Thread: Global Warming...Fact or Fiction?

Originally Posted by svguy

But, I have to vehemently disagree with your propostion (impliedly made) that changes in CO2 concentration do not lead to corresponding changes in thermal re-emission, holding all other variables constant. If I am over-reading your statement, my apologies in advance.

But the whole point is that the earth is not a constant, closed, static system. We can come up with a model to predict the weather IF we had all the variables. But we don't. Our computers are powerful but our models suck. How else do you explain that not a single climate model was able to predict the future. They can't even predict the past. All they can do is predict the present.

Originally Posted by Parihaka

So what you're saying is the earth is a static system and any significant anthropogenic activity will therefore impact on that system?

Not in the slightest. The retained energy is dynamic and subject to many different "signals", the composite is which is reflected in net energy retention
of the planet (both positive and negative, given the "net signal", so to speak).

Some are macro "natural" (i.e. solar activity, the main "driver" of the system and a potential secondary effector as well, cosmic rays and the formation of clouds, UV level).

Some are weather or climatologically based (i.e. El Nino and La Nina cycles each contribute, in summation, to the long term "end signal", as well as the Pacific Dodecennial (sp?) Oscillation (PDO) cycle, in which we seem to be heading into)

Significant anthro acivity also impacts the system; as does non-anthro activity. Each activity contributes its own signal (and in some cases, affects another in a way, such as my land use example previously, listing at least three potential effects to other "signals").

CO2 has its "signal" as well that contributes to the sum total. The thermal response to non-diatomic atmosphere components is well known. When the concentration of these atmoshperic components increase, each associated signal increases. In the case of CO2, the concentration is undoubtedly increasing per direct measurements. Further, the isotope studies clearly point to anthro sources as being a *major* contributor to the increased levels.

The question, at least for me, is *not* whether this has an effect. The science on the thermal response to increased levels to me is clear. The questins for me are: a) are the projected levels valid; and/or b) in sum toto, what is the relative net effect, given all the other signals.

For example: What I have read about the PDO, the "forcing" of this is seemingly currently greater than that of the net current CO2 load forcing. Accordingly the net energy balance will go down, at least while the PDO is on the downcycle.

Another example: The '98 El Nino event was among the most intense ever seen. This probably led to the huge spiking in temperature during the '98-'99 timeframe.

So, at least for me, the CO2 increases represents a monotonically (or worse) increasing "baseline signal" to the net energy signal. Placed on top of that are the "driver signals" (sun), the "weather signals" (El Nino,La Nina), "weather/climate signals" (PDO), land use signals, albedo signals, etc. Sometimes they combine to form big peaks ('98-2001), sometimes the combine to form troughs.

But the increase of CO2 will absolutely increase the magnitude of the CO2 signal.

Originally Posted by svguy

You somewhat misstate, dalem.

What you are asking for is what are the "superpositions" of each signal. Increasing the level and/or concentration of any non-diatomic component of the atmosphere definitely leads to increased thermal re-emission. That is absolutely known (and has been for over a century).

As an example, just ask any designer, manufacturer, or user of any semiconductor deposition equipment, for just one example of this.

I agree that the superposition of these other signals is absolutely germane to the total question of AGW. But, it is simple, fundamental physics that says "increased concentration" leads to increased thermal re-emission. I cannot see how you can doubt this.

As examples (a simple one): let the AGW "equation" be:
dT = Si * Tc + Oth (dT = change in retained energy, Si = solar input, Tc = the "plant function" of the instantaneous concentration, Oth = other "retained heat" factors)

In your example:
outgassing and oceanic absorption would affect Tc;
cloud cover, cosmic rays, UV, solar variation, and orbital mechanics all affect the "driver" function (Si)
wind patterns would probably be contained within the Oth component. This is an utterly simplistic "model" and is being shown for demonstrative purposes only (which is that there are many "signals" aside and apart from the AGHG signal w/i the total energy balance system....)

You have left out other components like land use issues (which affects albedo, retention of incoming thermal enery (leading to more radiated longwave radiation, and potential change in carbon sequestration via flora)

So there are other components (both inputs and linked effeects) to the "retained heat" question, which I would think would be the more correct way in which your comments would be directed.

Each component can be interlinked with another (you cloud cover, cosmic rays, and orbital mechanics are currently being shown to have interlinkage in the sense that some studies have shown that cosmic rays can be linked to cloud formation, .....)

But, I have to vehemently disagree with your propostion (impliedly made) that changes in CO2 concentration do not lead to corresponding changes in thermal re-emission, holding all other variables constant. If I am over-reading your statement, my apologies in advance.

So, holding everything else constant, how much CO2 from a chimney or tailpipe yields what global temperature change? What does the curve look like?

-dale

Originally Posted by gunnut

But the whole point is that the earth is not a constant, closed, static system. We can come up with a model to predict the weather IF we had all the variables. But we don't. Our computers are powerful but our models suck. How else do you explain that not a single climate model was able to predict the future. They can't even predict the past. All they can do is predict the present.

You are correct that the models do not "predict" (if you mean accuracy down to any arbitrary number). And we have a system in which many of the inputs are not static (insolation, net CO2 output, volcanoes, El Nino events, etc.)

The value in the models is not to say "there will be no clouds, and a temperature of 68.5 degrees at (some arbitrary point on the planet) at (an arbitrary point in time.)" The value is to identify long-term trends.

For example, in semiconductor deposition machinery, you *cannot* say that at (a particular point) on the substrate at (a particular nanosecond) there will be 4589 particles of germanium arsenide at a particular energy level in contact with the substrate. You can say 'when I increase (or decrease) the net energy in this system, my gross energy flow vectors will look roughly like this over time, and I can expect (to within a degree of probability) the energy in (this volume) to be x; +-y'

Interestingly enough, while these models cannot give 'specifics', the main value in them is over "macro-time", in which the models give quite decent results in a macro-sense.

So, some models have given a quite decent outcome to outputs. But, of course, no model could ever "predict" sporadic and not well understood events (like a volcanic eruption, or El Nino, or for that event, "projected" anthro drivers).

My best guess is that the despised models are continuously being updated to reflect newer understandings, such as the nth-order effects of land use on the system, or that of the secondary effect of particulates on the system.

And you are correct in your assumption that the "models do not predict" the current apparent downturn in temperature. The items I have read tend to implicate this as being a result of a "downtick" in the PDO; I do not know how anyone could have temporally "predicted" this event (if, in fact, the specualtion is correct as to the PDO being the root.) But, given that it *might* be happening, nothing prevents the modelers (and models) for attempting to input this "signal" into the systems that they are describing.