Trenberth’s diagram doesn’t include the deep ocean. Trenberth’s missing heat could be in deep ocean or in deep space

      • If you are using a flat earth model, 342 is something like the right number. But the earth is not flat. It is a sphere (1st approximation) that spins, orbits, and is tilted. The radiation in the 22.5° circle under noon may be more than 1000, but at the same time, the other side of the planet is radiating into the deeps of inter-galactic space. The enthalpy of CO2 in the atmosphere (0.04% of its content) is trivial and will not retain heat over night. Water, will, and that is what shapes weather.

      • In non-rotating Earth, it’s always noon in the area directly facing the sun. 1000 W//m^2 is a standard solar insolation for clear sky used in solar panels. Of course it varies with location.
        Earth’s surface area is constant whether it’s flat or spherical. You just spread the solar radiation received by Earth over its surface area because it is rotating at constant speed. To be more precise, you can do the energy balance per degree latitude and longitude. GHE is not from the enthalpy of CO2. It just absorbs and emits IR from the surface

    • “The Apogee instrument instruction book actually warns the owner/operator about this potential error noting that ground/surface ε can be less than 1.0.”
      Emissivity is assumed to be 1.0 because of the thermometer is in thermal equilibrium. Emissivity equals absorptivity. Whatever the value of its emissivity, divide it by itself gives 1.0. The same potential error also applies to bulb thermometers. It heats up by convective and radiative heat transfer. It does not measure air temperature. It measures the temperature of the liquid in the bulb and assumes it’s equal to air temperature.

  6. We find that framing energy balance in terms of 500-hPa tropical temperature better describes the planet’s energy balance.

    That’s a rule of thumb. 500 hPa is effectively half way up the atmosphere as we know it. link
    Rules of thumb work if you’re working with a well understood system. In terms of the Earth’s energy budget I don’t know how you justify that particular rule of thumb. All the interesting stuff is happening at lower altitudes.

    • The cloud tops of thunder storms, and larger tropical storms, are as much as 15 km high, and may be the major regulator of the thermal balance. That is pretty darned interesting. At that altitude the air pressure is more like 120 HPa.

  7. This is the same math and stats challenged Dessler whose 2010 paper concluded cloud feeback was positive, when in relaity his own data plot showed a classic shotgun pattern and hisown calculated r^2 was 0.02! Not surprised that Nic Lewis can eviscerate Dessler18 with ease.

  8. I chuckled over Nick’s take down of Dessler twice.
    The first one:
    “The result [of using Dessler18 argument] is to change the 5–95% range for estimated ECS [of Lewis and Curry, 2018, (LC18)] from 1.16–2.68 K on the original LC18 basis, to 1.19−2.65 K using internal variability corresponding to the Dessler18 results. The ECS estimate becomes slightly better constrained, not worse constrained.”
    So Dessler slightly better constrains Nick and Judith’s result, but effectively leaves it unchanged. Too funny when you consider the Harrumphing that Dessler must be going through.
    Then Nick adds this to the end of his post at :
    “[A] brief comment here on the Dessler18 proposal of replacing global surface temperature with tropical mid-tropospheric (500 hPa pressure) temperature, as being a better determinant of changes in outgoing energy. It appears to eliminate a minor source of uncertainty at the expense of introducing worse problems. Indeed, the authors admit, in the second paper,[20] that a key ratio they uses to convert 500-hPa tropical temperature interannual feedback strength into long term forced-response feedback strength “comes from climate model simulations; we have no way to observationally validate it, nor any theory to guide us”.”
    So, Dessler wants to use a climate model output as the input to the Energy Budget Analysis to validate/produce the results.
    Circular GIGO!! More too funny.

  9. “Andrew Dessler et al. claims, based on 100 simulations of the historical period (1850 to date) by the MPI‑ESM1.1 climate model”
    Stop right there. Dassler has committed mathematical onanism. He needs to stop or he will go blind.

  10. The energy imbalance balance whatever you want to call it is so much lower than the value needed to get to high CO2 sensitivity, that the answer is very clear.
    They play around with the math to get what they want but there is a crowd which likes their new math so the paper goes through.
    The whole political climate science movement lives by the fake news new math. Some day, they will be exposed and Dessler’s name will show up on the wrong side. The power of poop man. Look it up.

    • It is uncharitable of me but I cannot help but suspect that Dessler went looking for reasons why the L&C ECS was too low. Instead he should have been looking for reasons that it might be too low *or* too high. If you only look for errors on one side you only find errors on one side.

  11. . We find that framing energy balance in terms of 500-hPa tropical temperature better describes the planet’s energy balance.
    ===========?
    Showing that CO2 is not important. 500 hPa is 5500 meters. Times the wet air lapse rate of 6 C per km you get 33 C of warming at the surface without any CO2.

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