Guest Post by Willis Eschenbach
Well, for my sins I’ve been working on a paper with the hope of getting it published in a journal. Now that it’s nearly done, I realized that I have the worlds’ best peer-reviewers available on WUWT. So before seeing if I can get this published, I thought I’d take advantage of you good folks for some “peer preview”, to point out to me any problems you might see with the title, format, style, data, conclusions, or any other part of the following paper. All of the graphics are in grayscale because that’s what the journals want.
Many thanks for any and all contributions.
w.
The Emergent Thermostat
Abstract
The current paradigm of climate science is that the long-term change in global temperature is given by a constant called “climate sensitivity” times the change in downwelling radiation, called “radiative forcing”. However, despite over forty years of investigation, the uncertainty of the value of climate sensitivity has only increased.1 This lack of any progress in determining the most central value in the current paradigm strongly suggests that the paradigm itself is incorrect, that it is not an accurate description of reality. Here I propose a different climate paradigm, which is that a variety of emergent climate phenomena act in concert to keep the surface temperature within tight limits. This explains the unusual thermal stability of the climate system.
Overview
Several authors have analyzed the climate system as a heat engine. Here is Reis and Bejan’s description
The earth with its solar heat input, heat rejection, and wheels of atmo- spheric and oceanic circulation, is a heat engine without shaft: its maximized (but not ideal) mechanical power output cannot be delivered to an extraterrestrial system. Instead, the earth engine is destined to dissipate through air and water friction and other irreversibilities (e.g., heat leaks across finite ∆T) all the mechanical power that it produces. It does so by ‘‘spinning in its brake’’ the fastest that it can (hence the winds and the ocean currents, which proceed along easiest routes).2
When viewed as a heat engine, one of the most unusual and generally unremarked aspects is its astounding stability. Over the 20th Century, the global average surface temperature varied by less than one kelvin. This is a variation of ± 0.2%. Given that the system rejects a variable amount of incoming energy, with the variations mostly controlled by nothing more solid than clouds, this is a most surprising degree of stability.
This in turn strongly argues for some global thermoregulatory mechanism. The stability cannot be from simple thermal inertia, because the hemispheric land temperatures vary by ~ 20K over the year, and hemispheric sea temperatures vary by ~ 5K.
Emergence
There is no generally accepted definition of emergence. In 1874 Lewes proposed the following definition: “Emergence: Theory according to which the combination of entities of a given level gives rise to a higher level entity whose properties are entirely new”.3
For the purposes of this article, I will define emergent climate phenomena functionally and by example.
Emergent climate phenomena arise spontaneously, often upon passing some thermal or other threshold. Consider the daily development of the tropical cumulus cloud field. Upon passing a temperature threshold, out of a clear sky hundreds of individual cumulus clouds can appear in a short time.
They have a time of emergence and a limited lifespan. Dust devils form spontaneously at a certain moment, persist for a while, and then dissipate and disappear.
They form a separate whole, distinct from the surroundings. Tropical thunderstorms are surrounded by clear air.
They are often mobile and move in unpredictable ways. As a result, tropical cyclones have “prediction cones” for where they might possibly go next, rather than being accurately predictable.
They are often associated with phase changes in the relevant fluids. Convective cloud emergence involves a phase change of water.
Once in existence, they can persist below the threshold necessary for their emergence. Rayleigh-Benard circulation requires a certain temperature difference to emerge, but once in existence, the circulation can persist at a smaller temperature difference.
They are flow systems far from equilibrium. As such, in accordance with the Constructal Law4, they must evolve and mutate to survive.
They are not naively predictable, as they have entirely different properties than the substrate from which they emerge. If you lived somewhere that there were never clouds, you likely would not predict that a giant white object might suddenly appear hundreds of meters above your head.
Examples of natural emergent phenomena with which we are familiar include the behavior of flocks of birds, vortices of all kinds, termite mounds, consciousness, and indeed, life itself. Familiar emergent climate phenomena include thunderstorms, tornadoes, Rayleigh-Bénard circulation of the atmosphere and ocean, clouds, cyclones, El Ninos, and dust devils.
A Simple Example
To explain how emergent phenomena thermoregulate the earth’s surface temperature, consider the lowly “dust devil”. As the sun heats a field in the summer, the change in temperature is some fairly linear function of the “forcing”, the downwelling solar radiation. This is in accord with the current paradigm. But when the hottest part of the field reaches a certain temperature with respect to the overlying atmospheric temperature, out of the clear sky a dust devil emerges. This cools the surface in several ways. First, it moves warm surface air upwards into the lower troposphere. Second, it increases sensible heat transfer, which is a roughly linear function of the air velocity over the surface. Third, it increases evaporation, which again is a roughly linear function of the surface air velocity.
At this point, the current paradigm that the change in temperature is a linear function of the change in forcing has broken down entirely. As the sunshine further irradiates the surface, instead of getting more temperature we get more dust devils. This puts a cap on the surface temperature. Note that this cap is not a function of forcing. The threshold is temperature-based, not forcing-based. As a result, it will not be affected by things like changing amounts of sunshine or variations in greenhouse gases.
A Complete Example
The heavy lifting of the thermoregulatory system, however, is not done by dust devils. It is achieved through variations in the timing and strength of the daily emergence of tropical cumulus fields and the ensuing tropical thunderstorms, particularly over the ocean. This involves the interaction of several different emergent phenomena
Here is the evolution of the day and night in the tropical ocean. The tropical ocean is where the majority of the sun’s energy enters the huge heat engine we call the climate. As a result, it is also where the major thermostatic mechanisms are located.
Figure 1. Daily emergent phenomena of the tropical ocean.
As seen in Panel “Early Morning”, at dawn, the atmosphere is stratified, with the coolest air nearest the surface. The nocturnal emergent Rayleigh-Bénard overturning of the ocean is coming to an end. The sun is free to heat the ocean. The air near the surface eddies randomly.
As the sun continues to heat the ocean, around ten or eleven o’clock in the morning a new circulation pattern emerges to replace the random atmospheric eddying. As soon as a critical temperature threshold is passed, local Rayleigh-Bénard-type circulation cells emerge everywhere. This is the first emergent transition, from random circulation to Rayleigh-Bénard circulation. These cells transport both heat and water vapor upwards.
By late morning, the Rayleigh-Bénard circulation is typically strong enough to raise the water vapor to the local lifting condensation level (LCL). At that altitude, the water vapor condenses into clouds as shown in Panel “Late Morning”.
This area-wide shift to an organized circulation pattern is not a change in feedback, nor is it related to forcing. It is a self-organized emergent phenomenon. It is threshold-based, meaning that it emerges spontaneously when a certain threshold is passed. In the wet tropics there’s plenty of water vapor, so the major variable in the threshold is the temperature. In addition, note that there are actually two distinct emergent phenomena in Panel 2—the Rayleigh-Bénard circulation which emerges prior to the cumulus formation, and which is enhanced and strengthened by the totally separate emergence of the clouds. We now have two changes of state involved as well, with evaporation from the surface and condensation and re-evaporation at altitude.
Under this new late-morning cumulus circulation regime, much less surface warming goes on. Part of the sunlight is reflected back to space, so less energy makes it into the system to begin with. Then the increasing surface wind due to the cumulus-based circulation pattern increases the evaporation, reducing the surface warming even more by moving latent heat up to the lifting condensation level.
The crucial issues here are the timing and strength of the emergence. If the ocean is a bit warmer, the new circulation regime starts earlier in the morning and it cuts down the total daily warming. On the other hand, if the ocean is cooler than usual, clear morning skies last later into the day, allowing increased warming. The system temperature is thus regulated both from overheating and excessive cooling by the time of onset of the regime change.
Consider the idea of “climate sensitivity” in this system, which is the sensitivity of surface temperature to forcing. The solar forcing is constantly increasing as the sun rises higher in the sky. In the morning before the onset of cumulus circulation, the sun comes through the clear atmosphere and rapidly warms the surface. So the thermal response is large, and the climate sensitivity is high.
After the onset of the cumulus regime, however, much of the sunlight is reflected back to space. Less sunlight remains to warm the ocean. In addition to reduced sunlight, there is increased evaporative cooling. Compared to the morning, the climate sensitivity is much lower.
So here we have two situations with very different climate sensitivities. In the early morning, climate sensitivity is high, and the temperature rises quickly with the increasing solar insolation. In the late morning, a regime change occurs to a situation with much lower climate sensitivity. Adding extra solar energy doesn’t raise the temperature anywhere near as fast as it did earlier.
At some point in the afternoon, there is a good chance that the cumulus circulation pattern is not enough to stop the continued surface temperature increase. If the temperature exceeds a certain higher threshold, as shown in Panel “Late Afternoon”, another complete regime shift takes place. The regime shift involves the spontaneous emergence of independently mobile heat engines called thunderstorms.
Thunderstorms are dual-fuel heat engines. They run on low-density air. That air rises and condenses out the moisture. The condensation releases heat that re-warms the air, which rises deep into the troposphere.
There are two ways the thunderstorms get low-density air. One is to heat the air. This is how a thunderstorm gets started, as a solar-driven phenomenon emerging from strong cumulus clouds. The sun plus GHG radiation combine to heat the surface, which then warms the air. The low-density air rises. When that circulation gets strong enough, thunderstorms start to form. Once the thunderstorm is started, the second fuel is added — water vapor. The more water vapor there is in the air, the lighter it becomes. The thunderstorm generates strong winds around its base. Evaporation is proportional to wind speed, so this greatly increases the local evaporation. This makes the air lighter and makes the air rise faster, which makes the thunderstorm stronger, which in turn increases the wind speed around the thunderstorm base. A thunderstorm is a regenerative system, much like a fire where part of the energy is used to power a bellows to make the fire burn even hotter. Once it is started, it is much harder to stop. This gives thunderstorms a unique ability that is not represented in any of the climate models. A thunderstorm is capable of driving the surface temperature well below the initiation temperature that was needed to get the thunderstorm started. It can run on into the evening, and often well into the night, on its combination of thermal and evaporation energy sources.
Thunderstorms function as heat pipes that transport warm air rapidly from the surface to the lifting condensation level where the moisture turns into clouds and rain, and from there to the upper atmosphere without interacting with the intervening greenhouse gases. The air and the energy it contains are moved to the upper troposphere hidden inside the cloud-shrouded thunderstorm tower, without being absorbed or hindered by GHGs on the way. Thunderstorms also cool the surface in a host of other ways, utilizing a combination of a standard refrigeration cycle with water as the working fluid, plus cold water returned from above, clear surrounding air allowing greater upwelling surface radiation, wind-driven evaporation, spray increasing evaporation area, albedo changes, and cold downwelling entrained air.
As with the onset of the cumulus circulation, the onset of thunderstorms occurs earlier on days when it is warmer, and it occurs later (and sometimes not at all) on days that are cooler than usual. Again, there is no way to assign an average climate sensitivity. The warmer it gets, the less each additional watt per meter warms the surface.
Once the sun sets, first the cumulus and then the thunderstorms decay and dissipate. In Panel 4, a final and again different regime emerges. The main feature of this regime is that during this time, the ocean radiates the general amount of energy that was absorbed during all of the other parts of the day.
During the nighttime, the surface is still receiving energy from the greenhouse gases. This has the effect of delaying the onset of oceanic overturning, and of reducing the rate of cooling. Note that the oceanic overturning is once again the emergent Rayleigh-Bénard circulation. Because there are fewer clouds, the ocean can radiate to space more freely. In addition, the overturning of the ocean constantly brings new water to the surface to radiate and cool. This increases the heat transfer across the interface. As with the previous thresholds, the timing of this final transition is temperature-dependent. Once a critical threshold is passed, oceanic overturning emerges. Stratification is replaced by circulation, bringing new water to radiate, cool, and sink. In this way, heat is removed, not just from the surface as during the day, but from the entire body of the upper layer of the ocean.
Predictions
A theory is only as good as its predictions. From the above theoretical considerations we can predict the following:
Prediction 1. In warm areas of the ocean, clouds will act to cool the surface, and in cold areas they will act to warm the surface. This will be most pronounced above a temperature threshold at the warmest temperatures.
Evidence validating the first prediction.
Figure 2. Scatterplot, sea surface temperature (SST) versus surface cloud radiative effect. The more negative the data the greater the cooling.
As predicted, the clouds warm the surface when it is cold and cool it when it is warm, with the effect very pronounced above about 26°C – 27°C.
Prediction 2. In the tropical ocean, again above a certain temperature threshold, thunderstorms will increase very rapidly with increasing temperature.
Evidence validating the second prediction.
Since there is always plenty of water over the tropical ocean, and plenty of sunshine to drive them, thermally driven tropical thunderstorms will be a function of little more than temperature.
Figure 3. Cloud top altitude as a proxy for deep convective thunderstorms versus sea surface temperature.
As with clouds in general, there is a clear temperature threshold at about 26°C – 27°C, with a nearly vertical increase in thunderstorms above that threshold. This puts a very strong cap on increasing temperatures.
Prediction 3. Transient decreases in solar forcing such as those from eruptions will be counteracted by increased sunshine from tropical cumulus forming later in the day and less frequently. This means that after an initial decrease, incoming solar will go above the pre-eruption baseline until the status quo ante is re-established.
Evidence validating the third prediction.
Regarding the third prediction, my theory solves the following Pinatubo puzzle from Soden et al.5
“Beginning in 1994, additional anomalies in the satellite-observations of top-of-atmosphere absorbed solar radiation become evident, which are unrelated to the Mount Pinatubo eruption and therefore not reproduced in the model simulations. These anomalies are believed to stem from decadal-scale changes in the tropical circulation over the mid to late 1990’s [see J. Chenet al., Science 295, 838 (2002); and B.A. Wielicki et al., Science 295, 841 (2002], but their veracity remains the subject of debate. If real, their absence in the model simulations implies that discrepancies between the observed and model-simulated temperature anomalies, delayed 1 to 2 years by the climate system’s thermal inertia, may occur by the mid-1990s.”
Figure 4. Soden Figure 1, with original caption
However, this is a predictable result of the emergent thermostat theory. Here is the change in lower atmospheric temperature along with the ERBS data from Soden:
Figure 5. ERBE absorbed solar energy (top panel in Figure 4) and UAH lower tropospheric temperature (TLT). Both datasets include a lowess smoothing.
As predicted by the theory, the absorbed solar energy goes above the baseline until the lower troposphere temperature returns to its pre-eruption value. At that point, the increased intake of solar energy ceases and the system is back in its steady-state condition.
Prediction 4. The “climate sensitivity”, far from being a constant, will be found to be a function of temperature.
Evidence validating the fourth prediction.
Figure 6 below shows the 1° latitude by 1° longitude gridcell by gridcell relationship between net downwelling radiation at the surface and the surface temperature.
Figure 6. Scatterplot, CERES net downwelling surface radiation (net shortwave plus longwave) versus Berkeley Earth global surface temperature. The slope of the lowess smooth at any point is the “climate sensitivity” at that temperature, in °C per watt per square metre (W/M2)
The tight correlation between the surface temperature and the downwelling radiation confirms that this is a valid long-term relationship. This is especially true given that the two variables considered are from entirely different and unrelated datasets.
Note that the “climate sensitivity” is indeed a function of temperature, and that the climate sensitivity goes negative at the highest temperatures. It is also worth noting that almost nowhere on the planet does the long-term average temperature go above 30°C. This is further evidence of the existence of strong thermoregulatory mechanisms putting an effective cap on how hot the surface gets on average.
Prediction 5. In some areas, rather than the temperature being controlled by the downwelling surface radiation, the surface radiation will be found to be controlled by the temperature.
Evidence validating the fifth prediction.
Figure 7 below shows the correlation between net downwelling surface radiation (net shortwave plus longwave) and surface temperature. As expected, over most of the land masses the correlation is positive—as the downwelling radiation increases, so does the surface temperature.
Figure 7. Correlation between monthly surface temperatures and monthly surface downwelling radiation. Seasonal variations have been removed from both datasets.
However, over large areas of the tropical ocean, the temperature and downwelling surface radiation are negatively correlated. Since decreasing downwelling radiation cannot increase the surface temperature, the only possible conclusion is that in these areas, the increasing temperature modifies the number and nature of the overlying clouds in such a way to decrease the downwelling radiation.
CONCLUSIONS
1) The current climate paradigm, which is that in the long run, changes in global surface temperature are a simple linear function of changes in forcing (downwelling radiation), is incorrect. This is indicated by the inability of researchers to narrow the uncertainty of the central value of the paradigm, “climate sensitivity”, despite forty years of investigations, millions of dollars, billions of computer cycles, and millions of work-hours being throw at the problem. It is also demonstrated by the graphs above which show that far from being a constant, the “climate sensitivity” is a function of temperature.
2) A most curious aspect of the climate system is its astounding stability. Despite being supported at tens of degrees warmer than the moon by nothing more stable than evanescent clouds, despite volcanic eruptions, despite changes in CO2 and other GHG forcings, despite great variations in aerosols and black carbon, over the 20th Century the temperature varied by only ±0.2%.
3) This amazing stability implies and indeed requires the existence of a very strong thermoregulation system.
4) My theory is that the thermoregulation is provided by a host of interacting emergent phenomena. These include Rayleigh-Benard circulation of the ocean and the atmosphere; dust devils; tropical thermally-driven cumulus cloud fields; thunderstorms; squall lines; cyclones; tornadoes; the La Nina pump moving tropical warm water to the poles and exposing cool underlying water; and the great changes in ocean circulation involved with the Pacific Decadal Oscillation, the North Atlantic Oscillation, and other oceanic cycles.
5) This implies that temperatures are unlikely to vary greatly from their current state because of variations in CO2, volcanoes, or other changing forcings. The thresholds for the various phenomena are temperature-based, not forcing-based. So variations in forcing will not affect them much. However, it also opens up a new question—what causes slow thermal drift in thermoregulated systems?
REFERENCES
1 Knutti, R., Rugenstein, M. & Hegerl, G. Beyond equilibrium climate sensitivity. Nature Geosci 10, 727–736 (2017). https://doi.org/10.1038/ngeo3017
2 Lewes, G. H. (1874) in Emergence, Dictionnaire de la langue philosophique, Foulquié.
3 Reis, A. H., Bejan, A, Constructal theory of global circulation and climate, International Journal of Heat and Mass Transfer, Volume 49, Issues 11–12, 2006, Pages 1857-1875, https://doi.org/10.1016
4 Bejan, A, Reis, A. Heitor, Thermodynamic optimization of global circulation and climate, International Journal of Energy Research, Vol. 29, Is. 4, https://doi.org/10.1002/er.1058
5 Brian J. Soden et al., Global Cooling After the Eruption of Mount Pinatubo: A Test of Climate Feedback by Water Vapor,Science 26 Apr 2002, Vol. 296, Issue 5568, pp. 727-730, DOI: 10.1126/science.296.5568.727
Anyhow, that’s what I have to date. There are few references, because AFAIK nobody else is considering the idea that emergent phenomena act as a global thermostat. Anyone who knows of other references that might be relevant, please mention them.
Finally, any suggestions as to which journal might be willing to publish such a heretical view of climate science would be much appreciated.
My best to all, the beat goes on,
w.
As Always: I can defend my own words, but I can’t defend your interpretation of them. So if you comment, please quote the exact words you are discussing so we can all understand what you are referring to.
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