Well, not my model exactly. I developed and host a web interface to the modtran model of atmospheric infrared radiation, an early example of a line-by-line code which I downloaded and use to teach and as part of a textbook. Now David C. Archibald from Summa Development Limited, Perth, WA, Australia claims that my “University of Chicago modtran facility” proves that global warming won’t happen.
Archibald begins by discovering that the IR light flux at the top of the atmosphere is more sensitive to changes in atmosphere CO2 when the concentration of CO2 is lower. This will come as no surprise to regular readers of realclimate who will know that the energy flux scales with the logarithm of CO2. The log dependence is why the climate sensitivity parameter is often posed as a temperature change for doubled CO2 concentration; to first order, a change from 10 ppm to 20 would have about as much climate impact as a change from 1000 to 2000 ppm. So Archibald is right on this score, clearly climate is more sensitive to CO2 when levels are lower. However, I think most climate models are aware that atmospheric CO2 is 380 ppm rather than 10 ppm, and they predict global warming anyway. If we were starting out from 10 ppm, the warming would be even worse.
Archibald then takes an atmospheric increase of 40 ppm which he thinks will happen by the year 2030. I’d have guessed 60 ppm by then at least, the way things are going, but whatever, we’ll see. He uses my setup of modtran to calculate that the IR flux to space would drop by 0.4 Watts / m2 as a result of this 40 ppm. Try it yourself. Run the model once with 375 ppm CO2 and another time with 415 ppm, and compare the Iout values in Watts / m2. The exact number you get depends on humidity, setting, clouds, etc. Formulas given in IPCC would say 0.5 Watts / m2; zeroing out water vapor in modtran gets the IR response up to 0.6 Watts / m2 for the default tropical atmosphere case. At any rate Archibald isn’t wildly off here either.
But then Archibald multiplies the radiative forcing by an absurdly low value of the climate sensitivity parameter. In this case he is using the parameter in units of degrees C per Watt / m2. The two forms of the climate sensitivity parameter that we have discussed here are related by a factor of about 4 Watts / m2 for a doubling of CO2. The value Archibald uses is 0.1 degree C per Watt / m2 which was “demonstrated” in a paper entitled “CO2-induced global warming: a skeptic’s view of potential climate change” by Idso, 1998. Translated, Idso’s climate sensitivity winds up to be 0.4 degrees for doubling CO2. IPCC finds it essentially impossible (yeah, I know, highly unlikely or whatever) that the climate sensitivity could be less than 1.5 degrees C for doubling CO2, and 3 degrees C is a best-guess value.
In the end, Archibald concludes that the warming from the next 40 ppm of CO2 rise (never mind the rest of it) will only be 0.04 degrees C. Archibald’s low-ball estimate of climate change comes not from the modtran model my server ran for him, but from his own low-ball value of the climate sensitivity.
“It wont happen” Hello?
Ok- can someone please tell the eskimos and polar bears to stop hallucinating?
everything is really ok
That’s snow —not strawberry fields —“nothing to get hung about”
And now if Archibald could just change the laws of physics, we could make the problem go away! Sounds like an exercise in “faith-based” science. I wonder if he’d have much luck convincing some of the farmers in Oz who are losing everything they had due to drought?
Did anyone publish Archibald’s paper in a journal somewhere? The link goes to “climatepolice.com” — don’t science journals usually refuse to consider publishing papers that go out as PR first, preferring that peer review and journal publication precede public distribution?
This doesn’t even have something like “to be published in, well, submitted to, er, rejected by Energy and Environment” credentials. Yet.
A quick search on Google Scholar yeilds only one other paper by David Archibald which appeared in that bastion of critical peer review “Energy & Environment”:
http://www.lavoisier.com.au/papers/articles/Archibald.pdf
“Solar Cycles 24 and 25 and Predicted Climate Response” appearing in Energy and Environment, Volume 17 No. 1 2006, pages 29–35
ABSTRACT
“Projections of weak solar maxima for solar cycles 24 and 25 are correlated with the terrestrial climate response to solar cycles over the last three hundred years, derived from a review of the literature. Based on solar maxima of approximately 50 for solar cycles 24 and 25, a global temperature decline of 1.5°C is predicted to 2020, equating to the experience of the Dalton Minimum. To provide a baseline for projecting temperature to the projected maximum of solar cycle 25, data from five rural, continental US stations with data from 1905 to 2003 was averaged and
smoothed. The profile indicates that temperatures remain below the average over the first half of the twentieth century.”
Archibald seems to think the sun will save us from ourselves and with his most recent effort that even if the sun doesn’t step in the carbon isn’t much of a problem anyway.
Paul Middents
I think it is interesting that Archibald had to go back a decade to find a sensitivity estimate low enough to support his assertion. Even Schwartz’s musings wouldn’t do it for him. I suppose it’s an indication of the progress we’ve made if nothing else–now to be a denialist, you have to be not only delusional, but also woefully outdated.
Archibald’s garbage is not meant to fool science minded people. His article is meant for the lay public to create a sense of doubt and hesitation. This is one of the key principles of propaganda. It does not need to be true, it just needs to sound true, and then repeat it again and again and again.
I am sure someone is rewarding Archibald for his efforts. Watch for the shrill citations and repititions from the henchmen. I can only hope the organizations behind this get exposed sooner rather than later.
My understanding of the climate sensitivity parameter is that the pdf of its estimated value is heavily skewed, with a short, truncated tail to the lower (below mean) side, and a long (very long?) tail to the upper (above mean) side. Furthermore, I thought this was generally accepted amongst climate and other scientists viz. that the parameter occupied a range of possible values, hence a rigorous analysis, with whatever model, should be open enough to show an ensemble of results, generated using different values, with some indication of their relative likelihood. It’s not perfect, I know, but it’s better than saying, in effect, ‘I will assume the parameter has this value, over all other possible candidate values, and not concern myself with other possible model outcomes, however likely they might be …’. Therefore, I wouldn’t attach much credence, if any, to a modelling study that didn’t explore the range of possibilities arising from such uncertainty in parameter values, and particularly in the value of something as crucial as the climate sensitivity parameter, as in this example.
The Stephan-Boltzmann (blackbody) climate sensitivity is about 0.3 deg.C/(W/m^2). Idso claims to have “demonstrated” that it’s 0.1. How is it *possible* for climate sensitivity to be less than the S-B value? Does this require some exotic condition? Idso’s demon? Or is this actually possible for a physically plausible planetary condition?
[Response: It would require the negative feedbacks to be much stronger than they are. i.e. water vapour would have to go down as temperature rises, low clouds would have to be incredibly sensitive, high clouds not sensitive at all – and forget the ice-albedo feedback! – gavin]
A review of one of Archibald’s E&E paper is at http://n3xus6.blogspot.com/2007/02/dd.html titled “The worst climate science paper ever of all time anywhere”
Notably Archibald even has a 4 part video series on Youtube of his recent presentation to the Lavoisier Society.
http://www.youtube.com/watch?v=VDX2ExKYyqw (Part 1)
A remarkable effort.
Re: #5
Ray,
With no disrespect intended as I suspect you know as well as I that old science does not mean bad science. When wishing insights into how CO2 manages to be an effective greenhouse gas I refer to Einstein.
Best Wishes
Alexander Harvey
Archibald was doing fine until he introduced his unrealistic value of climate sensitivity parameter. George Bush Sr. once referred to a primary opponent’s ( Reagan’s) economic policy as voodoo economics. Now it seems we have voodoo climatology.
In comment #2, Ray refers (facetiously) to changing the laws of physics. Something like this has been tried before. In 1997, the Indiana House of Representatives unanimously passed a bill that attempted to legislate a value of pi. The title of the bill was “A bill introducing a new Mathematical truth”(source,”A History of Pi by Petr Beckmann-St. Martin’s Press, 1971, pp 174=177). It never did get through the state Senate and the value was grossly in error.You can’t fool Mother Nature.
Err, lawrence, when did the Indiana House of Reps try the Pi trick ? Your 1971 reference presumably doesn’t describe an event that happened in 1997.
Lawrence and David, It was 1897, and the culprit was a doctor who calculated 9 separate values for pi. The text of the law was:
“Be it enacted by the General Assembly of the State of Indiana: It has been found that a circular area is to the square on a line equal to the quadrant of the circumference, as the area of an equilateral rectangle is to the square of one side.
(Section I, House Bill No. 246, 1897) ”
http://www-groups.dcs.st-and.ac.uk/~history/HistTopics/Pi_through_the_ages.html
I sense a trend here–a learned “man of science” venturing into areas where he is untrained, just as today, most climate skeptics are not climate scientists.
Re# 11: Indiana Pi law
Lawrence, you have a typo. The law was introduced into the House in 1*8*97, not 1997. Wikipedia has a good article on the issue.
Thank you, David, Ray and Rafael. I can’t get away with anything around here!(And it’s a good thing too).
The culprit was indeed a doctor, Dr. Edwin J. Goodman and he hoped to profit from his brainchild as follows,from the preamble to the bill” A bill for an act introducing a new mathematical truth and offered as a contribution to education to be used only by the State of Indiana free of cost by paying any royalties whatever on the same, provided it is accepted and adopted by the official action of the legislature in 1897.” An ex teacher told the legislature “The case is perfectly simple.If we pass this bill which establishesa new and correct(sic) value of pi,the author offers our state without cost the use of this discovery and its free publication in our school textbooks,while everyone else must pay him a royalty.”
Perhaps those who would repeal the Stefan Boltzmann constant in the formula for the energy radiated by a black body,might try to profit from their findings, as well.
I had thought the pi=3.0 law was passed and was law for part of a year in Indiana. Maybe not, I guess. (and obviously you meant to type 1897.) I also heard it originated from collusion with the legislature/government and industry — textbooks in this case.
Gavin,
I tried e-mailing you this but your inbox was full. Apparently the Hudson Institute thinks you, Michael E. Mann, Thibeault De Garidel-Thoron and Stefan Rahmstorf are skeptics.
LogicalScience Linky
hi everyone
I’m an observer here at realclimate, with no axe to grind on any ‘debate’. Can someone please post me to any journal articles that calculate a climate sensitivity of 2xCO2 of 3-4 Watts/m2. Please no reference to IPCC documentation, blog entries, etc. but rather to scientific articles.
I’m a computational neuroscientist and am involved in plenty of dynamic, nonlinear modeling and I would like to follow through the empirically derived steps, even if my knowledge of the physical basis is very limited.
if anyone could help out, it would be much appreciated
thanks, Steve
[Response: Of course: you want the IPCC ar4 report, box 10.2, which summarises things and points you to all the papers you could wish to read http://ipcc-wg1.ucar.edu/wg1/Report/AR4WG1_Print_Ch10.pdf -William]
Your web interface to modtran is very great. I’ve spent some time messing around with HITRAN data, trying to convince some skeptics that the climate warms with increasing CO2 levels is based on well-established and very boring spectroscopy. As a spectroscopist, I think I get to say that. Anyway, the modtran tool makes it easier. Not that it’s likely to convince my skeptic friends, because I suspect they are in a place where evidence is not likely to make a difference. Nice job pointing out where Archibald went off, too.
[Response: Thank you. In your playing around with modtran and hitran, keep an eye out for any systematic differences between the two. The modtran model and database were old even when I installed them maybe a decade ago. If you find anything, I’d be very interested to hear. Thanks again, David]
Nothing Archibald, or the Lavoisier group says should be taken with any seriousness at all.
Archibald’s previous “scientific” “climate” paper has been described as the “The worst climate science paper, ever of all time, anywhere.”
http://n3xus6.blogspot.com/2007/02/dd.html
Here’s some of the absolute gold buried within his previous effort:
– To undertake his computations, which are supposed to indicate a strong correlation of surface temperature to the solar cycle, rather then use world wide temperature estimates (GISS, HadCRU ect…), he uses 5.
That’s right, 5 stations, all from the South East continental US, all within several hundred kilometers of each other.
– Strangely enough, each station shows a cooling trend. Hmmmmm…
– In order to make his “predictions”, of global temperature response from Archibald uses not 5 stations, but 1 station’s data (De Bilt in Holland). 1 data point. Of the thousands available.
– Archibald uses one data point per solar cycle. Why he does no use annual data for this station is a mystery, but it seems to torture the dat into giving a more impressive looking trend. No formal correlations / R^2 values are reported.
– He then uses really low estimates of Solar Cycle 24 and 25 to “predict” future world temperatures. Why he chooses these estimates is beyond me. He then confuses solar cycle length and solar cycle strength, but somehow concludes that global temperature will decrease over the next 2 cycles.
This paper is a load of garbage, and his new work seems to be no different.
The Lavoisier is an arch, Australian AGW septic group, who even our own (formerly) AGW septic government has tried to distance themselves from in recent years.
The 1.5 degree C IPCC lower end of the range for CO2 doubling climate sensitivity is suspect. Where it is based on models, nearly all the models are biased against solar activity and may be compensating for the missing solar energy with increased sensitivity or feed back to CO2. Furthermore, the models couple CO2 forcing to the whole mixing layer of the ocean while in reality the CO2 wavelengths barely penetrate more than a millimeter and so qualitatively are a complex surface effect.
Most of the non-model estimates of climate sensitivity are based on the analyses using other forcings such as solar and aerosols, and the assumption that sensitivity to CO2 will be the same, despite the differences in way these forcings couple to the climate system.
7 – It’s also worth pointing out that the “climate sensitivity” is a local linearisation of the climate system’s non-linear response to warming.
So it currently includes a [positive] contribution from the ice-albedo feedback, because our current climate possesses sea-ice that will be melted by a modest increase in temperatures. However, once the sea-ice has melted the contribution from the sea-ice albedo feedback will go, changing the climate sensitivity to further forcing.
In the other direction, at higher temperatures there is expected to be carbon-cycle feedbacks, that will amplify the warming, so then the climate sensitivty would be higher.
So climate sensitivity is not quite the be-all and end-all of climate science. In many respects it is an “old” concept, from a time of simpler models, and not one to be too hung up with.
Re: #17
Sagan was a proud skeptic and wrote an excellent book on the subject, the 2500 scientists who contributed to the IPCC were skeptics, and I like to think I am also skeptical about my own ideas. Unfortunaltely the Hudson Institue (and many others) have perverted the meaning of the word skeptic, the use of the word in their “study” is a (feeble and desperate) attempt to sow doubt by painting things in terms of scientists vs skeptics.
Sorry, just a pet peeve from an old school “hacker”.
Gavin – (My second attempt at a post). I’ve been reading your blog and Steve McIntyre’s as well, for some time now. I’ve recently posted at Climate Audit a complaint about their frequent accusations of fraud on the part of climate scientists. This generated a heated discussion. I’d like to be even-handed here and point out that the comment in #6 does not help any discussion of climate science. I would hope that such posts do not appear in the blog in the future.
wrt# 24, #6 is quite correct, this is exactly what the skeptical community appear to be doing. To deliberatly misrepresent the data in such a fashion requires either a high level of ignorance or some ulterior motive. I have noticed too many instances of the later and I find it somewhat distastful. The layperson should not be expected to be able to differentate between good science and properganda.
Martin Lewitt, Now hold on just a bleedin’ minute. The penetration of LWIR into water is immaterial, as by warming the surface, one also warms whatever water the surface layer then mixes with. Mixing occurs on very short timescales. I also see rather strong assertions of bias in your post, but zero evidence to back them up.
Off topic, but I was wondering if someone more learned than I, with access to research materials could do a post on past instances of ships “crossing the northwest passage.” The skeptical blogosphere is all abuzz with examples of ships making (or attempting to make) the journey, but there is always something fishy about them. Either they used reinforced boats/icebreakers, or it was a treacherous one way journey, or “if only the boats were faster,” or the routes were commercially inviable, or the trip took years to complete, or all fo the above.
Just a tip.
Erik – in this instance Archbald is not a climate scientist. Frankly the level of condemnation here compared to the blatant misrepresentation of science is mild.
Lavoisier Society’s own programme says “David Archibald is a Perth-based scientist operating in the fields of cancer research, climate science and oil exploration. In the cancer field, trials on a formulation he invented with professors from Purdue University are currently underway at Queensland University. In oil exploration, his company, Backreef Resources, is proceeding to a seven well programme in the Canning Basin, Western Australia. Mr Archibald has been an expert witness in the Supreme Court of NSW in the fields of petroleum geology and rolling mills in steelworks.”
http://www.lavoisier.com.au/papers/Conf2007/Workshop2007prog.html
> Martin Lewitt
Martin, where are you getting the information you post here? What source are you relying on? A cite or pointer would always be appreciated, or if you’re reporting your own work, please show it.
Other sources I find don’t match what you believe, for example
“IR radiation can represent 40%–60% (Mobley 1994) of the total downwelling surface ocean irradiance, it is almost completely (99.9%) absorbed in the upper 2 m of the water column. The
second process is the heating due to ultraviolet and visible wavelengths (VIS). VIS can penetrate much deeper than IR, and so its role in setting mixed layer depths (MLD) is far more important.”
http://www.gfdl.noaa.gov/reference/bibliography/2005/cos0501.pdf
See also http://www.agu.org/pubs/crossref/2005/2004JC002780.shtml
What are you reading that tells you the different information you posted, please?
For David Archibald/Purdue’s cancer pills (“… made from well know vegetables mainly broccoli and chilli …”), he was soliciting people to try them here: http://www.communitywebs.org/SAProstateCancer/pages/psaadelaide/documents/2005/septnlwv.pdf
I hve a question from for anyone that understands the greenhouse effect and warming simulations. We are obviously warming now. Is there a top end to the warming trend where we have so much CO2 in the air, more does not increase the greenhouse effect any more? If so what CO2 concentration would that be and what temperature would that take us to?
[Response: Not really. There are seventy atmospheres of CO2 on Venus, and if you added more, it would warm even further, is my understanding. David
[Response:
Chris, try the button labeled “Start Here” at the top of the page.
Re. Timothy (#22) and the climate sensitivity parameter, I agree totally that we shouldn’t get fixated on it, and I also accept that it’s something of a crude measure, hence the need for modelling studies to include some representation of the parameter uncertainty in the results, rather than sticking to just one value. These semi-empirical models are all prone to model equifinality to some extent, whether the simulated state in question is an end state, or a transient one to which particular scenarios run under different parameter values can converge.
That said, and despite the crudeness of the sensitivity measure, the long, upper tail on the pdf has to be a matter of concern. On the one hand, it gives those who wish to rebut the idea that Man is changing the climate an excuse to say that our forecasts are too vague to be useful, or to be taken seriously. On the other, it represents a possibility that we are not just in trouble, but that we could actually be in very serious trouble indeed. I know that Mike Schlesinger is going to be working on further studies to see what extra data, and over what timescales, might help us constrain the upper tail, but the possibility arises that no amount of data will do this, or at least, not in time for us to act on it with enough warning to prevent serious problems. One possibility is that the inherent non-linearities in the parameter, which you very rightly highlight, prevent constraint of the upper tail; another might be that the whole climate system gets much noisier and more chaotic, because of extra energy driving the system, so in some wise we lose the signals that might constrain the upper uncertainty. What then, guys, what then?
Nick O.
Hank, I tried that, I couldn’t find much about theoretical upper limits to global warming by CO2. I did find one 1985 paper that was pedicting a maximum of 4-5K which seems way too low. Can you give me any more specific references, or possibly to an earlier discussion of this on this site? Thanks
31 Chris
no there is no top end, but the radiative forcing by CO2 incraeases not linearly proportional to CO2 concentration, but logarithmically to CO2 concentration for more info I recommend previous posts:
https://www.realclimate.org/index.php/archives/2007/06/a-saturated-gassy-argument/
https://www.realclimate.org/index.php/archives/2007/06/a-saturated-gassy-argument-part-ii/
I can understand why Archibald, an Australian, would want to deny CC. Australia is perhaps CC’s first big victim among developed nations. It’s really bad there, with worse predicted.
I developed some survey Qs for a survey course around 1996, actually conducting it on residents in Chicago Collar Counties. Some Qs related to possible GW harms, like “has your house been flooded in the past 5 years”; and some related to GW beliefs. I expected that the flooded would be more likely to believe in GW, but the results were that they were much less likely to believe in GW (holding education and other variables constant). I then reasoned that people who had been harm would much prefer to believe their harm was a fluke (once in a 1000 year thing), and would find it untenable that the same or worse might be coming in the near future.
Unfortunately I didn’t reach .05 significance, more like .1 or .2 on that (can’t remember). The differences were between the harmed and not-harmed were huge, but the number of respondents was was very low. And that’s because the basment Public Opinion Lab on the NIU campus in DeKalb had been extremely flooded and the lab was only ready at the very end of the semester — flooded in a area that had never before in history experienced flooding.
Also, when the lab lady was instructing us on how to administer the Qs, I mentioned the flood may have been due to GW. She laughed in my face, but I whipped out a manual I’d just study from IL Natural Resources, a study on GW which predicted that area (among many others) might get flooded….
Another off-topic comment, but there are likely to be many who will want to obtain a copy of the .pdf file, “The Threat to the Planet: Dark and Bright Sides of Global Warming”, available from Dr. James Hansen’s web site, as the first file listed under the heading Files of Interest:
http://www.columbia.edu/%7Ejeh1/
(Hope I did this correctly. Hint: could certainly use a preview capability…)
[Response: Previews re-installed…. let me know if there is a problem – gavin]
#35 31 Chris
“no there is no top end, but the radiative forcing by CO2 incraeases not linearly proportional to CO2 concentration, but logarithmically to CO2 concentration for more info I recommend previous posts”
Thank you Andree that is what I was looking for.
Sorry to be off subject here. But I have two questions. 1) I have seen several places claims that the ENSO has been/ is being changed by AGW. Is there evidence for this? 2) The magnetic north pole is moving towards Russia (through the Arctic). Does this effect currents or climate? Thanks
Gary,
Re 1)–a pretty good, albeit brief discussion here:
https://www.realclimate.org/index.php/archives/2007/08/regional-climate-projections/
Re 2) Almost certainly not. The geomagnetic field only affects charged or magnetized particles. I suppose that when the field starts to flip, you could see some effect due to solar particle events, but that’ll be the least of our worries.
Re the topic, “My model, used for deception”…
Anyway, you know what the denialists say about models :)
There are other papers that state that solar cycle 24 will be the start of a Maunder like minimum. For example:
http://adsabs.harvard.edu/abs/2004ApJ…605L..81B
“We have examined the long-term trends in the solar variability that can be deduced from some indirect data and from optical records. We analyzed the radiocarbon measurements for the last 4500 years, based on dendrochronology, the Schove series for the last 1700 years, based on auroral records, and the Hoyt-Schatten series of group sunspot numbers. Focusing on periodicities near one and two centuries, which most likely have a solar origin, we conclude that the present epoch is at the onset of an upcoming local minimum in the long-term solar variability. There are some clues that the next minimum will be less deep than the Maunder minimum, but ultimately the relative depth between these two minima will be indicative of the amplitude change of the quasi-two-century solar cycle.”
There are also other papers that have presented arguments for a smaller climatic forcing function.
I have been following cycle 23 and can attested that it is very unusual. The sun is currently in a spotless state, the solar large scale magnetic field is dissipating. The solar cycle will be 132 months old (11 years) December 31, 2007. If the solar hypothesis is real the cycle will flat line, and the planet will cool.
I thought with flat lining there would be a 2C cooling and quite rapidly.
Re #35: […but the radiative forcing by CO2 incraeases not linearly proportional to CO2 concentration…]
But on the other hand, warming of the oceans should release significant amounts of CO2…
Re: #26 and #29
For a discussion of the ocean skin layer and infrared penetrance see:
https://www.realclimate.org/index.php/archives/2006/09/why-greenhouse-gases-heat-the-ocean/
It speaks of micrometers and not millimeters so I was being a little generous. Given such low penetrance, this CO2 radiation will be much more effected by mist, spray and foam, and should more directly impact evaporation than radiation which penetrates 10s of meters.
What differences in forcings is it safe to ignore in the models? Is radiation which mere micrometer penetrance at a complex ocean surface really equivilent to radiation which can support tropical kelp forests at 200ft depth? See:
http://www.sciencedaily.com/releases/2007/09/070926142907.htm
I don’t think, given what we know about the differences, that we can really accept immateriality or equivilence as the null hypothesis. Models based on that assumption have failed to reproduce solar cycle signatures found in the data:
http://www.amath.washington.edu/research/articles/Tung/journals/solar-jgr.pdf
I quote from the article:
“Our procedure for the solar-cycle signal yields an interesting pattern of warming over the globe. It may be suggestive of some common fast feedback mechanisms that amplify the initial radiative forcing. Currently no GCM has succeeded in simulating a solar-cycle response of the observed amplitude near the surface. Clearly a correct simulation of a global-scale warming on decadal time scale is needed before predictions into the future on multi-decadal scale can be accepted with confidence.”
Feeling the need to try to add a little insight, I have been taking a little look at “feedback factors” as in the equation:
dT(final) = dT(forcing) * f
or more usefully:
dT = dF * C * f
(where T = temperature, f = feedback factor and F a Flux or Forcing and C is the baseline climate sensitivity i.e. for a clear atmosphere)
and a formula for combining “feedback factors” :
f = f1*f2 / (f1 + f2 – f1*f2)
This can be rearranged to give:
f = 1/ ((1/f1)+(1/f2) – 1) and generalises to
f = 1/(SUM(1/fi) – (N-1)) where the fi are N individual “feedback factors”.
Rearranging again we have;
1/f = 1 – SUM(1-1/fi)
and substituting: ai for (1-1/fi) and a for 1 – 1/f
1-a = 1 – SUM(ai)
This gives an insight into what the “feedback factors” are.
for now dT = dF/(1-a) * C
Each ai represents the closure of a proportion of the channel through which passes heat from the surface into space. E.G. the proportion of the bandwidth that is blocked.
The ai are additive:
a = SUM(ai)
with the provision that the closure of a particular piece of bandwidth is not counted twice as where the spectra of two gasses overlap.
Now dT = dF/(1-a) * C generalises to
dT = d(F/(1-a)) * C = ( dF/(1-a) + F * d(1/(1-a)) ) * C
where d(1/(1-a)) = 1/((1-a)^2) * da
Now dF can be regarded as a true forcing but to make sense F must refer to the total outbound heat flux.
In general the ai are not constants but are dependent on T and possibly the evolved history of the planet.
So for an ai(T) that is dependent on temperature we have (in isolation)
dT = F / ((1-a)^2) * d(ai(T)) * C
It is important to note that it is the total heat flux F not just the originating forcing component dF that is acted upon. In this way very small changes in ai(T) can give rise to large changes in temperature.
As it happens the effect of increased CO2 could be regarded as a pseudo forcing (as it is most commonly) or as a small closure of the available bandwidth ie as a component of da. It is perhaps more consistent to regard all changes to the atmospheric content that reduce the available bandwidth in the same way. There is no fundamental difference between the ways that H20 and C02 act as greenhouse gases to imply one should be a forcing and the other a feedback, it is purely a matter of convenience. Also it can be noted that the “feedback factors” are not feedbacks in the strictest sense as they are simply temperature dependent modifications the proportion of the bandwidth that is blocked or as the “resistance” the atmosphere presents to the escaping heat flux.
We know that the earth is warmer than it would be without greenhouse gases. And we can give some experimental value to (1-a) and the various ai (H20,C02,CH4, etc.). We also have a value for C so some sort of lower limit can be put on the current effective instantaneous Climate Sensitivity that is undeniable. I sincerely hope so.
I do not have the time to continue this at this moment but I hope this part is of some interest to the circumspect.
Best Wishes
Alexander Harvey
Re # 27 cce: Ships crossing the Northwest Passage?
I don’t who is making that claim, but a recent Reuters news article suggests it is not likely:
Despite warming, ships to shun Northwest Passage
By David Ljunggren
OTTAWA, Oct 3 (Reuters) – While there has been much talk that Arctic trade routes will open up as northern ice melts, shipping companies and experts say using the fabled Northwest Passage through Canada’s Arctic archipelago would be too difficult, too dangerous and totally impractical… Michael Gardiner, assistant commissioner of the Canadian Coast Guard for the Arctic, said there had only been 150 transits in the last 100 years, most by coast guard vessels.
“The Northwest Passage in its entirety has often been described at shipping conferences … as a rock pile. It’s very tricky navigation through most of it,” he said.
And if a ship got into trouble the rescue effort would be massively complex and costly, said Bob Gorman of Enfotec, which provides ice navigation services in the Arctic. “It’s just not a route well traveled … there are no tugboats nearby, there are no shipyards nearby, there are no repair facilities, there is no port of safe refuge. You are really out in the wilderness,” he said. …
http://www.reuters.com/article/basicindustries-SP-A/idUSN2538211120071005
As a layman reading Alexander’s paper I thought it was phrased argumentatively and could lead to ad hom’s rather than examination of his ideas.
Alexander’s Figure 12 (showing A correlation between temperature and solar cycle length – rather than amplitude) seemed the key point of the paper, on which his predictions are based. The question: is this spurious or have others noted this correlation for other locations? Seems a basic way to test the main idea in the paper without getting sidetracked on other issues.
Also, his Figure 10 shows solar cycle amplitude which, by eye, seems to correlate somewhat with known temperature trends. I thought it would be helpful to have a plot of solar cycle length superimposed on this figure – is this available somewhere? That is, does solar cycle length correlate with the following solar cycle amplitude?
Why doesn’t increased water vapor lead to decreased insolation?
Several of the absorption bands seem not to be saturated.
http://en.wikipedia.org/wiki/Image:Solar_Spectrum.png
[[Where it is based on models, nearly all the models are biased against solar activity]]
In what way? All the models I’m familiar with take solar activity into account.
This is in response to Alexander Harvey in #44.
You are clearly familiar with some of the aspects which are involved and I appreciate your efforts.
I will set aside the mathematics at this time – although someone else may be better equipped to deal with it than I.
However, I believe there are a few issues worth pointing out.
First, you state in #44:
There is a fairly big difference between water vapor and carbon dioxide: water vapor doesn’t stay in the atmosphere for very long – perhaps a few weeks. It falls out in the form of rain and snow. As such a pulse of water vapor won’t stay in the atmosphere long enough to raise the temperature significantly and the original equilibrium (prior to the pulse) will be quickly re-established. However, carbon dioxide stays in the atmosphere for a very long time. In fact, a substantial percentage of a pulse of carbon dioxide will remain in the atmosphere even a hundred thousand years. For the original equilibrium to be reestablished, you have to have mineralization – and that takes a long time.
As long as there is more carbon dioxide in the atmosphere than before, it will reduce the percentage of thermal radiation which is able to leave the atmosphere, which means that the climate system must heat up if the rate at which energy leaves the climate system is to equal the rate an which energy enters the climate system. Since it stays in the atmosphere longer, it will raise the temperature gradually over the decades. As the temperature rises, water vapor evaporates at a higher rate, raising the water vapor content of the atmosphere, further amplifying the the increased greenhouse effect of the additional carbon dioxide.
Second, carbon dioxide isn’t always considered a forcing – and I believe this is somewhat in step with one of the points in your post – although there are certainly times even in the paleoclimate record when it has been so. (A good example would be the Permian Triassic extinction which was driven largely by the eruption of a supervolcano in Siberia, raising the CO2 levels to around 3000 ppm.) Sometimes increased insulation due to a periodic shifting of the earth’s orbit towards the sun will raise the temperature first and the carbon dioxide will follow – with higher temperatures reducing the amount of carbon dioxide which the ocean will have the capacity to hold – and the amount of carbon dioxide which plants are able to absorb given droughts. Another may be the raising of the temperature of permafrost which will release methane and carbon dioxide, increased moisture in the polar altitudes resulting in more methane in growing bogs, but there are other feedbacks to the carbon cycle.
The feedbacks from the carbon cycle may become important – inasmuch as higher temperatures brought on by our own anthropogenic emissions of carbon dioxide may raise temperatures enough that it will cause the climate system to start emitting more carbon dioxide of its own. Some of those feedbacks seem to be kicking in a little already.
What constitutes a forcing? Anything which reduces or increases the rate at which energy leaving the climate system is not equal to the rate at which energy enters the climate system – and does so long enough that the equilibrium temperature has the chance to shift.
Second, you state in #44:
There are a couple of problems here, one related to the physics and one related to the nature of science itself.
First the physics. There is no such thing as an instantaneous climate sensitivity. More greenhouse gas (whether it is carbon dioxide or water vapor) will reduce the ability of thermal radiation to leave the atmosphere, but it will not instantaneously raise the temperature. That takes time – as it will take time for the surface to rise in temperature – even before one takes into account any feedbacks.
Second, nothing in science is undeniable. Leave the “undeniable” to Descartes. What science deals with is the cummulative weight of the evidence – but if some skeptic is willing to snuggle up to the belief that everything that they see and remember was put there five seconds ago, they can certainly do so. Regardless, we are pretty confident that the Charney climate sensitivity is roughly three degrees Celsius. (We have about 400,000 years of climate data to back that up.) However, this is in the short-run.
According to Hansen, long-term is more like six degrees. Then of course there is the feedback from the carbon cycle itself.
One more point…
This is actually a little earlier in your post, but it is also a little more technical, so I am putting it off to last.
You state in #44:
The problem is that even if radiation is absorbed, lets say in the lower troposphere by water vapor, an equal amount of radiation will be emitted by water vapor in the same band. Some will be upwelling, some will be downwelling. For that which is upwelling, if the bands overlap with carbon dioxide in the upper troposphere or lower stratosphere where the atmsophere is dry, it will be absorbed and an equal amount will be reemitted in the same band. Likewise some of the emission by carbon dioxide will be upwelling and some will be downwelling. Whenever the thermal radiation is downwelling, it will tend to increase the greenhouse effect.
I suspect the problem here is that you are thinking of greenhouse gases as blocking thermal radiation such that once the radiation is absorbed there isn’t any reemission. But they don’t block – they absorb and emit – in both directions. Without the greenhouse gases thermal radiation would simply be radiated into space and there would be no downwelling of thermal radiation – just the absorbtion of sunlight.
But greenhouse gases are a part of the atmosphere and render it opaque to thermal radiation – which means that some will be downwelling. It is the downwelling that reduces the rate at which energy is leaves the climate system until the temperature of the system rises enough that the rate at which energy enters the system equals the rate at which energy leaves the system – and a new equilibrium is established.
However, overlapping bands in the lower troposphere where water vapor dominates will keep carbon dioxide from absorbing any significant amount of radiation – in the lower troposphere itself. This is where a band will be saturated by a given greenhouse gas – and one needs to avoid double-counting.
Anyway, thank you for throwing some light on this. Hopefully I have managed to illuminate things a little as well.