Sunday, May 09, 2010

Gavin Schmidt can retire Part I - The EPA sticks it to Steckis

Caerbanog brings word that Richard Steckis has been channeling Steve Goddard at the Sr. Pielke's vanity site WUWT, about Venus at Real Climate and Gavin is NOT amused. However, as Cthulhu has pointed out, the EPA has already answered the off earth questions. Sometimes, you just have to look it up

Comment (3-49):
A commenter (2210.1) states that Venus is not an example of the greenhouse effect but is merely warmer because it is closer to the sun. Another commenter (2210.5) attributes Venus' warmth to higher atmospheric pressure because compression causes temperature increases (for example, this occurs when inflating a bicycle tire, due to the proportional relationship between pressure and temperature represented in the ideal gas law, pV=nRT, i.e., pressure times volume equals amount of gas times temperature times a constant), and that a 95% CO2 atmosphere is actually cooler than a 100% biatomic atmosphere would be.

Response (3-49):
Venus is warmer than the Earth both because of the greenhouse effect and because of its distance to the sun; in contrast, Mercury is cooler than Venus despite being even closer to the sun. Were Venus’ atmosphere to be transparent to radiation, then the surface temperature of Venus would be determined only by the blackbody radiation of the surface, and the pressure of the atmosphere would not change this equilibrium temperature. There is a large body of literature on Venus’ climate; one example is Bullock and Grinspoon (2001)—all of which show that CO2 is a significant contributor to the planet’s warmth.

Because volume is not held constant, it is not appropriate to use the ideal gas law to determine the temperature on the surface of Venus based only on knowledge about its pressure. Therefore, the scientific literature shows clearly that the temperature of Venus is an example of a greenhouse effect, in contrast to the assertion by the commenters.

Comment (3-51):
One commenter (3013) mentions Mars and states that even given the lower atmospheric pressure, his calculation shows that it has twice as much CO2 as Earth, and further claims that the National Aeronautics and Space Administration (NASA) found that the even with this high CO2 concentration, the atmosphere of Mars does not retain heat.

Response (3-51):
The commenter did not provide any evidence for his claim that NASA has found that the atmosphere of Mars does not retain heat. Mars does have an atmosphere that is mainly carbon dioxide, but because of the low atmospheric pressure, it is only 16 times the quantity of carbon dioxide on Earth. At the same time, it receives less than 45% as much sunlight, so the increased radiative forcing from the CO2 is not sufficient to make up for the decrease in solar insolation. Thus, the commenter’s claim that the atmosphere of Mars does not retain heat is not consistent with the scientific literature.
Comment (3-39):
A few commenters (0717, 4003) noted that there is warming on other planets, mentioning Mars, Jupiter, and Pluto, and stated that this was evidence for the solar cause of global warming.

Response (3-39):

The commenters did not provide any peer-reviewed literature to support their argument. One indication that Mars is warming was a retreat of the South Polar Cap, but Colaprete et al. (2005) discuss the fact that the South Polar Cap is unstable, and that it is therefore difficult to extrapolate short-term changes in the cap to a long-term global trend. Martian climate is also influenced by non-solar mechanisms such as positive feedbacks between albedo changes and changes in dust storms (Fenton et al., 2007).

Therefore, it is neither clear that Mars is warming nor that the warming is solar induced. The climate on Jupiter is dominated by the dynamics of the massive standing vortices on the planet (Marcus, 2004), and solar energy is a less significant contribution to the temperature of Jupiter than it is for Earth. It is also unclear whether the warming of Jupiter is global or regional.

The changes in Pluto’s atmosphere have been detailed in Elliot et al. (2007). The basic atmospheric expansion is well modeled by the frost migrations models of Hansen and Paige (1996), without requiring any solar effects beyond Pluto's seasonally changing sub-solar latitude. Because Pluto takes about 248 years to orbit the sun, Pluto’s seasons can be measured in decades. Finally, Triton is the last commonly referenced “warming” planet. The last good measurements of Triton were in 1998 (Elliot et al., 1998), and the changes in Triton's pressure have been explained by the change in Triton's subsolar latitude uncovering polar icecaps to the sun as a result of Triton's obliquity.

Therefore, there is no indication that solar variability is the cause of recent warming on any solar system body. Additionally, the lack of recent observed trends in solar insolation (discussed in responses in this section of the Response to Comments document) makes it implausible that there would be such solar induced warming trends on solar system bodies.
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Thomas Palm said...

Don't retire just yet, some of those responses sucked.

"Because volume is not held constant, it is not appropriate to use the ideal gas law to determine the temperature on the surface of Venus based only on knowledge about its pressure."

This answer makes it seem as if you only used the law for adiabatic compression instead you'd be fine, which is what Goddard does over at WUWT. The more fundamental flaw is that the ideal gas law doesn't allow for heat transfer to the environment. A bicycle tire heats up when you pump it, but it rapidly cools again. Venus can only remain hot because the atmosphere doesn't let heat out in the form of radiation.

For Mars I think that you need to take into account that the lower atmospheric pressure give less pressure broadening of the absorbtion lines, which makes CO2 a considerably less efficient greenhouse gas.

EliRabett said...

What Goddard was discussing is the dry adiabatic lapse rate, which starts from the assumption that everywhere in the atmosphere the radiative energy absorbed is balanced by the energy emitted. If not, you get convective energy transport to re-balance the situation. That leaves gravitational compression, but it is not saying that radiative energy flow is negligible, just that it is balanced. As Nick Stokes and Leonard Weinsten say at Watts' place (and Eli has said before to similar things), the lapse rate does not set the surface temperature, which is determined by the solar radiation absorbed at the surface and the IR re-emitted by greenhouse gases in the atmosphere.

What does the lapse rate determine? Looking at extremes is useful. Nick points out that if the surface is at absolute zero the thickness of the atmosphere (at least for an ideal gas) would be zero. What if the surface were at infinite temperature. Then the height of the atmosphere would be infinite also. From this, we conclude that the height of the atmosphere is determined by the lapse rate and the surface temperature.

There are, of course, a few other things to consider. First, the dry adiabatic lapse rate is not 10 K/km for every atmosphere. For example it is 4.5 K/km on Mars and 2.0 K/km on Jupiter. Better put it is the ratio of the local gravitational constant divided by the specific heat (in J/(kg-K) or g/Cp. For the case of Venus, where the surface and the atmosphere are very hot, we have to account for the contribution of molecular vibrations to the specific heat, which will change with temperature and thus with altitude.

carrot eater said...

"The more fundamental flaw is that the ideal gas law doesn't allow for heat transfer to the environment."

I'll quibble with the working of this as well. Constitutive equations like the gas law are, well, constitutive. They aren't meant to describe heat transfer, but they still work just fine even while heat transfer is going on, provided you know what you're doing.

No, Goddard wasn't explicitly using the gas law for his crank idea, but some of his commenters were. So the idea is out there.

Anonymous said...

Snow Bunny laughed out loud at "Venus... is merely warmer because it is closer to the sun."

So nice of the commenter to impart this idea to the government.

This person has no idea what a stupid notion it is to think any scientist couldn't sort this out.

EliRabett said...

Eli is rather fond of his explanation, so innocent little bunny that he is he put it over at Watts' place about 12 hours ago in response to Judith Curry's admonition to play nice.

Eli is still waiting. Ever hopeful little bunny.

Angliss said...

What, no comments that Venus is hot because of a collision a billion years ago or because of internal heating from the hot core? I'm disappointed.

Unknown said...

I think you guys can't see the wood for the trees. There is the perfect solution to all our problems stareing us in the face. We fill a large pressure vessel with compressed air at say 3000 atmospheres(nice round figure) It will be very hot. We simply use this heat to make steam for a generator forever and ever and ever-----. For cars we have air compressed at tens of thousands of atmospheres in a thimble sized capsule made of unobtainium. My back of the envelope calculations suggest you would get more power than a supercharged 427 v8. I am sure all you other contributers to this site have an innate sense of fairness which will preclude you from getting to the patent office first with this world changing idea.

Hank Roberts said...

Wait, is global warming actually happening because we've let all this highly compressed oil and gas come gushing out of the ground?

Or is that the cause of global cooling, since it's no longer compressed?

I'm so confused.

Anonymous said...

Angliss, close but no cigar - it's cos of volcanoes. Oh and the sun, cos it's made of iron. Or something...

Marsupial Mouse

David B. Benson said...

This would be hilarious if only ...

Connor a.k.a bit_pattern said...

I've scanned through some of the endangerment findings, but am looking for a response to Spencer Braswell (2008), their paper on radiative forcing, want to find a peer reviewed response (RC Wiki only has Tamino's rebuttals. HAs anyone seen anything in the EPA findings, or can point me to a reviewed rebuttal?

Thx in advance

Anonymous said...

As I was flying past eltoid, I saw they had Mars Attacks, playing at the Sinclair Drive. I love that music!... The FX are GREAT...they even had help from Nasa & Bollywood right from the start, no screwin around this time:) It's funny bunnies!

The director of this film sure can string out a punch line, he used a bunch of may and shoulds and coulds and if's and maybe's & need-too's; its a real tear jerker, with a happy face:) Anyway, after reading all the posts that were up their... They all voted as a block and often more than once hopping to get a desired affect... Mike Mann did the same thing with his 1 trix pony, just to get an affect. May you see a pattern of behavior among AGW folks? Hey, I am jumping into the transporter now, gotta catch the second feature... MMMWirrrrrrrzzing

Anonymous said...

The second feature sucked... but it was one of those movies that are so-bad-ya-just-gotta-seeum. And talk about 'dry adiabatic lapse rate', wow!

Hope you don't end up with butter all over your fur. Bye-bye

Anonymous said...

Connor a.k.a bit_pattern, This is a good place to search for rebuttals to denialist papers