Comments for RealClimate

Comment on More on sun-climate relations by john

john — Wed, 10 Mar 2010 07:35:05 +0000

the gatesphere seems to believe that AGW theory is falsified say if a certain glacier does not recede, etc, so is it true to say that AGW theory starts and ends in itself with the physics and the prediction of temperature rise associated with doubling of co2,
that everything else, eg , more storms , glacier loss etc are theories that
are based on but not part of the actual AGW scientific theory ,
i know that this is a simple interpretation but does seem to cause lots of confusion

Comment on Daily Mangle by BobFJ

BobFJ — Wed, 10 Mar 2010 07:22:18 +0000

Ray Labury, further my 459
I forgot to ask, but since you assert that Mauna Loa has insufficient altitude to determine “volcanic forcing” effects, and you say that Tamino uses “standard volcanic forcing” way back to 1880, at what altitude was it determined; how; and by whom?

Comment on Close Encounters of the Absurd Kind by Edward Greisch

Edward Greisch — Wed, 10 Mar 2010 07:09:09 +0000

see:
http://www.juancole.com/2010/02/advice-to-climate-scientists-on-how-to.html

Comment on Close Encounters of the Absurd Kind by BobFJ

BobFJ — Wed, 10 Mar 2010 07:03:00 +0000

Hank Roberts,
Reur 905; I have no problem with some of what you say but not all of it. But so what? How about you get back on track and indicate where and why YOU apparently think my items a), b), c), and d) in 903, do not conform to the laws of physics!?

Reur 909; You cite a medical paper where I see, (upon quickly flicking through), that they use an IR laser to determine point responses on hairy and non-hairy skin etc. But so what! They could also determine a response with a suitable electrical probe. Or, they could do it with a point concentration of filtered sunlight only in the visible light range, (excluding IR), where they would also find a hotness response!!!!

I’ve noticed previously that you seem to like citing various stuff that has no value for the topic in hand!

Comment on Close Encounters of the Absurd Kind by Edward Greisch

Edward Greisch — Wed, 10 Mar 2010 06:49:07 +0000

Education is key
How much easier this would all be
If everybody had a B.S. in Physics.

Comment on Arctic Methane on the Move? by Gilles

Gilles — Wed, 10 Mar 2010 06:33:54 +0000

154.”No, that still doesn’t make “why is methane a problem when we’re getting it naturally” true.

Go look up the volume of methane in the atmosphere and the amount of methane trapped in the tundra and under the water.

[edit]. Do something real. Investigate.”

Obviously David’s answer is much more relevant to my question than your comment. Thanks David.

Comment on More on sun-climate relations by Gilles

Gilles — Wed, 10 Mar 2010 06:28:10 +0000

“Over this time period, the planet has actually cooled considerably: with mean global temperature more than 8°C higher at the end of the time of the dinosaurs. This, despite the increased solar output.

Over this timespan, the atmospheric concentration of CO2 has ranged from between 1,000 and 2,000 ppm ”

So this gives 8°C for about 8 times the preindustrial concentration, so 3 doublings, and a sensitivity of 2.6 °C/doubling , right ? with climate inertia, is it right that with such a value, we won’t be over 2°C if the CO2 concentration stays below 560 ppm ?

Comment on Arctic Methane on the Move? by Patrick 027

Patrick 027 — Wed, 10 Mar 2010 05:56:25 +0000

Re Blair Dowden – it should be clear from my subsequent comment (first increase the temperature, then add water vapor and see what that does).

Comment on Arctic Methane on the Move? by Imback

Imback — Wed, 10 Mar 2010 05:31:08 +0000

Blair wrote:
Imback, I agree with your statement up to the conclusion. The effective emission height for H2O is raised, but so is its temperature. I fail to see how that changes the radiation balance.

I do understand you want a heuristic model. The situation is tricky because H2O depends on temperature and temperature depends on H2O, so we have to think in simultaneous equations.

Let’s start from the radiation balance equation (bottom of post 177). (Note gamma is the lapse rate.) –

bandwidth(CO2)*(T(surface)-gamma*height(CO2))^4 +
bandwidth(H2O)*(T(surface)-gamma*height(H2O))^4 +
bandwidth(window)*(T(surface))^4 = constant

Let’s assume constant RH and a linearized Clausius-Clapeyron (here the baseline heights and temperatures are subtracted, and chi is the linearized C-C slope) –

(height(H2O) – height(H2O)@t=0) = (T(surface) – T(surface)@t=0)*chi

So now we raise height(CO2). Algebraically we can see that T(surface) will increase, holding more H2O so height(H2O) goes up, which will force a further increase in T(surface) to keep the radiation balance.

Comment on Arctic Methane on the Move? by Blair Dowden

Blair Dowden — Wed, 10 Mar 2010 03:54:01 +0000

First, let me be clear that I do not believe my “result” that there is no water vapor feedback. I am aware that both modeling and empirical results indicate that it is significant. I am trying to understand how it works so I can explain it to others. This should be possible without doing a line by line calculation.

Does anyone have a problem with the following: Low altitude water vapor has little impact on the greenhouse effect from a radiation balance point of view. This water vapor may absorb every single photon in its absorption band, but Kirchhoff’s Law says they will be emitted again at the same wavelengths. They are at about the same temperature as the Earth’s surface, so this re-emission does not change the energy balance. (See page 152 of this Pierrehumbert paper.) However, this process may affect convection, which change the temperature distribution of the atmosphere.

Patrick 027, you said “water vapor reduces the upward LW flux at the tropopause more not because it is colder but because the surface and lowermost water vapor are warmer.” I do not understand this statement. Temperature difference affects convection, but not radiation.

Imback, I agree with your statement up to the conclusion. The effective emission height for H2O is raised, but so is its temperature. I fail to see how that changes the radiation balance.

I think the problem is that the atmosphere is not saturated with water vapor, so Classius Clapeyron is not sufficient to determine moisture content. Relative humidity may change, perhaps differently at different altitudes. Also, changes in convection may be important. It would be nice to have some idea how all this works.