CO2 Experiment

[smerby]

Hi All,

Does anyone know of a lab experiment where realistic levels of C02 where used to measure temperature rises in a greenhouse effect reproduction. I have seen the experiments where pure C02 caused a 5C rise compared to regular air. It would be nice to see temperature rise results where C02 levels of 400 PPM, 600 PPM, or even 1000 PPM were used. Thanks for your help.

Bob

[WeatherRusty]

Hi All,

Does anyone know of a lab experiment where realistic levels of C02 where used to measure temperature rises in a greenhouse effect reproduction. I have seen the experiments where pure C02 caused a 5C rise compared to regular air. It would be nice to see temperature rise results where C02 levels of 400 PPM, 600 PPM, or even 1000 PPM were used. Thanks for your help.

Bob

That type of experiment does not measure the greenhouse effect of CO2. It demonstrate that the molecules of CO2 absorb radiant thermal energy. High up in the troposphere where the greenhouse effect is most effective, the temperatures are way below zero. It is not the direct warming of those molecules which produces the greenhouse effect. The slow down in the rate of thermal energy loss from the surface to space is the greenhouse effect. This involves the thickening of optical density to the wavelengths of radiation emitted by the surface. The temperature difference caused by this slowdown is of little relevance....the colder upper layers of air can not radiatively warm the already warmer surface. The net flow of energy is outward from surface to atmosphere.

[salbers]

True, though from the perspective of the surface, I think there is more longwave radiation coming down from above, even if it's from a colder layer, this brightness temperature is relatively warmer than it would have been without the extra GHG. This additional radiation helps keep the surface warmer.

I agree it would be hard to replicate what happens in the entire column of the atmophere in a lab experiment. At least though absorption spectra can be measured in the lab.

[smerby]

Thanks for you responses guys.

The thickening of the optical density and the net flow of energy outward from the surface to the atmosphere makes sense to me. So what I got from that C02 lab experiment (http://www.espere.net/Unitedkingdom/water/uk_watexpgreenhouse.htm) is that a placed black body bottom in each chamber emitted long wave wave radiant energy to the space inside the chamber. The pure C02 slowed the escape of long wave radiant energy so much that the ambient temperature in its chamber rose 5C warmer than the chamber filled with regular air. With all the technology and equipment out there, one would think that this experiment could be recreated in a lab to mirror the real atmosphere. I would like to see what 400, 500, or 1000 ppm of C02 would do in a lab experiment that mimics the real atmosphere as closely as possible, and see the measured results. I mean how much of a temperature rise will 1000 ppm actually cause in a real time measured experiment. This could do a lot to convince people of the effects of rising C02.

Thanks

Bob

Thanks

Bob

[salbers]

I wonder if the experiment linked to above could be better done with flourescent lighting that has less IR to worry about filtering it out?

It would be interesting to try and come up with a lab experiment. However simulating the way the various gases change (such a water vapor) over the various atmospheric levels with temperatures and pressures that change would be quite a challenge. Maybe there is a way to do this though with some simplifications.

Here's a simple, though fun science experiment on YouTube:

[WeatherRusty]

Thanks for you responses guys.

The thickening of the optical density and the net flow of energy outward from the surface to the atmosphere makes sense to me. So what I got from that C02 lab experiment (http://www.espere.ne...pgreenhouse.htm) is that a placed black body bottom in each chamber emitted long wave wave radiant energy to the space inside the chamber. The pure C02 slowed the escape of long wave radiant energy so much that the ambient temperature in its chamber rose 5C warmer than the chamber filled with regular air. With all the technology and equipment out there, one would think that this experiment could be recreated in a lab to mirror the real atmosphere. I would like to see what 400, 500, or 1000 ppm of C02 would do in a lab experiment that mimics the real atmosphere as closely as possible, and see the measured results. I mean how much of a temperature rise will 1000 ppm actually cause in a real time measured experiment. This could do a lot to convince people of the effects of rising C02.

Thanks

Bob

Thanks

Bob

The real greenhouse effect requires a vertical temperature gradient to work with. There is no such gradient in the chambers of that experiment. The greenhouse effect does not add energy to the system like the Sun does, it merely concentrates the available energy to within the lower troposphere. The upper troposphere becomes cooler (see qualifier in my next post) along with the stratosphere since the rate of energy *radiation* propagation upward is reduced.

I don't know that these conditions could be duplicated in a closed chamber, the temperature in the chamber equilibrates quickly due to convection. There can be no greenhouse effect under isotropic conditions.

[okie333]

The real greenhouse effect requires a vertical temperature gradient to work with. There is no such gradient in the chambers of that experiment. The greenhouse effect does not add energy to the system like the Sun does, it merely concentrates the available energy to within the lower troposphere. The upper troposphere becomes cooler along with the stratosphere since the rate of energy propagation upward is reduced.

I don't know that these conditions could be duplicated in a closed chamber, the temperature in the chamber equilibrates quickly due to convection. There can be no greenhouse effect under isotropic conditions.

So what you're saying is, the 500-1000mb thks would actually fall in an AGW scenario? Or is 500mb still the "lower" troposphere?

[BethesdaWX]

Hi All,

Does anyone know of a lab experiment where realistic levels of C02 where used to measure temperature rises in a greenhouse effect reproduction. I have seen the experiments where pure C02 caused a 5C rise compared to regular air. It would be nice to see temperature rise results where C02 levels of 400 PPM, 600 PPM, or even 1000 PPM were used. Thanks for your help.

Bob

The climate system and a chamber experiment are not the same thing, it is well known CO2 is a GHG and that is pretty basic but in the climate system there are many many factors at play to determine sensitivity.

In order to quantify how much effect CO2 has had so far via the scientific method, we must first:

1) Determine the dispersion of the gas (yes, this is still up for debate).

2) Understand the causative mechanism behind ENSO, and why the geomag flux ap correlates perfectly on a 6 year lag.

3) Understand the impact ozone destruction has had.

4) Understand how the Sun may influence the AO/NAO, which significantly alter global heat intake.

The process behind number 2 is a real headscratcher, because the correlation is preserved for 6 years of processing. If a geomag flux variation spike of 30 or more leads to a mod or strong nino 6 years later every time, then not only does the answer to El Nino have to lie in cloud variation and(or) ozone destruction, but the warming since 1979 can be explained fully by the Sun by statistical means taking into account the lag.

La Nina likely is the climate system's 'response' in negative feedback to the solar induced El Nino, and not driven by the Sun. Warmings always occur faster than coolings (see the Volstok Cores), which makes sense why you will never see a multi year strong El Nino, but see Multi year La Ninas in response (to balance).

The cooling from 1945 to 1965 is harder to explain by solar means and may be related to the PDO switching negative around 1945.

[WeatherRusty]

So what you're saying is, the 500-1000mb thks would actually fall in an AGW scenario? Or is 500mb still the "lower" troposphere?

Well no, not really. The surface radiation reaching the upper levels is gradually reduced with increasing heights promoting some cooling, but because the troposphere is well mixed by convection up to the tropopause, the whole troposphere as a unit is warmed. A warmer lower troposphere supporting higher specific humidity will release additional latent heat of condensation into the mid and upper troposphere. Lapse rates become more moist based and it cools less with increasing height.

This lapse rate feedback has a negative impact on surface warming. The lapse rate feedback is a negative feedback which partially counteracts the growing greenhouse effect, because as I stated earlier, the greenhouse effect depends on cooler air aloft to work with. We should hope for the tropical "hot spot".

Since the stratosphere supports a stable environment the same process of convective warming does not work there and the temperature is more dependent on the reduction in IR propagating upward, the stratospheric temperature cools, everything else remaining equal, ie. ozone....

[BethesdaWX]

Well no, not really. The surface radiation reaching the upper levels is gradually reduced with increasing heights promoting some cooling, but because the troposphere is well mixed by convection up to the tropopause, the whole troposphere as a unit is warmed. A warmer lower troposphere supporting higher specific humidity will release additional latent heat of condensation into the mid and upper troposphere. Lapse rates become more moist based and it cools less with increasing height.

This lapse rate feedback has a negative impact on surface warming. The lapse rate feedback is a negative feedback which partially counteracts the growing greenhouse effect, because as I stated earlier, the greenhouse effect depends on cooler air aloft to work with. We should hope for the tropical "hot spot".

Since the stratosphere supports a stable environment the same process of convective warming does not work there and the temperature is more dependent on the reduction in IR propagating upward, the stratospheric temperature cools, everything else remaining equal, ie. ozone....

The tropical hotspot exists on the terms that thermal increase is achieved through an alteration in the greenhouse effect, namely humidity assuming it's warmer oceans leading to increased moisture content of the atmosphere. If it is related to cloud cover and atmospheric momentum change, rather than water vapor or CO2 the profile will feature a surface trend slightly higher than the lower tropospheric trend through the mid troposphere since you'd have more SW entering transferring upon interaction canceling out any "hotspot" that would result from the increase in water vapor/CO2, since sensitivity to those gases is low relative to Radiative Forcing change that is imposed by an alteration in clouds. The lack of a hotspot confirms lower sensitivity and mainly natural causation, given the warming ceased in the middle of the 2000s in both the LT and the Surface. That should essentially give it away but many do not want to hear of contradictory evidence.

The stratospheric cooling thing is utterly worthless in determining the causative mechanism of the warming because tropospheric warming always coincides with stratospheric cooling regardless of the mechanism since all change in energy is achieved through the GHE profile, but it doesn't take an enhancement of the GHE to cool the stratosphere, simply the GHE existing results in equal profiling w/o any hotspot in the LT, but above the boundary of expansion cooling will result. It's mostly affected by ozone and aerosol values.

Proof: In the NH summer there is less CO2 present than in NH winter, the LT temps are warmest in the NH summer while the stratospheric temps are coolest in the NH summer, has nothing to do with CO2 count in this circumstance. All change in energy is processed through the GHE regardless of the source, in this case change in aerosol and ozone counts.

If the change exists due to alteration in cloud cover, it'd have to be driven by magnetic solar winds and the AO index, its key because the solar wind destroys ozone. So obviously the stratosphere should cool until solar activity diminishes, which it has...slight warming of the stratosphere has resulted as ozone was consistantly depleted through the mid 1990s and bottomed out through the early 2000s before slowly rebounding since.

[The_Global_Warmer]

Hi All,

Does anyone know of a lab experiment where realistic levels of C02 where used to measure temperature rises in a greenhouse effect reproduction. I have seen the experiments where pure C02 caused a 5C rise compared to regular air. It would be nice to see temperature rise results where C02 levels of 400 PPM, 600 PPM, or even 1000 PPM were used. Thanks for your help.

Bob

I clicked on your thread the other day and couldn't wait for an answer. I was excited to see the relpys...and I appreciate the good ones. But I also see some more talk about clouds and Geomag, which you asked nothing about. Which will probably end up in a long debate that has nothing to do with your question. I would love to see an aswer but I have the feeling it next to impossible to get a direct answer.

Like what would regular air consist of? How would it be affected by adding enough Co2 to go from 400ppm to 600ppm. Also look at the Earth. Snow and Ice are major game changers in all of these. If Co2 was 600ppm and arctic sea ice was gone by August 1st all the way gone. Then it would warm the Earth much faster than if the ice was the same as it is now on August 1st. That is just one example. A great question, but a very complex and loaded one.

[WeatherRusty]

Hi All,

Does anyone know of a lab experiment where realistic levels of C02 where used to measure temperature rises in a greenhouse effect reproduction. I have seen the experiments where pure C02 caused a 5C rise compared to regular air. It would be nice to see temperature rise results where C02 levels of 400 PPM, 600 PPM, or even 1000 PPM were used. Thanks for your help.

Bob

The lab experiments coupled with theoretical physics that have been done give us the information and confirmation you are looking for. In Earth's atmosphere as currently constituted (including atmospheric pressure), any doubling of CO2 produces a positive radiative forcing on climate the equal to 3.7W/m^2 as measured at the tropopause.

This energy increase when applied to the relevant black body equations is expressed as just under a temperature rise of 1.2C at the surface once radiative equilibrium is reestablished at the tropopause. This is the case in isolation before any consideration of complicating feedback mechanisms.

As I stated earlier, the actual temperature changes in the CO2 molecules at various concentrations (and surrounding gas) do not represent the greenhouse effect.

[WeatherRusty]

True, though from the perspective of the surface, I think there is more longwave radiation coming down from above, even if it's from a colder layer, this brightness temperature is relatively warmer than it would have been without the extra GHG. This additional radiation helps keep the surface warmer.

I agree it would be hard to replicate what happens in the entire column of the atmophere in a lab experiment. At least though absorption spectra can be measured in the lab.

This is another way of describing the same phenomena as what I did by mentioning optical density. Once CO2 absorbs outbound IR, half of that energy is subsequently radiated down toward the surface. All the countless absorptions and subsequent emissions in random directions slow the loss of energy to space.

[smerby]

Thanks for your replies. They all shed some light on how C02 affects the atmosphere. Weather Rusty you mentioned that the lapse rate feedback will have a negative impact on surface warming. I understand that temps decrease less with height in moist adiabatic situation, but how would that reverse surface warming. Would that occur by warming the upper levels of the trop through latent heat of condensation and weakening the vertical temp gradient and lessening the GHE? I also think that to convince everyday people and non scientists about the of the effects of current and future levels of C02 it would be more beneficial to let them visually see the results from an experiment. Maybe we do not have the technology to do that yet.

Thanks

Bob

[WeatherRusty]

Thanks for your replies. They all shed some light on how C02 affects the atmosphere. Weather Rusty you mentioned that the lapse rate feedback will have a negative impact on surface warming. I understand that temps decrease less with height in moist adiabatic situation, but how would that reverse surface warming. Would that occur by warming the upper levels of the trop through latent heat of condensation and weakening the vertical temp gradient and lessening the GHE? I also think that to convince everyday people and non scientists about the of the effects of current and future levels of C02 it would be more beneficial to let them visually see the results from an experiment. Maybe we do not have the technology to do that yet.

Thanks

Bob

The greenhouse effect works by partially confining thermal energy closer to the surface, while limiting the rate of propagation to higher levels where the effect is a cooling and thus a reduction in the rate of energy lost to space. If the lapse rate is weakened the temperature aloft will be warmer than it otherwise would be.

The Stephan-Boltzmann Law states that the energy radiated is proportional to the 4th power of the temperature, so a warmer upper air will radiate away energy much more efficiently to space than would a cooler condition. This is the exact opposite of what the greenhouse effect is doing, so this lapse rate feedback is negative. It is also most pronounced in the tropics and may even be reversed in the mid latitudes. The positive water vapor feedback and negative lapse rate feedback partially cancel each other out, with a slight nod going to the water vapor feedback.

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[BethesdaWX]

If the question is the effect of CO2 increase, convective overturning induced by the GHE could be better understood in looking at temps in the TLT, and now efficiently the climate system can shed energy initially and relatively can possibly be determined by that aspect as well as the speed of processing LW release through the total atmospheric window. Energy distributes through all molecules in the atmosphere and how much energy exists is what will be transferred in full porportional value in release, to restore balance to the SW budget.

The transfer of thermal energy to kinetic energy is something that could be missing significant details, and it can go both ways. Convective overturning is literally driven by the GHE, Wind and Convection is the process of the thermal to kinetic process in works. Which is why climate models show what they do, but this is only true of change induced by the means of LW and not SW.

So the TLT warming slightly without a hotspot suggests either a missing link in the processing of LW energy, or a different causative mechanism to the warming trend which could give a clue to sensitivity...and it comes back to how quickly energy is processed and released by the climate system, by any means whether it be through kinetic transfer or simply speed in processing.

[smerby]

Thanks for the input all.

Bob