New rule: When declaring that climate models are misleading in a high profile paper, maybe looking at some model output first would be a good idea.
This is a reference to an otherwise interesting paper in Nature this week (Graversen et al) on the vertical structure of heating in the Arctic in recent decades. One of the key results is that during the summer, when temperatures near the surface are constrained to be close to zero by the presence of open water and sea ice, the troposphere heats up anyway. The mechanism for this heating is hypothesised to be related to changes in atmospheric heat transport. So far so good.
But towards the end, there is this curious line:
Our results do not imply that studies based on models forced by anticipated future CO2 levels are misleading when they point to the importance of the snow and ice feedbacks. …. Much of the present warming, however, appears to be linked to other processes, such as atmospheric energy transports.
The clear implication is that climate models don’t suggest that atmospheric heat transports will change and that all polar amplification in those possibly misleading models is driven by snow and ice feedbacks. But is this correct? Well, it’s hard to tell from this paper because they don’t look at any model results!
This didn’t stop the AP from declaring the heat transports to be part of some “natural and cyclical increase”! For National Geographic it was just ‘mysteriously occurring’….
But in order to see what models have to say, all one has to do is look. With the easy availability of the CMIP3 archive, it’s not too difficult to do the analysis for all the IPCC AR4 simulations for this exact period. As a short cut (and just because there is an easy interface) you can also go to the GISS archive and to pull down the figure for the summertime (Jun-Aug) temperature changes in the “all forcings” run for the same time period (1979-2001). If you do so, you’ll see that in the Arctic, the models also suggest that summer time surface changes are small and that there is heating aloft – similar to the analysis in this paper. The match to the ERA-40 analysis isn’t perfect by any means (but the match between different analyses products is not that great either). More analysis would need to be done to work out what was forced and how large the weather noise is etc, but the basic phenomena seems to be quite universal and not mysterious at all.
The point is that this isn’t difficult stuff, and it should be standard practice to at least give a cursory look at what models actually show before accusing them of being misleading.
I imagine you’re talking about that piece put up by ONE MEMBER of the Russian Academy of Science???
> 97
Yep, that was just a random grab by an uneducated reader to note there’s work available. Interesting that the Navy was looking into this issue a decade or more ago. I’m sure there’s more, don’t consider that one paper a best answer, just a possible clue about where the heating may happen and where it may go.
Mike (inline to #89) wrote:
I was thinking about the Sriver and Huber paper. Oceanic advection has also been mentioned not too long ago as one element that models may have been underestimating due to low resolution. Presumably, Wieslaw Maslowski is doing a better job of capturing the oceanic advection in the artic which is melting the ice from below and thus of explaining the trend in Arctic sea-ice using a higher resolution model. Their model predicts 2013 without taking into account the data from either 2005 or 2007.
And of course it is my understanding that poleward atmospheric and oceanic heat transport are likely strongly coupled. And while I am not sure how important this is, 2005 was a record year for hurricane activity in the Atlantic, and 2006 was a record year for hurricane/cyclone activity worldwide — with the Pacific picking upon the Atlantic’s slack. However, at least with regard to Sriver and Huber, having no background, I do not know how important the mechanism would be inasmuch as they seemed to be estimating that hurricanes were responsible for 15% of poleward heat transport tops.
*
For those who are interested, Nature has an Open Access copy of Sriver and Huber (2007) at:
http://emboj.org/nature/journal/v447/n7144/edsumm/e070531-08.html
Re: #72 Actually Nick, I was more concerned about winter (night) effects, as per this article:
Night flights give bigger boost to global warming
14 June 2006
NewScientist.com news service
Richard Fisher
Tools
THE romance of night flight has inspired all kinds of artists, from writers to rock musicians. Rather less romantic is the impact of night-time flights on global warming revealed by an analysis of aircraft movements over England.
Aircraft contrails – the streams of water droplets and ice that form when hot exhaust meets cold, moist air – can persist for many hours, spreading to an average width of 2 kilometres before dispersing. They are known to contribute to global warming by trapping the infrared radiation emitted from the Earth’s surface (New Scientist, 19 October 2002, p 6).
Nicola Stuber of the University of Reading, UK, and her colleagues used computer models to study the warming effect of contrails created by aircraft entering the North Atlantic flight corridor over south-east England. This showed, as expected, that winter flights make a disproportionate contribution to warming because winter weather favours the formation of contrails.
More striking was the difference between night and day. While night flights accounted for only 25 per cent of air traffic at the monitored site, their contrails contributed up to 80 per cent of the warming in cloud-free conditions. That’s because daytime contrails partly offset the overall warming effect by blocking incoming sunlight (Nature, vol 441, p 864).
The team also showed that the 36 per cent of flights over the US east coast that occur during the night account for 53 per cent of the warming. The 48 per cent of all flights in the North Atlantic corridor that are at night account for 58 per cent of the warming. The simplest way to minimise the warming effect of contrails would be to reschedule flights for the daytime, Stuber says.
Bob Noland of Imperial College London, who also works on contrail-induced warming, says this research should help persuade a sceptical aviation industry to address the issue. “They’ve done a fine job, using well-established data,” he says of Stuber’s team.
But shifting all night traffic to the daytime would be unrealistic, he says. Instead, he suggests planes should be manoeuvred around regions where contrails would form, just as they avoid thunderstorms. However, Stuber says it is difficult to forecast conditions that favour the formation of contrails.
Re #100
Grand Exhaulted Poobah is too pretentious. Why not simply “The Wizard of On” referring to Louis M. Michaud, of Sarnia, Ontario, Canada, the inventor of the “technology” most likely to save the world, the “Atmospheric Vortex Engine”. Meanwhile, there will be opportunities to nominate him for a Nobel Prize BOTH for Peace and Physics.
Of course there is still time for Gavin, as well as the other Founders and Contributers here at realclimate.org to claim the title of “Assistant Wizards” by signing off on the technology in group fashion in order to get its development in motion more quickly.
AVE_fan #1
PS to 103
As I remember, Sriver and Huber were focusing on oceanic polward heat transport, but it seems obvious that this would apply equally to the atmosphere. One point: presumably we had been thinking of hurricanes as mostly local, not having the kind of global effect that Sriver and Huber describe, although according to Mike the view that they may have a global effect actually goes back to Emanuel. 2003 I would presume. However, I remember myself as having thought of their heat transport as essentially vertical before I started digging into any of this stuff. Ad hoc air conditioning units for the planet, I suppose.
However, with increased convective vertical heat transport due to moist air convection, qualitatively at least, I would expect both the atmosphere and ocean to more easily re-organize itself horizontally. This would be a form of self-organization. Moreover, as this involves convection with structure at various levels and positive feedbacks by which more efficient paths of heat transport are “chosen,” I would expect models to do a better job of capturing this sort of phenomena with higher resolution and to underestimate its effects with lower resolution.
*
One more point: I remembered from my evo days that presumably hurricanes couldn’t get above 40 mph windspeed — much like bumblebees can’t fly. But the trick with the bumblebees is a reliance upon turbulence generated by their velvety coat. And with hurricanes, presumably the water droplets from sea spray serve to lubricate their winds so that they can achieve much higher speeds despite the viscosity of air.
Looking it up just now I found the following two articles:
Ocean Spray Lubricates Hurricane Winds
ScienceDaily (Jul. 26, 2005)
http://www.sciencedaily.com/releases/2005/07/050726074054.htm
Barenblatt et al., The turbulent wall jet: A triple-layered structure and incomplete similarity (2005), PNAS, Vol. 102, Issue 25, pp. 8850-8853
http://www.lbl.gov/Science-Articles/Archive/sabl/2005/August/assets/docs/Hurricanes.pdf
Now one question: the sea spray water droplets are able to kick into action well below 40 mph (64 kph) at just over 25 mph (40 kph). So would water droplets play a similiar role in poleward convection? Or would their role in this be limited to fascilitating vertical transport and thereby facilitating poleward transport only insofar as vertical transport sets up conditions under which poleward transport arises through spontaneous self-organization?
I had provided the link to:
Editor’s Summary
31 May 2007
Cyclones in the mix
http://emboj.org/nature/journal/v447/n7144/edsumm/e070531-08.html
… earlier for the Sriver and Huber (2005) on how hurricanes may fascilitate poleward oceanic heat transport. The link to an open access copy is there.
However, it also includes a link to the news article:
Churn, churn, churn
How the oceans mix their waters is key to understanding future climate change. Yet scientists have a long way to go to unravel the mysteries of the deep. Quirin Schiermeier reports.
This mentions Kerry Emanuel’s view that hurricanes might play such a role as being expressed back in 2001 among other things. Stuff to explore.
And yes — I am just trying to stir the pot at this point.
[Response: Thanks for your comments Timothy. Thus far, the impact of TC-related ocean mixing and heat transport on global climate has been looked at rather crudely. It will take some time for this to implemented in models (ocean-only and ultimately coupled models) in a realistic enough way that we can draw more firm conclusions. You can expect to hear more about this in the months and years ahead. But, in my view, its the best current prospect for explaining our way out of the ‘equable climate’ paleoclimate problem and perhaps, we may learn, other current inconsistencies as well. This is the way science is supposed to work. Stay tuned! -mike]
I took a closer look at the Nature news article “Churn, Churn, Churn” I gave a link to above.
It mentions the how, if hurricanes play a stronger role in shaping heat transport in warmer climates this may help to explain the near Mediterranean conditions the Arctic enjoyed during the Eocene — something that Raypierre expressed an interest in back in 89.
It states that tides evidently play a much larger role in ocean mixing that proceeds along the ocean bottom — and that this may prove to be important to models.
It also mentions that Earth and Space Research Institute is in Seattle where Robin Muench lead a group focusing on the rate of mixing in the oceans, both as a whole and in specific regions. Eric might want to give him a call and have a coffee if that sort of information might be of value to Gavin.
> 800 watts per square meter heat flux is interesting, isn’t it?
Yes. Mainly since it was the only intelligible phrase in the whole paragraph! [;>)
Re # 56, 66, 70, 71, 75, 79, 80 and 82: The 2005 RealClimate post by David Archer referred to by #79 on the lifetime of anthropogenic CO2 in the atmosphere was updated by his later publication [1]. In it Archer states:
“The idea that anthropogenic CO2 release may affect the climate of the earth for hundreds of thousands of years has not reached general public acceptance. …”
“The carbon cycle of the biosphere will take a long time to completely sequester anthropogenic CO2. … The mean lifetime of fossil fuel CO2 is about 30-35 kyr. …”
“… if the fate of anthropogenic carbon must be boiled down into a single number for popular discussion, then 300 years is a sensible number to choose, because it captures the behaviour of the majority of the carbon. … However, the 300 year simplification misses the immense longevity of the tail on the CO2 lifetime, and hence its interaction with major ice sheets, ocean methane clathrate deposits, and future glacial/interglacial cycles. … A better approximation of the lifetime of fossil fuel CO2 for public discussion might be ‘300 years, plus 25% that lasts forever.'”
The IPCC AR4 cites Archer’s paper when stating, “about 50% of an increase in atmospheric CO2 will be removed within 30 years, a further 30% will be removed within a few centuries and the remaining 20% may remain in the atmosphere for many thousands of years.” [2]
So, while Steve Reynolds (#66) is correct that, “the half-life of CO2 in the atmosphere is much less than 80 years” in the sense that 50% is removed in 30 years, Archer’s work indicates that Ray Ladbury (#56) is also correct to refer to the effect of anthropogenic CO2 emissions being felt for hundreds of years. Nice to settle an argument by both being right :-)
References:
[1] Archer D (2005), ‘Fate of fossil fuel CO2 in geologic time’ Journal of Geophysical Research Vol 110, C09S05, doi:10.1029/2004JC002625.
[2] IPCC (2007), Climate Change 2007: The Physical Science Basis. Contribution of WGI to the AR4, Ch 7, p 514. Available at http://www.ipcc.ch/ipccreports/ar4-wg1.htm
Chris McGrath, the ~30 year # is the time for most of the excess CO2 to make its way into the biosphere–but this does not remove it from the climate. Rather, unless we grow a lot of redwoods, in a few decades much of the carbon gets back into the air, some as CH4, with a higher gh potential. Moore and Braswell say themselves that ignoring the biosphere, the half-life is closer to 92 years. Moreover, if we have cooling due to decreased insolation, this would adversely affect plant growth, and the uptake would be even slower.
“Half-life” is misleading and not the description used by anyone in the field.
A half-life describes radioactivity — a process that is going to go on at the same rate regardless of anything happening in the environment. No feedback, no forcing, nothing changes.
Applied to biogeochemical cycling, it suggests, falsely, a steady rate of removal.
CORRECTION to 106 (sea spray and hurricane formation)
For sea spray reducing the viscocity of air and thus making it possible for hurricanes to be far more powerful than they would otherwise be, I had given after a quick search:
Barenblatt et al., The turbulent wall jet: A triple-layered structure and incomplete similarity (2005), PNAS, Vol. 102, Issue 25, pp. 8850-8853
http://www.lbl.gov/Science-Articles/Archive/sabl/2005/August/assets/docs/Hurricanes.pdf
However, the correct paper is:
Barenblatt et al., A note concerning the Lighthill “sandwich model” of tropical cyclones (2005), PNAS, Vol. 102, Issue 32, pp. 11148-11150
http://www.pnas.org/cgi/content/full/102/32/11148
Same authors, same periodical, same year and related topics, but obviously not the same paper. And yes, it is open access.
[Response: You don’t want to believe everything you read in the newspapers…. – gavin]
I don’t believe everything I read in the papers, but I believe this! I realize that Gavin is the flag bearer for all the heavy hitters(to add to Congressman Inslee’s analogy of stepping up to the plate) that run RC,including the guest hosts like Figen who posted earlier. The Lonborg’s of the world are necessary as well. What’s the point of running for a touchdown if the opposing team is sitting on the bench?
The only modification might be that instead of saving the planet, which will survive with or without homo sapiens, at least they have the potential of saving civilization. Especially if more decision makers like the Congressman come aboard.
Inserting the period 1979-2001 and Jul-Aug. in the pull down menu for the model runs referred to in the lead article does indeed show small(-0.1 to +0.3C)for surface change temperatures in the Arctic, and more heating at higher altitudes, if I’m reading the results correctly.In addition, the global mean graph shows a gradual heating from the surface to about 300 mb and then a more rapid cooling in the upper atmosphere.
#91 Russell. Got something to ponder, cross two Polaroid sheets perpendicularly, no visible light gets through, in the case of thermal layers having UV or IR take a look at this sequence inspired and executed by Physicist Gunther Kletetschka, first a sunrise without ducts:
http://www.eh2r.com/mp/data4.html
The problem is to differentiate between UV and IR, UV should refract above the sun disk and IR below, clouds and moisture may show as IR.
Now a sunset with a thermal duct or three:
http://www.eh2r.com/mp/data5.html
THere are artifacts, still unknown, in the last cross Polaroid pictures, if you look
at the visual to Polatroid sequences, there is a tripling of the sun line, is the top one UV? Unknown, but this testing can be repeated and Ill try to find out.
Lawrence Brown: interesting post, but something bothers me in your outlook. The Lomborgs of the world are not necessary, they are a nuisance, as are advocates from the opposite side who disregard reality for ideology. This is not a football game or a courtroom argument. Nature does not give a damn about our bickerings, it does not need to be given a voice, it is the only authority. Way too much BS is already out there under the pretext of “balancing views.” Balance is of interest only if it is grounded in firm scientific underpinnings and stems from a genuine desire to understand, both of which exclude Lomborg and ideologues in general. Understanding the workings of Nature is the function of science, it must supercede all ideological predispositions. Only when we accept that fact will we have a real future as a species, in which we’ll be somewhat responsible.
Re #111, Ray, not being a climate scientist or an ocean chemist (as Archer is) and just trying to understand this issue by reading the IPCC AR4, Archer (2005), and Archer’s 2007 text, Global Warming: Understanding the Forecast (Ch 10 of which deals with the perturbed carbon cycle), I understand a major sink for fossil CO2 emissions in the short and medium terms is the ocean based on chemical (not biological) dissolution of CO2 into carbonic acid, bicarbonate and carbonate ions.
Re # 112, Hank, point taken. I was trying to incorporate Steve’s earlier terminology because both he and Ray seemed to be making valid (if somewhat incomplete) points.
Many congratulations to Gavin and to the entire RC team. RC is truly a phenomenal blog site which I believe has already changed the world by making extremely accomplished scientists and their ideas accessible to the public. What makes RC invaluable is not just the high quality of its posts, but also the way it operates behind the scenes and the creative, thoughtful and courteous community of readers and commenters it cultivates and supports.
When I first approached Gavin (through e-mail) to ask if I could do some translations for RC, I didn’t know him and actually only knew one of the 11 editors of the site. All the editors here are high profile scientists with very impressive publication records. So I felt nervous about wanting to participate on RC thinking I won’t measure up. Gavin was open and welcoming, and later when I submitted a post he and the rest of the team were extremely supportive. All posts go through peer review here and the process is tough but I learned so much!! So they aren’t just doing a service for the general public but for scientists like myself by providing us with support and exposure to the general public (I am one of the most recent guest hosts here but they have had many others like me). And I use RC as a teaching tool in class by not only having my students read their posts but encouraging them to post comments. And so the community grows. I think that alone is a huge contribution to civilization.
Many congratulations again.
The mystery for me is this is a huge effort on their part, so how do they find the time for producing all this science as well as running RC? Do they somehow have 30 hours in their day? :)
Re 116: Yes, thank you Phillippe for the correction.On thinking it over, the serial naysayers are a net minus,placing obstructions in the path of progress. If they are of any worth at all, it’s to keep the rest of us on our toes as to what faux attribution regarding global warming they’ll come with next.
“…..If they are of any worth at all, it’s to keep the rest of us on our toes….”
It’s a tough job, but somebody has to do it…
We are pleased to see the lively discussion here related to our recent study on the Arctic warming amplification.
We state in the final paragraph of our paper that “Our results do not imply that studies based on models forced by anticipated future CO2 levels are misleading when they point to the importance of the snow and ice feedbacks”. We mean just that: models showing a connection between an amplified warming in the Arctic and the ice-albedo feedback mechanism do not have to be wrong. We welcome a model intercomparison study dealing more in depth with this question, but that was beyond the scope of our study.
In some media, it has been claimed that we find evidence suggesting that natural variability underlies much of the recent Arctic climate change. In our paper we show that a shift in the northward energy transport into the Arctic has played a considerable role for the Arctic amplification; we do not know whether this shift is due to natural variability or if it is anthropogenically induced.
R. G. Graversen, T. Mauritsen, M. Tjernström, E. Källén and G. Svensson, Stockholm University, Sweden.
[Response: Thanks for stopping by. Do you have an idea why some of the media reports got this wrong? – gavin]
RE #112: Hank Roberts @ 9:17 PM:
Hank, there is another scientific field in which the term “half-life” is used, and that is pharmacokinetics (a subject near and dear to my heart). For more complex systems (with compartments), there are parameters for absorption, distribution and finally elimination. We might think of the organic parts of the carbon cycle as the distribution phase (in which there is exchange between tissue and the circulation) and mineralization as elimination.
I know it’s off-topic for this thread, but I have a question concerning the latest IPCC report.
In chapter 2 of the WG1 section of the 4thAR, section 2.4.5 discusses aerosol cloud albedo effect. Figure 2-14 shows graphically the cloud albedo forcing results of 28 GCM runs. See here: http://www.ipcc.ch/pdf/assessment-report/ar4/wg1/ar4-wg1-chapter2.pdf (page 177)
After a lengthy discussion of the various issues involved in estimating this particular forcing, the authors summarize on page 180 as follows:
“Based on the results from all the modeling studies shown in Figure 2.14, compared to the TAR it is now possible to present a best estimate for the cloud albedo RF of –0.7 W m–2 as the median, with a 5 to 95% range of –0.3 to –1.8 W m–2.”
However, according to my Excel spreadsheet, the median of the data shown in figure 2-14 is not -.7 — the median is actually -.99. (The values that were graphed in Figure 2-14 are shown in Table 2.7, pages 174 – 176. I used the values from that table. Note that only the values shown in bold were included in Figure 2.14, so those were the ones I used.)
Does anyone know how they came up with a median of -.7 instead of -.99?
I also don’t see how they came up with that confidence interval. According to my Excel spreadsheet, +/- 2 sigma on the data in the table is -.12 to -1.87. Does anyone know how they derived their confidence interval?
RE # 121
Dr.Graversen et al.,
Have you submitted a letter of clarification to the editor of any of the papers in which Seth Bernstein’s article was posted? I believe that would help clear things up.
RE: The 50 people…With special attention to #118 and as evidenced by;#121.
Saving the world may or may be an exaggeration, but Gavin is certainly in a league with Eric Clapton.
Thanks to Gavin and everyone else here who has made this a great place to learn and clear the air.
> pharmacokinetics half-life
— That’s a great nitpick.
But I doubt wossname was using ‘half-life’ to mean that kind of biological rate of change. He’d be endorsing the Gaia Hypothesis:
“… For some substances, it is important to think of the human or animal body as being made up of several parts, each with their own affinity for the substance, and each part with a different biological half-life. Attempts to remove a substance from the whole organism may have the effect of increasing the burden present in one part of the organism.”
http://en.wikipedia.org/wiki/Biological_half-life
The denial guys use “half life” to pretend the excess CO2 in the atmosphere from fossil fuel burned will go away fast and predictably. That’s not true.
The CO2 experiment, in progress, is a very fast overdose. We’ll see what happens to vital subsystems (or to subsystems that like to think of themselves as vital because, er, sapient).
Re #123 Michael Smith: About the median, yes I see that too. I get, without Excel, by averaging the two values straddling -1.0:
Quaas and Boucher 2005 (control): -0.90
Chen and Penner 2005 (UM_3): -1.07
yielding a median of -0.985.
The median of only the last 20 values isn’t it either: -0.81.
As for the 5% – 95% confidence interval, for a normal distribution this corresponds to +/- 1.65 sigma, not 2 sigma — or 1.96 sigma, which is for two-sided 95% significance, i.e., 2.5% – 97.5% :-)
Anyway, I would be surprised if this data were actually normally distributed… one way to get at -0.3 to -1.8 is to remove the bottom 5% of the data — in practice, Chuang et al 2002 — and the top 5% — Dufresne et al 2005 –, after which the smallest and largest values are
Chen and Penner 2005 (UM_6) -1.79 (rounded -1.8)
Quaas and Boucher 2005 (MODIS) -0.3
which is what the report states, and does not assume normality. It is slightly conservative in that for 28 data sources, 5% > one data source.
Hi, I know this is quite a ways down this comment thread, and a little off-topic, but I was hoping someone could answer a question that I heard from a sceptic who claims to be very knowledgeable about modelling and pooh-poohs the IPCC AR4.
I’ll just cut and paste what he said. He’s not a native English speaker, so please be patient with his sometimes clumsy expression:
As I have pointed out in my previous message, that the members of the public tend to follow the simplistic view of the IPCC, where in reality the simplistic models quoted in the IPCC are inefficient. The most inefficient of them all the the modeling of climate feedback systems. Again, if I had to make a claim, then I must point to the source which is shown below (see link), where this workshop was a NASA sponsored one, and they (about 30 of them) wanted to address the shortfall of modeling climate feedback systems. Shortfall means misleading, unless one had to persist in accepting that the model inefficiencies are not misleading. Such a scientist must be living in a dreamland if he/she had to keep using inefficient models.
http://grp.giss.nasa.gov/reports/feedback.workshop.report.html
This workshop was chaired by Dr. William Rossow of NASA , who had published his peer review work on the subject of non-linear coupled feed-back climate systems. I had made a few email exchanges with Dr. Rossow in the past, regarding his paper on the subject, in which I have read.
Dr. Rossow, was an IPCC author in 2001, but his report on feedback from 2001 is still unchanged in 2007, since there has been slow progress in the modeling of the most complex subject of them all in climate modeling domain. If someone is close to solving climate feedback systems, then we’re looking at getting closer to understanding the big question? Is human responsible or not?
[snip]
I have said in the past […] that there is no single model in the whole IPCC report that nailed down CO2 as the driver (forcing) and this is fact and not perception, unless you can point me out to a model where CO2 is included as the driver function (forcing).
Does this guy have a point, or is he simply waving his hands to dazzle people and distract attention? Or (alternatively), is he cherry picking some uncertainties and exaggerating them?
I appreciate any response from modellers. Or lack of response; my feelings won’t be hurt ^^
I have an off-topic question I hope someone can clear up for me. I’m writing RCMs again (or attempting to do so), and my latest one handles everything in bands. To find out how much a (homogeneous) layer of atmosphere radiates, I’m using the following code:
fraction = D(hi[b], LT[L]) – D(lo[b], LT[L])
blackbody = aband[L, b] * sigma * LT[L] ^ 4.0
RadiatedUp[L, b] = fraction * blackbody
RadiatedDown[L, b] = RadiatedUp[L, b]
I’m getting screwy results, and I think the problem may lie in how I’m setting these variables. The D function gives the amount of the electromagnetic spectrum a body radiates, from zero wavelength to lambda, by the Planck function. So the algorithm I’m using is essentially
radiated amount = (amount that would be radiated by a black body) x (absorptivity/emissivity in the band) x (fraction of radiation emitted in that band.)
But it strikes me that with different values of a/e in each band, the fractions are no longer the same as you’d get with a pure Planck distribution. Is there some way to account for this that I’m missing? I’d appreciate any help.
-BPL
Nigel Aimes,
I am not a climate scientist–jut a physicist, but if your skeptic friend were waving his hands anymore, he would levitate. “Inefficient” is not an word a knowledgeable critic would apply to the models.
RE #126 Hank Roberts — 9 January 2008 @ 11:21 AM:
Thanks for replying. I guess the analogy I was trying to make was more on the mathematical/rate constant end. I’ll see if I can explain myself a little better.
The relatively short “half-lives” that get quoted seem to me to describe distribution of CO2 to biological systems (or oceans, I guess – why not a two compartment model. LOL.) – but distributed CO2 really doesn’t really go away. The real “elimination” is the sequestering. Of course, when CO2 is continually added to the system “half-life” becomes less important. Obviously we’re adding CO2 faster than it can be eliminated, or else levels would not be rising. Anyway, just a little diversion from this medical researcher, but when I see the smokestack, carbon cycle and rock pictures, with arrows, that’s what comes to mind for me.
Re: #87, thanks Hank – I vaguely thought I had seen that graph before. The article is a bit longer and more technical than I had in mind, but still very good.
Nigel Aimes (128) — The physics of carbon dioxide as a global warming (so-called greenhouse) gas is well understood. For example, in the Science section of the sidebar, the first link is to the Discovery of Global Warming web pages. One section is devoted to Carbon dioxide as a Greenhouse Gas.
No computer models are necessary to explicate this fundamental fact.
Your correspondent is levitating on the light gas he is emiting.
Nigel, would the unnamed person you’re quoting, who points to
http://grp.giss.nasa.gov/reports/feedback.workshop.report.html have looked for subsequent reports and cites to know what’s changed in this work on his own, do you think?
If so, you could ask him what’s new, since that’s old.
We can do the ‘homework help’ searching — I do see that Dr. Rossow has a lot of publications if you look for his name +NASA with Google Scholar for recent years. I didn’t do anything serious about checking forward from that old report to see what’s happened in a systematic way, just glanced at a few searches.
I know its off topic but as it hasn’t been mentioned, Bert Bolin passed away last week on the 30th December. He was a pioneer in the research and recognition of the issue of climate change, as well as the IPPC chairman from 1988-1997. Here are a few obituary links:
http://www.timesonline.co.uk/tol/comment/obituaries/article3153999.ece
http://www.guardian.co.uk/obituaries/story/0,,2237392,00.html
http://www.ipcc.ch/news-040107.htm
#15 Aaron Lewis points to http://afp.google.com/article/ALeqM5hWas1ATOsqlUcRqZ021v5ubeO3IA which coincidentally also points to an article of interest to those asking about biosphere sequestration:
Shilong Piao, Philippe Ciais, Pierre Friedlingstein, Philippe Peylin, Markus Reichstein, Sebastiaan Luyssaert, Hank Margolis, Jingyun Fang, Alan Barr, Anping Chen, Achim Grelle, David Y. Hollinger, Tuomas Laurila, Anders Lindroth, Andrew D. Richardson & Timo Vesala. Net carbon dioxide losses of northern ecosystems in response to autumn warming, Nature 451, 49-52(3 January 2008)
doi:10.1038/nature06444
For those who don’t have a Nature subscription: http://www.globalcarbonproject.org/news/AutumnWarming.htm
Short summary: biosphere sequestration is on the way down, with northern autumn warming more than compensating for increased spring growth in terms of CO_2 absorption.
This whole discussion, important though it may be, left me with a bit of a feeling of unreality. The odd loosely worded conclusion in Nature is a minor problem compared with the truly horrendous stuff being published elsewhere (blogs, obviously biased journals, newspaper articles, financial press), much of which is very easy for me to debunk with only undergrad physics and a computer science academic background. Yet this stuff gets equal weight in the popular conception because most people don’t read Science, Nature, etc.
The depressing thing is in the process of debunking this stuff, I would really like to find hard evidence that things aren’t as bad as reported (taking on Exxon-Mobil doesn’t strike me as a soft target), but everything I find that is outside the IPCC “consensus” and not easy to debunk actually makes things worse. (Faster than expected sea level rise, slower CO_2 environmental sequestration, evidence of CO_2 involvement in mass extinction events …)
Keep up the good work, we have a planet to save…
Re 130.
I think there are some very knowledgeable critics that are saying, in fact, the models are “inefficient.” I for one, think that “Python” (http://www.python.org/) would be a better work environment.
I submitted card decks of Fortran programs to the NCAR computer in 1965. In those days, Fortran was a cutting edge technology. Now it is a legacy. We have invested so much in these models, that we are afraid to move to a new platform. However, reduced maintenance costs, improved flexibility, and reduced capital costs in the future make moving to a work environment such as Python a smart policy. Not an easy policy. There would be a lot of folks scrambling up Python’s steep learning curves. Then, they would have to rebuild the models. That would be a serious capital investment. However, then we would have models made for faster, better, cheaper climate science.
Will it happen? Yes! There will be a global warming “surprise event,” and then policy makers will get serious about giving climate studies the resources it needs.
[Response: Actually, Python has a very gentle learning curve. That’s why I’ve adopted it for most of my teaching. The computational exercises for my ClimateBook are built around Python (follow the link from geosci.uchicago.edu/~rtp1), and most of my own modelling has been done using Python for the past 5 or 6 years. That includes the Titan model Jonathan Mitchell and I wrote about in PNAS. Usually to get performance, Python, like all interpreted languages, needs to be supplemented by compiled code in Fortran or c. However, with Python it’s easy to build new Python commands from compiled code. We’ve even gotten a Python parallel ocean model running. I absolutely agree that Python is the right platform. It’s not the learning curve so much as the fact that physical scientists are uncomfortable with the object-oriented way of doing things, and also the inertia behind Fortran. And also, now that they have Fortran90, they think there’s really no need to go beyond Fortran. I think Fortran90 is a real impediment to progress, especially since it doesn’t inter-operate well with other languages or environments. I’m working hard to change that, one grad student and one postdoc at a time.
However, none of this has much bearing on the “criticism” originally levelled against models. Fortran is quite “efficient” in the sense of numerical performance. If it can be considered “inefficient” it is inefficient with regard to allowing flexibility in model design. That’s a real issue for the future, but that hardly affects the extent to which one can make use of or trust the existing climate simulations. It would be fair to say that debugging would be a lot easier if models were built on a platform like Python, but it is possible to write clean, maintainable code in Fortran (many modelling groups do so), and there are enough physical cross checks on full models and model components to assure that significant bugs get found. –raypierre]
I don’t know, I’m getting a heck of a lot of mileage out of Fortran-95, and for us non-pros, there are free compilers for it out there. And I’ve never much cared for the object-oriented stuff — speaking as someone with 15 years of professional computer programming experience, that is. Nyaah.
Aaron Lewis, Read what I wrote as it applies to the comment by our denialist. He is trying to cast doubt on the conclusions of the models, and “inefficiency” would merely prolong the time and increase the resources for calculation, not invalidate the conclusions. This is a guy who took maybe one computer science class in college and is trying to pass himself off as an expert. The only thing he still remembers from that class is that efficiency is good, so therefore since climate change in his eyes is a product of Satan and all his minions, climate models must be inefficient. His screed reads like technobabble from an episode of CSI–he’s probably even pronouncing his lines phonetically.
Does anybody know about this site ( http://www.earthlab.com ) ? I have seen other environmental sites with carbon calculators like yahoo and tree huggers, but I am wondering what the deal with earthlab.com is? I saw they also published a list last month of the top ten greenest cities ( http://www.efficientenergy.org/Top-Ten-Green-Cities-in-the-United-States ). Does anyone know if this site is better than the others? Fill me in!
I took their carbon foot print test and it was pretty interesting, they said that I put out 4.5 tons of carbon, does anyone know about any other tests?
>earthlab
Never heard of them. _Scary_ jargon. They specialize in “reverse research” and have a full page of marketing jargon:
” … EarthLab is the leading climate crisis community and multi-platform media brand … ”
and
” … providing unsurpassed real-time data collection from consumers worldwide.”
So I looked up “reverse research” and — I sure hope this is not what they mean:
“After either writing a paper based on things you already know or after copying a paper without bibliography, reverse research is the process of searching for books and websites to include for one’s works cited page. ….”
http://everything2.com/index.pl?node_id=852289
The bios of the people sound reasonable. But it sounds like they’re being used for some sell-the-customers-to-the-businesses marketing.
I hope I’m wrong. Don’t see how their nonprofit status fits with the jargon on the website at all, at all.
I’m not cynical enough yet.
> earthlab.com
Well, I’d say — look for a privacy policy on their site. I couldn’t find one, in a few minutes’ searching.
If they aren’t asking you for info and reselling it, then they look to have a decent program. But only if they’re not using what they learn from you for marketing.
In my sole amateur opinion of course.
raypierre (inline to 137) wrote:
I suspect the very thought of it might give you nightmares, but…
1.
2.
3.
Wouldn’t matter what languages they were programming in as long as it was all in the DotNet framework. A Fortran.Net exe could use a Python.Net DLL along with a C# custom control and what-have-you just as if they were all written in the same language since it all pre-compiles to the same pseudo-machine Intermediate Language. But I’m not suggesting anything. Just wanted to let you know that its out there – assuming you didn’t know already.
Ray, David B, & Hank – Thanks for your responses. This guy is very aggressive in the way he discounts anyone else having the relevant expertise (which I find irritating) unless they can answer his pop quizzes. And, while I thought this contention of his was way off-base:
I have said in the past […] that there is no single model in the whole IPCC report that nailed down CO2 as the driver (forcing) and this is fact and not perception, unless you can point me out to a model where CO2 is included as the driver function (forcing)
I had to admit I really didn’t have the expertise to argue against it. I mean, is he on another planet here, or is it in fact true that CO2 isn’t explicitly modelled as a forcing?
[Response: The radiative effects of CO2 are explicitly modeled in all general circulation models, as are the radiative effects of other significant greenhouse gases and other climate forcings such as aerosol effects and the effect of solar variability. Point to any GCM discussed by IPCC and you have your answer to this ignorant person. –raypierre]
Philip Machanick (#136) wrote:
The operative sentence in what you linked to seem to be:
In otherwords, if autumn warms more quickly than spring, then the carbon sink will gradually fail to keep up with our emissions — and do so ahead of schedule. And in fact autumn is warming more quickly than spring in North America, but not in Eurasia — there it is the reverse. Checked the Nature article, and it says basically the same thing. As such, the net biosphere sink would seem to be keeping up for the time being, at least according to this story. It will be interesting though to see what happens once the Arctic sea-ice is gone. Currently there is some cooling in Siberia.
However, another article to keep in mind regarding biosphere sequestration is:
Knorr et al, Impact of terrestrial biosphere carbon exchanges on the anomalous CO2 increase in 2002–2003
Geophysical Research Letters, Vol 34, L09703, doi:10.1029/2006GL029019, 2007
Drought and forest fires are going up, at least during the hotter, drier — and this means less carbon sequestration.
But it is worthwhile to keep in mind the fact that on the whole the sinks appear to be keeping up, with net uptake being a constant percentage of our annual emissions, at least for the time being:
On the whole at least, it appears that sinks are keeping up, even though some are showing signs of weakening. For the time being.
#89 raypierre
Just going through the latest edition of Science, and I think you may be very interested in the paper on possible ice during the Cretaceous given your comment…this will be very interesting, and I suspect will generate a lot of discussion in the paleoclimate community; it is here
# 136: Some press summaries of this study are ambiguous concerning the fact that the results are based on observed behavior of the whole forest ecosystem. In addition to trees, the ecosystem includes all the undergrowth and the multitude of biological processes in the soil.
A critical difference is that the growth (sequestration) requires light energy, whereas the decomposition of organic matter in the soil does not. Decomposition (and emission) goes on as long as suitable temperature and humidity conditions are available, even in darkness. In the northern latitudes daylight in the autumn months is very scarce, also because of generally dense cloudiness. In early December, for instance main parts of the northern conifer forests receive any light at all for about 3 hours daily. Decomposition in the soil goes on as long as the ground is not frozen, and so carbon emissions dominate.
Another factor is that plants ability to grow is partly driven by genetic adaptation to a local climate, not just temperature, humidity and light. While in the summer there is plenty of light, suitable temperatures and water, there is also a genetic cycle that terminates growth and prepares a tree for the winter. A longer summer season has therefore a limited impact on growth.
In intensive forestry a practical recommendation is that seed origin should not be more than 200 km north or south from an intended planting location. A southerly origin causes damage due to frost bites as the trees remain in a sensitive growth phase for too long. A northerly origin causes growth to terminate too early with respect to available climatic resources.
Due to warming autumns and winters, there is an obvious disturbance to the equilibrium, another perhaps significant feed-back loop.
Re #143 Timothy Chase and dot-net: Weren’t religious posts banned on this forum? :-)
Anyway, what’s wrong with Scientific Python? Some of us prefer platform independent solutions. And linking with precompiled Fortran isn’t exactly a new invention…
Following up on my above comment on the paper involving possible glaciation during the Cretaceous, I am not very convinced yet
On one hand, you have the paradox of sea level change on large scales over short time which we can now only explain by glacio-eustasy and this paper showing geochemistry (18O) changing like it would with large-scale glaciation, but you have high tropical SST’s and associated biomass. Glaciation could only occur in Antarctica with the paleogeography, but no clue on paleoelevation. This is where gavin needs to model and figure out what kind of elevaion might be needed to get ice :-)
It would also be interesting to see how these recent papers on arctic amplification hold up, and see if they will hold any relevance to the Cretaceous mystery
Chris
I am abit surprised by what I read here. It is unabigious that the world warmed between 1980 -2000 and that the hadley centre and other say the temperatures have been flat since 2001.
yet you hold great store by the first period and not the later because you say 15 years is long term climatic variation and 7 years is short term weather variation!!!!
thst’s surely silly.
[Response: No. It’s statistics. – gavin]