Update: It seems that the UNFCCC background page referred to below has changed and the link no longer works – see table of contents.
A response from Justin Wood, writing to me from Australia after my previous post (cited with permission below), has prompted me to write a follow-up on the story of the greenhouse effect (GHE).
I wonder if you’ve seen this terrible description of the greenhouse effect on a UNFCCC background page? http://unfccc.int/essential_background/feeling_the_heat/items/2903.php
It actually says that incoming solar energy is ‘reflected’ by the planet’s surface ‘in the form of a calmer, more slow-moving type of energy called infrared radiation. … Infrared radiation is carried slowly aloft by air currents, and its eventual escape into space is delayed by greenhouse gases’ (emphasis added).Given your recent excellent explanation of the real physics on RC, I thought you might be interested! It’s downright disturbing that this silliness comes from such an important source; and I’ve found it repeated all over the place. (On that RC post, I would humbly suggest that the section on stratospheric cooling could helpfully be expanded to make that clearer?)
I won’t discuss the stratospheric cooling now, but rather try to place recent events (including floods in Niger), which involve the hydrological cycle and atmospheric circulation, into the framework from my previous post ‘A simple recipe for GHE‘.
Again, it can be useful to stop and contemplate whether a simple conceptual framework can provide greater understanding of climate model predictions and the observations we make on the climate system. I think that there are not too many simple descriptions, as Wood pointed out, that are convincing in terms of physics.
Can we use such simple conceptual explanations for events such as the recent spate of extreme rainfall and heat waves then? I want to stress, as we did when discussing tropical cyclones, that single events do not constitute evidence of a climate change. Since climate can be defined as ‘typical weather pattern’ (or weather statistics), then climate change can be that extremes become more or less typical, and such change must start with a few events. This touches the difference between weather and climate, and each of these events can be considered as weather. But there is a connection between these weather events and results obtained from climate models.
There are fascinating as well as disconcerting sides to the fact that global climate models reported in the IPCC AR4 suggest warming in the upper troposphere in the tropics (Figure 1 below). I regard these traits as important clues that may help unveil the secrets of the troposphere; The key into this mystery involves energy conservation, planetary energy balance, and the planetary energy input taking place at its surface while its heat loss mainly occurs at higher levels, as discussed in ‘A simple recipe for GHE‘.
This story is about surface fluxes, a fuzzy connection between energy flow and circulation of water, and physical constraints pin-pointing the solutions. In other words, the hydrological cycle associated with moisture transport is tied to the energy flow associated with moist convection.
Another simple mental picture
I will yet again try to present a simplified physical picture: Our climate includes energy transport both from the equatorial region to the poles as well as a vertical flow from the surface to the height from which it can escape freely into outer space. The story behind mid-to-upper tropospheric warming strongly involves the vertical energy flow, which will be the focus of the discussion. In very simple terms, the laws of physics say there has to be a flow of energy from the planet’s surface, where energy is deposited, to the heights from where the heat loss takes place (see schematic below).
The vertical energy flow can take several forms: radiative, latent, and sensible heat. The radiative energy transfer has a character of diffusion (photon diffusion), and the more opaque the atmosphere, due to increased GHG concentrations, the slower the effective radiative energy transfer. A similar situation is believed to take place in the outer layer of the Sun, in the opaque convective zone, where convection is the main mode of energy transfer (which by the way subsequently play a role in solar activity).
If this were the whole story, then an increase in GHG concentrations would imply a deficit between the rate of energy gained at the surface and heat loss from the upper atmosphere due to hypothetically lowered energy transfer between the two levels: The emission temperature would decline as a result of net heat loss high up, and surface temperature would increase as a result of net gain in energy on the ground.
One consequence of a deficit in the vertical energy flow would be different heating and cooling rates at different heights that subsequently would alter the atmosphere’s vertical structure (lapse rate). The planetary heat loss would drop if the emission temperature were to drop, and the planet would no longer be in energy balance, resulting in energy accumulation. However, planets will eventually reach new equilibrium states where the heat-loss balances the energy input.
Other forms for heat flow between the two levels are expected to compensate for the reduction in radiative energy transfer (despite greater temperature differences) if the planetary energy input and heat loss are to balance. One such candidate is convection, carrying both latent and sensible heat and where the energy transfer takes place in form of heat-carrying vertical motion. Indeed, warming below and cooling aloft give rise to more unstable conditions that favours convection.
Higher temperatures near the surface also cause increased evaporation according to a physical law known as ‘the Clapeyron-Clausius equation‘. Evaporation requires energy so that heat, which otherwise would go to increase temperatures, is instead used to transform water to water vapour (phase change). Differences in the molecular weights of N2 and H2O means that moist air is lighter than dry air. Thus, increased evaporation favours convection, which transports both energy – as sensible (higher temperature) and latent (vapour) heat – and moisture. This is seen occurring naturally, especially in association with warm ocean surface in connection with the El Nino Southern Oscillation. Convection can therefore compensate for reduced radiative transfer if its mean vertical extent reaches the height of the planetary heat loss. Convection also is one of the factors that determines the thickness of the tropopause (Wikipedia on Troposphere: “The word troposphere derives from the Greek: tropos for “turning” or “mixing,” reflecting the fact that turbulent mixing plays an important role in the troposphere’s structure and behavior.”).
Moist convection results in cloud formation: water vapour condenses and form cloud drops. The condensation releases heat and hence increase the temperatures, which subsequently has an effect on the black body radiation. Hence, cloud formation plays a crucial role for the planetary heat loss – in addition to affecting the planetary albedo.
The reason why Figure 9.1 in IPCC AR4 is disconcerting is that the temperature anomaly in the upper tropical atmosphere bears the signature of increased moist convective activity, which means that the hydrological cycle probably gets perturbed by increased GHG forcings, hence affecting rainfall patterns.
There have been some misunderstanding regarding the enhanced warming in the upper troposphere – mistakenly taken as being inconsistent with the climate models, or taken as the “finger print” of GHE, rather than as a plausible consequence predicted for an enhanced GHE due to the perturbation of the hydrological cycle (the “finger print”-misconception assumes that the models are perfect).
Changes in the convective activity also have other repercussions. Air just doesn’t pile up, but if is rises in some places, it means that there is sinking air elsewhere. A typical example of this is the Hadley cell, where the circulation involves rising air near equator associated with low sea level pressure and downward motion poleward of this region – an arid region known as the subtropics with high sea level pressure. A change in convection on a planetary scale, due to compensating a reduction in the vertical radiative energy transport, hence may have a bearing on drought and flooding events – and this is what the global climate models seem to suggest. If a shift in the hydrological cycle were to lower the response in the global mean temperature, there may be a poisonous sting in such a negative feedback: changes in the precipitation patterns.
When GHG concentrations change, there is also a disruption in the vertical energy flow so that the planetary energy balance is perturbed. This is the frequently cited extra forcing estimated at the top of the atmosphere (TOA), and this is where some of the assumptions made above don’t quite hold (the picture is correct for a planet in equilibrium, but during a transition the planet is no longer in an equilibrium) and extra energy is taken up by warming of the oceans and surface.
As a physicist, the key to understanding the relationship between GHE and the hydrological cycle – and indeed the troposphere – is in embedded in the question of what happens with the energy flow between the two levels where the planet receives its energy and where it leaves the planet. For more numbers and details, I’d recommend a number of posts previously published here on RC (here, here, here, here, and here).
HR@248
Follow up
Now I understand what happened to Ray. Reflecting on RC servers contributions to AGW after reviewing http://kb.iu.edu/data/afhc.html , I’ll give it a serious try. Thanks (for future reference, remember I prefer access to the full story.)
249 (John Peter)
The statements were:
5) The climate changes in complex ways
6) The world we know (as in our own localities, perceptions, and life style influences) changes
The unspoken qualification on both, clear when placed in the context of the other four points, was that these result, in our current case, from CO2 and GHE.
There have been many climate swings in the past, caused by many different events and types of events.
We’re causing this one. The fact that other events have caused other climate swings have little baring on the discussion, except as sources of information to help us understand what we’re doing now.
This isn’t that hard, and I know that you know that.
Your responses are starting to look like gamesmanship instead of honest efforts to engage.
FWIW, I also like Ramanathan. The papers I’ve read verge on elegant. What I don’t understand is how anyone could take from this the idea that Ramanathan casts serious doubt on anthropogenic causation of the current epoch of climate change. Aerosols are a bit of a wildcard, and because different aerosols can have opposite effects, and are almost always mixed, the effects can be quite difficult to sort out. However, aerosols have a finite lifetime. If we stop spewing them into the atmosphere, voila, a few months later the effect goes away. In contrast, CO2 is a gift that keeps on giving for centuries or even millennia. CO2 wins eventually–just as it would if we tried to mitigate with aerosols.
The history of aerosols is also interesting. The famous paper by the late Stephen Schneider that predicted cooling was wrong, precisely because the CO2 related forcing was underestimated. One more piece of evidence telling us we get more than 2 degrees of warming for a doubling of CO2. Likewise, despite the dimming discussed by Ramanathan, I would note that warming continues apace.
John Peter, Look, I understand you wanting to be “sure” and that different people might have different levels of what constitures sure. But we are talking 95% confidence here. Where is that not good enough to accept a proposition? Where can you not take that to the bank?
guys
This is my second try at saving energy by reducing the load on the RC servers. I hoped that a twitter-like approach would help. It does, for straight forward Q&As. However as pointed out in Hank Roberts reference on trolling http://kb.iu.edu/data/afhc.html
“…The content of a troll posting generally falls into one of several categories. It may consist of an apparently foolish contradiction of common knowledge, a deliberately offensive insult to the readers of a newsgroup or mailing list, or a broad request for trivial follow-up postings. The result of such postings is frequently a flood of angry responses. In some cases, the follow-up messages posted in response to a troll can constitute a large fraction of the contents of a newsgroup or mailing list for as long as several weeks. These messages are transmitted around the world to thousands of computers, wasting network resources and costing money for people who pay to download email or receive Usenet news. Troll threads also frustrate people who are trying to carry on substantive discussions… ”
OK. This my second try will be to try to post in real time, only OT questions or answers that can meet a couple of sentence, twitter-like requirements. The rest of our enjoyment, I will try move my part to the end of the day to save energy by transmiting at nighttime, Pacific Time, when networks are less crowded and surplus power may be available. I hope you will help me do our part to try to reduce AGW.
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JPR @204
I am a member of APS and I support its policies, including the one addressing incontrovertible Climate Change, I was and am skeptical but became even more supportive when 5000 members reviewed the policy and APS board kept it and added an interpretation of each sentence on their web-site. I’m sure you are familiar with both the policy and its interpretation.
When it can or could be interpreted that I am not in tune with the APS policy including the interpretation detail, I would appreciate being notified and will try to address the issue. BTW I am confident that Climate Scientists appreciated the thoughtful action of the APS board and their attempts to address the problems of Climate Change http://www.aps.org/policy/statements/07_1.cfm
Let me thank you for the references and your long time fine work and mention that I found most of the non-referenced portions of your posts 204, 205, 206 and 207 patronizing at best.
@220
What did you intend to do with the ice that you claim we are “losing”. Doesn’t it come back each winter as snow?
@224
We can agree that it’s the warming that is equivocal, not the science.
@233
Archer->IPCC AR4 WG1->googlescholar->papers is the path I use.
Steve or Linl or someone mentioned WG2. He was right, i had missed it. I’m reading it now, it’s good.
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Didactylos@209
I believe we’re closer together than you think. We SHOULD reduce the CO2 emissions because it might help and it won’t hurt. What “basics” precisely am I missing.
My glacier man ref illustrates just how late we really are. http://www.sciencemag.org/cgi/content/short/326/5953/659
@ 231
We agree
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Bob@208
You are ranting
@227
Very good, but if you mean very likely why not say it.
@235
The problem I have is that someone makes a statement about the science and a debater says that the science is unequivocal. At this point coherent communication ceases.
It’s the warming that is incontrovertible, not the science.
Bob@252
You said “triggered”, not “caused”. In the past GHGs partially caused CC. The triggers were small changes in the sun’s orbit, volcanic eruptions, meteors, etc. After the heating was triggered, it was helped along by CO2. Most people including yourself may not care about the difference but real CS do. Please be more careful in your choice of words, especially verbs.
I thought we had agreed to be explicit and not rely on qualifications developed after the fact.
You’ve got things backward again. The causes are always the sun. The way we know CO2 is involved is because it always has been in the past after it got hot enough and wasn’t there for the cold periods. If we knew the triggers, we could look for them. We don’t and that’s one of the scary parts of AGW. We pump more CO2 into the atmosphere and oceans, making them more and more dangerous to current life when CC gets triggered.
I view your last sentence as evocative and ad hominem. You are causing the RC server s to use waste more energy, the very thing we are all trying to prevent. Otherwise my response would have been “Beauty is in the eye of the beholder”.
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BTW You might find this quite unlike the Dr. Feynman you imagine, more like the Richard or Dick that I knew.
http://books.google.com/books?hl=en&lr=&id=1-D0tayXZ9cC&oi=fnd&pg=PR2&dq=nature+climate+feynman+richard&ots=aNiHGi4SGu&sig=TO0k9IS22UhhMSB7g88PszJTC1U#v=onepage&q&f=false
and I am not alone
http://www.amazon.com/review/R1YU8YO70IPCE
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Secular Animist@232
I agree with your very good point but the guys can’t hear us
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BPL@234
AGW has to be real. It must be anthropogenic because tha’s what the A stands for. Three sounds like good science fiction and I’d like to hear more of it.
Ray@253
Yes I picked Ramanathan because he’s an excellent climate scientist and a good teacher. The physical climatologists understand, the biological climatoligists respect him.
Ramanathan describes GHE in the first reference. He describes dimming in the second, 22 years later. The descriptions are different. The science is different. The science has evolved. Same kind of stuff happens in every good science – it evolves. If I say that’s not as true for religions they tend to be more static, some guy will accuse me of “playing the religion card” whatever that may mean.
What can be incontravertable, unequivocal, settledd,… are FACTs. Global warming, anthropogenic global warming, Climate Change are FACTs. They are not science like chemistry, biology, physics,geology,.. which are DISIPLINES and are changeble.
Statements such as ” climate science is unequivocal” are menaingless if you want it to be a science. Any science that is truly settled is dead. Facts can be settled, but not science. Certainly not climate science.
So RAM can fit his new science of dimming into his old different science of GHE. To be correct, both sciences have to explain the same unequivocal warming data. Seems ok to me.
When you tell people climate science is immutable you are wrong. Not only do you turn them into deniers but you also sound like priests of the only true religion.
You’re the editor. Fix it…
Thanks for listening
Bob (Sphaerica) (243), both “unequivocally there is warming” and “unequivocally it is not warming” are statements with consistent logical form. “Unequivocally it is possible that it might be warming” is a statement that is an inconsistent illogical contradiction of terms. It says ‘unequivocally maybe…, unequivocally maybe not’.
Ron 238: BPL, your 234 comment is hand waving (which may be acceptable in other environs) and does not refute John Peter’s 233 comment.
BPL: Ron, go look up what the cake said to Alice.
Setting aside for a moment the real-world impact of the AGW denialists — who on behalf of their godfathers at ExxonMobil, Koch Industries, etc. have succeeded in obstructing and delaying action for a generation, with grave consequences — with regard merely to the endless, drawn-out, repetitive, predictable, nearly mechanical \arguments\ that they engender on this and other blogs, there is just this to say:
They are tiresome and boring.
John Peter – How do you reconcile your position, as expressed in post 70, with the position of the APS, set out in the link in post 250?
254 (John Peter)
Tell us all something else very, very basic that everyone here already knows.
I said “triggered” because it was what I meant. Climate change in our lifetimes is being triggered by instead of merely accelerated by CO2. This point is obvious and should not need to be stated.
Still seems like gamesmanship on your part.
Please be less condescending, and listen to what I actually say. If you don’t understand it, reread it a few times. If you still don’t understand, ask a reasonable question. I can help you through this.
[Condescension is less appealing on the receiving end, isn’t it?]
258 (SecularAnimist),
Agreed. The two deniers are on this thread are both predictable and unimaginative, and the level of discussion is miles below where it should be.
It feels like a visit to WUWT (shudder).
I’m done with both of them.
BPL (259), Hey! More hand waving!
John Peter, I wish you’d get a blog. Let this thread go back to the topic.
“@220
What did you intend to do with the ice that you claim we are “losing”. Doesn’t it come back each winter as snow?”
No. There is a long term decrease in winter ice as well. http://arctic.atmos.uiuc.edu/cryosphere/IMAGES/seasonal.extent.1900-2008.jpg
Furthermore, even if the ice did come back completely in the winter (or increase around Antarctica in the winter, which it does, but not enough to balance the concurrent Arctic loss), the positive albedo feedback would still be there. No ice in the summer, when the sun is high, trumps ice in the winter, when the sun is low or below the horizon.
Third, the ice isn’t the only thing melting in the summer. Methane and CO2 from the thawing seabed and permafrost don’t come back in the winter. Methane has an atmospheric lifetime of 12 ± 3 years and a GWP of 72 over 20 years[1], and it “disappears” by conversion to CO2. The lifetime of CO2 is comparable to man’s oldest cave paintings[2][3].
[1] http://www.ipcc.ch/pdf/assessment-report/ar4/wg1/ar4-wg1-chapter2.pdf
[2] http://geosci.uchicago.edu/~archer/reprints/archer.2005.fate_co2.pdf “… we expect that 17-33% of the fossil fuel carbon will still reside in the atmosphere 1 kyr from now, decreasing to 10-15% at 10 kyr, and 7% at 100 kyr. The mean lifetime of fossil fuel CO2 is about 30-35 kyr.”
[3] http://www.sciencemag.org/cgi/content/full/290/5491/419 “The slabs, painted with red ochre, had apparently fallen from the cave roof and become embedded in floor sediments previously dated to between 32,000 and 36,500 years ago. That would make the images at least as ancient as some found in the Grotte Chauvet in southern France–the current record holder at 32,000 years”
Rod B 262,
I don’t propose to educate you in climate science in one post. What I said was factually correct, so deal with it, pal.
Rod B., On the basis of your #256, I am ready to hand you the trophy for most pathetic misunderstanding of the word “unequivocal”. The fact that you think “maybe” and “unequivocal” belong in the same sentence is just sad.
John Peter, Uh, I am sorry, but where on fricking EARTH did you get the idea I was saying climate science or any other science is immutable?! Of course science changes. If you aren’t imporving the theory continually, you aren’t doing science. THAT DOES NOT, however, mean you get to go all postmodern on us and tell us that science can make no definitive statements! It is simply true that the planet is warming. It is simply true that greeenhouse gasses warm the planet, and that we’re increasing the amount of ghg in the atmosphere. And it is definitively true that you cannot understand JACK about the planet’s climate if you assume a climate sensitivity less than 2 degrees per doubling, The evidence (which for shorthane, we sometimes call “the science” meaning “the results of the scientific investigation of the phenomena”). Now on one side you have mountains of evidence. On the other side…well, bupkes, really. So much so that these propositions are established with better than 95% confidence.
Or let’s put it another way. Let’s say that we have an urn full of balls that are either black or white, with unknown percentage of black balls. We draw with replacement 30 balls, and none are black. This establishes with 95% confidence that 10% or fewer of the balls in the urn. I now give you 10:1 if you b_e_t that the next ball is black. So what’s it gonna be, punk. Feel lucky?
Ray, you missed my point completely, which was “unequivocal” and “maybe” DO NOT go together.
Ray Ladbury (267), I respond about 1 out of 10 times just to try to keep it honest. Briefly, there has never been any macro observations that support the forcing as precisely (within small wiggles) as the ln of the concentration ratio taken to the 5th power when CO2 was leading temperature and starting from roughly where we are today. There have been some highly constrained and stylized lab experiments using e.g. enclosed tubes, gas, LEDs and spectrographs that point in the general direction despite the vagaries, uncertainties and surmising about the molecular absorption process. The 95% confidence comes from a looks-pretty-good-to-me projection (supported by a man made mathematical construct) of a statistical record sans alot of physics underlying support.
GHG forcing is not anything akin to drawing balls out of a jar.
255John Peter says:
Any science that is truly settled is dead.
… like the old dead coral that gives structural support to the next generation (sorry if my understanding of coral is wrong). The boundary shifts. Part of a science may be dead while the whole still lives.
Facts can be settled, but not science.
I think sometimes people use the term ‘science’ to refer to either the body of scientific knowledge that the process of science produces, and/or to the process itself. Maybe that’s incorrect(?) but why bother too much with it?
Re Rod B 269 – optical thickness (at a particular time, along a particular path, at a particular frequency, at a particular polarization) adds linearly. You really don’t need to measure optical properties at every point in the atmosphere. But rest assured that predictions from laboratory work (and/or quantum mechanics theory, which can be verified by lab work of course) can be verified by satellites.
You need to know other climate variables (temperature, clouds, humidity) to calculate CO2 forcing, and some uncertainty can be found there; of course, there will always be some uncertainty even with the results from the controlled environment of a lab. But we know there are clouds, and we also know there are clear skies. We have constraints – strong constraints. Some things are settled.
My attempt to reduce AGW
http://kb.iu.edu/data/afhc.html
Silk@ 259
Sure.
JP@70: John Baker’s post (69) illustrates precisely what you may be overlooking.
The science of GHE is not complete enough to provide a basis for the engineering and the physical calculations that we need to be able to do.
The extensions and connections of GHE science to Climate Change are even less complete. In fact, it is the details of the incomplete pieces that provide “…wondrously complex and entertaining hobbies for amateurs…” (like me) as well as the real (tough) scientific work yet to be done by professional climatologists.
APS policy: With regard to the last sentence of the APS statement, the role of physicists is not just “…to support policies and actions…” but also to participate actively in the research itself. Physicists can contribute in significant ways to understanding the physical processes underlying climate and to developing technological options for addressing and mitigating climate change.
JP@70: It would seem that your six points are not at all as evident as you would claim.
While most skeptics and warmers would probably agree that “GHGs hinder the escape of energy (through IR) from the planet”, quantification such as how much, where, and when require more knowledge of the “details” than we yet have in climate science (think radiative- convective energy balance). That said, your statement #1 is probably OK, but certainly not incontrovertible.
APS policy: The evidence for global temperature rise over the last century is compelling. However, the word “incontrovertible” in the first sentence of the second paragraph of the 2007 APS statement is rarely used in science because by its very nature science questions prevailing ideas. The observational data indicate a global surface warming of 0.74 °C (+/- 0.18 °C) since the late 19th century.
JP@70: It is probably true that, while we are releasing various amounts of many GHG into earth’s atmosphere, to claim in #2 – even for CO2 – that it is “too much” implies the existence of quantitative science details that have yet to be determined (think oceans). I certainly don’t want try to make a case for pollution, I am just pointing out that, for effective mitigation, we need solid quantification of more of the details.
Were I to continue in this same vein, I would suggest that “mostly” in your #3 is unquantified, as is “heats” in your #4 (think “natural”).
APS policy: With regard to the last sentence of the APS statement, the role of physicists is not just “…to support policies and actions…” but also to participate actively in the research itself. Physicists can contribute in significant ways to understanding the physical processes underlying climate and to developing technological options for addressing and mitigating climate change.
HR@263 OK.
As far as I am concerned, I have:
1-My answer from Urs Neu as to the chances for a Broekner THC plug in near future.
2-Stated my belief that the ocean parameters and the lost heat need to be established.
3-Showed an example of CC mitigation, glacier man, that is regional and unsupported by CS in sufficent detail to use CS as a CC mitigation tool.
4- Presented the APS CC policy statement as a valuable contribution to CS.
5-Have re-examined this thread and become much more aware of how easy it is for a comment to become a tipping point for thread diversion OT.
6- Demonstrated to myself, once again, that most important beliefs can not be overcome by logic alone.
That’s more than enough for me for now. OK
Brian Dodge@264
Thank you very much. Following up on your references will be my next learning project. Thanks for pointing me in a better direction.
Ray Ladbury@267
I thought you would be helpful. I stand corrected.
Patrick 027 @270
Believe you’re right, a science that does not build new layers on top of old layers is dead also. I haven’t understood much such structure in CS yet – but I intend to keep looking for it.
I think sometimes people use the term ’science’ to refer to either the body of scientific knowledge that the process of science produces, and/or to the process itself. Maybe that’s incorrect(?) but why bother too much with it?
I don’t know. Experimental physics and theoretical physics are refered to as physics in any but fairly detailed discussions. Software scientists keep programs separate from data or get into all sorts of maintenance difficulties, but still software is the term generally used. Practioners ought to keep processes separate from results, but I really don’t know…
Patrick 027 wrote: “I think sometimes people use the term ’science’ to refer to either the body of scientific knowledge that the process of science produces, and/or to the process itself. Maybe that’s incorrect(?) but why bother too much with it?”
Because prolonged semantic quarreling is useful to people who enjoy wasting other people’s time on blogs.
JP 254,
How does “global agriculture failing and human civilization collapsing as a result” grab you?
JP 254: It must be anthropogenic because tha’s what the A stands for.
BPL: It must be anthropogenic because we’ve known since the ’50s that the new CO2 is coming from anthropogenic sources (Suess 1955, Revelle and Suess 1957). The term “radioisotope signature” ring a bell?
JP: Three sounds like good science fiction and I’d like to hear more of it.
BPL: You think insulting me because of my profession is an argument? Yes, I write science fiction. I also have a degree in physics and write atmosphere models. Rising drought will break human agriculture, and human civilization with it, if we do nothing to control greenhouse gases. That’s science, not science fiction.
Rod B 269: The 95% confidence comes from a looks-pretty-good-to-me projection (supported by a man made mathematical construct) of a statistical record sans alot of physics underlying support.
BPL: “sans alot [sic] of physics underlying support???”
Which part of “the greenhouse effect is radiation physics” do you not understand?
Or “the Clausius-Clapeyron relation is physical chemistry?”
>>Response: They are nonsense and so it is unlikely that anyone will take the time. See Roy Spencer’s discussion for probably the best rebuttal yet. Some others are listed here. Further discussion on this is OT. – gavin]
Gavin–the link leads to an empty page. It looks like someone deleted all the info.
[Response: Just a mistyping. The link is still there. – gavin]
I’m looking for info clarifying climate sensitivity, modeling and/or GHG forcing budget implications arise from the Beer et. al. and Mahecha et. al. papers, which are referenced here:
http://www.sciencemag.org/cgi/content/summary/sci;329/5993/774
I’m only aware of these papers because of a response to a claim Fuller made this morning at Watts:
“CO2 should cause about a 1.5 to 2.1 degree Celsius rise in temperatures if we double its concentration in our atmosphere.”
What are the interesting or important points these papers make? What (if any) fraction do processes related to GPP and R contribute to the output from current climate models?
I’ll need to visit a library even to read the PB Reich commentary I linked above….so please assume that I don’t know anything and please don’t hold my ignorance against me.
andrewo, this may help, you’ll find articles on climate models and plant respiration.
I didn’t find a short simple clear general answer to your question (as an amateur reader, in five minutes) but did find it’s a lively area in modeling, much written quite recently, some models described.
Each idividual specific model will differ in what difference this makes (and answers only emerge with time and enough runs after they improve that particular model). Some modelers have written about doing that.
http://scholar.google.com/scholar?hl=en&q=plant+respiration+Q10+climate+model&btnG=Search&as_sdt=2001&as_ylo=2010&as_vis=1
#279 -Hank Roberts
Thanks! This search result/discussion has proven very helpful:
http://onlinelibrary.wiley.com/doi/10.1111/j.1469-8137.2010.03343.x/full
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Historically, such models have handled respiration rather crudely, with little or no attempt being made to predict the rates of respiratory CO2 release using process-based approaches or to account for the impact of dynamic responses to factors such as temperature and drought on scaling relationships. In some modelling scenarios, respiration is assumed to represent a constant fraction of photosynthesis, even though we know that the ratio of respiration to photosynthesis often varies (e.g. increasing under drought – Jaume Flexas, Universitat de les Illes Balears, Spain). In other models (e.g. that used by the Hadley Centre; Cox, 2001), rates of respiration at 25°C are linked to variations in tissue nitrogen, with respiration being assumed to be temperature dependent (with a constant Q10 of 2.0 – indicating that no account is made for thermal acclimation). Impacts of drought are also estimated without reference to the consensus emerging from empirical data (Jaume Flexas). Moreover, while the assumption of a strong relationship between respiration (R) and nitrogen (N) is supported by global data sets (Peter Reich, University of Minnesota, USA), variations in R-N scaling often occur (Atkinson et al., 2007;Wright et al., 2006; Atkin et al., 2008). Thus, there is a pressing need for models to move away from reliance on outdated and potentially inaccurate algorithms linking respiration and other plant traits.
How should the next generation of dynamic vegetation–climate models better account for spatial and temporal changes in plant respiration? Should efforts be placed on constructing a new process-based model equivalent to that of the Farquhar et al. (1980) biochemical model of photosynthesis? Or should we continue to rely on correlative approaches (e.g. R-N scaling relationships) that better account for the dynamic effects of temperature, light, nutrient availability and drought on respiration? While there was no overwhelming consensus to these questions among meeting participants, all participants agreed that only by strengthening linkages among the different scales shown in Fig. 1 can we more rapidly understand the impacts of climate on respiratory metabolism.
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I suppose the next thing on my reading list ought to be Cox 2001.
( My end goal is to figure out if/how much the argument made here actually matters:
http://www.theresilientearth.com/?q=content/climate-co2-sensitivity-overestimated )
> theresilientearth
> … more proof that the climate models used by the IPCC
> and other climate researchers don’t have a chance in
> hell of getting future climate change correct….
Notice he’s got the answer and is just searching for references that support what he wrote. This kind of after-the-fact “citation” is perilous, as those who write this way don’t happen to mention or even remember reading stuff obviously incompatible with their conclusion.
I’d suggest trying to read the science without the blogger’s filter.
Watch for “gross” rather than “net” CO2/respiration numbers.
I am somewhat new to RealClimate, have always enjoyed the content though have not attempted to understand many of the details. From scanning through these comments and the enormous amount of technical info in them, I assume that many if not all the posters are scientists involved in disciplines touching the GW issue, rather than (like me) simply interested non-scientists (I was a software engineer before recently retiring). Would it be possible for someone who is familiar with many of these posters to comment on that assumption?
Thanks. I’m going to touch this site more often now that I have more “free” time. :)
ted schmeckpeper @282 — Many of the regular commenters here on RealClimate are indeed scientists by training, but only a selection of them in disciplines “touching the GW issue.” For example, I am not, but being (like you) retired choose to learn a fair bit of climatology.