So the 'natural' cycle is heat first, then CO2 goes up, then temps come down, isn't that saying that CO2 COOLS, not warms?
:sigh: No. The planet cools because the earth radiates energy. Greenhouse gases will trap heat and alter the amount of radiation emitted back to the atmosphere, but if you notice the temperature is important. Going by the Stefan-Boltzmann law, the hotter an object is, the more energy it will radiate out (all things being equal).
If CO2 causes radiative forcing, shouldn't any given warming period have turned Earth into a boiling cauldron, devoid of live?
Yes, if you completely fail to understand anything I just said.
Yet all previous warm periods did abate, naturally. Man made or not, this one will too.
The law that I posted (Stefan-Boltzmann law) relates the amount of heat an object radiates to a constants, emissivity, and temperature. In other words, NO, I have not in any way said that the planet will continue forever to heat. In fact, I have said exactly the opposite of that- that as the planet gets hotter, it should also COOL a large amount, as evidenced by the temperature graph I posted. i.e., the angle that I am looking at it predicts both increases AND
decreases in temperature over given intervals. How could someone possibly miss that?
I swear, warmers are just a smidgen away from turning AGW non-falsifiable.
I am not a warmer. I presented an accepted law of physics (Stefan-Boltzmann law) and showed how temperature graphs qualitatively match what it predicts. It is unfortunate that you failed to understand what I was saying.
What with "It's NOT the temperature, it's the ENERGY". Cripes, latest satellite data show the world cooling. The peak is over, glaciers and ice will recover. It was melting for hundreds of years, it isn't "Ice Nine" that will freeze up instantly.
Not relevant at all to my post. It is unfortunate you could not understand my post well enough to see that.
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I can see why a prediction based on the law would hold for short timeframes (minutes, hours) but please elaborate on application of the law to rate of temp increase or decrease over a timescale of thousands of years.
The Stefan-Boltzmann law should apply to any time interval (unless there is some quantum development I am unaware of). What I am particularly interested in is the relationship between outgoing energy flux and incoming energy flux, at equilibrium:
Incoming Energy Flux = πR2S(1-A)
Outgoing Energy Flux = 4πR2εσT4
where S(1-A) is a function related to the sun's output, ε is earth's emissivity, σ = Stefan-Boltzmann constant, and T = temperature, R is the radius of the earth.
Equilibrium is satisfied when the two are equal. This leads to some terms canceling, giving:
S(1-A) = 4εσT4
When that condition is satisfied, the system is in equilibrium.
Suppose solar output increases. Therefore temperature will increase. And, supposedly, greenhouse gases will then be released.
So, what is the effect on the outgoing energy flux of the planet (this is what I'm concerned about)?
Well, according to the function for outgoing energy flux, a higher temperature should correspond to a higher energy flux.
This is seen in the temperature graphs at locations when temperature has high peaks, there shortly follows a large "nosedive." (however, this is a qualitative judgment. Since I have no idea how emissivity has changed, I can't really be sure. But at least roughly the law seems to be followed)
The only pertinent thing for "man made global warming" is the hypothesis that increased temperatures and/or man "artificially" increasing greenhouse gases would to a degree temper the increase in outgoing energy flux due to temperature.
Therefore, what my conclusion has been is this:
IF the outgoing radiation flux is different than what we would expect due to some certain change in temperature, then there must have been a slight countering or magnifying effect due to a change in emissivity. Unfortunately, it seems to be the case that a rise in temperature itself would naturally slightly alter emissivity, so how the heck would you know if human beings were an important factor? (based on this one relationship I have been talking about)
Regardless of the above, the temperature changes in the graph I posted does seem to roughly agree with what I have been saying: namely, if temperature increases by a certain amount, it should rapidly decrease as well, due to the fact that a hotter body radiates energy out faster than a colder one (as seen by the relationship I am talking about- where temperature is related by the forth power to the outgoing radiation flux).
Tell you what. I will give a quick computational look that will give a qualitative idea of what I'm talking about. (notice that each of these stages are over "some time" interval. It doesn't matter what time interval, because this relationship is dealing with "unit time intervals," so pick whatever you want)
Start with:
Outgoing Energy Flux = O = 4πR2εσT4
With initial temperature being 288 Kelvin, and emissivity being (randomly chosen), say 0.64, the earth's radius being 6 378 100 meters.
So, O is then:
O = 4π(6 378 100 m)2(0.64)(5.67 x 10-8 W/m2K4)(288 K)4
O = 1.277 x 1017 W or J/s. Per meter this would be (divide this by Earth's radius2- and pi, I suppose... ) ==> 999.2 W/m2
Then, say temperature increases by, say, 2 K. Then we'd have:
O = 4π(6 378 100 m)2(0.64)(5.67 x 10-8 W/m2K4)(300 K)4
then divided by R
2 and pi gives:
1175.8 W/m2.
This means that with an increase in temperature of 2 K due to solar activity, if emissivity remains constant, energy should radiate 179.7 W/m
2 faster.
Now what happens if temperature decreases emissivity due to greenhouse gases released?
Say the emissivity decreases by .10 due to the subsequent release of greenhouse gases. This gives:
O = 4π(6 378 100 m)2(0.54)(5.67 x 10-8 W/m2K4)(300 K)4
then, dividing by R
2 and pi again:
O = 992.2 W/m2.
Which means that even with the effect of higher temperature leading to faster radiation of heat, if the emissivity lowers by .10, you'd get a NET decrease in the earth's radiation. Which would lead to increases in temperature when more energy from the sun comes in (for a certain time interval however, NOT permanently! It happens until equilibrium is reached. I have no idea where some of these guys are getting that idea...)
But, here is the kicker: this depends crucially on how much solar radiation enters into earth.
Next time interval, higher temperatures:
So, let's say in the next given interval of time, the sun then pumps in more energy, to the point that the decrease in emissivity is then offset by the increase in temperature due to solar radiation and due to the greenhouse effect. Then what?
Well, obviously, then you'd once again come back to where we started from: higher temperatures would lead to more energy being radiated out, which would, after a given time interval, result in a net DECREASE in temperature, until equilibrium is again reached. Which, if the hypothesis is correct about greenhouse gases being temperature dependent, would lead to LESS greenhouse gases in the atmosphere, which would lead to a COOLING period.
Then what?
Then the cycle starts again. Change in solar output alters temperature, which alters emissivity, which alters temperature, which alters emissivity, etc.
With the above model, you would expect periods of warmth and cooling, both of which depending upon how long it takes to reach thermal equilibrium (heat coming in = heat going out).
How people responding to me get that the model would lead to an infinite increase in heat is way beyond me. It is very simple. I don't understand where the misunderstanding is coming from.
The only thing relevant to humans is this:
Will human activity screw up the cycle a bit?
Assuming human activity DID screw up the cycle, does that matter?
Yes, but only for the short term. Because anything we did to alter this would simply put stress on the system forcing it to return to equilibrium. As it does when other sources of variation throw it out of equilibrium.
In short, as I understand it (and this is limited understanding, no doubt), there really isn't a difference between "natural" climate change and "human helped" climate change. Either way, even if humans "speed up" a warming phase, it will just eventually lead to a new cooling phase.
And of course, it took a relatively large change in emissivity (from 0.64 to 0.54) to produce a lowering of radiation flux with only a small increase in temperature. Which would mean that even if human activity contributed a non-negligible amount to the change in emissivity, unless that change is HUGE, the net change on the climate would be relatively small anyway.
Yes, unfortunately most commonly the other gases are quoted and considered in terms of "CO2 equivalents".
Huh. I was unaware of this. Why do they do this?
But that analysis has been done by McIntyre for several cases relating to the 1988 Hansen models, using standard IPCC equations for contribution of each major species.
http://www.climateaudit.org/?p=2645
the graphic below shows my estimates of how the forcing breaks down between GHGs within each of the three scenarios using contemporary or near-contemporary "simplified expressions".
Formulas and calculations are there for the reverse engineering.
Well, the model I'm talking about is for vague generalities, and it's only value is that it agrees with temperature graphs, to a degree. As you can see from my post, I am not really concerned with the details of which and how each greenhouse gas affects the heat radiation cycle.
People, I think, have read more into what I was actually saying.
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Raze you really need to look at energy not just temperature....
The Stefan-Boltzmann law is a relation of energy (namely, heat energy). I mentioned temperature only because of it's importance in the relation (it is an important factor, mathematically, because of the T
4 relation).
one reason cryosphere indicators are excellent both now and in the past is that they represent a very strong signal due to latent heat.
You can have very large scale energy absorption with miniscule temp changes - the cryosphere buffers changes as does deep ocean.
Energy absorption with respect to the flow of energy is the only thing that would have meaning here, I think. As in, how far is it disturbed from equilibrium.
Regardless, the emissivity level at a given instant would take into account energy absorption. That is effectively what it does. Again, the hotter something is, the more heat energy it should radiate out, all things being equal. However, radiated energy also depends on emissivity, which of course, depends on how the body absorbs energy (in fact, that is exactly what emissivity tells you: how much energy radiated in gets radiated out in a given interval- which of course is related to how much energy is absorbed rather than simply radiated back out or reflected back out).
Tunnel visioning on temperature minutia is a fav denier trick....they've got nothing left...
I don't see how I ignored energy absorption, since I mentioned both important factors:
(1) Temperature
(2) Emissivity
Would you care to explain to me how I (allegedly) did ignore energy absorption? Of course, I wasn't nearly this explicit in my other two posts, so maybe that is the cause. But really, since I have expressly mentioned emissivity (which by default includes energy absorption), I can't say that I agree with your summary of my position.
ETA- The emissivity would slow the decent of temperature over an interval if the change in emissivity brought about by increased solar activity (*or human activity), so that a large change in emissivity would result in the slope UP in temperature having a little bit steeper magnitude than the slope back DOWN (this appears to be the case in the graphs I have seen).
