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Is CO2 a negative feedback within earth's climate system?
#1
Hi all,

Why is positive or negative feedback important?
Because of the currently dominant GH " theory" based paradigm in climate science we are supposed to be (very) concerned that our CO2 emissions are causing global warming. This is because the paradigm advocates, without any evidence, that, our CO2 emissions are increasing the supposed greenhouse effect, and that will make our planet warmer. If this were the case then CO2 would be a positive feedback, increasing any change towards warming.

The IPCC itself defines a positive feedback as something that increases the direction of change, and a negative feedback as something that reduces the direction of change. This is the widely accepted definition of what positive and negative feedbacks are, and do.

Wikipedia describes a positive feedback as follows -
"Positive feedback tends to cause system instability. When the loop gain is positive and above 1, there will typically be exponential growth, increasing oscillations or divergences from equilibrium.[3] System parameters will typically accelerate towards extreme values, which may damage or destroy the system,"

Wikipedia describes a negative feedback as follows -
"Negative feedback occurs when the result of a process influences the operation of the process itself in such a way as to reduce changes. Negative feedback tends to make a system self-regulating; it can produce stability and reduce the effect of fluctuations. Negative feedback loops in which just the right amount of correction is applied in the most timely manner can be very stable, accurate, and responsive."

In short, positive feedback/s leads to instability, and negative feedback/s causes a system to be stable. It is therefore obvious that earth's climate system, which within quite narrow limits IS stable, must be dominated by negative feedbacks, otherwise the climate system of this planet would already have run away. It has not, at least partly because it is dominated by the negative feedbacks of the oceans thermal inertia, and the water cycle which acts much like a thermostat.

1) It is the case that CO2 directly reduces warming, and reduces cooling at earth's surface, and therefore is a negative feedback at earth's surface?

It is often said only water goes through phase changes in earth's climate regime. This is WRONG.
CO2 is dissolved, and degassed by the oceans. These are phase changes, from gas to liquid when being absorbed by the oceans (exothermic reaction - gives off heat / energy), and from liquid to gas when being de-gassed by the oceans (endothermic reaction - requires heat / energy).

CO2 is absorbed in large quantities in the cold ocean around Antarctica, where the exothermic reaction (from gas to liquid) will reduce the oceans cooling (negative feedback),
and, the tropical oceans mostly de-gass CO2 (liquid to gas - endothermic reaction), where this gaseous release will reduce ocean warming (by direct sunlight), again this is a negative feedback. And, all in agreement with Henry's law.

CO2, in effect, has trapped "cold", or at least a requirement for heating, and transported it from the Antarctic ocean to the tropical oceans, by the ocean currents.

2) It is the case that CO2 is a negative feedback within earth's atmosphere?

Recycling of Heat in the Atmosphere is Impossible: A Note from Nasif S. Nahle
Excerpt -
The principal physical factor that inhibits the recycling of heat in the atmosphere is the degradation of the energy each time it is absorbed and emitted by any system. This degradation of energy is well described by the second law of thermodynamics6, whose fundamental formulation is as follows:

The energy is always dispersed or diffused from an energy field with lesser available microstates towards an energy field with higher available microstates.

In other words, the energy is always dispersed or diffused from the system with a higher energy density towards the system with a lower energy density.
"

A very simple explanation by Richard111 in this comment at WUWT.
"Radiation is transport of energy not heat. High frequency radiation has high energy levels and low frequency radiation has low energy levels. Planck's rule.
If you could create a laser that emits a very narrow band of radiation of about 2 or 3 microns wide and direct that radiation at a black body, Wien's Law will predict the maximum possible temperature. The black body, being a black body, will be radiating a much wider band of radiation and thus will not quite reach the predicted temperature. EVER!
CO2 molecules in the atmosphere are effectively black bodies with an emissivity/absorbance factor of 1 over the electromagnetic range 13 to 17 microns and two further bands centred around 2.7 and 4.3 microns. The CO2 molecules have ZERO emissivity/absorbance at all other radiation frequencies (apart from one very weak band at ~1.9 microns which seems to be ignored).
CO2 is a gas with a lower heat capacity than standard air thus the CO2 easily aquires the local air temperature via kinetic collisions with other other molecules in the atmosphere. These collisions effect the vibrational levels of the CO2 molecule to raise the molecule's temperature to the local air temperature.
Peak radiative temperature of 13 microns is ~223K (-50C) from Wien's Law.
From the surface to the tropopause, some 80% of the total atmosphere, the air temperature is much warmer than -50C. Thus all the CO2 molecules in the atmosphere, from the surface to the tropopause, will be fully occupied RADIATING over the 13 to 17 micron band. These molecules are in no condition to ABSORB any 13 to 17 micron radiation from the surface. Also the surface will be unable to absorb any so called 'back radiation' from the CO2 as IT IS ALSO TOO WARM!
When the sun is shining the CO2 in the atmosphere can absorb energy in the 2.7 and 4.3 micron bands and little, if any, of that energy will reach the surface. The CO2 molecules are unlikely to re-radiate in the 2.7 and 4.3 micron bands as this requires the molecules to reach temperatures in excess of 200C, not encountered in the atmosphere, but those CO2 molecules can emit strongly at the lower frequency levels of 13 to 17 microns but the surface is too warm to absorb at those bands. CO2 has some 3,800 lines of absorbance/emittance over the 13 to 17 micron band making it quite effective at converting high energy radiation to low energy radiation.
Increasing or decreasing the quantity of CO2 in the atmosphere will not change the radiative characteristics of the CO2.
CO2 cools the atmosphere but is most effective above the tropopause where radiation can escape directly to space. By cooling the top of the atmosphere CO2 helps maintain the convective path for heat up through the atmosphere otherwise known as the lapse rate.
To blame CO2 in the atmosphere for hurricanes and other extreme weather events is absolutely ludicrous.
"

In short, CO2 is a negative feedback at earth's surface. CO2 is also a coolant in earth's atmosphere, which is not surprising as a radiatively able gas, such as CO2, has more ability to redistribute heat / energy than a gas that has no radiative ability. If the concentration in a mixture of gases of the radiatively able gases is increased, then the mixture of gases will have to have more ability to redistribute heat / energy. That is not warmer.

Why is it important that the oceans, water vapour and CO2 ARE negative feedbacks?

The IPCC ignored water in the atmosphere as much as it could (for example water vapour [THE radiatively able gas of the atmosphere] is not given a greenhouse gas value compared to CO2 by the IPCC) to avoid the issue that they are obviously looking at earth's climate system from the wrong view point. In short, they are using the wrong paradigm. That is why the IPCC et al tries to portray water vapour and CO2 in particular, as positive feedbacks.

The oceans and the water cycle are the dominant and negative feedback within earth's (stable) climate system, AND, CO2 is also a negative feedback and coolant within earth's climate system. The GH "theory" based paradigm that AGW fears are based upon has failed and it is already way past the time it should have been abandoned.
The whole aim of practical politics is to keep the populace alarmed
(and hence clamorous to be led to safety)
by menacing it with an endless series of hobgoblins, all of them imaginary.

H. L. Mencken.  

The hobgoblins have to be imaginary so that
"they" can offer their solutions, not THE solutions.
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#2
(01-13-2014, 09:21 AM)Derek Wrote: The IPCC ignored water in the atmosphere as much as it could (for example water vapour [THE radiatively able gas of the atmosphere] is not given a greenhouse gas value compared to CO2 by the IPCC) to avoid the issue that they are obviously looking at earth's climate system from the wrong view point. In short, they are using the wrong paradigm. That is why the IPCC et al tries to portray water vapour and CO2 in particular as positive feedbacks.

The oceans and the water cycle are the dominant and negative feedback within earth's (stable) climate system, AND, CO2 is also a negative feedback and coolant within earth's climate system. The GH "theory" based paradigm that AGW fears is based upon has failed and it is already way past the time it was abandoned.

Excellent, Derek. The IPCC is so intent on condemning anthropogenic CO2 that they make the lesser gas (CO2) dominant over the greater gas (H20 vapor), even though H20 vapor covers up almost all of the frequencies that CO2 responds to. I've never understood how the IPCC can get away with this bizarre argument of a 3x positive feedback.
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#3
Does anyone remember which thread/s I posted the following in please?
I think it might be useful to this thread. Heck, I might even then be able to find the excel sheet too...
[Image: Slide14.jpg]
and,
[Image: Slide16.jpg]
The whole aim of practical politics is to keep the populace alarmed
(and hence clamorous to be led to safety)
by menacing it with an endless series of hobgoblins, all of them imaginary.

H. L. Mencken.  

The hobgoblins have to be imaginary so that
"they" can offer their solutions, not THE solutions.
Reply
#4
Sorry, no memory of that Derek. Mind you, that could be me! :-) As to feed back, here are a couple of personal observations.

I've spent a few years in desert regions and can confirm stories of parcels of cold air falling out of the sky on a clear night. It is not just radiation into the clear night sky that is causing the rapid surface temperature drop. AGW tells us radiation from the ground warms the air above due to 'greenhouse gases', so what is causing these parcels of cold air? I say the 'greenhouse gases' are more effective at cooling the air after the sun has set. If it wasn't for the 'greenhouse gases' how else can a 'transparent gas' cool? This was the reason for the rapid air temperature drop in the middle of the day during a total solar eclipse in Libya reported elsewhere on this forum. Keep in mind the fact that the air temperature record is from just 30cm, one foot, above the hot desert sand! No sign of CO2 warming that air very quickly.

Next, cloud effects, especially at night. Here is an example we will all have experienced many times. You have a clear sunny day with not too much wind and it gets nice and warm. Come evening and the sun has set. The temperature starts to drop. Still a clear sky and the temperature drop can be rapid. Later in the evening a band of cloud arrives overhead and the TEMPERATURE STARTS TO CLIMB!
Important point; I've never noted the cloud induced temperature increase exceed the day time maximum temperature. Now that is 'backradiation'! Clouds of course are physical droplets of water with excellent radiative characteristics and can be considered to be reflecting the full value of upwelling radiation back to the surface. The surface is no longer cooling from escaping radiation and deep set heat is returning to the surface which is why the temperature increases. It is not the 'backradiation' from the clouds warming the surface. It is the reduced rate of cooling allowing stored heat to reach the surface.

The top of the cloud layer is written off as 'albedo', but look at what is happening under the cloud! Never mind what's going on INSIDE the cloud, enthalpy and saturated adiabatic lapse rates and such. If 30% cloud provides albedo for solar then there must be ANOTHER 30% cloud on the night side of the planet doing its stuff. I think global energy budgets are severely lacking information.
Environmentalism is based on lies and the lies reflect an agenda that regards humanity as the enemy of the Earth. - Alan Caruba
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