Visitor Submit by Willis Eschenbach
It is a follow-on from my earlier submit entitled Greenhouse Equilibrium. When you haven’t learn it, you would possibly need to, because it introduces most of the ideas I’ll focus on on this submit.
I bought to fascinated about the oft-repeated declare {that a} doubling of CO2 will increase top-of-atmosphere (TOA) radiative forcing by 3.7 watts per sq. meter (W/m2) … and that in flip, the extra 3.7 W/m2 of TOA forcing causes a ~3° warming of the temperature. In different phrases, they are saying that ~ 1.2 W/m2 of further radiative forcing causes one diploma of warming.
What set me to considering was the Stefan-Boltzmann equation. It relates temperature to the quantity of thermal radiation emitted. It seems that the radiation varies because the fourth energy of the temperature, T4. What this implies is that the hotter an object is, the extra vitality must be added to the item to boost the item’s temperature by every further diploma.
So how a lot further vitality does it take to boost the temperature of the earth (which is at about 15°C) by one diploma C?
Per the S-B equation, it requires a further ~ 5.2 W/m2 absorbed by the floor to boost the temperature of the earth by one diploma C. However as mentioned in my earlier submit, solely ~ 80% of the floor absorbed vitality is expressed as temperature. Which means to heat the earth by 1°C requires 5.2 / .8 = 6.5 W/m2 absorbed vitality on the floor per 1° warming.
Now, recall that their declare is that 1.2 W/m2 of TOA forcing causes one diploma of warming … which in flip requires 6.5 W/m2 on the floor.
Presumably, their declare is that numerous feedbacks amplify the change in radiative forcing. However turning 1.2 W/m2 on the TOA into 6.5 W/m2 on the floor? That’s a neat trick. I’m not seeing that occuring in any respect.
Now, let me again as much as a graphic from my earlier submit, together with the caption.
Determine 1. Greenhouse multiplier. The multiplier is calculated as upwelling longwave floor radiation divided by incoming photo voltaic radiation (after albedo reflections). A multiplier of two would imply that the floor could be radiating two W/m2 of vitality for every one W/m2 of photo voltaic vitality truly coming into the system. This exhibits that the greenhouse has elevated the incoming photo voltaic radiation by about two-thirds, as measured on the floor.
Now, over the interval of the CERES document, greenhouse fuel forcing elevated by about 0.7 W/m2.
Theoretically, this is able to be elevated by suggestions within the ratio 6.5/1.2 to the worth on the floor. on this case, it converts the 0.7 TOA W/m2 to three.8 W/m2 on the floor.
This permits us to see what the change within the greenhouse effectivity proven in Determine 1 ought to seem like if the absorbed floor radiation elevated by 3.8 W/m2. Determine 2 is similar as Determine 1, however together with the anticipated change from the extra 3.8 W/m2 absorbed.
Determine 2. As in Determine 1, however together with the development within the multiplier that might be anticipated from the rise in TOA greenhouse fuel forcing.
Hmmm … a number of factors.
First, I merely don’t imagine their numbers. Their declare is {that a} doubling of CO2 offers a further 3.7 W/m2 on the TOA, and it ends in 3°C of floor warming. That’s about 1.2 W/m2 per diploma of warming.
However we all know that it takes 6.5 W/m2 to boost the earth’s temperature by one diploma …
I’m not seeing any bodily processes by which the 1.2 W/m2 might someway be elevated to six.5 W/m2.
Second, even when the warming have been just one°C per doubling of CO2, we nonetheless would have the ability to see it within the graphic. Determine 3 exhibits that end result.
Determine 3. As in Determine 2, however with the CO2 forcing figured at one diploma of warming per doubling of CO2, which is one diploma per 3.7 W/m2.
However we don’t see that lesser development within the multiplier both. As an alternative, the multiplier has a slight however not important lower, and it’s nothing like what we’d see if growing GHGs truly have been growing the floor temperature.
Nonetheless, not less than that lesser development is a bit plausible for the reason that enhance from the TOA to the floor is from 3.7 W/m2 to six.5 W/m2. Nonetheless a giant attain, although … it might require robust optimistic suggestions, and I haven’t seen that wherever.
Now, the necessary factor to recollect about this measurement of the effectivity of the system is that it’s end-to-end. By that I imply we begin with the vitality coming into the system (photo voltaic minus reflections) and we find yourself with floor temperature.
In between the solar and the floor, now we have a variety of emergent local weather phenomen. Inter alia they embody variable cloud shortwave and longwave radiation results, adjustments in floor albedo and TOA albedo, huge variable advection of vitality from the tropics to the poles, adjustments in aerosols, the La Nina/El Nino pump, variations in timing and power of thunderstorms, variations in wise/latent warmth loss from the floor … and adjustments in greenhouse gases.
And what seems to be occurring is that, as I’ve mentioned for years, the adjustments in greenhouse gases are being counteracted by some mixture of the opposite emergent local weather variables included above.
What a marvelously advanced world we inhabit!
w.
PS—As with the earlier submit, please persist with the subject. Claims that the greenhouse impact isn’t actual or that downwelling radiation doesn’t exist haven’t any place within the feedback on this submit, and they are going to be frowned upon from a terrific peak. You might be welcome to debate these points … simply not on this specific submit.
My Normal—I can defend my very own phrases. I can not defend your (mis)interpretation of my phrases. Please QUOTE THE EXACT WORDS you’re discussing in your feedback, so we are able to all perceive who and what you’re replying to.
