Guest Post by Willis Eschenbach
Back in 1987, V. Ramanathan noted that we can measure the very poorly named “greenhouse effect”. This effect has nothing to do with greenhouses. Instead, what happens is that some of the upwelling longwave radiation from the surface is absorbed by “greenhouse gases” in the atmosphere, mainly CO2 and H2O. This absorbed energy, of course, is added to the thermal energy in the atmosphere, which is then radiated again with about half going to space and about half going back to the ground.
What Ramanathan noted is that to calculate the size of the “greenhouse effect”, you simply subtract the longwave emitted to space at the top of the atmosphere (TOA) from the longwave emitted upwards at the surface. Here’s Ramanathan’s drawing of the concept:
Figure 1. Drawing by Ramanathan showing upwelling surface longwave of 398.6 watts per square meter (W/m2), TOA radiation to space of 267.5 W/m2, and atmospheric absorption (greenhouse effect) of 131.1 W/m2. Note that Ramanathan has also calculated the absorption as a fraction of surface radiation (0.334, or 33.4% of radiation absorbed).
The use of a percentage to measure the “greenhouse effect” eliminates one of the variables. Where it is warmer the ground emits more radiation, so naturally more will be absorbed by the atmosphere. That means if we want to compare different areas of the earth, we need to use percentages instead of absolute values. Below are two graphs showing the percentage of the upwelling surface longwave radiation absorbed by the atmosphere, shown from two opposite sides of the planet.
Figure 2. Percentage of upwelling longwave absorbed by the atmosphere, Pacific-centered and Atlantic-centered.
There are a few things of interest here. First, where it’s very cold, almost no upwelling longwave is absorbed by the atmosphere. Second, in the cloudy areas around the equator, about half of the upwelling radiation is absorbed. Third, you can see the Gulf Stream along the east coast of the US …
Much is made by climate alarmists of the fact that the percentage of the upwelling surface radiation absorbed by the atmosphere is increasing. This indeed shows that the greenhouse effect is real … but it shows nothing about whether that affects the temperature. Figure 3 shows the rate of increase.
Figure 3. Change in absorbed upwelling surface radiation from March 2000 to February 2021.
Now, I entitled this post “A CO2 Puzzle”, and true to my word, here it is. The increase in the absorbed upwelling radiation is supposed to be from the increase in CO2 … but in fact, the increase in absorbed upwelling longwave is slightly less than half of what we’d expect from CO2. And that’s without the claimed increases in absorption due to methane and other minor greenhouse gases, from”water vapor feedback”, and from “cloud feedback”, all of which are said to increase the slope of the trend in absorption.
Figure 4. As in Figure 3, but also showing the expected trend from the increase in CO2 over the period.
So there’s the mystery. Between CO2, methane and minor greenhouse gases, water vapor, and cloud feedback, the percentage absorbed should be increasing far faster than it actually is … why isn’t it?
And what is the answer to the puzzle? I don’t know, other than to note that as I’ve pointed out in a number of contexts, emergent climate phenomena act to minimize factors that tend to warm the earth. However, I have no idea exactly what is occurring here, all suggestions welcome.
Me, I’m currently in Florida with my gorgeous ex-fiancee, enjoying the rain, the sunshine, and the pleasant and friendly people here. Our profound thanks to the most interesting and kind WUWT folks who have hosted, educated, and entertained us on our peregrination, you know who you are, much appreciated.
My best to everyone from the land of oranges and bikinis …
w.
PS—Two things. First, I implore you not to turn this into a discussion of whether a cold object can warm a hot object, or whether the greenhouse effect is real. There are plenty of places for you to have those discussions. This is not one of those places, and I will snip comments that go over the line. And please, if you get snipped, don’t whine about censorship or the like. It is merely my effort to keep the conversation focused on the topic of the post, you’ve been asked in the strongest terms to stay away from those topics, and if you don’t, it’s on your head, not mine. Oh, and please, leave out the politics … there’s plenty enough division of opinion in the climate world, no need to increase it by including politics.
Second, as always, I request that you quote the exact words you are discussing, so that all of us can understand just who and what you are referring to.
Excellent data presentation again, thanks Willis!
From the illuminating maps it’s clear that “greenhouse effect” as in absorbed IR is correlated with one thing: surface supply of water vapour, from warm oceans or tropical forests. What has CO2 got to do with it?
Probably because the LW cloud feedback is negative in short term observations but positive in the models.
https://www.researchgate.net/publication/328808813_Space_lidar_observations_constrain_longwave_cloud_feedback
w. ==> We could instead discuss the prevalence of bikinis on the beaches of Florida? and compare to Southern California?
Alternately, what do you make of the post 2016 values? Flat then falling. Of course, the differences are in tenths of a opercent, but still . . .
“However, I have no idea exactly what is occurring here, all suggestions welcome.”-Willis
I think the problem is one of perspective. We view the world as surface dwellers see it. Two dimensional. Perhaps the solution to the puzzle is to look upwards.
I see that the derived equilibrium temperature is 255K (-18 C.). There is a point in the vertical air column for every geographic coordinate location that resides at the equilibrium point, at all times. It fluctuates in altitude with diurnal time and season.
According to the aviation weather center ( https://aviationweather.gov/windtemp?gis=off ) Temp aloft chart the equilibrium temp at Las Vegas currently resides at 24,000 feet. Honolulu is about 22,000 ft. Antarctica is no doubt well below equilibrium temp.
This modulates the size of the sphere surface area that is radiating out. This is all part of your emergent thermo-regulating theory.
Best to you and your ex-fiancee.
Quotation: “The increase in the absorbed upwelling radiation is supposed to be from the increase in CO2 … but in fact, the increase in absorbed upwelling longwave is slightly less than half of what we’d expect from CO2. “
The idea the Outgoing Longwave Radiation (OLR) would increase due to the increased Greenhouse Effect (GHE), for example due to increased CO2 concentration, is totally wrong. The opposite is true, and it is based on the mechanism of GHE. When the GH gases absorb the surface emitted longwave radiation (LR), the OLR will decrease. Yes, you read right, it will decrease.
Since the absorbed radiation by the GH gases increases the downward LR, it will warm up the surface, and at the same time the surface will warm up because the cooling of the Earth is less than the incoming SW radiation: The Earth will automatically move into balance. The warming of the surface continues as long as the OLR has increased to the original value, which is the same as incoming SW radiation.
I am really astonished that this basic knowledge is still a mystery for most readers of this WUWT. On the other hand, this is not a surprise, since so many readers of WUWT do not believe in the GH effect or in the reradiation by the atmosphere to the surface.
There is a simple explanation for the increased upwelling absorption flux. The reason is that there has been a strong positive SW anomaly starting 2001 and especially this anomaly has been strong after 2014, and it was the reason for the ending of the pause. It means that the OLR must increase since it must be about the same as incoming SW radiation. I cannot include any figure but I give once again a link to my web page: https://www.climatexam.com/single-post/greenhouse-gases-did-not-cause-the-end-of-the-pause
If you think that the SW anomaly is my misconception, you can check that Norman Loeb et al. has exactly the same graphical presentation of the SW trend in their paper, Figure 2a: Satellite and Ocean Data Reveal Marked Increase in Earth’s Heating Rate
If you can get the data, I suggest plots of absorbed radiation as a function of (1) CO2 concentrations at representative locations, and (2) humidity at the same locations. Correlation coefficients for each would be interesting.
Twenty years of data is meaningless!
That is proof of nothing.
[… his usual excrement and stupid personal attacks deleted …]
Looking at one effect of a situation while ignoring all others is not a good way to arrive at the truth. The article shows the fraction of surface radiation absorbed by GHG’s but it ignores a VERY major other impact of GHG. By creating a cold junction at the tropopause which can radiate energy to space it allows the atmosphere to function as a heat engine. That is what creates weather on Earth. More directly, it allows convection and surface evaporation of water which between them (According to NASA) allow 86.4 + 18.4 = 104.8 watts/sqM of surface cooling. Also, by allowing evaporation it allows precipitation and hence clouds which reflect a significant amount of incoming solar energy and thus stop it reaching the surface. Again according to NASA – around 77 watts/sqM. Thus they reduce surface energy balance by 104.8+77= 181.8 watts/sqM. But according to the diagram above the reduction in radiative loss is only 131 watts/sqM. So do GHG’s net cool or warm the surface? Of course, that is only the surface energy balance but then we live on the surface.
GHG’s ameliorate surface temperatures. Without them the noon summer temperature would be about the same as in a closed car which as we know, even in mid latitudes kills people, especially children, in minutes. Night time temperatures would be far below zero – more like the temperature on the antarctic high plateau. These would kill people from exposure again in minutes. So if the presence of GHG’s ameliorates temperature extremes making life on Earth possible, why should a small increase suddenly exacerbate them. Is there a point of inflection wrt to the impact of GHG’s and if so why does it exist and at what total GHG concentration does it occur.
Splendid discussion, Willis.
I am interested in both history and theory, as you are.
The theory is masterfully presented by Bob Wentworth, https://wattsupwiththat.com/2021/06/04/mathematical-proof-of-the-greenhouse-effect/ (which is why we love wuwt so much). His discussion encompasses all GHGs, with a theoretical maximum average temperature of 21C.
So… the disjunction that occasionally occurs between theory and practice can be disconcerting. It doesn’t bother me, philosophically, but I am curious. If the maximum temp with GHGs in accoount is 21C, how to explain, for example, the P-T extinction maximum of >28C?
Clearly, the answer is: something else… but what?
Greenhouse theory converts surface temperatures into upwelling power flux, W/m^2, while assuming that surface radiates as an ideal BB.
THAT, as demonstrated by experiment, is WRONG!!
ALL the rest is moot handwavium.
Almost all natural surfaces have an emissivity of >0.95. As a result, assuming earth is a blackbody makes very little difference in the results.
w.
Straight line vs a polynomial trend? At first glance the data appears to represent an approximate 12 year cycle. Sounds familiar…solar?
A great graphic.
Except it leaves me a bit confused.
A) I assume that “upwelling longwave radiation from the surface is absorbed by greenhouse gases” in the atmosphere, mainly CO2 and H2O” represents the entire spectrum of longwave radiation? Not just CO₂ and H₂O?
Which means the graphic does not identify or separate all of the various GHG interactive wavelengths emission frequencies or LWR frequencies attributable to Earth’s surface and surface objects?
Basically the graphic is one lump sum minus TOA lump sum?
B) “Figure 4. As in Figure 3, but also showing the expected trend from the increase in CO2 over the period.“
This is where I get confused.
a) The graphic does not identify the CO₂ forcing scale or resolution.
b) The graphic shows the “Theoretical CO₂ Forcing, +3.7 W/m2 per 2XCO₂” as a fairly even aggressive rise across the time period.
Yet we know that CO₂ atmospheric concentration is not a steady rise, especially seasonally.
We also know that that CO₂ concentration increase since 2000 to present is 15-20ppm.
15-20 CO₂ ppm, is approximately 4.9% of 412 ppm and difficult to believe such a small incremental increase for a minimally interactive GHG molecule causes such an aggressive Forcing trend?
In addition approximately 4% of the CO₂ atmospheric increase is attributed to humans, i.e. a maximum human caused increase of 1ppm. Making it appear that humans are blamed for the entire global atmospheric CO₂ increase.
Shouldn’t the scale of that CO₂ Forcing be included in the graphic?
C) Eyeballing that TOA LWR emission trend, it sure looks like a minimally positive trend from 2000 through approximately 2012.
D) As others’ have pointed out, periodic leaps in trend appear to be El Nino or water vapor increases related.
a) H₂O increases in extremely dry environments are massive enough to cause significant temporary temperature increases.
b) CO₂’s gradual miniscule increments are very unlikely to cause sudden climbs or drops, as occurs from 2019-2021. Especially as the theoretical CO₂ Forcing shouldn’t have such dramatic rises/falls.
ATheoK July 14, 2021 9:56 pm
It is the area-weighted average of the gridcell-by-gridcell surface upwelling longwave minus the TOA upwelling longwave, expressed as a percentage of the surface upwelling longwave.
The scale is the same as the scale for the other variables—increase in CO2 divided by upwelling longwave from the surface.
Finally, regarding the change, note that the theoretical change in downwelling LWIR from CO2 is less than half a percent … so that’s in line with the change in CO2.
Regards,
w.
Willis – I’ve always felt queasy about the ‘half goes up half goes back down’ thing about longwave re-radiation.
As a matter of simple geometry, about 59% of isotropic radiation escapes to space at 100km up. The world is, after all, not flat.
So there at least, ‘up’ radiation is about 44% bigger than down. Given that you are searching for a factor of two, this might get you part way there.
R.
Thanks, Russell. I discussed this upthread. The majority of the atmospheric longwave is emitted from well below the tropopause. Virtually none is from 100km. The “effective radiating altitude” is only about 5 km. And at that altitude, the dip of the horizon is only a couple of degrees … and that’s not even considering that much of the absorption is within the first km, and down that low, the mountains are above the true horizon.
w.