Guest Post by Willis Eschenbach
Buoyed by equal parts of derision and praise for my last post, “Surface Radiation: Absorption And Emission“, I once again venture into the arena. I had an odd thought. The temperature has been generally rising over the period 2000-2021. I wondered if there was a way I could measure the efficiency of the greenhouse effect to see if the warming was due to increasing greenhouse gases (GHGs). If the GHGs were the cause, then the greenhouse effect would need to be more efficient in terms of warming the surface.
A Prologue: The earth is much warmer than the moon, which receives the same amount of solar energy per unit area. It’s generally accepted, including by me, that the warmth is from the very poorly named “greenhouse effect”, which has nothing to do with greenhouses.
Now, if you don’t think the “greenhouse effect” exists, this is NOT the thread for you. There are lots of places to make that argument. This isn’t one of them. We know the earth is warmer than expected. Nobody has ever come up with an explanation for that except the greenhouse effect.
If you are unclear about how the greenhouse effect works, the physical basis of it has nothing to do with CO2 or with the atmosphere at all. I explain this in my posts “People Living In Glass Planets“, and “The Steel Greenhouse“.
To reiterate: PLEASE do not post your opinions here on why the greenhouse effect isn’t real, or why there’s no such thing as downwelling radiation, or that scientists don’t understand the instruments that measure IR. The web is a very big universe. Somewhere out there is the perfect place to make those arguments.
This is not that place.
To return to the question at hand, which is the efficiency of the greenhouse effect, here’s the temperature change during the period of the CERES satellite data.
Figure 1. Surface temperature changes, CERES data. It is a conversion of the CERES surface upwelling longwave data to units of degrees Celsius using the Stefan-Boltzmann equation. It agrees well with e.g. the MSU lower tropical temperature, with a residual standard error of about a tenth of a degree C.
So the question, of course, is why did it warm over that period?
I thought, well, what the greenhouse effect does is to increase the surface temperature. The greenhouse effect starts with a certain amount of energy entering the climate system, and it ends with the surface being warmer and thus emitting more thermal radiation than would be expected if one were to look at say the moon, which gets the same energy from the sun as does the earth.
So … I figured that I could express the efficiency of the greenhouse effect by comparing the upwelling longwave radiation from the surface with the amount of solar energy entering the system. This measures the “end-to-end” efficiency of the entire system, including all feedbacks and interactions. I’ve chosen to express it as a “multiplier”—for every W/m2 of solar input, how many W/m2 of upwelling surface radiation do we get?
The amount of solar energy at the top of the atmosphere is about 340 watts per square meter (W/m2). However, about 100 W/m2 is reflected by the clouds and the surface. This means that the solar energy entering the system is on the order of 240 W/m2.
Upwelling longwave from the surface, on the other hand, is on the order of 400 W/m2. This means that the average greenhouse multiplier is approximately:
400 W/m2 / 240 W/m2 ≈ 1.66
In other words, for every watt per square meter of solar input, we get ~ 1.7 watts per square meter of upwelling surface radiation.
Now, we can run this calculation for each month, looking at the amount of thermal radiation emitted by the surface divided by the solar energy entering the system. Figure 2 shows that result. Remember that for increased greenhouse gases to be responsible for the warming, the greenhouse multiplier needs to increase.
Figure 2. Greenhouse multiplier. The multiplier is calculated as upwelling longwave surface radiation divided by incoming solar radiation (after albedo reflections). A multiplier of 2 would mean that the surface would be radiating two W/m2 of energy for each one W/m2 of solar energy actually entering the system. This shows that the greenhouse has increased the incoming solar radiation by about two-thirds, as measured at the surface.
Now, this is a most interesting finding. The efficiency of the planetary greenhouse has decreased slightly over the period—not significantly, but not increasing either.
In fact, the stability over the period is of interest in itself. Note that the standard deviation of the multiplier is 0.004 W/m2. Over the period, the end-to-end efficiency of the entire greenhouse system hardly varied at all. I’ve written before about the amazing stability of the system. This is another example.
So given the evidence above that the increase in upwelling surface radiation cannot be due to a change in greenhouse efficiency from increased CO2 or any other reason, what is the cause of the temperature increase? Here are the graphs of the two datasets that make up the greenhouse multiplier—the upwelling surface radiation, and the incoming solar radiation.
Figure 3. Upwelling surface thermal radiation (yellow, left panel), and incoming solar radiation after albedo reflections (red, right panel). Blue/black lines are LOWESS smooths of the data.
In Figure 3, we can see why the efficiency of the system hardly varied—the upwelling surface longwave was increasing pretty much in lockstep with the incoming solar energy actually entering the system.
Conclusions: We have observational evidence that the temperature increase from 2000-2021 was not due to an increase in greenhouse gases, or any increase in the efficiency of the greenhouse effect from any cause. The efficiency has been very stable over the period, with a standard deviation of 0.2% and no significant trend.
On the other hand, the change in incoming solar energy is both adequate to explain the increase in warming, and has the same shape as the change in surface radiation (blue LOWESS smooths in both panels in Figure 3). While there are undoubtedly other factors in play, the main cause of the warming is clearly the increase in the amount of solar energy after reflections from the clouds and the surface.
And once again, the clouds rule … go figure …
w.
Math Note: I tend to use “upwelling longwave surface radiation” and “temperature” interchangeably. Yes, I know that radiation varies as the fourth power of temperature, T4. However, the difference is trivial in the narrow range shown in e.g. Figure 3.
Figure 4 shows a comparison of the upwelling longwave shown in Figure 3 and the Stefan-Boltzmann derived temperature. Basically identical in form.
Figure 4. Temperature (yellow, left scale) and surface upwelling radiation (red, right scale)
Policy Note: I was 100% serious about asking people to refrain from commenting about things like how downwelling radiation doesn’t exist and the greenhouse effect isn’t real. Don’t make me tap the sign.
My Usual Request: Misunderstandings abound in communication. When commenting, PLEASE quote the exact words you are discussing, so we can all understand exactly who and what you are responding to.
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No new heat can be generated from a static pressure.
==≠======(
Misconception. The lapse rate is a result of convection. The pressure is not static from the point of view of an air molecule or parcel of air moving vertically. The pressure is truly only static if you remove the sun which would end all convection.
In any case new heat is not being generated. It is being pumped downwards using solar energy to move air and water vapor through a pressure gradiant, similat to a mechanical heat pump.
The lapse rate is actually due to well mixed GHGs controlling the energy levels allowed at varying densities.
The lapse rate is actually due to well mixed GHGs
========
Nowhere in rhe formula for lapse rate does well mixed GHG appear.
Not relationships are easy to see.
Well mixed GHGs means their concentration follows the changes in atmospheric density. What determines density? Good old gravity. And of course, gravity does appear in the lapse rate equation
It is a simple matter to generate 33C of warming by pumping a gas through a pressure gradiant. You are not creating energy. You are moving energy from one place to another.
Atmospheric convection driven by solar energy does this all day long.
Build a huge mechanical heat pump run via solar energy with the low pressue (cold) coils at altitude and the high pressure (warm) coils at the surface. That is convection.
Ps: this is a continuation of my earlier post based on Willis showing that greenhouse efficiency was not determined by CO2. It follows from that that the greenhouse effect must be based on some other gas other than CO2.
First of all, thank you for such a concise and informative post. The CERES data indicates an underlying fall in reflected sunlight of approximately 1.4% between 2000 and 2021. This could be due to a change in average cloud cover, but the reduction in average arctic sea ice & snow cover (from 10.5 to 9.5.10^6 km2 from AMSR data) could be having a significant effect. A very rough calculation, assuming a change in albedo from 0.8 to 0.15, gives an expected reduction in expected solar reflection of about 0.7%. It may be worth someone calculating a more accurate figure, accounting for ice cover & sun angle throughout the year.
The efficiency used here is simply the inverse of the effective emissivity of the Earth: In this essay from 3 years ago, I calculated this effective emmissivity as 0.61 (ie 1.64 in Willis’s terms) but this presupposes an average albedo in the solar spectrum of 0.30. What goes on with regard to a secular trend in “efficciency of greenhouse effect” is actually a secular trend in the figure of merit of the Earth treated as a solar collector. What is good about the figure of merit is it takes into account both the effective emissivity and the effective solar absorptivity.
I’ll see here if LaTeX still works…figure of merit =
It works!
The lapse rate is actually due to well mixed GHGs
========
it this is a prediction of Greenhouse theory, then it is surprising it has not been dealt with.
On Earth there is no term for well mixed gas in the lapse rate.
The lapse rate is a function of gravity and the work required to compress air. This contradicts the notion that heating/cooling due to compression is a one time event.
In addition the lapse rate is a function of the condensation of water and the energy released via phase change.
This is all driven by low pressure in places where the sun is shinning and high pressure in places that are dark. These are continually changing because of orbital mechanics.
True, Mr. Ferdberple. It is very difficult to get people to understand that temperature (a proxy for internal energy at fixed composition) is a reflection of the first law of thermodynamics, towit, change in internal energy = heat in – work out; or,
It is generally recognized that the atmisphere below 500mb is opaque to IR and as a result there is little cooling of the surface due to outgoing radiation. The heavy lidting below 500mb is done by convection.
No, the atmosphere is not opaque to IR, as shown in the spectrum below it’s fairly transparent at many wavelengths. The regions of the spectrum where it is opaque are where certain components (CO2, H2O, O3 etc) absorb.
In most places, perhaps, but where I live cooling by radiation predominates after sundown and is substantial and quite apparent even without instruments.
“The earth is much warmer than the moon, which receives the same amount of solar energy. It’s generally accepted, including by me, that the warmth is from the very poorly named “greenhouse effect”
Earth’s sunlit side at any given time is cooler than on the Moon because of clouds and water vapour. Earth’s dark side at any given time is much warmer than on the Moon, primarily because of the sea surfaces barely cooling at night.
The Moon has an albedo of 0.12 as opposed to the Earth which has an albedo of 0.30 so the Moon receives about 26% more solar energy than the Earth. On the dark side of the Moon the surface has a lot longer to cool (~14 days) it gets a lot colder.
The lunar equator cools about 270K in a quarter rotation from midday to dusk, and then cools about 40K from dusk to dawn for half a rotation. So in twice as long, the dark side cools much less.
Yes the day-time temperatures are close to radiative equilibrium so the maximum temperature is at noon (~390K), due to the change in incidence angle the temperature drops rapidly before dawn (7 Earth days later) to about 200K (high std dev ~30K). By the Lunar midnight 7 Earth days later it reaches ~95K, since loss depends on T^4 further losses are slow. As I said, much longer cooling time than on Earth.
“due to the change in incidence angle the temperature drops rapidly before dawn (7 Earth days later) to about 200K”
Dusk comes after midday, by which time the equator has cooled down to around 120K. The night time cooling over ~14 days is only 40K.
Yes mistyped dawn instead of dusk.
Double or quadruple the lunar rotation rate, and the sunlit side will be virtually the same temperature, except for a slightly warmer dusk terminator and a slightly cooler dawn terminator. The dark side mean temperature would be virtually the same.
Well I was comparing it to the Earth which rotates 28 times faster!
Reaches its maximum after 7 days of heating (noon) and proceeds to cool for 21 days after that.
The moon surface at the equator is warmer than the Earth for about 6 days around noon, colder the rest of the time.
The lunar sunlit side is roughly in equilibrium with solar irradiance, it does not take days to heat up, the surface temperature is mostly dependent on the angle of incidence.
This is totally hilarious!
griff, loydo and simon have been allowed to post here for years on WUWT despite being CAGWers and yet I have been placed on moderation for disputing the existence of the GHE.
All I ever asked for was evidence that the GHE exists and that it causes surface warming. I also asked for evidence that Equilibrium Climate Sensitivity was a true measurement.
What can I say?
WUWT is a cancel culture website.
If you want me to go just ban me. WUWT is not really worth the effort in its current lukewarmist stance.
It will just convince me and a few others on this website (not many it seems but also the more intelligent and informed ones, I’m sure) that WUWT is just a supporter of lukewarmists and not really an edge-cutting protester against government policy on climate change.
WUWT had a great platform for change but the platform moved so much WUWT just slid off into the mire.
Yours
Very Disappointed
(You have 1322 posts and allowed this one because it shows how far off the path YOU are when it comes to following the blog policy:
and,
No one here is forcing you to be here but this blog has a policy in place to help people stay on topic and be reasonably civil, you are in MODERATION now because our lack trust in you has fallen to the point that your future posts have to be in the moderation bin first to see if you are here to contribute to the debate without the baiting the trolling and the numerous personal attacks.
Deleted 10 posts to clean up the thread) SUNMOD
Uh-oh, leitmotif is threatening us with leaving …
I’m quaking in my boots.
w.
… I have been placed on moderation for disputing the existence of the GHE.
It is unfortunate for you that you don’t realize that the problem is not “disputing the existence of the GHE,” but rather your uncivil behavior and unwillingness to abide by WE’s request to not ‘thread jack’ the topic. You have some issues and this is not the time to air them.
Something to consider is that the moon has no liquid water. The surface of rocks are heated to high temperatures by direct sunlight, and because of the S-B 4th-power law, it is radiated away rapidly.
On the other hand, Earth with abundant water (with a specific heat capacity ~5X greater than rocks) only gets to about 1/5th the temperature and radiates at 1/625 (0.2%). Also, the evaporation of water and transpiration from plants keeps the surface at a low S-B base temperature, keeping the rate of radiation low.
Willis,
I don’t necessarily have an argument about this work or your earlier essay, but you begin with the statement
When someone says TOA I take that to mean where the atmosphere ends. But at such a height the radiation leaving the Earth cannot be anything other than what is entering from the Sun, with perhaps some small adjustment for lack of equilibrium due to a slowly warming planet. There is nothing going on within the atmosphere that can increase a TOA radiative flux up or down by any amount.
Now it may be that when people say “greenhouse” effect they actually mean at top of the troposphere, or stratosphere, or perhaps truly out where the atmosphere ends. In your opening words, what does TOA mean?
Possibly by a forcing of 3.7 watts they mean that solar albedo has declined for some reason by this amount, so that this is an increase of solar reaching the ground surface, but LWIR increases by the same. Is this what is claimed?
For any greenhouse effect, its maximum magnitude will be obeserved at the surface — whether measured by temperature or downwelling radiation. Even saying “surface” has its pitfalls. They must mean that the surface sees an additional LWIR downwelling, which raises its temperature, and this in turn increases upwelling LWIR at the surface — but none of this has anything to do with TOA.
Howard Hayden has made a presentation about the IPCC and claims about three things (greenhouse effect, surface temperature, and stefan-boltzmann law) that cannot be made consistent. Are you aware of his work?