Why CO2 does not govern the earth's surface temperature

Ask yourself what would happen if all non-condensable trace gases were removed from the atmosphere. The Earth's global mean temperature would drop
by nearly 35 degrees Celsius in 50 years. Virtually all of the water vapor would condense and be removed from the atmosphere. The amount of water
vapor in the atmosphere is a function of temperature and adding carbon dioxide to the atmosphere increases the Earth's GMT. Water vapor rises and falls
as the temperature rises and falls. The concentration of atmospheric carbon dioxide does not vary with temperature or dense out of the atmosphere like
water vapor. Water vapor is a climate feedback, a positive feedback that approximately doubles the temperature change caused by a rise in atmospheric
carbon dioxide.

Climate: Why CO2 Is the “Control Knob” for Global Climate Change | TIME.com

Water vapor is the most important agent behind the greenhouse effect—it has more than twice the warming effect that CO2 does, and water vapor and clouds account for about 75% of the Earth’s greenhouse effect, with CO2 accounting for 20% and the other greenhouse gases and aerosol particulates accounting for the remaining 5%. But despite that, it is changes in CO2 concentrations in the atmosphere that is responsible for changing the climate—in other words, as the research team led by the physicist Andrew Lacis makes clear in the Science paper, CO2 is the principal “control knob” governing the Earth’s temperature.

Lacis and his colleagues note that water vapor, while much more common in the atmosphere than CO2, has a short atmospheric lifespan, eventually condensing and falling as precipitation as it responds to changes in temperature and air pressure. CO2, however, is a well-mixed gas that just builds up in the atmosphere over time, which is part of the reason why carbon dioxide emitted today can have a warming effect that lingers for hundreds of years. The amount of water vapor in the atmosphere is a function of temperature—the warmer it gets, the more water will evaporate and the more water the atmosphere can hold. And water vapor does have a warming effect, and it can act as a positive feedback—the warmer it gets, the more water vapor there is in the atmosphere, which makes it warmer, and so on.

But as the Science authors point out, it’s CO2 that provides the stable temperature structure for the climate, the skeleton on which climate is built. Here’s how they know: Lacis and his colleagues created a simple climate experiment where they removed all CO2, aerosols and other greenhouse gases from the model atmosphere, but left in the water vapor. They let the climate model run forward in time, and the results were startling. In just one year without any carbon, global annual mean temperature fell by 4.6 C. After 50 years, the global average temperature had fallen to -21 C, 34.8 C less than it is today. As the average global temperature fell, so did the water vapor in the atmosphere, while global sea ice cover increased from 4.6% to 46.7%, further increasing the planetary albedo effect and freezing the planet further. Without carbon and other greenhouse gases, we’d be living on Planet Hoth.

See also, Explaining how the water vapor greenhouse effect works (skepticalscience.com)

 

Jason Smerdon is obviously a science denier who is full of BS...

It is IMPOSSIBLE to trap heat. There is no such thing as a perfect insulator.

Additionally, per the Stefan Boltzmann Law, if Earth is supposedly "radiating less", then Earth would be COOLER, not warmer...

 

Notice how vague he is, no energy based numbers at all in it, he is being misleading and deceptive since the energy transfers is actually very small.

Really you have no idea how little of the IR window that CO2 absorbs OLWR in?

He is Bsing you when he makes this crap up:

Actually most of it is at the 15 micron band, the other two spikes are at the low end of the energy area thus have little effect. It doesn't soak up much because most of the OLWR is OUTSIDE of the main CO2 absorption band.



LINK

 

Ah. the notorious study stating that CO2 greenhouse gas traps exponentially more heat in the earth's atmosphere than let's say, water vapor...Where's the environmental science proving that? Hum?

BTW, stating that CO2 increases are occurring in the atmosphere doesn't show anything in regards to increasing climate change if CO2 hasn't been proven to be the dastardly trapper of heat in the atmosphere you claim it to be.

 

What Jason Smerdon said is correct if you read his entire article. I have copied one paragraph of the article.

"You’ve probably already read that carbon dioxide and other greenhouse gases act like a blanket or a cap, trapping some of the heat that Earth might have otherwise radiated out into space. That’s the simple answer. But how exactly do certain molecules trap heat? The answer there requires diving into physics and chemistry."

The analogy of a blanket is a poor one that doesn't explain what is physically happening. What he says in the paragraph following that one is the
physical explanation for what is happening. He says, " As CO2 soaks up this infrared energy, it vibrates and re-emits the infrared energy back in all directions. About half of that energy goes out into space, and about half of it returns to Earth as heat,"

What he doesn't say is that the process is more complicated than the above description since a carbon dioxide molecule can collide with a nitrogen or oxygen
molecule, for example, and transfer kinetic energy to them, thus warming the atmosphere. He also doesn't say that photons emitted away from the Earth's surface
are often reabsorbed by other carbon dioxide molecules and then the same process is repeated. Carbon dioxide molecules only "trap heat" for a matter of
microseconds before emitting the energy away or by colliding with other air molecules. Energy from the earth-atmosphere system is lost to space when the
density of carbon dioxide molecules drops to a level where there aren't enough nearby carbon dioxide molecules to absorb an emitted carbon dioxide photon.
As the concentration of atmospheric carbon dioxide increases, the energy radiated to space occurs at a higher elevation and lower temperature, thus reducing
the efficiency of the earth-atmosphere system to remove heat. As the concentration of atmospheric CO2 increases, the spectrum of CO2 emission broadens
with nearly all of the emission occurring near the edges of approximate 14 to 16 micrometer band. It is the "back-radiation" that warms the Earth's surface either
directly or indirectly by warming the atmosphere or by transferring energy to water vapor.

I think that the phrase "trapping heat" is appropriate but like Jason Smerdon says it is a simple explanation that doesn't tell us what is physically happening.
Increasing greenhouse gas levels warm the atmosphere and makes the earth-atmosphere system less efficient at radiating energy back to space
The Earth's surface temperature must increase in order to balance the energy at the top of the atmosphere and at the Earth's surface as a response
to increasing levels of greenhouse gases.


Climate and Earth’s Energy Budget (nasa.gov)

"When greenhouse gas molecules absorb thermal infrared energy, their temperature rises. Like coals from a fire that are warm but not glowing, greenhouse gases then radiate an increased amount of thermal infrared energy in all directions. Heat radiated upward continues to encounter greenhouse gas molecules; those molecules absorb the heat, their temperature rises, and the amount of heat they radiate increases. At an altitude of roughly 5-6 kilometers, the concentration of greenhouse gases in the overlying atmosphere is so small that heat can radiate freely to space."

"Because greenhouse gas molecules radiate heat in all directions, some of it spreads downward and ultimately comes back into contact with the Earth’s surface, where it is absorbed. The temperature of the surface becomes warmer than it would be if it were heated only by direct solar heating. This supplemental heating of the Earth’s surface by the atmosphere is the natural greenhouse effect."

 

The diagram below shows the spectrum of carbon dioxide absorption and its overlap with water vapor. Carbon dioxide absorbs energy near the
Earth's blackbody peak. Notice the big chunk taken out of the blackbody curve centered around 15 micrometers (CO2 and water vapor) and the
much lower temperature of that chunk viewed from space. The smaller chunk at 9-10 micrometers represents the effects of tropospheric ozone.

Climate and Earth’s Energy Budget (nasa.gov)

"Carbon dioxide forces the Earth’s energy budget out of balance by absorbing thermal infrared energy (heat) radiated by the surface. It absorbs thermal infrared energy with wavelengths in a part of the energy spectrum that other gases, such as water vapor, do not. Although water vapor is a powerful absorber of many wavelengths of thermal infrared energy, it is almost transparent to others. The transparency at those wavelengths is like a window the atmosphere leaves open for radiative cooling of the Earth’s surface. The most important of these “water vapor windows” is for thermal infrared with wavelengths centered around 10 micrometers. (The maximum transparency occurs at 10 micrometers, but partial transparency occurs for wavelengths between about 8 and about 14 micrometers.)"

"Carbon dioxide is a very strong absorber of thermal infrared energy with wavelengths longer than 12-13 micrometers, which means that increasing concentrations of carbon dioxide partially “close” the atmospheric window. In other words, wavelengths of outgoing thermal infrared energy that our atmosphere’s most abundant greenhouse gas—water vapor—would have let escape to space are instead absorbed by carbon dioxide."





All atmospheric gases have a unique pattern of energy absorption: they absorb some wavelengths of energy but are transparent to others. The absorption patterns of water vapor (blue peaks) and carbon dioxide (pink peaks) overlap in some wavelengths. Carbon dioxide is not as strong a greenhouse gas as water vapor, but it absorbs energy in wavelengths (12-15 micrometers) that water vapor does not, partially closing the “window” through which heat radiated by the surface would normally escape to space. (Illustration adapted from Robert Rohde.)

 

Water vapor is in an equilibrium that people can't shift significantly with current technology.

 

Your claim of a problem in the paper based on the relationship between temperature and water vapor is risible. Water vapor varies with altitude and local wind and weather conditions incomparably more than it does with a 1 or 2C increase in temperature. The effect of that microscopic additional amount of water vapor on IR absorption would be at the very limits of measurability.

Sorry, but they are at this moment laughing at you.

 

Yes, it is, but for every cotton CO2 blanket there are already 50 wool H2O blankets.

 

That's roughly analogous to how the fibers of a blanket slow the loss of heat from one's body. Each blanket molecule is receiving and transmitting kinetic (heat) energy almost instantaneously, like the CO2 and H2O molecules in the atmosphere.

Yes, like I said: one cotton CO2 blanket for every 50 wool H2O blankets. Doubling the cotton blankets will have almost no effect at the bottom of the stack, but because the wool H2O blankets can't be on top, there will be an effect there. The top CO2 blanket will be slightly cooler than the previous top one, which will be slightly warmer.

Additional CO2 does slow the loss of heat from the earth's surface via IR radiation. The effect is just derisory compared to that of H2O and the CO2 that was already present in pre-industrial times.

 

Absorption/emission of IR radiation in the relevant wavelengths.

 

Wrong. It is very close to being accurate because a 1 or 2C increase in temperature has an insignificant effect on water vapor concentration, and a far smaller effect on IR absorption by water vapor. Water vapor varies far more with altitude and local weather conditions, as anyone with any knowledge of climate science is aware.

It's not erroneous. The difference resulting from including the increase in water vapor would be a fraction of the thickness of the blue curve. Water vapor is in an equilibrium that would barely be affected by a temperature increase of a few C, and its IR absorption would be affected far less.

Yes, one can, because the effect is microscopically small in the relevant temperature range.

It is exactly as shown in the graph, because the difference is a fraction of the width of the blue curve.

It is essentially impossible for CO2 to drop much below 200ppm as a result of natural processes.

No, only slightly less.

And the result is similar: almost no change in temperature.

Nope. Only slightly higher.

Wrong. Anyone with a little understanding of atmospheric chemistry immediately knows your "argument" is bull$#!+ because a temperature difference of only a few C can't possibly have any significant effect on either H2O concentration or IR absorption.

Wrong, because it is close enough to being constant.

No, it just ignores an insignificant variable.

That is exactly why your "argument" is laughable: clouds, weather, changes in winds, altitude, seasons, latitude, day-night variation, etc. all cause vastly greater differences in H2O concentration than a few C in temperature ever could. The effect of temperature is completely swamped by other sources of variation that cause H2O concentration to vary by an order of magnitude between the driest and wettest places on the earth's surface, and that's not including the even greater effect of altitude and winter cold at high latitudes where there is effectively no sunlight for months at a time.

Right. Notice the microscopically small effect of a few C increase in temperature on H2O concentration within typical earth surface temperature ranges of 10C-30C. The effect on IR absorption is of course far smaller, as it is logarithmic.

 

We have been through this. People buy blankets even though they are not perfect insulators. They do this because a blanket can warn one's body even though it is cooler than one's body.

It is the effective radiating layer in the upper troposphere that is cooler, not the surface, and the effect of additional CO2 on temperature is essentially confined to that layer.

 

So you are saying that it is valid for the model to use today's sea level water vapor concentration for Earth's atmosphere when the atmospheric carbon
dioxide level is 10 ppm and the water vapor levels throughout the troposphere are modeled with HITRAN code using 80% relative humidity?
Earth's water vapor level remains the same for this model for all doublings of atmospheric carbon dioxide up to 1600 ppm. This was done even though
water vapor is a feedback that adjusts to temperature and there would be far lower levels of atmospheric water vapor if atmospheric carbon dioxide
were to drop to 10 ppm with all other atmospheric gases held constant at today's levels. The author, David Coe, does not even discuss this anywhere
in the article. The only mention of it is in the caption above Table 2. It makes for simple calculations and a simple model but the results are bogus.

An article published in Science is described here, NASA GISS: How Carbon Dioxide Controls Earth's Temperature
reveals how removing all non-condensable greenhouse gases would plunge the earth into an ice age. That would
virtually eliminate all water vapor. However, the article written by David Coe and company, used a model that doesn't allow
water vapor to decline rapidly if atmospheric carbon dioxide drops to 10 ppm or allow water vapor to rise if carbon dioxide levels increase to
1600 ppm. That is why he gets very little global mean temperature change
when he varies atmospheric carbon dioxide or methane or nitrous oxide.

 

Meaning that people can't affect the amount of water vapor in the atmosphere?...Oh I see, this is the whole point of CO2 emphasis: that man is creating an abundance of CO2 in the atmosphere (and not that environmental science evidence shows that too much CO2 in the atmosphere causes climate change catastrophe).

 

Right. The anti-fossil-fuel hysteria-mongers' claim that increased CO2 will somehow lead to a significant increase in atmospheric concentration of water vapor and thus water vapor IR absorption is simply false.

Pretty much.

 

I'm not convinced 10ppm is a meaningful datum, as it is impossible for CO2 to get anywhere near that low in any plausible scenario. But certainly the model is valid at 100ppm, which is still far lower than CO2 has ever been, or could be in the future.

Which is close enough to be accurate, as the effect of CO2 on surface temperature in the plausible range is so tiny.

That's not clear. As CO2 is reduced, there is a threshold effect beyond which the CO2 window in the upper troposphere is no longer closed, and water vapor begins to emit significant IR radiation directly to outer space, radically changing the radiative heat transfer regime and dramatically reducing water vapor through a positive feedback loop that results in a "snowball earth." I have no idea if that threshold is at 10ppm, 1ppm, or some other number, but it is certainly far lower than any physically plausible number. CO2 is currently ~400ppm, and there is zero probability that it will decline to less than 200ppm, which is below Ice Age level.

Because it is irrelevant to any physically plausible atmosphere.

No, the results accurately show the effect of CO2 on surface temperature for the relevant range of plausible CO2 concentrations.

Yes, because of the threshold effect I described above. That can't happen as long as the CO2 window in the upper troposphere is closed so water vapor is not emitting significant IR radiation directly to outer space. And as long as the CO2 window is closed, CO2's effect on surface temperature is derisory.

Because it is not clear that 10ppm is low enough to open the CO2 window, while zero certainly is low enough. See how that works?

Because once the CO2 window in the upper troposphere is closed, additional CO2 has almost no effect on surface temperature and thus water vapor.

Right: as long as the IR window is closed at a sufficient altitude that water vapor can't emit significant IR radiation directly to outer space, water vapor is so abundant in the lower atmosphere that other greenhouse gases are irrelevant to surface temperature.

 

The study's conclusion is based on a patently false and highly disingenuous assumption that the effect of CO2 concentration on surface temperature is uniformly logarithmic down to zero. But in fact, there is a threshold effect at some very low concentration of CO2 that closes the CO2 window in the upper troposphere, preventing water vapor from emitting significant IR radiation directly to outer space. Near the threshold, additional CO2 has an enormous impact on surface temperature through a positive feedback loop, but beyond that point, almost none because water on >90% the earth's surface is liquid (i.e., except at the poles and very high elevations,) and water vapor is thus at equilibrium in the lower troposphere, swamping the effects of all other greenhouse gases on surface temperature.

 

It's far better than the analogy of a greenhouse. At least the physical mechanism is similar: with blankets as with GHGs, there is a logarithmic relationship of thickness to effect. With a greenhouse, there is either a layer of glass blocking convection or there isn't.

That is a very misleading and wildly inaccurate explanation. How much IR goes out into space depends on how much CO2 is above the emitting molecule, but ultimately, it all goes out into space because that is the only way the earth can reach any given stable surface temperature. Much like a blanket enables your body to reach a higher stable surface temperature by slowing the loss of heat through IR radiation and convection.

Wrong. That process happens just as often in reverse, with a transfer of kinetic (heat) energy from an N2 or O2 to a CO2 molecule, which then radiates it outward by emitting IR.

No, the equilibrium point just rises because geometrically, a photon emitted at a higher altitude has a larger window to escape to outer space through. The efficiency of heat removal is unaltered because while the emission temperature is lower, the concentration of emitting molecules at the effective emission altitude is higher, and so is the probability that an emitted photon will escape to outer space.

No, the back radiation has almost no effect on the earth's surface temperature because it is all absorbed and re-emitted by water vapor in the lower troposphere long before it reaches the ground.

No. As explained above, it just changes the effective emission altitude and temperature, like adding a cotton blanket to the top of a stack of 50 wool blankets.

False, as explained above. The effect is confined to the effective emission altitude because downward IR is all absorbed and re-emitted by water vapor long before it gets near the ground. The stack of blankets gets higher, but you don't feel any warmer.

False, as explained above.

What NASA neglects to mention: it is specifically the drastically reduced concentration of water vapor that becomes so small that heat can radiate freely to outer space, because the temperature at that altitude is so low, the water vapor has all condensed out. So IR radiation emitted at that altitude can reach outer space, but it can't reach the ground because of all the water vapor below it, waiting to absorb it.

That is extremely misleading and disingenuous. The amount of IR energy that ever gets back down to the earth's surface from the effective emission altitude is far too small to be measured.

By maybe 0.01C...

Utter garbage. The greenhouse effect at the surface is effectively all due to water vapor, not CO2. Additional CO2 only changes the effective emission altitude and equilibrium temperature thereat, and has almost no effect on the earth's surface temperature.

 

All technically accurate, but highly misleading, as it mixes significant and relevant physical relationships with insignificant and irrelevant ones, and pretends they are all equally significant and relevant.

No, that is just baldly false. CO2 has a very strong positive feedback on temperature, but only in a temperature range so low that the earth's surface is mostly frozen. Once temperatures are high enough that >90% of the earth's surface is at a temperature where water is liquid, the equilibrium level of water vapor dominates the effect of all other greenhouses gases on surface temperature.

No. Water vapor accounts for more than 90%, CO2 probably less than 5%.

As it is at equilibrium, the fact that it is transient is utterly irrelevant.

Wrong. CO2 is absorbed by the oceans and by plants, shellfish, plankton, etc. and thus is also at a natural equilibrium unless more is continuously added by burning fossil fuels, major volcanic activity, etc. than can be absorbed.

Highly misleading. The increase in water vapor IR absorption with temperature in the relevant range is insignificant as the positive feedback is far too small to be relevant to surface temperature.

Again, that is highly misleading. That model opens the CO2 window, which as far as we know has never been open in the whole history of the planet, and cannot be opened under any physically plausible scenario. It's like simulating the effect of price on bread consumption by assuming a price of zero, and noting that no bread would be produced at that price, and thus consumers would not consume any bread if it were free! Additional CO2 would no doubt have a large effect on temperature if there were so little of it in the atmosphere that the CO2 window was open, and water vapor could emit significant IR radiation directly to outer space. But there has never been that little CO2 in the atmosphere, and can't be, so the relationship is irrelevant to the effects of actual greenhouse gases in the actual atmosphere.

skepticalscience is one of the most dishonest websites on the Net.

 

Viewing emissions from space understates water vapor's role because H2O all condenses out below the altitude from whence emissions can reach space.

That is a bald falsehood. The effective emission altitude simply reaches a new equilibrium.

And that window is already fully closed at CO2 levels far below the pre-industrial level, so adding more CO2 has almost no effect on surface temperature.

No, the window was already completely closed even in the Ice Ages, when CO2 was at half the current level because more was absorbed by the oceans.

And even a lot less CO2 than the pre-industrial level is ample to exhaust that effect.

But having no further effect if the amount is increased, because the window is already completely closed at far lower levels.

 

Quite the contrary. I've explained things to you all several times, and you've all run each time. All you've offered is "I LIKED THE RESULTS, SO IT MUST BE TRUE!"

I pointed out that the paper only managed a simple 1-D model of an idealized atmosphere. That is, it's where climate science was in the 1970s.

I pointed out that the real world demonstrates ECS has to be > 2.0

I pointed out that one paper with bad methodology by non-climate-scientists does not overturn a consensus.

Whatever. Preach to your cult here. That'll change things. Really it will.

 

According to that theory, everything in an area should freeze the instant the sun sets. Since it doesn't, your theory there is clearly very wrong.

 

Irrelevant conclusion.

 

Absolutely wrong, which causes your really dumb theory to faceplant hilariously.

People have shifted it, and we have measured that. Absolute humidity has risen, just as AGW theory said it would.

I don't know if you're just that completely ignorant of the basics, or if you're lying deliberately for the glory of your cult. It doesn't really matter. Since you're just screaming crazy propaganda, there's no reason for anyone to pay attention to you.