Guest Essay by Willis Eschenbach
Abstract
The Thermostat Hypothesis is that tropical clouds and thunderstorms, along with other emergent phenomena like dust devils, tornadoes, and the El Nino/La Nina alteration, actively regulate the temperature of the earth. This keeps the earth at an equilibrium temperature.
Several kinds of evidence are presented to establish and elucidate the Thermostat Hypothesis – historical temperature stability of the Earth, theoretical considerations, satellite photos, and a description of the equilibrium mechanism.
Historical Stability
The stability of the earth’s temperature over time has been a long-standing climatological puzzle. The globe has maintained a temperature of ± ~ 3% (including ice ages) for at least the last half a billion years during which we can estimate the temperature. During the Holocene, temperatures have not varied by ±1%. And during the glaciation periods, the temperature was generally similarly stable as well.
In contrast to Earth’s temperature stability, solar physics has long indicated (Gough, 1981; Bahcall et al., 2001) that 4 billion years ago the total solar irradiance was about three-quarters of the current value. In early geological times, however, the earth was not correspondingly cooler. Temperature proxies such as deuterium/hydrogen ratios and 16O/18O ratios show no sign of a corresponding warming of the earth over this time. Why didn’t the earth warm as the sun warmed?
This is called the “Faint Early Sun Paradox” (Sagan and Mullen, 1972), and is usually explained by positing an early atmosphere much richer in greenhouse gases than the current atmosphere.
However, this would imply a gradual decrease in GHG forcing which exactly matched the incremental billion-year increase in solar forcing to the present value. This seems highly unlikely.
A much more likely candidate is some natural mechanism that has regulated the earth’s temperature over geological time.
Theoretical Considerations
Bejan (Bejan 2005) has shown that the climate can be robustly modeled as a heat engine, with the ocean and the atmosphere being the working fluids. The tropics are the hot end of the heat engine. Some of that tropical heat is radiated back into space. Work is performed by the working fluids in the course of transporting the rest of that tropical heat to the Poles. There, at the cold end of the heat engine, the heat is radiated into space. Bejan showed that the existence and areal coverage of the Hadley cells is a derivable result of the Constructal Law. He also showed how the temperatures of the flow system are determined.
“We pursue this from the constructal point of view, which is that the [global] circulation itself represents a flow geometry that is the result of the maximization of global performance subject to global constraints.”
“The most power that the composite system could produce is associated with the reversible operation of the power plant. The power output in this limit is proportional to
where q is the total energy flow through the system (tropics to poles), and TH and TL are the high and low temperatures (tropical and polar temperatures in Kelvins).
The system works ceaselessly to maximize that power output. Here is a view of the entire system that transports heat from the tropics to the poles.
Figure 1. The Earth as a Heat Engine. The equatorial Hadley Cells provide the power for the system. Over the tropics, the sun (orange arrows) is strongest because it hits the earth most squarely. The length of the orange arrows shows relative sun strength. Warm dry air descends at about 30N and 30S, forming the great desert belts that circle the globe. Heat is transported by a combination of the ocean and the atmosphere to the poles. At the poles, the heat is radiated to space.
In other words, flow systems such as the Earth’s climate do not assume a stable temperature willy-nilly. They reshape their own flow in such a way as to maximize the energy produced and consumed. It is this dynamic process, and not a simple linear transformation of the details of the atmospheric gas composition, which sets the overall working temperature range of the planet.
Note that the Constructal Law says that any flow system will “quasi-stabilize” in orbit around (but never achieve) some ideal state. In the case of the climate, this is the state of maximum total power production and consumption. And this in turn implies that any watery planet will oscillate around some equilibrium temperature, which is actively maintained by the flow system. See the paper by Ou listed below for further information on the process.
Climate Governing Mechanism
Every heat engine has a throttle. The throttle is the part of the engine that controls how much energy enters the heat engine. A motorcycle has a hand throttle. In an automobile, the throttle is called the gas pedal. It controls incoming energy.
The stability of the earth’s temperature over time (including alternating bi-stable glacial/interglacial periods), as well as theoretical considerations, indicates that this heat engine we call climate must have some kind of governor controlling the throttle.
While all heat engines have a throttle, not all of them have a governor. In a car, a governor is called “Cruise Control”. Cruise control is a governor that controls the throttle (gas pedal). A governor adjusts the energy going to the car engine to maintain a constant speed regardless of changes in internal and external forcing (e.g. hills, winds, engine efficiency, and losses).
We can narrow the candidates for this climate governing mechanism by noting first that a governor controls the throttle (which in turn controls the energy supplied to a heat engine). Second, we note that a successful governor must be able to drive the system beyond the desired result (overshoot).
(Note that a governor, which contains a hysteresis loop capable of producing overshoot, is different from a simple negative feedback of the type generally described by the IPCC. A simple negative feedback can only reduce an increase. It cannot maintain a steady state despite differing forcings, variable loads, and changing losses. Only a governor can do that.)
The majority of the earth’s absorption of heat from the sun takes place in the tropics. The tropics, like the rest of the world, are mostly ocean; and the land that is there is wet. The steamy tropics, in a word. There is little ice there, so the clouds control how much energy enters the climate heat engine.
I propose that two interrelated but separate mechanisms act directly to regulate the earth’s temperature — tropical cumulus and cumulonimbus clouds. Cumulus clouds are the thermally-driven fluffy “cotton ball” clouds that abound near the surface on warm afternoons. Cumulonimbus clouds are thunderstorm clouds, which start life as simple cumulus clouds. Both types of clouds are part of the throttle control, reducing incoming energy. In addition, the cumulonimbus clouds are active refrigeration-cycle heat engines, which provide the necessary overshoot to act as a governor on the system.
A pleasant thought experiment shows how this cloud governor works. It’s called “A Day In the Tropics”.
I live in the deep, moist tropics, at 9°S, with a view of the South Pacific Ocean from my windows. Here’s what a typical day looks like. In fact, it’s a typical summer day everywhere in the Tropics. The weather report goes like this:
Clear and calm at dawn. Light morning winds, clouding up towards noon. In the afternoon, increasing clouds and wind with showers and thundershowers developing as the temperature rises. Thunderstorms continuing after dark, and clearing some time between sunset and early hours of the morning, with progressive clearing and calming until dawn.
That’s the most common daily cycle of tropical weather, common enough to be a cliché around the world.
It is driven by the day/night variations in the strength of the sun’s energy. Before dawn, the atmosphere is typically calm and clear. As the ocean (or moist land) heats up, air temperature and evaporation increase. Warm moist air starts to rise. Soon the rising moist air cools and condenses into clouds. The clouds reflect the sunlight. That’s the first step of climate regulation. Increased temperature leads to clouds. The clouds close the throttle slightly, reducing the energy entering the system. They start cooling things down. This is the negative feedback part of the cloud climate control.
The tropical sun is strong, and despite the negative feedback from the cumulus clouds, the day continues to heat up. The more the sun hits the ocean, the more warm, moist air is formed, and the more cumulus clouds form. This, of course, reflects more sun, and the throttle closes a bit more. But the day continues to warm.
The full development of the cumulus clouds sets the stage for the second part of temperature regulation. This is not simply negative feedback. It is the climate governing system. As the temperature continues to rise, as the evaporation climbs, some of the fluffy cumulus clouds suddenly transform themselves. They rapidly extend skywards, quickly thrusting up to form cloud pillars thousands of meters high. In this way, cumulus clouds are transformed into cumulonimbus or thunderstorm clouds.
The columnar body of the thunderstorm acts as a huge vertical heat pipe. The thunderstorm sucks up warm, moist air at the surface and shoots it skyward. At altitude the water condenses, transforming the latent heat into sensible heat. The air is rewarmed by this release of sensible heat and continues to rise within the thunderstorm tower.
At the top, the rising much dryer air is released from the cloud up high, way above most of the CO2, water vapor, and other greenhouse gases. In that rarified atmosphere, the air is much freer to radiate to space. By moving inside the thunderstorm heat pipe, the rising air bypasses any interaction with most greenhouse gases and comes out near the top of the troposphere. During the transport aloft, there is no radiative or turbulent interaction between the rising air inside the tower and the surrounding lower and middle troposphere. Inside the thunderstorm, the rising air is tunneled through most of the troposphere to emerge at the top.
In addition to reflecting sunlight from their top surface as cumulus clouds do, and transporting heat to the upper troposphere where it radiates easily to space, thunderstorms cool the surface in a variety of other ways, particularly over the ocean.
1. Wind driven evaporative cooling. Once the thunderstorm starts, it creates its own wind around the base. This self-generated wind increases evaporation in several ways, particularly over the ocean.
a) Evaporation rises linearly with wind speed. At a typical squall wind speed of 10 meters per second (“m/s”, about 20 knots or 17 miles per hour), evaporation is about ten times greater than at “calm” conditions (conventionally taken as 1 m/s).
b) The wind increases evaporation by creating spray and foam, and by blowing water off of trees and leaves. These greatly increase the evaporative surface area, because the total surface area of the millions of droplets is evaporating as well as the actual surface itself.
c) To a lesser extent, the surface area is also increased by wind-created waves (a wavy surface has a larger evaporative area than a flat surface).
d) Wind-created waves in turn greatly increase turbulence in the atmospheric boundary layer. This increases evaporation by mixing dry air down to the surface and moist air upwards.
e) As spray rapidly warms to air temperature, which in the tropics can be warmer than ocean temperature, evaporation also rises above the sea surface evaporation rate.
2. Wind and wave driven albedo increase. The white spray, foam, spindrift, changing angles of incidence, and white breaking wave tops greatly increase the albedo of the sea surface. This reduces the energy absorbed by the ocean.
3. Cold rain and cold wind. As the moist air rises inside the thunderstorm’s heat pipe, water condenses and falls. Since the water is originating from condensing or freezing temperatures aloft, it cools the lower atmosphere it falls through, and it cools the surface when it hits. Also, the droplets are being cooled as they fall by evaporation.
In addition, the falling rain entrains a cold wind. This cold wind blows radially outwards from the center of the falling rain, cooling the surrounding area. This is quite visible in the video below.
4. Increased reflective area. White fluffy cumulus clouds are not very tall, so basically they only reflect from the tops. On the other hand, the vertical pipe of the thunderstorm reflects sunlight along its entire length. This means that thunderstorms reflect sunlight from an area of the ocean out of proportion to their footprint, particularly in the late afternoon.
5. Modification of upper tropospheric ice crystal cloud amounts (Lindzen 2001, Spencer 2007). These clouds form from the tiny ice particles that come out of the smokestack of the thunderstorm heat engines. It appears that the regulation of these clouds has a large effect, as they are thought to warm (through IR absorption) more than they cool (through reflection).
6. Enhanced night-time radiation. Unlike long-lived stratus clouds, cumulus and cumulonimbus often die out and vanish in the early morning hours, leading to the typically clear skies at dawn. This allows greatly increased nighttime surface radiative cooling to space.
7. Delivery of dry air to the surface. The air being sucked from the surface and lifted to altitude is counterbalanced by a descending flow of replacement air emitted from the top of the thunderstorm. This descending air has had the majority of the water vapor stripped out of it inside the thunderstorm, so it is relatively dry. The dryer the air, the more moisture it can pick up for the next trip to the sky. This increases the evaporative cooling of the surface.
8. Increased radiation through descending dry air. The descending dry air mentioned above is far more transparent to surface radiation than normal moist tropical air. This increases overall radiation to space.
In part because they utilize such a wide range of cooling mechanisms, cumulus clouds and thunderstorms are extremely good at cooling the surface of the earth. Together, they form the governing mechanism for the tropical temperature.
But where is that mechanism?
The problem with my thought experiment of describing a typical tropical day is that it is always changing. The temperature goes up and down, the clouds rise and fall, day changes to night, the seasons come and go. Where in all of that unending change is the governing mechanism? If everything is always changing, what keeps it the same month to month and year to year? If conditions are always different, what keeps it from going off the rails?
In order to see the governor at work, we need a different point of view. We need a point of view without time. We need a timeless view without seasons, a point of view with no days and nights. And curiously, in this thought experiment called “A Day In the Tropics”, there is such a timeless point of view, where not only is there no day and night, but where it’s always summer.
The point of view without day or night, the point of view from which we can see the climate governor at work, is the point of view of the sun. Imagine that you are looking at the earth from the sun. From the sun’s point of view, there is no day and night. All parts of the visible face of the earth are always in sunlight—the sun never sees the nighttime. And it’s always summer under the sun.
If we accept the convenience that the north is up, then as we face the earth from the sun, the visible surface of the earth is moving from left to right as the planet rotates. So the left-hand edge of the visible face is always at sunrise, and the right-hand edge is always at sunset. Noon is a vertical line down the middle. From this timeless point of view, morning is always and forever on the left, and afternoon is always on the right. In short, by shifting our point of view, we have traded time coordinates for space coordinates. This shift makes it easy to see how the governor works.
The tropics stretch from left to right across the circular visible face. We see that near the left end of the tropics, after sunrise, there are very few clouds. Clouds increase as you look further to the right. Around the noon line, there are already cumulus. And as we look from left to right across the right side of the visible face of the earth, towards the afternoon, more and more cumulus clouds and increasing numbers of thunderstorms cover a large amount of the tropics.
It is as though there is a graduated mirror shade over the tropics, with the fewest cloud mirrors on the left, slowly increasing to extensive cloud mirrors and thunderstorm coverage on the right.
After coming up with this hypothesis that as seen from the sun, the right-hand side of the deep tropical Pacific Ocean would have more clouds than the left-hand side), I thought “Hey, that’s a testable proposition to support or demolish my hypothesis”. So in order to investigate whether this postulated increase in clouds on the right-hand side of the Pacific actually existed, I took an average of 24 pictures of the Pacific Ocean taken at local noon on the 1st and 15th of each month over an entire year. I then calculated the average change in albedo and thus the average change in forcing at each time. Here is the result:
Figure 2. Average of one year of GOES-West weather satellite images taken at satellite local noon. The Intertropical Convergence Zone is the bright band in the yellow rectangle. Local time on earth is shown by black lines on the image. Time values are shown at the bottom of the attached graph. The red line on the graph is the solar forcing anomaly (in watts per square meter) in the area outlined in yellow. The black line is the albedo value in the area outlined in yellow.
The graph below the image of the earth shows the albedo and solar forcing in the yellow rectangle which contains the Inter-Tropical Convergence Zone. Note the sharp increase in the albedo between 10:00 and 11:30. You are looking at the mechanism that keeps the earth from overheating. It causes a change in insolation of -60 W/m2 between ten and noon.
Now, consider what happens if for some reason the surface of the tropics is a bit cool. The sun takes longer to heat up the surface. Evaporation doesn’t rise until later in the day. Clouds are slow to appear. The first thunderstorms form later, fewer thunderstorms form, and if it’s not warm enough those giant surface-cooling heat engines don’t form at all.
And from the point of view of the sun, the entire mirrored shade shifts to the right, letting more sunshine through for longer. The 60 W/m2 reduction in solar forcing doesn’t take place until later in the day, increasing the local insolation.
When the tropical surface gets a bit warmer than usual, the mirrored shade gets pulled to the left, and clouds form earlier. Hot afternoons drive thunderstorm formation, which cools and air conditions the surface. In this fashion, a self-adjusting cooling shade of thunderstorms and clouds keeps the afternoon temperature within a narrow range.
Now, some scientists have claimed that clouds have a positive feedback. Because of this, the areas where there are more clouds will end up warmer than areas with fewer clouds. This positive feedback is seen as the reason that clouds and warmth are correlated.
I and others take the opposite view of that correlation. I hold that the clouds are caused by the warmth, not that the warmth is caused by the clouds.
Fortunately, we have way to determine whether changes in the reflective tropical umbrella of clouds and thunderstorms are caused by (and thus limiting) overall temperature rise, or whether an increase in clouds is causing the overall temperature rise. This is to look at the change in albedo with the change in temperature. Here are two views of the tropical albedo, taken six months apart. August is the warmest month in the Northern Hemisphere. As indicated, the sun is in the North. Note the high albedo (areas of light blue) in all of North Africa, China, and the northern part of South America and Central America. By contrast, there is low albedo in Brazil, Southern Africa, and Indonesia/Australia.
Figure 3. Monthly Average Albedo. Timing is half a year apart. August is the height of summer in the Northern Hemisphere. February is the height of summer in the Southern Hemisphere. Light blue areas are the most reflective (greatest albedo)
In February, on the other hand, the sun is in the South. The albedo situation is reversed. Brazil and Southern Africa and Australasia are warm under the sun. In response to the heat, clouds form, and those areas now have a high albedo. By contrast, the north now has a low albedo, with the exception of the reflective Sahara and Rub Al Khali Deserts.
Clearly, the cloud albedo (from cumulus and cumulonimbus) follows the sun north and south, keeping the earth from overheating. This shows quite definitively that rather than the warmth being caused by the clouds, the clouds are caused by the warmth.
Quite separately, these images show in a different way that warmth drives cloud formation. We know that during the summer, the land warms more than the ocean. If temperature is driving the cloud formation, we would expect to see a greater change in the albedo over land than over the ocean. And this is clearly the case. We see in the North Pacific and the Indian Ocean that the sun increases the albedo over the ocean, particularly where the ocean is shallow. But the changes in the land are in general much larger than the changes over the ocean. Again this shows that the clouds are forming in response to, and are therefore limiting, increasing warmth.
How the Governor Works
Tropical cumulus production and thunderstorm production are driven by air density. Air density is a function of temperature (affecting density directly) and evaporation (water vapor is lighter than air).
A thunderstorm is both a self-generating and self-sustaining heat engine. The working fluids are moisture-laden warm air and liquid water. Self-generating means that whenever it gets hot enough over the tropical ocean, which is almost every day, at a certain level of temperature and humidity, some of the fluffy cumulus clouds suddenly start changing. The tops of the clouds streak upwards, showing the rising progress of the warm surface air. At altitude, the rising air exits the cloud, replace by more air from below. Suddenly, in place of a placid cloud, there is an active thunderstorm.
“Self-generating” means that thunderstorms arise spontaneously as a function of temperature and evaporation. They are what is called an “emergent” phenomenon, meaning that they emerge from th background when certain conditions are met. In the case of thunderstorms, this generally comes down to the passing of a temperature threshold.
Above the temperature threshold necessary to create the first thunderstorm, the number of thunderstorms rises rapidly. This rapid increase in thunderstorms limits the amount of temperature rise possible.
“Self-sustaining” means that once a thunderstorm gets going, it no longer requires the full initiation temperature necessary to get it started. This is because the self-generated wind at the base, plus dry air falling from above, combine to drive the evaporation rate way up. The thunderstorm is driven by air density. It requires a source of light air. The density of the air is determined by both temperature and moisture content (because curiously, water vapor at molecular weight 16 is only a bit more than half as heavy as air, which has a weight of about 29). So moist air is light air.
Evaporation is not a function of temperature alone. It is governed a complex mix of wind speed, water temperature, and vapor pressure. Evaporation is calculated by what is called a “bulk formula”, which means a formula based on experience rather than theory. One commonly used formula is:
E = VK(es – ea)
where
E = evaporation
V= wind speed (function of temperature difference [∆T])
K = coefficient constant
es = vapor pressure at evaporating surface (function of water temperature in degrees K to the fourth power)
ea = vapor pressure of overlying air (function of relative humidity and air temperature in degrees K to the fourth power)
The critical thing to notice in the formula is that evaporation varies linearly with wind speed. This means that evaporation near a thunderstorm can be an order of magnitude greater than evaporation a short distance away.
In addition to the changes in evaporation, there at least one other mechanism increasing cloud formation as wind increases. This is the wind-driven production of airborne salt crystals. The breaking of wind-driven waves produces these microscopic crystals of salt. The connection to the clouds is that these crystals are the main condensation nuclei for clouds that form over the ocean. The production of additional condensation nuclei, coupled with increased evaporation, leads to larger and faster changes in cloud production with increasing temperature.
Increased wind-driven evaporation means that to get the same air density, the surface temperature can be lower than the temperature required to initiate the thunderstorm. This means that the thunderstorm will still survive and continue cooling the surface to well below the starting temperature.
This ability to drive the temperature lower than the starting point is what distinguishes a governor from a negative feedback. A thunderstorm can do more than just reduce the amount of surface warming. It can actually mechanically cool the surface to below the required initiation temperature. This allows it to actively maintain a fixed temperature in the region surrounding the thunderstorm.
A key feature of this method of control (changing incoming power levels, performing work, and increasing thermal losses to quelch rising temperatures) is that the equilibrium temperature is not governed by changes in the amount of losses or changes in the forcings in the system. The equilibrium temperature is set by the response of wind and water and cloud to increasing temperature, not by the inherent efficiency of or the inputs to the system.
In addition, the equilibrium temperature is not affected much by changes in the strength of the solar irradiation. If the sun gets weaker, evaporation decreases, which decreases clouds, which increases the available sun. This is the likely answer the long-standing question of how the earth’s temperature has stayed stable over geological times, during which time the strength of the sun has increased markedly.
Gradual Equilibrium Variation and Drift
If the Thermostat Hypothesis is correct and the earth does have an actively maintained equilibrium temperature, what causes the slow drifts and other changes in the equilibrium temperature seen in both historical and geological times?
As shown by Bejan, one determinant of running temperature is how efficient the whole global heat engine is in moving the terawatts of energy from the tropics to the poles. On a geological time scale, the location, orientation, and elevation of the continental land masses is obviously a huge determinant in this regard. That’s what makes Antarctica different from the Arctic today. The lack of a land mass in the Arctic means warm water circulates under the ice. In Antarctica, the cold goes to the bone …
In addition, the oceanic geography which shapes the currents carrying warm tropical water to the poles and returning cold water (eventually) to the tropics is also a very large determinant of the running temperature of the global climate heat engine.
In the shorter term, there could be slow changes in the albedo. The albedo is a function of wind speed, evaporation, cloud dynamics, and (to a lesser degree) snow and ice. Evaporation rates are fixed by thermodynamic laws, which leave only wind speed, cloud dynamics, and snow and ice able to affect the equilibrium.
The variation in the equilibrium temperature may, for example, be the result of a change in the worldwide average wind speed. Wind speed is coupled to the ocean through the action of waves, and long-term variations in the coupled ocean-atmospheric momentum occur. These changes in wind speed may vary the equilibrium temperature in a cyclical fashion.
Or it may be related to a general change in color, type, or extent of either the clouds or the snow and ice. The albedo is dependent on the color of the reflecting substance. If reflections are changed for any reason, the equilibrium temperature could be affected. For snow and ice, this could be e.g. increased melting due to black carbon deposition on the surface. For clouds, this could be a color change due to aerosols or dust.
Finally, the equilibrium variations may relate to the sun. The variation in magnetic and charged particle numbers may be large enough to make a difference. There are strong suggestions that cloud cover is influenced by the 22-year solar Hale magnetic cycle, and this 14-year record only covers part of a single Hale cycle. However, I have yet to find any significant evidence of this effect on any surface weather variables, including clouds.
Conclusions and Musings
1. The sun puts out more than enough energy to totally roast the earth. It is kept from doing so by the clouds reflecting about a third of the sun’s energy back to space. As near as we can tell, over billions of years, this system of increasing cloud formation to limit temperature rises has never failed.
2. This reflective shield of clouds forms in the tropics in response to increasing temperature.
3. As tropical temperatures continue to rise, the reflective shield is assisted by the formation of independent heat engines called thunderstorms. These cool the surface in a host of ways, move heat aloft, and convert heat to work.
4. Like cumulus clouds, thunderstorms also form in response to increasing temperature.
5. Because they are temperature driven, as tropical temperatures rise, tropical thunderstorms and cumulus production increase. These combine to regulate and limit the temperature rise. When tropical temperatures are cool, tropical skies clear and the earth rapidly warms. But when the tropics heat up, cumulus and cumulonimbus put a limit on the warming. This system keeps the earth within a fairly narrow band of temperatures (e.g., a change of only 0.7°C over the entire 20th Century).
6. The earth’s temperature regulation system is based on the unchanging physics of wind, water, and cloud.
7. This is a reasonable explanation for how the temperature of the earth has stayed so stable (or more recently, bi-stable as glacial and interglacial) for hundreds of millions of years.
Further Reading
Bejan, A, and Reis, A. H., 2005, Thermodynamic optimization of global circulation and climate, Int. J. Energy Res.; 29:303–316. Available online here.
Richard S. Lindzen, Ming-Dah Chou, and A. Y. Hou, 2001, Does the Earth Have an Adaptive Infrared Iris?, doi: 10.1175/1520-0477(2001)082<0417:DTEHAA>2.3.CO;2, Bulletin of the American Meteorological Society: Vol. 82, No. 3, pp. 417–432. Available online here.
Ou, Hsien-Wang, Possible Bounds on the Earth’s Surface Temperature: From the Perspective of a Conceptual Global-Mean Model, Journal of Climate, Vol. 14, 1 July 2001. Available online here (pdf).
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Further to my post (16:06:58) and playing ‘Devils Advocate’.
1) Under Svensmark:
Suppose the ocean energy emissivity is stable.
Increase cloudiness from,say, the Svensmark theory (weak sun and more cosmic rays).
Less energy reaches the surface from the sun, Earth’s air cools, equatorial air masses contract, all the air circulation systems move equatorward, oceanic SSTs fall.
On the face of it that sounds plausible but the observed changes in SSTs and the accompanying shifts in the air circulation systems occur at approximately 30 year intervals which does not match the timing of the necessary variations in solar energy and the levels of cosmic rays. Furthermore the timings of the cycles differ from ocean to ocean whereas one would expect them all to change in unison (albeit at differing rates) if cosmic ray/cloudiness variations were the driver.
2) Under Willis’s Thermostat Hypothesis:
Suppose the ocean energy emissivity is stable.
Warming of the Tropics from ANY cause results in enhanced convective activity in the Tropics which prevents the air from warming beyond 305 Kelvin and that has the side effect of preventing warming of the rest of the globe as well or at least keeping temperature variation within a narrow range.
Again, initially plausible but:
If the process of Tropical convection is that efficient there would be no need for any latitudinal shift in the air circulation systems. Yet such shifts clearly occur.
The degree of stability imposed by such a fast day to day response to warming would preclude any warming of the underlying ocean surfaces at all let alone anything that might exceed 305 K. Yet we see that ocean SSTs do vary and not just in the Tropics.
That idea ignores the possibility of any large natural forcings such as might overwhelm the Tropical convective response and reset the base equilibrium (solar variations) and ignores also the likelihood that there will be variation of energy flows away from the Tropics from time to time such that the Tropical activity may decline but the energy remains in the global system because it has been transported elsewhere.
All such issues are resolved if independently varying oceanic energy emission rates are the real driver.
It was not long ago that significant solar variation was discounted. The discovery of the Maunder and other minima has pretty much scotched that (with all due respect to Leif). We are currently at a point where significant variation in oceanic energy emissivity is being discounted. I beg to differ.
Alternative attempts to knock down my hypotheses are invited.
Stephen Wilde (15:42:17), you say:
Stephen, it appears we may have a terminology problem here.
The amount of radiation emitted by a body is equal to
e * s * T^4
where “e” is the emissivity, “s” is the Stefan-Bolzmann constant, and T is the temperature in Kelvins.
“e”, the emissivity, is how well the material in question emits IR radiation. For water, this is usually taken to be 0.96. It generally doesn’t vary much.
You seem to be saying that the amount of energy transferred from the ocean to the air is greater when the ocean is warmer, which is true. However, this has little or nothing to do with the emissivity of the ocean, and everything to do with the temperature of the ocean.
w.
Williis Eschenbach said:
“Regarding your question, the amount of heat coming out of the earth is quite small. From memory it’s on the order of hundredths of a watt per square metre. That’s why snow sticks when it falls on the ground, there’s not enough heat emerging to melt it.
So even if geothermal heat was ten times the size in the past, it still wouldn’t make a perceptible difference.”
I fully agree that the wpsm is not so much now, but it is way warmer than zero K, and 4.5B yrs ago, the thickness of the mantles would be logarithmically thinner, not linearly thinner. The relative newness of the core in organizing itself, as demonstrated by the repeated early flips of the magnetic poles, would in itself, demonstrate a near quantum level higher energy quotient. This is a thought more to do with geologic theory, despite the physics.
My real question is how does any one explain the balance in an energy equation involving galactic, and solar, winds, and their influence on atmospheric activity. This always seems to be brushed aside for one reason or another.
And thank you for your patience.
Willis (19:10:39)
Thank you for correcting me on the terminology point.
I had assumed that the term ’emissivity’ would suffice as a term for the rate of energy ’emission’ from the oceans.
In fact it seems that the term is usually reserved for the normal radiative property of a material such as water.
I will take account of that in future posts.
This has been an interesting thread, that shows the need for a new framework, in my opinion based on chaotic dynamics that can incorporated all these interesting features in tandem. To an outsider it is evident that most of the hypotheses put forth are a part of the solution, and not the total as the proposer hopes.
All of us have been trained in our science courses to think linearly, to expect well behaved functions and trust first and second order expansions in various series because this method works in the laboratory conditions most of the time. All solutions to equations can be expanded as
a +bx +cx**2 + etc
The crux is whether c is smaller than b and etc expansion constants. This is the way climate modeling is being done, but it becomes more and more evident that In turbulent and chaotic systems this is not true.
Our training goes with the linear approximation naturally, but the research into dynamical chaos and the ongoing research into complex systems shows that this thinking limits us and does not allow us to see solutions outside the box.
Both in climate and in sun science chaos has to be used with more than lip service if the arguments are not to deteriorate in the famous elephant example ( one blind man holding the tail says an elephant is like a snake, another holding a leg says an elephant is like a tree).
Willis
“In general, a warmer world is a wetter world, because of increased evaporation”
On average maybe, but you’re assuming that the increase in evaporation at point A will also result in an increase in precipitation at point A; whereas it’s actually more likely that point B will get the increase in precipitation. So you might end up more like drying out some regions, and ‘water logging’ some others.
>> This is called the “Faint Early Sun Paradox” (Sagan and Mullen, 1972), and is usually explained by positing an early atmosphere much richer in greenhouse gases than the current atmosphere. <<
There was a paper published in 2001 that deals with this problem (see The First Million Years of the Sun: A Calculation of the Formation and Early Evolution of a Solar Mass Star, G. Wuchterl and Ralf S. Klessen, The Astrophysical Journal, 2001 October 20). From the abstract: . . . at an age of 1 million yr, the proto-Sun is twice as bright and 500 K hotter than according to calculations that neglect the star formation process.
There may not be a paradox, but I’m not sure if their theory is correct.
Jim
Melinda (20:04:57), thanks for your thoughts. You say:
To put some real numbers on your interesting ideas, the current flow of geothermal heat from the interior of the earth is on average about 0.06 W/m2.
By the Stefan-Bolzmann equation, this is enough to raise the temperature by a whopping 0.01°C. If it were ten times as large, it is still only enough to warm the earth by a tenth of a degree.
I know nothing about how the mantle thickness has changed in the past. However, if the sun has strengthened by say only 4% in the last half a billion years, this would be a change in average solar forcing of about 12 W/m2 … hardly something that could be counterbalanced by even a hundred-fold increase in the current flow rate of geothermal heat.
It would take a 200-fold decrease in the geothermal heat flow to counterbalance the ~ 12 W/m squared increase in solar forcing in the last half-billion years. Do you have a citation showing that magnitude of change in the mantle? I find nothing in a short google search.
All the best,
w.
ginckgo (22:36:53), you raise an interesting point:
Certainly any change will not be uniform, nature never is uniform. But in the historical record, there’s more droughts during cool times than during warm times. This makes perfect sense, as with less heat there is less evaporation. Since every drop of rain comes from evaporation, we will definitely have less rain in cool times and more rain in warm times. It will be distributed unevenly as it always is, we can forecast that the Sahara Desert will not get a hundred inches per year … but there will definitely be more rain falling.
w.
PS – see, for example, Huang, C.C., J. Pang, X. Zha, H. Su, Y. Jia, and Y. Zhu. 2007. Impact of monsoonal climatic change on Holocene overbank flooding along Sushui River, middle reach of the Yellow River, China. Quaternary Science Reviews, 26, 2247–2264.
Note they say that the disruption of climate patterns (complete with your “drying out some regions, and ‘water logging’ some others”) that you postulate occurred, not when the earth warmed, but when it cooled …
w.
anna v (22:31:53), I appreciate your most thought-provoking post.
I’m sorry for the lack of clarity of my writing. I have described, not the “total solution” you describe, but the mechanism of the governor of the planet-sized heat engine we call “climate”.
I also included a host of things that could affect, in both the short and longer terms, the running temperature of the earth. The main one of these is the Constructal Law that governs flow systems. How my understanding fits in with Bejans work is still not clear to me. I continue to experiment with various models
We use linear methods because we are desperately short of non-linear methods.
I’ll see your elephant, and raise you an elephant:
SOURCE: David K. Campbell 1987 NONLINEAR SCIENCE from Paradigms to Practicalities, Los Alamos Science Special Issue 1987
I wish you sunlight,
w.
Willis Eschenbach (01:59:32) :
I’m sorry for the lack of clarity of my writing. I have described, not the “total solution” you describe, but the mechanism of the governor of the planet-sized heat engine we call “climate”.
Fair enough and clear enough. I was including Stephen’s different POV also in my comments.
Now on droughts and temperatures, this ice core record is quite clear:
http://upload.wikimedia.org/wikipedia/commons/thumb/c/c2/Vostok-ice-core-petit.png/400px-Vostok-ice-core-petit.png
One should note that dust level in ppm peaks at temperature minima and disappears at the maxima. Dust comes from desertification and if that is not the result of drought, what is? Too much water is tied up in ice during the cold.
Willis Eschenbach (01:59:32) :
corrected italics :
I’m sorry for the lack of clarity of my writing. I have described, not the “total solution” you describe, but the mechanism of the governor of the planet-sized heat engine we call “climate”.
Fair enough and clear enough. I was including Stephen’s different POV also in my comments.
Now on droughts and temperatures, this ice core record is quite clear:
http://upload.wikimedia.org/wikipedia/commons/thumb/c/c2/Vostok-ice-core-petit.png/400px-Vostok-ice-core-petit.png
One should note that dust level in ppm peaks at temperature minima and disappears at the maxima. Dust comes from desertification and if that is not the result of drought, what is? Too much water is tied up in ice during the cold.
Willis Eschenbach (13:39:33) :
…. Perhaps you believe that a change in CO2 levels from 0.03% (three hundredths of a percent) to 0.04% will radically change the earth’s temperature.
I wish people would stop intimating that changes in trace gas concentration can obviously have no effect.
Consider ozone:
Ozone concentrations are greatest between about 20 and 40 km (66,000 and 130,000 ft), where they range from about 2 to 8 parts per million.
http://en.wikipedia.org/wiki/Earth%27s_atmosphere
so this gas with 1/100th the concentrration of co2 will have no effect on life if for instance the level halved.
Wrong/
http://www.publish.csiro.au/?act=view_file&file_id=SP06004.pdf
Figure 1
this shows measured UV vs ozone levels at South Pole. reduce the ozone by 50% and double your exposure to UV.
i.e. a change of 0.0002% (approx) in ozone concentration will double your exposure to UV.
Willis, I referenced a document above which you did not comment on:
bill (06:13:27) :
Another good one I referenced above is:
http://ams.allenpress.com/archive/1520-0442/7/4/pdf/i1520-0442-7-4-559.pdf
This seems to suggest that there is no overall cloud forcing. The data is taken from 2 series of satellites measurements of LW and SW radiation and cloud cover. I assume this would therefore include any of your heat transport engines (thunderstorms).
So even if they are transporting/reflecting heat to space the overall effect is neglegable.
Are there later documents from measurements that support you proposition?
Willis, I’d be grateful if you’d take a look at this graph I’ve produced and let me know whether you think it might be relevant to the discussion. It might fit in with what Stephen Wilde has been saying and Bob Tisdales work on heat retained and re-emerging from the Pacific Warm Pool too.
Thanks
http://s630.photobucket.com/albums/uu21/stroller-2009/?action=view¤t=ssa-sst-ssn.jpg
Willis,
Have you seen this recent paper by Tapio Schneider et al., “Water vapor and the dynamics of climate changes”?
http://www.gps.caltech.edu/~tapio/papers/revgeophys09.pdf
“”” Willis Eschenbach (19:10:39) :
Stephen Wilde (15:42:17), you say:
Willis (13:19:44)
During an El Nino the SSTs in the Pacific become warmer and impart more energy to the air.
During a La Nina the SSTs in the Pacific cool and withhold energy from the air.
Those are the most obvious examples of changing ocean energy emissivity.
Stephen, it appears we may have a terminology problem here.
The amount of radiation emitted by a body is equal to
e * s * T^4
where “e” is the emissivity, “s” is the Stefan-Bolzmann constant, and T is the temperature in Kelvins.
“e”, the emissivity, is how well the material in question emits IR radiation. For water, this is usually taken to be 0.96. It generally doesn’t vary much.
You seem to be saying that the amount of energy transferred from the ocean to the air is greater when the ocean is warmer, which is true. However, this has little or nothing to do with the emissivity of the ocean, and everything to do with the temperature of the ocean.
w “””
When we are talking about the EM radiation emitted from a surface as in Watts Per square metre; the correct technical term is “Radiant Emittance”, which is universally shortened colloquially to just “Emittance”. If we were talking about the radiation emitted per unit of solid angle (from ideally a point source) the term is “Radiant Intensity” or simply “Intensity”, and finally if we are talking about the emission from a finite source per unit of area and per unit of solid angle then the Term is simply “Radiance” which is Watts per square metre, per steradian.
“Emissivity” (e) is the factor which connects and actual real source “emittance” to the ideal emittance of a black body; which is defined as a body that absorbs 100% of all electromagnetic radiation that falls on it at any wavelength from down to but not including DC, up to and far beyond the upper reaches of the gamma ray spectrum.
So a body that absorbed or emitted say 90% of the emittance of a black body over the whole wavelenght range, would be described as a “grey” body with an emissivity of 0.9, or 90%.
Any real body emitting thermal radiation, even if close to a black body for some wavelenghts may not do so at all wavelengths, so “emissivity” of real surfaces is a spectrally varying value; so we talk a about “spectral Radiant emissivity” or simply “spectral emissivity”
Bodies that may emit efficiently at shorter wavelengths but less so at long wavelengths are often referred to as “blue” bodies, and the reverse condition would be referred to as “red” bodies (or sometimes pink).
Deep ocean water makes a very good grey body with a total emssivity of 0.96-0.97, close enough to black body like. And the reason is that only about 3% of incident light in the solar spectrum reflects off the surface via ordinary Fresnel optical reflection. The normal reflection coefficient is” ((n-1)/(n+1))^2 where n is the refractive index of the water to air interface.
For water the visible light index is about 1.333 or 4/3, so r = ((4/3-1)/(4/3+1))^2, which is (1/7)^2 or 2%. Over the whole hemisphere iof incidence angles the total reflectance is between 3 and 4 %. All the rest of the radiation enters the water, some of it to 100 metre depths and more but it ultimately gets absorbed by something, so the ocean behaves very much like a black body.
On the emission side, the water temperature ranges from a low of -3 deg C to a high of +32 deg C (305K) so thermal emission is in the range of about 9.5 to 10.5 microns peak wavelength; long wave IR where water is essentially totally opaque.
Consequentially, the radiation emitted form the ocean can only come from the top few microns, since any emission from deeper down would be re-absorbed before reaching the surface. So ocean thermal emission is completely characterised by the sea surface temperature, and has as willis says the very high emissivity of 0.96-0.97, and for all practical purposes the emissivity is spectrally flat since the ocean SST is constrained in such a narrow temperature range (-3 -> +32 C)
I’m not exactly sure what the spectral emissivity of ice is, but i suspect that in the infrared range it too is black, for the same reason as sea water is black.
Caution ; Seawater is black (dark grey) for solar spectrum radiation, but ice is not; well heck we can see the reflectance of ice; but both are likely black for the thermal radiation spectrum.
George
“”” Stephen Wilde (16:06:58) :
George E Smith (15:26:51)
You say:
“So the oceans are hardly the global temperature drivers; althought they do play an immense role via the evaporation cloud formation cycle.
Certainly oceanic circulations affect local climates and weathers, but they are not the drivers of temperature extremes.”
The oceans do and must control the flow of solar energy passing into the air because such a huge amount is stored in the oceans. “””
Stephen, solar energy is not stored in the ocean and passed to the air.
Of the incident solar eenergy, only about 3% is reflected immediately into the atmosphere, most of it to immediately escape to space.
The remaining 97% enters the ocean depths where it is mostly dissipated to become thermal (heat) energy. Some small amoutn of solar energy is absorbed into aquatic plant life (phytoplankton and seaweed (algae) but most of it is thermalized and very little emerges in the original solar spectrum form.
Once absorbed it is simple thermal energy, and it matters not a jot that it originated from the sun; it is now molecular agitation of the seawater. As a result it’s interraction with the atmosphere has little to do with the original supplier of the energy.
As a result of the thermal heating of the ocean the sea water expands since it has an always positive coefficient of expansion, so an upward convection force is generated and permanently present, sot he warmer waters eventually move to the surface where conduction, radiation and evaporation transfer thermal energy and latent heat energy to the atmosphere; but the original solar radiation is long gone before that happens.
George
bill (05:09:38):
I wish people would stop intimating that changes in trace gas concentration can obviously have no effect…
That’s the reason of the existence of thermodynamics and heat transfer science. At its current concentration, carbon dioxide has not the thermal properties as to have an effect on climate.
tallbloke (09:00:59)
Thanks for the link to those charts. I assume they are lined up to each cover the same time period.
On the basis of them the sunspot activity appears to dictate the general slope of the global temperature trend whilst the ENSO signal superimposes variability on it. Exactly the data which underlies my suggestions.
Willis’s Thermostat Hypothesis would prevent Tropical waters going above 305 K but would not appear to prevent the solar activity trend from creating a general temperature trend over multidecadal periods of time.
Nor does it seem to be able to suppress the variations in the trend superimposed on the solar trend by the ENSO signal.
However it may be critical to the process which I have described because if there is a maximum set for Tropical SSTs then if extra energy tries to raise those SSTs further that excess energy has to be redirected and that redirection would then drive the changes in the air circulation systems that I have mentioned.
Thus Willis’s Thermostat Hypothesis meshes perfectly with what I have described here and elsewhere (and as The Hot Water Bottle Effect) by identifying the precise mechanism in the air by which any excess energy in the air can be redirected and neutralised without affecting the global temperature equilibrium.
Changes in the sun and in oceanic energy output will still change the global equilibrium temperature but changes in the air alone cannot. In particular extra GHGs cannot do it because as soon as they try to do so the extra energy is redirected within the air and ejected to space.
There is a global thermostat. It applies to the air alone althought it’s effect is to put a top limit on SSTs. Willis’s observations identify the starting point of the process in the air which I had previously described in a general global context. The reason being that if the Tropical SSTs cannot go above 305 K then the air temperatures cannot go above that figure either and the speed of the hydrological cycle simply accelerates with a consequent shift in all the air circulation systems.
Likewise falls of Tropical SSTs below 305 K are met with the opposite response in the air.
As I had hoped, if one gets the initial scenario right then everything else falls into place.
Thanks Willis.
anna v
I’m trying to create a first step towards a total hypothesis by concentrating on the entire flow of energy from sun to sea to air to space. Critical to the way that flow varies is the characteristics of both oceans and air because both materials slow down the transmission of solar energy and thereby generate heat which sets the global equilbrium temperature.
That equilibrium is constantly varying due to solar variation but additionally because both ocean and air circulations are always both varying due to their very different internal circulations the interplay is very difficult to unravel.
My hypotheses are incomplete because we do not yet have enough data about ocean imposed variations in the energy flow to be able to link the solar variations to the variations in the air (climate).
The observations of underlying long term variability of the rate of energy emission from the ocean surfaces are very recent and their significance has been underappreciated.
Likewise, many have noted the latitudinal movement of the air circulation systems but the implications have not been properly considered.
I have created what I think is the first description of the energy flow from sun to space through the oceans and air whilst at the same time incorporating both oceanic variations in the release of that energy to the air AND the observed response in the air by way of the shifts in the air circulation systems.
Willis has provided a very useful building brick.
I do not say it is complete but it is new. It cannot be proved by laboratory experiments, only by continuing observation and analysis of the real world.
It complies fully with basic physics and observations which is currently an advantage over any of the existing models.
George E Smith (10:36:10)
“Stephen, solar energy is not stored in the ocean and passed to the air.
Of the incident solar eenergy, only about 3% is reflected immediately into the atmosphere, most of it to immediately escape to space.
The remaining 97% enters the ocean depths where it is mostly dissipated to become thermal (heat) energy. Some small amoutn of solar energy is absorbed into aquatic plant life (phytoplankton and seaweed (algae) but most of it is thermalized and very little emerges in the original solar spectrum form.
Once absorbed it is simple thermal energy, and it matters not a jot that it originated from the sun; it is now molecular agitation of the seawater. As a result it’s interraction with the atmosphere has little to do with the original supplier of the energy.
As a result of the thermal heating of the ocean the sea water expands since it has an always positive coefficient of expansion, so an upward convection force is generated and permanently present, sot he warmer waters eventually move to the surface where conduction, radiation and evaporation transfer thermal energy and latent heat energy to the atmosphere; but the original solar radiation is long gone before that happens.”
I think you have missed my point.
Obviously the solar energy is converted to thermal energy within the oceans. That happens as a direct result of the oceans slowing down the speed of transmission of that solar energy.
Shortwave goes in, longwave comes out. Exactly analogous to the reduction of voltage when a current passes through a resistor and generates thermal energy.
My point is that the longwave comes out at varying rates on multidecadal time scales for whatever reason but no doubt due to internal ocean circulations.
That variation in the flow of thermal energy from ocean to air changes the sea surface temperatures and drives temperature changes in the air.
Variations in the input of shortwave solar radiation to the oceans over longer timescales alter the amount of thermal energy in the oceans and therefore ultimately drive the release of that energy as longwave subject to modulation by variations within the oceans.
Stephen Wilde (11:48:20) :
I know that most of us following this board are allergic to computer modeling, nevertheless appropriate computer models can be useful tools.
In Tsonis url http://www.uwm.edu/~aatsonis/BAMS_proofs.pdf is described an approach of modeling a nonlinear chaotic climate system using neural nets. They have been incorporating the effects of the ocean currents and thus come to predict a cooling for the next thirty years, as mentioned in the recent news.
I would think that such an approach would allow for modeling much more than what they have included so one would not need to wait for observations to see the validity of a climate model.
Another way of integrating non linear differential equation systems is by analogue computing, ( which neural nets resemble) but that road has not been traversed for some decades.
Having merged Willis’s Thermostat Hypothesis with my previous description of the climate mechanisms there now seems to be a plausible mechanism whereby changes in greenhouse gases can naturally be prevented from influencing the global air temperaure equilibrium.
1) There is a maximum attainable sea aurface temperature of about 305 Kelvin. That maximum has already been attained as a result of the current global temperature.
2) That maximum sea surface temperature is set by the temperature of space and the density of the air.
3) There is an overall global equilibrium temperature but it is set by sun and oceans combined and varies over time and is influenced by the speed of the hydrological cycle.
4) If extra greenhouse gases try to raise the sea surface temperature in the tropics above the current level they cannot do so and instead the extra energy is redirected into an acceleration of the hydrological cycle and a miniscule latitudinal shift of the air circulation systems.
5) Such extra energy is thus ejected to space without being able to affect the temperature equilibrium of the air set by sun and oceans.
Although the water on the Earth is not at 100 C it is nevertheless ‘boiling’.
The situation is analogous to an open pan of boiling water on a stove. If extra energy is added from any source the temperature of the boiling water will not increase. All that happens is that the rate of evaporation increases.
So it is with the Earth. Extra energy in the air alone just accelerates the hydrological cycle and the air gets no warmer from that cause.
The analogy is not quite right for the Earth because of the capacity of the oceans to hold thermal energy initially received from the sun and which is, I believe, released at variable rates.
The oceans are so large that they can alter the equilibrium temperature temporarily by releasing energy to the air faster than the hydrological cycle can dispose of it. However the area of sea surface temperatures around 305 K increases, the hydrological cycle speeds up, the air circulation systems migrate poleward and after a while a new equilibrium is restored until the release of energy from the oceans declines again.
Note that when the temperature of the air is trying to rise due to increased energy emission from the oceans the thermal energy stored in the oceans is declining unless solar input is high enough to offset the losses.
So, extra GHGs apparently cannot raise the equilibrium temperature of the globe, the oceans or even the air.
Stephen Wilde (11:48:20) :
tallbloke (09:00:59)
Thanks for the link to those charts. I assume they are lined up to each cover the same time period.
On the basis of them the sunspot activity appears to dictate the general slope of the global temperature trend whilst the ENSO signal superimposes variability on it. Exactly the data which underlies my suggestions.
Hi Stephen, yes same timescales, the bottom graph has month numbers from may 1874. We are thinking on the same lines here. I’m reposting the following from Bob’s thread because it seems to have better context and more fertile ground here:
=====================
it’s not so much SSN in red I want you to look at, but the cumulative total of sunspot area below. The build up and sudden release of peaks in SST coincide with the ends of el nino dominant periods around 1880, 1940 and 1998. The 60year oscillation overlays the underlying cumulative solar trend it seems to me.
I agree with what you and Bob say anout the PWP, but in the end, the energy is coming from the sun (where else?). The issue is the mysterious way it hides in the climate system and manifests in the 30 up 30 down 60 year cycles. I think my graph goes some way to explaining that. The downslope in the cool la nina dominated period from 1880-1910 is steeper than the fall in my cumulative solar index. Then an el nino dominated phase takes over while the solar accumulation is bottoming out. It then crashes at 1945 and we get a cool phase as the solar accumulation is picking up again in the background.
I don’t see why there couldn’t be both fairly immediately felt effects of solar energy via cloud mediation, as well as longer term buildup and releases such as the big events in 1998. It just means there’s more than one type of oscillation going on, with more than one factor involved.
========================
I’d like to be able to swap further ideas so please drop me a line to rog at tallbloke dot net if you find the time or keep this thread going because I’m getting a lot out of this.
Thanks for your contributions
The physics by means of which thunderstorms transfer heat to space have been well known for many decades; what makes Willis’ elegant hypothesis so original is the proposal that this mechanism is both necessary and sufficient to explain the long-term stability of Earth’s temperature. Maybe so, maybe not, but it is certainly leaning the right direction and doen’t need no stinkin’ CO2 to work.
Steven Wilde’s contributions add considerable understanding to the subject and no, the phenomenon isn’t confined to the tropics. Thunderstorms are found in the continental interiors throughout the temperate zones. Most of the AGW proponents happen to live in costal areas and have far less exposure to these events.
The deserts of the Southwest (from SE California to the Gulf of Mexico) are known for frequent thunderstorms, particularly during our “monsoon” season. Most years, by mid-July, moist warm air from the Gulf is moving westwards and rising and condensing to create the earliest monsoon storms. Once it begins, the system remains in place for 6-8 weeks. Most of the intense rain that falls most afternoon has evaporated by sunset providing the water vapor needed for the next day’s storm; little additional moisture from the Gulf is required to keep the process going. But each cycle removes heat from the desert, so July and August are comparatively cooler than June. By September when the storms abate, the seasonal cooling has already begun.
For the record, Tucson had five days in May in the 100’s and none in June, so far. Local conditions to be sure, but May was warmer than usual and June much cooler. Last year at this date we had had more than twenty consesecutive days above 100. Hard not to notice.
Finally, I prefer that Dr. Strangelove confine his sulfate belching and man-made waterspouts to the privacy of his bathroom.
Willis, So in a nutshell, when El Nino warms the surface you expect an increase in clouds that reduce the overall insolation to the surface ie El Nino removes heat from the oceans and the consequent additional clouds further reduce the level of solar warming of the oceans, so the effective net loss of heat from the ocean is amplified. Additionally the consequent extra precipitation that follows further cools the surface. So I should expect to see an amplified reduction of surface temperature following a strong El Nino.
Is there historically a statistically significant correlation between the magnitude of El Nino temperature rise above average and the subsequent fall below average? Am I right in thinking that this would be needed to support your theory and that a contrary result or no correlation would discredit it?