Discussion between Roy Spencer and Ned Nikolov About the N-Z Climate Concept

After careful consideration, I decided to make public an email correspondence I had with Dr. Roy Spencer in April of 2026 about the new Nikolov-Zeller (N-Z) climate theory, which took place before a large group of CLINTEL Foundation members. My decision was guided by the desire to shed light on key deeply held misconceptions by PhD climate scientists about fundamental atmospheric processes. The narrative offered by Dr. Roy Spencer relies on “thought experiments”, which he employed to criticize data-driven discoveries and conclusions described in peer-reviewed publications. Aside from the fact that “thought experiments” are the least appropriate method to argue against observations and empirical relationships, Dr. Spencer’s line of reasoning also reveals a surprising level of misunderstanding of atmospheric thermodynamics, which is not uncommon among professional climate scientists with a narrow expertise in atmospheric radiative transfer.

First, I present a structured email message sent by Dr. Spencer to the CLINTEL group that critiqued the new N-Z climate-science paradigm. This is followed by my response to the most important points/claims made by Dr. Spencer. Finally, as a follow-up, I address a key question raised by Dr. Spencer, which is, what would happen to Earth’s global surface temperature and the lapse rate, if the atmosphere could not absorb and emit infrared radiation?

On Apr 24, 2026, at 5:25 AM, Roy Spencer wrote:

All:

After working in meteorology and then climate during my 40+ year career, I think I can offer some insight into the issues being discussed in these emails. Like Ned, I have always been skeptical of what I have been told until I could fully understand an issue for myself.

I’m sure the following explanations will be of help to many of you. (I suspect Ned is too invested in his theories to change his mind.) Many of the concepts are not trivial, and I will admit it wasn’t until many years after all of my education (PhD Meteorology) that I finally understood a few of them, because they were not taught in school.  Dick Lindzen helped me in this in the early climate research years. 

Most of what follows is fundamental atmospheric thermodynamics, and I question whether Ned really did take a university-level Atmospheric Thermodynamics course. If he did, I’d like to know where. 

And if he shows me his grades, I’ll show him mine.

A THOUGHT EXPERIMENT

Imagine you could suddenly dump an extra 1 atmosphere of air on top of the existing atmosphere, what would happen to air temperature in the 1 ATM below? Just as Ned would predict, the temperature of the original atmosphere below would increase greatly through adiabatic compression.

But what would happen NEXT?….

The high atmospheric temperatures in the lower atmosphere would then be far out of energy balance compared to what existed before. The result would be cooling of all of that air that was heated through adiabatic (or nearly so) compression (work done on the lower atmosphere) until a new state of energy equilibrium was reached. The energy loss would be through infrared radiation of the hotter air.

In fact, is it always ENERGY BALANCE that determines temperature, through the 1st Law of Thermodynamics. A change in temperature is proportional to the rate of energy input minus the energy output (which includes any work done in the process). 

In contrast, the Ideal Gas Law (PV=nRT) cannot tell you what the temperature “should be”. It only says how the variables P, V, and T are interrelated during the process of re-equilibration, and in the final equilibrium state. What Ned misses in is theory is the “n” part of the equation (the number of moles, or mass… which is in the density form of the equation, P = rho RT). In the hypothetical 2-atmosphere thought experiment, as the lower atmosphere cools to reach a new state of energy equilibrium with the solar input, the decreasing temperature causes and increase in the air density (“shrinkage”), and the pressure remains the same… even while the temperature is changing.

Specifically, following the 1st Law, the internal temperature of a volume of atmosphere exposed to an energy INPUT will increase until the temperature-dependent energy OUTPUT processes equal the rate of energy gain. This is true of every physical system… the atmosphere, a pot of water on the stove, a car’s engine, the human body, the interior of the sun, etc.  That energy equilibrium is what determines the final temperature. (In the real atmosphere, there are constant energy imbalances and thus changes in temperature; Trenberth’s energy balance diagram is only useful to gain a conceptual understanding of the relative role of the major energy flows in the global average climate system.

THE IDEAL GAS LAW

Again, the Ideal Gas Law equation (PV=nRT) cannot tell you what the temperature of a gas should be, only energy flows in and out can do that. The gas law just tells you how the P, n, and T are interrelated for a given volume (V) of air. Yes, Ned, on short time scales, ascending air cools and descending air warms, but if all of that motion was to stop, energy flow processes would then determine what the final temperature would be… not what the air pressure is. 

For a given surface air pressure, a huge range of temperatures is possible, and that huge range is all due to energy flow processes. Again, if the near-surface air temperature over the whole planet is much higher than local energy flow processes can support, the temperature falls, and the air’s volume shrinks (or density, rho, increases, according to the equivalent Ideal Gas Law equation, P = rho R T). The surface air pressure remains the same because the total mass of the atmosphere is unchanged.  

SO WHY MIGHT THERE BE A CLOSE RELATIONSHIP BETWEEN DIFFERENT PLANET’S LOWER ATMOSPHERIC TEMPERATURE AN PRESSURE?

I haven’t studied the atmospheres of other planets, because I don’t care. Even if those other planets did not exist, they are not necessary for understanding our own atmosphere. But if indeed Ned is correct about a close statistical relationship between different planets’ surface air pressure and temperature, after adjusting for solar input, then I suspect it’s because the more atmosphere there is, the more greenhouse gases there are.

 On the subject of GHGs, I’ve forgotten… does Ned believe that air absorbs and emits IR energy? Because the greenhouse effect is a necessary consequence of that absorption/emission. Energetically, the GHE is a radiative insulator. It’s analogous to adding insulation to a heated building’s walls in winter. For a given energy input into the building, the air temperature inside will rise, and the outside of the walls will experience a temperature fall. This is exactly what the GHE does to the atmospheric temperature profile. 

If Ned doesn’t believe air absorbs IR energy, how does he explain all of the thousands of spectroscopic measurements of CO2, water vapor, and methane as a function of temperature and pressure? And if he does believe the atmosphere absorbs and emits IR energy, then he must also believe in a greenhouse effect, because it is a necessary consequence…. the greenhouse effect in planetary atmospheres always causes warming of the lower atmosphere and cooling of the upper atmosphere.

(BTW, it is a common misconception that air that absorbs IR energy immediately loses that energy through emission of IR. Not true. Look up the kinetic theory of gases and related concepts. CO2 or H2O vapor molecules absorbing IR photons extremely rapidly lose their extra energy to other air molecules through collisions. This happens much faster [by a factor of ~50,000] than the time it takes to re-emit energy through IR photons. This is how IR absorption immediately leads to “thermalization” [a term I hate]. Furthermore, it is crucial to understand that since IR absorption is largely independent of temperature, but IR loss is VERY dependent upon temperature, almost all air in the atmosphere is in a continual state of IR energy imbalance. Much of that imbalance is what causes convective overturning.)

WHAT IS THE ROLE OF THE ADIABATIC LAPSE RATE?

The lapse rate in the troposphere (9.8 deg C per km without moisture condensation) is the RESULT OF convective overturning. If condensation of moisture is involved in updrafts, then the lapse rate is lower. Like the Ideal Gas Law, it doesn’t tell you what the temperature “should” be. It just tells you how the temperature of an air parcel changes during ascent or descent, if there is no energy gain or loss (a-diabatic).

HOW DOES THE GREENHOUSE EFFECT PLAY INTO THE LAPSE RATE?

This is a very interesting subject. It is something that even many atmospheric scientists and climate don’t understand. The combination of solar heating of the surface and IR absorption and emission by the surface and atmosphere ALONE, WITHOUT ANY CONVECTIVE OVERTURNING would result in an extremely steep tropospheric lapse rate, with very high surface temperatures and exceedingly cold upper tropospheric temperatures. This was first demonstrated by Manabe & Strickler (1964), and it’s called the “pure radiative equilibrium” case. It is sort of what makes the “greenhouse effect” technically correct… like a real greenhouse inhibiting convective heat loss, the greenhouse effect is, by definition, what happens WITHOUT the resulting convective overturning. 

But in the real world, convective overturning is the RESPONSE to this GHE destabilization! So, that 33 deg. warming people talk about? That’s not the GHE. It’s the GHE + CONVECTION.  Without convection, that 33 deg. C figure would be more like 65 or 75 deg. C. Which then leads to another fascinating question…

WHAT WOULD HAPPEN IF THE ATMOSPHERE DID NOT ABSORB AND EMIT IR ENERGY?

Imagine a cold atmosphere (even near absolute zero) with no energy input. Then, turn on the sun. Solar heating of the surface would warm the atmosphere through convective overturning. But the atmosphere would have no way to shed that energy to cool in the presence of all of that energy input. The temperature of the atmosphere would then continue to rise until it had the same temperature as the surface, through its entire depth. Long before that process finished convective overturning would have stopped, because the atmosphere would be too stable to support convection. The atmosphere would eventually become isothermal (or nearly so, since there might be some planetary scale overturning between the tropics and the poles, due to their different rates of solar input), with the same temperature as the surface. Interestingly, all weather activity would cease. All clouds would probably disappear, resulting in higher temperatures. Any circulation systems would have a planetary scale, because the horizontal scale of those systems is related to the lapse rate (through the “Rossby radius of deformation”), which is also why the stratosphere only has planetary scale circulations).

-Roy

On 4/26/2026 6:24 PM, Ned Nikolov wrote:

To All,

Since Roy Spencer specifically addressed me in his email below, I feel obliged to reply and clarify a few points that he misunderstood. 

Thought experiments are only useful as long as the underlying assumptions are correct. Roy employed a number of assumptions in his “thought experiment” that are not supported by physical reality. I’ll address them below:

1. The claim that the Ideal Gas Law (PV = n R T) does not tell us, what the temperature of a gas “should be”, is ill-posed. The Gas Law establishes a unique relationship between gas temperature T, gas pressure P, gas volume V and the amount of gas in moles. If P, V and n are known, then the absolute temperature of a gas T is uniquely defined. Roy missed to point out that the product PV = Joule (energy). Hence, the correct way to write the Gas Law from the standpoint of physical understanding is (PV)/n = RT. In other words, the absolute temperature of a gas is proportional to the average kinetic energy contained in a mole of gas. In this sense, the Gas Law tells us exactly, what the temperature of a gas should be.

2. With respect to the atmosphere, the average surface pressure is determined by the atmospheric mass above a unit area (Ma/A) and the gravitational acceleration (g) and it is independent of temperature, i.e. P = (Ma/A) g. The atmospheric volume, however, depends on the amount of absorbed solar radiation by the system and, therefore, on the surface temperature. It’s the energy provided by the Sun that expands the atmosphere against gravity and gives its volume. 

3. The Gas Law provides an important insight that Roy completely missed. The kinetic energy and temperature of a thermodynamic system cannot exist without pressure. This is because pressure is a force per unit surface area, and energy cannot exist without a force. Even electromagnetic radiation has pressure. Thus, the energy flux measured in W m^-2, when dimensionally decomposed and applied to electromagnetic radiation, becomes W m^-2 = Photon_pressure * Speed_of_Light.  So, pressure is a fundamental controlling factor of the energy content and temperature in any thermodynamic system… Did Roy learn this in school? 

4. Roy appears to have misunderstood our model relating pressure to temperature. As explained in our 2017 paper, pressure only has a relative effect on temperature, not an absolute one. Pressure as a force in a compressible fluid only provides a relative enhancement of the energy delivered by the Sun. So, a given atmospheric pressure can be associated with a wide range of absolute global surface temperatures. This is mathematically accounted for by our universal planetary temperature model.

5. There is no meaningful relationship between global temperature, distance to the Sun, and the amount of atmospheric greenhouse gases across planetary bodies in the Solar System. We showed this in our 2017 paper. So, Roy’s explanation for the relationship we discovered between P and Ts/Tna across planets and moons is incorrect. The real explanation is that atmospheric pressure determines the Relative Atmospheric Thermal Enhancement (RATE) through its adiabatic effect on surface temperatures.

4. Roy appears to completely misunderstand the cause of the adiabatic lapse rate in the troposphere. This lapse rate results from the temperature dependence on pressure and the pressure decrease with altitude, i.e. dT/dz = (dT/dP)*(dP/dz). As such, it has nothing to do with “convective overturning” as assumed by Roy. The derivative dT/dP can be obtained from the adiabatic form of the 1st Law of Thermodynamics and the Ideal Gas Law, while the derivative dP/dz is defined by the hydrostatic equilibrium requirement. This Wiki page provides the math details on computing the adiabatic lapse rate… In general, the tropospheric lapse rate is a consequence of a polytropic thermodynamic process operating in the vertical and defined as PVⁿ = constant. I explained this in a special podcast earlier this year, where I provided a slightly different derivation of the adiabatic lapse rate than the one presented in Wikipedia, but it’s based on the same principles. The dry adiabatic lapse rate (-9.8 K/km) is reduced to the environmental lapse rate of about -6 K/km by water vapor, which transports latent heat from lower altitudes and releases it at higher altitudes… Thus, convective overturning does not determine the lapse rate. Instead, lapse rate and gravity enable the convective overturning. There cannot be convection or a lapse rate without gravity! 

Not understanding the cause of the lapse rate in the troposphere reveals a fundamental lack of textbook knowledge about atmospheric thermodynamics!

5. The mathematical nature of the adiabatic lapse rate in the troposphere clearly shows that the drop of temperature with altitude is not caused by “greenhouse gases” (GHGs), because GHGs are not part of the lapse-rate formula, and that an atmosphere without GHGs will not be vertically isothermal as assumed by Roy, Happer and Lindzen. This is also textbook thermodynamics.

6. The above explanation of the lapse rate shows that, in a large system such as a planetary atmosphere, a static vertical pressure gradient (caused by gravity and the hydrostatic equilibrium requirement) creates a permanent temperature gradient. Therefore, Roy’s assumption that doubling the atmospheric mass will only cause a temporary increase of surface temperature followed by a quick dissipation of the compression heat through outgoing radiation, has no basis in reality. Hence, it’s a failed “thought experiment”. 

Current climate theory lacks the understanding that planetary surface temperatures are determined by both diabatic and adiabatic processes working simultaneously. The absorption of solar energy by planets and the emission of long-wave radiation to Space are examples of diabatic processes, while the Atmospheric Thermal Effect is due to an adiabatic process, which is a pressure-induced enhancement of the absorbed solar energy. Grasping this is pivotal!

7. The absorption and re-emission of outgoing LW radiation by certain gases in the atmosphere, while real, has no effect on the global temperature, because atmospheric LW radiation is a byproduct of atmospheric temperatures (set by solar heating and pressure), and as such, it’s not a source of extra heat to the system.  Also, CERES satellite data show that there is no trapping of heat by the so-called “greenhouse gases” in the atmosphere. That’s evident from the fact that changes in the TOA outgoing long-wave flux are totally in phase with changes in global surface temperature on annual basis.  

I hope this clarifies some important points for the group…

Cheers,
-Ned Nikolov

On 4/29/2026 10:41 AM, Ned Nikolov wrote:

Well, Roy Spencer has not responded to my comments thus far. I wonder why… 

I would only add that, what Roy Spencer described in his message below under section “HOW DOES THE GREENHOUSE EFFECT PLAY INTO THE LAPSE RATE?”, is physically completely wrong, because Manabe & Strickler (1964) and all other scientists after them looking at the atmosphere strictly through a “radiation lens” have missed the polytropic process in the troposphere defined as PVⁿ = constant or alternatively as P^(1-n) Tⁿ = constant, where
1 n . See this podcast for details:

Follow-up to Roy Spencer’s Remarks

In my reply to Roy Spencer and the CLINTEL group, I did not specifically address Spencer’s claim made in the last section of his message entitled “WHAT WOULD HAPPEN IF THE ATMOSPHERE DID NOT ABSORB AND EMIT IR ENERGY?”. In it, Spencer argues, as have many “climate experts” before him that, if an atmosphere could not emit long-wave radiation, it will become vertically isothermal. Aside from the fact that it is physically impossible for an open system not to emit infrared energy to Space, Spencer’s line of reasoning suffers from a profound misunderstanding of atmospheric thermodynamics.

Let’s assume for the sake of the theoretical argument that a planetary atmosphere has no ability to radiate IR energy to Space. What will happen in this case? Well, the energy absorbed from the Sun will keep accumulating inside the system, which will lead to a continuous rise of the global surface temperature without ever reaching an equilibrium. This in turn will cause a continuous expansion of the volume of the atmosphere (V), because a portion of the internal energy will be used for thermal expansion of the gas against gravity. That’s the work-flow energy in the Gas Law defined by the product PV = Joule. Hence, the atmospheric volume will keep expanding driven by rising surface temperatures. This will preserve the lapse rate (i.e. the drop of temperature with height), because air pressure will still be decreasing with altitude in this ever-expanding atmosphere just as it does in our present “steady-state” troposphere. As a result, the vertical convective overturning will keep intensifying due to rising surface temperatures and an expanding atmospheric volume. Therefore, in a gas system impacted by gravity such as the atmosphere, where the system volume is not constrained, it would be thermodynamically impossible to achieve isothermal conditions in the vertical. A non-radiating atmosphere can only become vertically isothermal, if its volume is fixed, i.e. if the gas expansion is obstructed by a rigid barrier! However, the atmosphere is not an isochoric (fixed-volume) system!

In addition to the above theoretical explanation, one could also argue that it is thermodynamically impossible to have a non-radiating atmosphere, because any material object with a temperature above absolute zero must (and does) emit radiation. Even nitrogen and oxygen have non-zero IR emissivities under high pressures. More importantly, however, in the absence of the so-called “greenhouse gases” such as CO₂, CH₄ and water vapor, a real atmosphere would continue to emit unobstructed IR radiation to Space due to the presence of dust particles. A dry planet devoid of water or other solvent on the surface such as Mars will harbor winds that transport huge quantities of dust into the atmosphere. Dust particles have higher IR emissivity/absorptivity than most gases typically ranging between 0.70 and 0.95, and can serve as an effective cooling agent. Thus, a natural, open system will always find a way to cool, and could never trap heat, since this would violate the 2^nd Law of Thermodynamics!

In conclusion, the “thought experiments” proposed by Roy Spencer in an effort to refute the N-Z climate concept are misleading, since they rely on misconceptions about atmospheric thermodynamics.

Source: https://tallbloke.wordpress.com/2026/05/23/discussion-between-roy-spencer-and-ned-nikolov-about-the-n-z-climate-concept/