## Friday, 27 November 2020

### How much radiation can 1kg of CO2 'trap'?

Further to my previous post, I shall continue my merry trolling of AGW theory.

Here's a graphic to illustrate the point. The AGW theory is that if CO2 is above a certain concentration (about 0.5g/m3) then radiation (at certain frequencies) emitted below that altitude cannot escape to space and warms the atmosphere, oceans and land. If CO2 levels increased by 50% above current levels, the effective emitting altitude (for certain wavelengths) would go up from 5 km to 9.5 km. As a result, everything below that altitude warms by about 1.5 degrees. All figures expressed in terms of a 10km high column of air with a 1m2 cross-section.
In round figures:

1. The amount of energy required to heat such a column of air by 1.5 degrees is about 15 million Joules.

2. The additional CO2 in each such column which has this effect is the amount above the dashed line and between the orange and yellow lines, which looks to be about 1.5 kg.

3. Therefore, each kg of extra CO2 above the line must be able to 'trap' about 10 million Joules, or about 12 hours' worth of all the radiation from each m2 of Earth's effective emitting surface (which is two-thirds clouds).

4. In case you're wondering, that is a huge number. The biggest number in this context is the latent heat of evaporation of water, which is 2.256 million Joules/kg. Remember, the additional energy required to get boiling water to turn to water vapour (i.e. 'dry' steam rather than visible steam, which is a mix of water vapour and water droplets) is five times as much as the energy required to get water from just above freezing point to boiling point. So it is a huge amount of energy.

5. Or to put it another way, if 1 kg CO2 could absorb 10 million Joules and convert it all to thermal energy without being able to cool down, it would be about 10,000 degrees (difficult to estimate, as specific heat capacity is higher the hotter you go). "That's hot", as Paris Hilton would say. To put it another way, if you did CO2 capture from the air, collected one-third of it, heated it to 10,000 degrees, released it back into the atmosphere and let it mix again, the average temperature of the whole atmosphere would go up by about 1.5 degrees. Clearly, that is a silly analogy, but would lead to the same result.

This just does not seem plausible, does it? Especially as this extra energy seems to be both radiation (electro-magnetic energy, which has no particular temperature) and warmth (thermal energy, which is not electro-magnetic energy on the large scale) at the same time. That's never made clear is it? Is it one or t'other? Or would we need double that amount of Joules, which flip constantly back and forth between the two forms?

Dinero said...

The theory is that the co2 is a conduit for a flow of heat, between the infra red radiation from the surface to thermal energy of molecules in the atmosphere. Does that make sense.

Din, makes perfect sense.

In which case air warms up and emits infrared at longer wavelengths which are unaffected by CO2 and go out to space.

Don't forget that most of the thermal energy in the air gets there by conduction, convection and latent heat of evaporation. Radiation is a minor issue, and on a molecular level, there isn't really much difference between two atoms or molecules exchanging energy by radiation or by conduction.

AGW rules say that N2 and O2 can't absorb or emit infra red radiation (clearly not true), but they can exchange thermal energy by conduction, so what's the difference anyway?

Dinero said...

The mechanism of the conduit is that the Co2 absorbs infra red , the co2 then has vibrational thermal energy. And then the thermal flow from the co2 to the other gasses occurs by conduction and convection. And so the Joules do not have to be a stock in the Co2, they are a stock in all the gases. Once it is in there it can radiate upwards and also downwards.

Din, I agree with all of that. But it's only part of the story.

Radiation goes in all directions. Sure. So does the transfer by conduction. Convection clearly goes mainly upwards, but this is more than cancelled out by the gravito-thermal effect.

And it appears to be agreed that all moving i.e. warm molecules emit infra red, that must mean ALL, including N2 and O2. Admittedly, they don't emit very much (so they stay warm longer) but there's still 2,500 times as much N2 and O2 as there is CO2.

Dinero said...

OK. Your responses to my comment are just plane weird. So I will be explicit. Your post states that all the extra heat is in the Co2. I Pointed out that that is not the case.