What If There Was No Greenhouse Effect?
by Roy W. Spencer, Ph. D.
The climate of the Earth is profoundly affected by two competing processes: the greenhouse effect, which acts to warm the lower atmosphere and cool the upper atmosphere, and atmospheric convection (thermals, clouds, precipitation) which does just the opposite: cools the lower atmosphere and warms the upper atmosphere.
To better understand why this happens, it is an instructive thought experiment to ask the question: What if there was no greenhouse effect? In other words, what if there were no infrared absorbers such as water vapor and carbon dioxide in the atmosphere?
While we usually only discuss the greenhouse effect in the context of global warming (that is, the theory that adding more carbon dioxide to the atmosphere will lead to higher temperatures in the lower atmosphere), it turns out that the greenhouse effect has a more fundamental role: there would be no weather on Earth without the greenhouse effect.
First, the big picture: The Earth surface is warmed by sunlight, and the surface and atmosphere together cool by infrared radiation back to outer space. And just as a pot of water warming on the stove will stop warming when the rate of energy gained by the pot from the stove equals the rate of energy loss by the pot to its surroundings, an initially cold Earth would stop warming when the rate at which solar energy is absorbed equals the rate at which infrared energy is lost by the whole Earth-atmosphere system to space.
So, let’s imagine an extremely cold Earth and atmosphere, without any water vapor, carbon dioxide, methane or any other greenhouse gases – and with no surface water to evaporate and create atmospheric water vapor, either. Next, imagine the sun starts to warm the surface of the Earth. As the surface temperature rises, it begins to give off more infrared energy to outer space in response.
That’s the Earth’s surface. But what would happen to the atmosphere at the same time? The cold air in contact with the warming ground would also begin to warm by thermal conduction. Convective air currents would transport this heat upward, gradually warming the atmosphere from the bottom up. Importantly, this ‘dry convection’ will result in a vertical temperature profile that falls off by 9.8 deg. C for every kilometer rise in altitude, which is the so-called ‘adiabatic lapse rate’. This is because rising warm air parcels cool as they expand at the lower air pressures aloft, and the air that sinks in response to all of that rising air must warm at the same rate by compression.
Eventually, the surface and lower atmosphere would warm until the rate at which infrared energy is lost by the Earth’s surface to space would equal the rate at which sunlight is absorbed by the surface, and the whole system would settle into a fairly repeatable day-night cycle of the surface heating (and lower atmosphere convecting) during the day, and the surface cooling (and a shallow layer of air in contact with it) during the night.
The global-average temperature at which this occurs would depend a lot on how reflective the Earth’s surface is to sunlight in our thought experiment. ..it could be anywhere from well below 0 deg F for a partially reflective Earth to about 45 deg. F for a totally black Earth.
So, how is this different from what happens in the real world? Well, notice that what we are left with in this thought experiment is an atmosphere that is heated from below by the ground absorbing sunlight, but the atmosphere has no way of cooling…except in a very shallow layer right next to the ground where it can cool by conduction at night.
Why is this lack of an atmospheric cooling mechanism important? Because in our thought experiment we now have an atmosphere whose upper layers are colder than the surface and lower atmosphere. And what happens when there is a temperature difference in a material? Heat flows by thermal conduction, which would then gradually warm the upper atmosphere to reduce that temperature difference. The process would be slow, because the thermal conductivity of air is quite low. But eventually, the entire atmosphere would reach a constant temperature with height.
Only the surface and a shallow layer of air next to the surface would go through a day-night cycle of heating and cooling. The rest of the atmosphere would be at approximately the same temperature as the average surface temperature. And without a falloff of temperature with height in the atmosphere of at least 10 deg. C per kilometer, all atmospheric convection would stop.
Since it is the convective overturning of the atmosphere that causes most of what we recognize as ‘weather’, most weather activity on Earth would stop, too. Atmospheric convective overturning is what causes clouds and rainfall. In the tropics, it occurs in relatively small and strongly overturning thunderstorm-type weather systems.
At higher latitudes, that convection occurs in much larger but more weakly overturning cloud and precipitation systems associated with low pressure areas.
There would probably still be some horizontal wind flows associated with the fact that the poles would still be cooler than the tropics, and the day-night heating cycle that moves around the Earth each day. But for the most part, most of what we call ‘weather’ would not occur. The same is true even if there was surface water and water vapor…but if we were able to somehow ‘turn off’ the greenhouse effect of water vapor. Eventually, the atmosphere would still become ‘isothermal’, with a roughly constant temperature with height.
Why would this occur? Infrared absorbers like water vapor and carbon dioxide provide an additional heating mechanism for the atmosphere. But at least as important is the fact that, since infrared absorbers are also infrared emitters, the presence of greenhouse gases allow the atmosphere — not just the surface — to cool to outer space.
When you pile all of the layers of greenhouse gases in the atmosphere on top of one another, they form a sort of radiative blanket, heating the lower layers and cooling the upper layers. (For those of you who have heard claims that the greenhouse effect is physically impossible, see my article here. There is a common misconception that the rate at which a layer absorbs IR energy must equal the rate at which it loses IR energy, which in general is not true.)
Without the convective air currents to transport excess heat from the lower atmosphere to the upper atmosphere, the greenhouse effect by itself would make the surface of the Earth unbearably hot, and the upper atmosphere (at altitudes where where jets fly) very much colder than it really is.
Thus, it is the greenhouse effect that continuously de-stabilizes the atmosphere, ‘trying’ to create a temperature profile that the atmosphere cannot sustain, which then causes all different kinds of weather as the atmosphere convectively overturns. Thus, the greenhouse effect is actually required to explain why weather occurs.
This is what makes water such an amazing substance. It cools the Earth’s surface when it evaporates, it warms the upper atmosphere when it re-condenses to form precipitation, it warms the lower atmosphere through the greenhouse effect, and it cools the upper atmosphere by emitting infrared radiation to outer space (also part of the greenhouse effect process). These heating and cooling processes are continuously interacting, with each limiting the influence of the other.
As Dick Lindzen alluded to back in 1990, while everyone seems to understand that the greenhouse effect warms the Earth’s surface, few people are aware of the fact that weather processes greatly limit that warming. And one very real possibility is that the 1 deg. C direct warming effect of doubling our atmospheric CO2 concentration by late in this century will be mitigated by the cooling effects of weather to a value closer to 0.5 deg. C or so (about 1 deg. F.) This is much less than is being predicted by the UN’s Intergovernmental Panel on Climate Change or by NASA’s James Hansen, who believe that weather changes will amplify, rather than reduce, that warming.
If the atmosphere would be without any GHG would it be heated and cooled only from the earth surface. That would result in that the atmosphere over time would be heated close to the earths maximum day temperature. NOT the average temperature. Observe that is the maximum temperature not the average maximum temperature.
Warmer air raising, colder air sink. A cooling only from the bottom of the atmosphere is not very efficient an the warmer air will be kept in altitude.
Cold floor at home anyone but still warm at the ceiling?
The lapse rate would of course be working but the “average” atmosphere temperature would be decided from where it is heated.
A greenhouse effect without ANY GHG.
Adding any GHG or cloud will increase radiation = cooling capacity of the atmosphere. Yes, adding radiation capacity to the atmopsher will cool the atmosphere.
This is precisly the opposite from general AGW theory.
But in line with Dr spencers theory that cloud is a negative forcing.
Roy could you answer a few questions,my physics needs help.
1. What is the “turn-over rate”, the rate of absorption of infra-red vs emission for a given molecule of H20 or CO2? Would it be more correct to think that added GH gasses add more layers that absorb and emit thus slowing down the rate of cooling vs “trapping heat”?
2. How does the cooling rate via absorbing and emitting heat waves when there is no convection, compare to a rate of cooling when there is convection? Does extra CO2 resulting in heating by absorbing heat waves, cause increased convection and that increased convection allows heat to more quickly escape into the stratosphere and to some degree offset heating by absorption? Are there papers that researched this?
3. When a CO2 molecule that has absorbed infra-red, then collides with say an O2 molecule, transferring some kinetic energy, will the CO2 still emit the same wavelength it absorbed, or a different wavelength.
I am going to have to call BullSh*t on this!
The major disruption of stable air masses he proposes will still exist. They are still going to be the Lunar declinational tides, that move the heat off of the Equator into the mid latitudes. Unless he also proposes to remove the Moon, and it’s influence from the total equation, as they have done for the forecast models the NWS uses.
The atmosphere of Venus has the sun side thermal expansion, and poleward spiral movement to effect what polar cooling goes on, that discribes what will happen to the Earth, with out the moon, not the CO2 / water vapor he is going on about.
Without removing the Moon’s influence, as well as the GHG’s, there will still be the perturbation of large masses of warmed surface air, moved off of the equator into the mid latitudes, with the attendant Coriolis Effects, added into the momentum, still churning the global circulation.
What these people seem to NOT understand, is that the tidal effects of the Moon, are the major driving mechanism of the Weather. He thinks he is removing the Lunar tidal influences simply by taking away the GHG’s feed backs to the system.
When the overall driving forces that create the global circulation are put into the weather / climate equations in their proper strengths, and interactions we will be able to come up with methods, that will be able to forecast longer terms, (5 to 7 days) than the time it takes for the Moon to go from North to South, or back again.
Quote “Since it is the convective overturning of the atmosphere that causes most of what we recognize as ‘weather’, most weather activity on Earth would stop, too. Atmospheric convective overturning is what causes clouds and rainfall. In the tropics, it occurs in relatively small and strongly overturning thunderstorm-type weather systems.
At higher latitudes, that convection occurs in much larger but more weakly overturning cloud and precipitation systems associated with low pressure areas. /Quote
It is the convective over turning, due to the tidal displacement, that mixes the air having high thermal and moisture differentials, causing the rapid precipitation, that results in the lowered pressure along a front, in proportion to the precipitation rates.
It is the combination of the interplay between the heat retention of the GHG’s and the variation in the cooling effects, of the Lunar declinational tides spreading the heat and moisture off of the Equator, that is the weather short term.
Decade length periods, of climate shifts are due to the 18.6 year Mn long period, of the changes in declinational angle at 27.32 day cycles of culminations, interacting with the synod conjunctions of the outer planets, that produce the patterns, they cannot model, with just the physics of the atmosphere considered.
The response I will get from the mainstream, is that I have it backwards.
For their immense budget, huge payroll, and years of study, they cannot get a consistent 10 to 30 day forecast.
From my work, on less than a total $60,000 budget (of my own funds) over 25 years, I can show ~80% accurate daily forecasts for the next 4 years, I think the proof is in the pudding, so to speak.
http://www.aerology.com/national.aspx
Is where you can find the mentioned daily maps by my method.
blokeinfrance (14:27:07) :
Roy is referencing the Dry adiabatic lapse rate at 10 deg C per km roughly. On average the lapse rate in the lower atmosphere approximates the Saturated adiabatic lapse rate which in lower levels is around 2/3 of the Dry. Which ought to be a clue about the importance of the dominant minor atmospheric constituent gases.
I’ll have to think hard about the rest of his article.
Invariant (13:56:45) :
What would we talk about without the weather?
We would be talking about the burglars who stole the weather and tried to pawn it at Copenhagen. Fortunately for us, the hot items cooled substantially and all they could produce was a blinding snowstorm. It went over like a ton of ice off the high-dive at the YMCA And, just like the Titanic, they are still plowing about in the dark and short on the lifeboats.
Re: peter_dtm (14:19:11) :
“IR – is emitted by any thing that is above 0 deg Kelvin
so not only does the surface of the earth emit IR but ANY gas; liquid or solid that is above 0K does so to.”
Not so, at least in practical terms. Try looking for measurements of the IR spectrum of Helium, I doubt you will find much data as it does not radiate readily below the visible, and hardly at all at any wavelength when at earthlike temperatures.
Alex
Here is an interesting paper that claims there is no such thing as “greenhouse effect”:
http://arxiv.org/PS_cache/arxiv/pdf/0707/0707.1161v4.pdf
I like the lava lamp analogy of how our climate works. The system is so chaotic, it can never be modeled with any reasonable degree of certainty for distant future projections. The current generalized model of sun, ocean, and atmospheric interaction is probably as good as it’s going to get. Scientists should try to model a simple lava lamp first, to see if their models can predict with reasonable accuracy where blobs of all sizes of lava will be at any given time across all temperature ranges in 3D space. If they can do that, I’ll consider their climate models with a modicum of trust. Until then, NO.
Re¨ vigilantfish (14:57:43) :
“Surely the oceans would have convective effects even in you model sans water vapour? How would the variable heating of different land and sea masses affect your model?”
Roy wrote:
So, let’s imagine an extremely cold Earth and atmosphere, without any water vapor, carbon dioxide, methane or any other greenhouse gases – and with no surface water to evaporate and create atmospheric water vapor, either.
Alex
Dr. Spencer,
OT, but while you are here, I would appreciate it if you would clarify a statement made by Lord Monckton. Were the equations to derive temperature anomolies from the satellite MSUs calibrated using the surface data? If the surface data was adjusted incorrectly, could this have created an error in the lower troposphere data?
Re; pochas (14:46:12) :
“The lapse rate is maintained by the PVT relationships of air. If you heat an element of air, it will decrease in density. Then, archimedes principle will cause it to rise and cool (adiabatically) until its density again matches that of the surrounding air. Thus, even with a transparent atmosphere the sun will heat the earth, the earth will heat the layer of air next to the earth by conduction, causing it to become buoyant, it will rise, etc, etc, etc.”
I think you will find that for convection to be maintained in the long term you need not just heating from below but cooling from above. It is the cooling from above that is lacking in an IR transparent atmosphere.
Alex
Here is a concrete example that climate change really is happening.
Man is 4th victim of cold weather
FAR SOUTH SIDE | Found in park near home after 14-Degree Night
http://www.suntimes.com/news/metro/1969595,cold-weather-deaths-010210.article
Nice article. The earth, with its eccentric orbit around the sun, its rotation period, the inclination of its axis, the composition of its atmosphere and oceans, its strangely huge moon, its geography, geology and topology, etc., is ideally suited for life as we know it. The more I think about it, the more convinced I am that that there are way too many coincidences for the whole thing to be just a coincidence. Whoever it was that planned all this is obviously much more powerful and intelligent than we are and they will not suffer us to destroy it. And no cockamamie climate hypothesis conjured up by imperfect and dishonest men and women will change that.
Just a thought.
Dr. Spencer,
Talked to Happ and Wolk lately??
http://climatechange1.wordpress.com/
if i had to pick two processes it would be the sun and the ocean. then it gets complicated. to say the least.
I may have missed it in the verbiage above, but my impression, unscientific though it may be, is that the ROTATION of the Earth about its axis every 24 hours, at speeds approaching 1,000 miles/hour at the Equator, and the angular momentum therefrom, have something to do with the WIND, which is an aspect of weather, at least around here it is, but what do I know, not being a climatologist and all.
We may have long abandoned the bone in the beard, peer-reviewed shamanism of the past but we still seem to be caught in the twin headlights of conceit and consensus group-think when it comes to the “We’re all going to die” mantra!
Today’s Science may turn out, once again, to be yesterdays superstition. Who knows? Without the benefit of a time machine, we’ll never know!
As a small and rather insignificant species of sentients let us keep nibbling away at the margins of Nature that keep us ticking along. Adequate foodstuff, shelter, happiness come to mind!
As for the big stuff e.g. Why does big momma Gaia hate us so much, is it ‘cos we is bad, forget it folks.
Irrespective of how many £3 monthly contributions, to adopt a trilobite(sp?), the most-liberal of dinosaurs once made, they still got wiped out!
The reason that we can still argue, make love and blog is because Natures dice have rolled in our direction thus far.
No amount of taxpayers pennies, cast into the accounts of advertising companies, will make one iota of difference to what happens next.
It does, however, make an enormous change to the fortunes of those companies favoured by our political masters.
I would walk 500 miles and I would walk 500 more, if I truly believed that not driving my car would avert a catastrophe. I just don’t believe that is the case. I also believe that I’m being robbed.
The people should have been warned we would be in for another brutally cold winter this year. There was plenty of scientific evidence prior to the fact. The people could have prepared themselves better and many people could have been saved. The warmists have blood on their hands, or should I say, frozen blood on their hands. The victims families should file a class action law suit against the forecasting agencies and people should be fired for not doing the job we hired them to do.
I take no pleasure in posting articles of increased death due to global cooling, I only post them to make a point, for people to be outraged as I am, and for truth to Not be hidden.
Dr. Spencer,
I have a question speaking of temperatures, radiation and conduction. Not so much convection. In the hot summer, in Oklahoma it gets to be 100+ for usually 10-30 days. Setting in the shade on my patio you can just feel the hot IR radiation off the brown fences, roofs and the patio concrete. Uncomfortable! I recently put an atomizer in the tree at the far edge. This atomizer turns a few gallons per hour to a super fine mist over the patio.
My question, when the atomizer is turned on, there seems to be a marked drop in the temperature you perceive, I mean immediately, before the evaporation of the air and evaporation off the hot concrete has occurred and the air has begun to cool. I have always thought this was related to the absorption of the IR radiation because the mist is between myself and the fences, roofs and concrete. Since I’m sitting in the shade, the visible spectrum is reduced and most radiation would be in the IR portion. Does water vapor then absorb a very large portion? It’s a weird effect. Of coarse, after 10-15 minutes it then feels 85 degrees not 105 but by then the patio is lightly wet and the heat in the concrete has dispersed and the air around has cooled.
Could the immediate drop be strictly IR absorption of the water vapor and droplets? Does water absorption bands absorb that much? Never have been able to pin that down.
“Cold Lynx (15:14:10) :
[…]
Adding any GHG or cloud will increase radiation = cooling capacity of the atmosphere. Yes, adding radiation capacity to the atmopsher will cool the atmosphere.
This is precisly the opposite from general AGW theory.”
Attention: as explained by Willis in The Steel Greenhouse, your “GHG cloud” will radiate (to cool down) upwards and downwards. So a cooling down of the cloud leads to a slight warming up of the earths surface! (Which in turn will radiate upwards, warming up the cloud again etc…)
James Hansen has headed NASA’s Goddard Institute for Space Studies since 1981. Prior to that, his Wikipedia page says that “[a]fter graduate school, Hansen continued his work with radiative transfer models and attempting to understand the Venusian atmosphere. This naturally led to the same computer codes being used to understand the Earth’s atmosphere. He used these codes to study the effects that aerosols and trace gases have on the climate.” This is quite worthy of note.
It seems Hansen’s views of the effects of greenhouse gases on the Earth’s atmosphere may have been influenced by his earlier research interests. (For the benefit of those who may not know, the atmosphere of Venus consist of 96% CO2, and the greenhouse effect makes it the hottest planet in the Solar System.)
One can only speculate whether there would have been any greenhouse gas scare or an AGW movement at all, if the person who headed one of the leading institutions in climate science for 30 years ago wasn’t an expert in the atmosphere of Venus.
Would we have the AGW debate we are having now if Richard Lindzen was the head NASA GISS, instead of James Hansen? And just how Climate Science would have been shaped if Lindzen had the vast resources that Hansen enjoyed for the last 30 years.
Peter (15:12:36) :
Its not pedantic to be consistent with the laws of physics.
What Roy Spencer is talking about is what would happen if the Earth had a thin isothermal atmosphere. But the radiative properties of the atmosphere depend on its composition.
DirkH (14:42:14) :
Unfortunately Willis’ “Steel Greenhouse” is unphysical rubbish. Putting hot food in a Dewar flask does not cause the food’s temperature to rise – it simply reduces the rate at which the food cools.
Jim Steele
Study the global radiation relationships discovered by Ferenc Miskolczi.
Miskolczi’s theory by Zagoni
The new climate theory of Dr. Ferenc Miskolczi
Roy Lofquist
See:
Constructal theory of global circulation and climate Reis & Bejan, International Journal of Heat and Mass Transfer, Volume 49, Issues 11-12, June 2006, Pages 1857-1875
wayne (16:20:07) : Sorry, correction myself again.
“Could the immediate drop be strictly IR absorption of the water vapor and droplets?”
Should be ‘by’, not ‘of’.
Fascinating material, Dr. Spencer, thank goodness for people like you, Dr. Lindzen, and Dr. Pielke to leaven all of the alarmist nonsense, and return common sense to the discussion.
You are all mentioned in a wonderful article in a magazine for young people:
http://www.buffalobeast.com, Pants on Fire (forgive the lewd implication).