Who says that the climate debate is not evolving? According to the daily newspaper the Guardian, a new application (‘app‘) has been written for iPhones that provides a list of climate dissidents’ arguments, and counter arguments based on more legitimate scientific substance. The app is developed by John Cook from ‘Skeptical Science‘. It’s apparently enough to have the climate dissidents up in arms – meaning that it’s likely to have some effect? Some dissidents are now thinking of writing their own app.
Here on RC, we have developed a wiki, to which I also would like to bring the reader’s attention. Furthermore, I want to remind the readers about other useful web sites, listed at our blog roll.
“429
Henk Hak says:
23 February 2010 at 5:51 PM
I would say the science is settled enough rather than settled.”
So already you disagree with Spencer’s central thesis.
“NO, not BAU. Severely curtail CO2 emissions? I would love to see that but how?”
I’m afraid you’ve lost me.
Is this meant to be a rhetorical question or are you merely asserting that humanity will never do the obvious things?
PS Henk, you’ve gone from accusatory “So please don’t tar everyone who isn’t convinced of the “settled science” with the same “denial sphere”” to this one where that accusation has been forgotten when evidence that “settled science” IS an appropriate label when you understand what is meant by “settled science” as “settled enough”.
Now what about those who complain that “settled science” means that all future discussion about what ISN’T known doesn’t exist and shouldn’t happen?
This is NOT what RC, the IPCC, the figureheads or we posters here on RC think of when we talk of “settled science”.
Therefore they are building a strawman.
Why would someone build a strawman?
Because they want to break down a conclusion by making a different statement than one that was made and prove this made up statement is wrong therefore (don’t look at the straw, forget this isn’t the statement you’re looking for) the IPCC are wrong and unscientific.
Why?
Deny the evidence by denying the strawman and going “ergo AGW is not happening”.
Deny.
Denialist.
If you’d said “I’ve heard of this “settled science” but it seems silly to think there’s nothing about the IPCC that says there’s nothing more to discuss in science. What does the IPCC *really* mean when they talk of “settled science”?” then the link to that page would come forth and no accusation of denialism would appear.
Of course, after the 10,000th repeat from another noob on the same query, it no longer looks like anything other than a sockpuppet astroturf snowjob.
It then becomes “why do you believe this and ask for clarification? It’s not like this hasn’t been explained 10,000 times before.”.
JPR (433),
Spencer [edit]
http://BartonPaulLevenson.com/Spencer.html
Ray Ladbury (413), I don’t know if you read the referred review, but it has no direct contradictions with my assertions in #. First they come up with the current sensitivity by looking at other estimates and finding a good close average then compare that with other analyses which mostly see if the GCM models produce similar close averaged results (oddly not addressing that the GCM outputs rely on equivalent, though not direct, sensitivity inputs — but it’s still a decent numerical assessment.) They project sensitivities into the future from the current concentration not based on physics, but on relatively simple numerical extrapolation. Actually they test that by assessing paleoclimatic assessments, which is a rational process, and find no reason why the current sensitivities can not be reasonably projected (which is not exactly the same as finding that it can be projected.) There is some major uncertainties with this: One, it assumes the sensitivities are the same if CO2 precedes temp or temp precedes CO2. There is no evident indication that this is wrong, but neither is there solid physical evidence that it is correct with high confidence. Two, it compares a widely varying correlation between CO2 and temp in paleoclimatic information covering up to millions of years with a few decades of extrapolating current sensitivities. That is a reasonable thing to do, but mainly because they have no other alternative.
Some relevant short quotes from the Knutti and Hegerl Review:
The review is a good analysis of the current estimate of sensitivities and does a rigerous [sic] job of assessing the problem of the uncertain upper bound of the current accepted range. (Though the studies that show a low (less than 1 degree) sensitivity are simply and conveniently pooh-poohed.) [The current process of essentially adding up everyone’s projections (61 in BPL’s case) and finding a good average with somewhat constrained deviation and range to help explain the actual physics is a bit shaky — but that’s another problem; I’ll accept it for the time being.] The future sensitivity projections (i.e. the marginal sensitivity for concentrations that increase from current levels) are simple mathematical extrapolations with little (but more than none, to be sure) basis in physics. Is this reasonable from a scientific viewpoint? Absolutely. It’s a best guess made by knowing scientists. Is it probably close to accurate? Maybe. Maybe not. Is it a highly confident and certain physical projection? Absolutely not… which was my main point: the fact that there is some common near agreement on today’s sensitivity does not by itself make tomorrow’s sensitivity certain, even if it might be indicative.
453, Barton Paul Levenson, from Spencer.html I extracted the following: Now, from the tables of Houghton (2002) and some fancy mathematical footwork on my part, the absorption coefficient of carbon dioxide between the wavelengths of 14.3 and 16.0 microns is about 163 square meters per kilogram. The Earth, at a mean global annual surface temperature of 288.15 K and a surface emissivity of 0.95, radiates an average of 371.4 watts per square meter. Assuming what’s called a Planckian distribution, about 7.85% of that falls between 14.3 and 16.0 microns in wavelength. That’s about 29.2 watts per square meter.
I do not understand “the absorption coefficient of carbon dioxide between the wavelengths of 14.3 and 16.0 microns is about 163 square meters per kilogram.” How can the absorption coefficient have units of square meters per kilogram?
llewelly says:
“”” Richard Ordway says: If these natural eco/bio feedbacks come into play, there is nothing we can do by changing our burning of oil, coal and gas.”””””
“””Not true. More greenhouse gasses will always make things worse. If additional positive feedbacks come into play, than the impact of human-produced greenhouse gasses will be increased. Even if we reach a point where a large and rapid warming cannot be prevented, more greenhouse gasses will still make it worse.
“”””
______________________________________________________________________________________________________________________________________________________
I agree with you llewelly. Thanks for bringing it up. If we reach tipping points (‘The term “tipping point” commonly refers to a critical threshold at which a tiny perturbation can qualitatively alter the state or development of a system.”)-Lenton, 2007, PNAS
(“Examples that have received recent attention include the potential collapse of the Atlantic thermohaline circulation (THC) (1), dieback of the Amazon rainforest (2), and decay of the Greenland ice sheet (3). Such phenomena have been described as “tipping points” following the popular notion that, at a particular moment in time, a small change can have large, long-term consequences for a system, i.e., “little things can make a big difference”) -Lenton, 2007, PNAS
Lenton, 2007, PNAS
These tipping points are blatantly there according to scientific literature (see ref. below), and burning even more oil, coal and gas would indeed make things worse and perhaps push us to even more tipping points even faster such as the more-distant-in-the-future East Antarctic Ice Sheet collapsing or the marine methane hydrates.
___________________________________________________________________________
References to tipping points in history: (Rahmstorf S Et al, (2001) in Encyclopedia of Ocean Sciences, eds Steele J, Thorpe S, Turekian K (Academic, London), pp 1–6; Lockwood JG (2001) Int J Climatol 21:1153–1179; National Research Council (2002) Abrupt Climate Change: Inevitable Surprises (Natl Acad Press, Washington, DC); Alley RB rt al., (2003) Science 299:2005–2010; Timothy M. Lenton et al., PNAS, 2007 (200 citations); Rial JA et al., (2004) Clim Change 65:11–38).
__________________________________________________________________________
If we kept burning more oil, coal and gas at that point, it would further expose our civilization to perhaps some tipping points of its own (mass diseases, mass immigration, mass de_aths due to starvation, war) etc.
I was bringing up the point that if we pass a threshold, that we can’t most likely by definition, turn back that particular threshold at that point by stopping burning oil, coal and gas and stopping deforestation. By definition, a tipping point means that the Earth’s system has most likely gone on autopilot for that particular tipping point.
For instance, if a huge forest-wide fire starts in a future-dried out/beetle killed Amazon or Canadian Boreal forest respectively, it is most likely on autopilot (these are self running events of “biblical proportions” that would feed on themselves on “never before seen scales” and would very possibly burn from one end of the continent to the other before stopping..unheard of fires like that most likely create their own self-perpetuating firestorms.
Or for example, if enough of the tundra/permafrost starts melting and releasing greenhouse gases on its own, the tipping point/threshold would mean that it is producing so much greenhouse gases all on its own that the melting would continue even if we stopped burning all oil, coal and gas the next hour (which of course is impossible anyway).
I should have been clearer.
http://www.pnas.org/content/105/6/1786.full
There seems to be a lot of newer posters who are expressing some “skeptical” viewpoints and challenging the science. For those readers, first, welcome; you’ve come to the right place for reliable information; second, before posing your question or challenging the scientific literature, is it too much to ask you to download the app that is the subject of this post (or for the i-device naive, go to http://www.skepticalscience.com/) and see if your question has already been answered?
I’ve see waaaayyy too many posts questioning such basic items as climate sensitivity (to the tune of “…based only on models…”) when a quick examination of the app brings the user to “It’s not bad” -> “Climate sensitivity is low” and lo and behold, there is a nice list of papers, with sensitivities calculated using modeling and observations. A look at the web site brings you to this post:
http://www.skepticalscience.com/Working-out-climate-sensitivity.html
which is a description of the Knutti & Hegerl review article.
I dunno – maybe check out the article before heading to the comments?
While I think the iPhone app idea will make little difference, I just noted your Wilki. That one looks much more useful and I hope it can be expanded.
That being said, I continue to doubt that any meaningful legislation will get through the US Congress this year — or, indeed, for many years. I am advising my grandchildren accordingly. Some of this advice:
Don’t buy property in Galveston, or, indeed, in any town which has an altitude close to sea level.
Consider investments in Iceland and Greenland.
Don’t even think about Arizona. Colorado looks OK.
Sloop commented on my post:
“You view exemplifies pure free-market economism; a perspective on reality championed in much (not all) of contemporary American society. But even if you do score big on equity investments in coal-based energy, what kind of world will you and your progeny have to enjoy all those additional ‘bio-survival coupons’ ?
(1) As a card carrying Democrat, I assure you that you have misread my post.
(2) I don’t know what kind of world we will have in 2100. But I do know thatsurvival then will, in part, depend on what wealth one can accumulate before CO2 levels rist to 1,000 ppm. I want my grandchildren to survive.
Sloop also wrote: “the denialists are going to win” is one of the most poignent ironies I’ve read in a while. ”
Not sure here if you are agreeing or disagreeing with me. I’ll try again.
Specifically, my belief is that the denialist are going to win means that I also believe that meaningful climate legislation is just not going to happen and that, ipso facto, CO2 levels are going to reach 1,000 ppm by the year 2100. I wish this were not so. But I see no way to prevent it. I’m going to keep on trying, of course, but I see that I am on the weaker side. I fully believe that one of my great grandsons will, someday, look back at the family history and say — Great grandpa Burgy — why did you not do more.”
Here’s a simple calculation to get a handle on climate sensitivity. Since 1880 CO_2 has increased from 219ppm according to CDIAC’s ice core records. Current CO_2 is approximately 388ppm. Over the same period, NASA’s world temperature anomaly has increased about 0.8°C.
If the relationship between CO_2 and temperature is logarithmic, we expect the change in temperature dT from concentration C0 to the current level C to be given by:
dT = k (log(C/C0))
If you have a decent model you can determine k but let’s see what the numbers give us vs. the expected effect of a doubling resulting 1.5-4.5°C warming after feedbacks, with 3°C most likely.
Using the numbers we have and natural logs (the base doesn’t matter: it will change the value of k but that remains consist for all calculations),
0.8 = k (ln (388/291))
0.8 = k (ln (1.33333)
so k = 2.78
This being the case a doubling would result in a temperature increase of
2.78 (ln 2) = 1.9°C
This is on the low side of prediction but feedbacks such as loss of ice will take time and we have various short term slow-downs such as aerosols in the mid twentieth century and from volcanoes.
I would like to see the argument for how an increase on this scale is possible with the very low climate sensitivities some are insisting on.
Support science against political attack here: http://www.petitiononline.com/clim4tr/petition.html
re 442 John Reisman.
Fee and Dividend looks straight forward enough on first reading. Have to mull that over a bit. Maybe indeed a way to make the real environmental cost of eg the tar sands development come in to play. The inefficiency of that process is staggering ( about 25% of the energy harvested goes up in smoke, the gas/diesel burned to get it extracted ); the environmental destruction is a travesty. We have been told that newer technologies will solve that. Will believe it when I see it.
It is worthwhile looking at places like Holland where the overpopulation has really stimulated some good initiatives that work. Gas prices are very high, close to 3 times the US prices. (Except now the Euro is down so less) You will find many car pooling areas. People drive smaller and more fuel efficient cars.
Agree also that cap and trade is a scheme. Interestingly both Znet http://www.zcommunications.org/ and National Post
had articles extremely critical of the carbon trading
business; sorry can’t find the exact references any more.
Maybe some of the dividend should go to innovation, in the long run our best chance of success.
Rod B., You still haven’t understood the various estimates. Whether CO2 precedes or follows temp is irrelevant. What matters is that you are putting a given amount of energy into the system, and the feebacks respond. Look again. Also note that Knutti and Hegerl cite 10 separate INDEPENDENT lines of evidence–and they line up quite nicely. There are more resources on Barton’s site and here:
http://agwobserver.wordpress.com/2009/11/05/papers-on-climate-sensitivity-estimates/
There are really no credible papers pruducing a sensitivity less than about 2.
Ray Ladbury (462), the only thing in this post I disagree with is the irrelevancy thing. Asking the scientific question, if CO2 doubling causes X temp increase (steady state) given the present circumstances, does increasing temp by X cause a natural doubling of CO2? No physicist worth his salt would simply say, “I would guess it O.K.” and move on. He would look into it and study and try to verify it. That makes it relevant because of using that info to project future sensitivities.
I agree(d) with everything else in your post, but it isn’t a rebuttal to my assertion.
t_p_hamilton (891), How is it that someone can run an experiment that indicates doubling CO2 increases temp 2 degrees and come up with a 90% confidence in his result? Why not 100%? Did he only do 90% of one step in his experiment so assumed he is probably only 90% correct in his results? Or did part of his experiment require something that he wasn’t sure exactly how much to add but had a good idea — maybe 90% close? Or does some Bayesian genie pop up from one of his lab test tubes and pronounce, “n_i_n_e_t_y … p_e_r … c_e_n_t”?
Gavin, impressive response to Kate in #903
Philip Machanick (#460), with all due respect but your ‘simple calculation’ with respect to climate sensitivity is really far too simple.
No serious climate scientist would claim that all of the temperature rise since 1880 is due to increasing CO2. The temperature increase from 1910-1940 was primarily due to increased solar irradiance. The contribution of rising CO2 to warming during that period was about 25% of the CO2 contribution to warming in the recent years (see my discussion with Ray Ladbury on this topic, #259 and #269). And even for the warming in the recent years the IPCC statement is that ’MOST of the observed increase in globally averaged temperatures since the mid-20th century is very likely due to the observed increase in anthropogenic greenhouse gas concentrations’ (my capitals). There are several other contributing factors that were already known at the time of the IPCC report, and since then there have been several important new articles, for instance Susan Solomon’s recent paper in Science, suggesting that about 30% of warming during the 1990s is related to decreased water vapor in the stratosphere (see my post #383).
So if you were to make a rough estimate of the contribution of CO2 increase to global warming during the whole period since 1880, then I would suggest for the whole period a mean value of approximately 40 % (let’s say 65 % in the recent years, and a quarter of that meaning about 15% during 1910-1940). In that case your calculation for a doubling of CO2 would yield a value of about 0.8 degree Celsius. If that value would be correct than there is apparently a net negative feedback (compared to the generally accepted ‘pure’ effect of CO2 doubling of about 1 degree Celsius).
Rod B.: “if CO2 doubling causes X temp increase (steady state) given the present circumstances, does increasing temp by X cause a natural doubling of CO2?”
Certainly not generally — since temperature increases logarithmically with CO2, you’d need CO2 to increase exponentially with temperature, but luckily, that’s not expected. As for what is expected, go back and read Jim’s recent post on the CO2 feedback. And why would you expect a reverse relationship to hold, anyway, when the physical processes involved are entirely different? And what does that question have to do with whether CO2 leads or lags temps in the historical record?
wilt #466, solar irradiance increased in the first part of the twentieth century but is pretty much at the same level now (ftp://ftp.pmodwrc.ch/pub/data/irradiance/composite/DataPlots/composite_d41_62_0906.dat and http://www.acrim.com/TSI%20Monitoring.htm) as in 1880 (http://www.mps.mpg.de/projects/sun-climate/data/tsi_1611.txt): 1365W/m^2.
Wilt, the thing about papers like Solomon’s is that they do not affect the estimates of CO2 sensitivity–you still expect 3 degrees per doubling. It is just a matter of how rapidly that occurs. In some ways, a slower warming is good, but in some ways it causes greater damage and implies a much slower recovery even if we bring CO2 under control.
Rod B. says, “Asking the scientific question, if CO2 doubling causes X temp increase (steady state) given the present circumstances, does increasing temp by X cause a natural doubling of CO2?”
Huh? Rod, you are confusing things. The relationship is not recip-rocal. The CO2 sensitivity is based on the climate’s response to energy added by increasing CO2. There is no way for the climate to know whether an added Joule of energy comes from CO2, insolation or a Martian heat gun.
“464
Rod B says:
24 February 2010 at 10:57 PM
t_p_hamilton (891), How is it that someone can run an experiment that indicates doubling CO2 increases temp 2 degrees and come up with a 90% confidence in his result? ”
Who?
It’s 3 degrees anyway
“Why not 100%?”
Why would it not being 100% be a problem?
Rod B., you cannot achieve 100% confidence in a prediction using a statistical analysis using a finite sample.
Philip Machanick (#468), it seems you are missing my point. If you read my comment (#466) carefully you will see that I am not claiming that increased solar irradiance could explain all or even most of the warming in recent years. I wrote that it was very important for the 1919-1940 warming, and that the contribution of CO2 increase was much less important during those years compared to the recent warming. Therefore if you estimate the climate sensitivity with respect to CO2 from the temperature increases since 1880 (as you proposed) then you will end up with a value of approximately 0.8 degrees Celsius as I explained in my post.
Ray Ladbury, yes I agree that there are other (and perhaps better) ways to estimate CO2 sensitivity. But if you take the approach that was proposed by Philip Machanick then in my view you end up with the value of 0.8 degree Celsius.
I do not completely understand your remark “In some ways, a slower warming is good, but in some ways it causes greater damage”. Can you explain in what way it would be damaging if the warming is slower?
“473
wilt says:
25 February 2010 at 8:24 AM
you will see that I am not claiming that increased solar irradiance could explain all or even most of the warming in recent years. I wrote that it was very important for the 1919-1940 warming, and that the contribution of CO2 increase was much less important during those years compared to the recent warming.”
Can you help me out here wilt.
What is the sudden desire for stating something that is “dog bites man” in newsworthyness.
That is what the IPCC report states.
It doesn’t disprove anything the IPCC states by saying it.
So why add so many words?
What IS it with obfuscators and their desire to state non-news all over the place?
Wilt, slower warming also implies slower cooling. It implies greater mixing into the mid-to-deep ocean, and so more global effects.
464: Rod B sed “How is it that someone can run an experiment that indicates doubling CO2 increases temp 2 degrees and come up with a 90% confidence in his result? Why not 100%?” and then continued on with even more silliness
For starters they aren’t determining the sensitivity w/ laboratory experiments. But measurements ALWAYS have errors. A measurement produces a result. The next measurement produces a slightly different result. The next a slightly different result again, etc. Confidence intervals can then be extracted from the data.
Mr (or Mrs??) Completely Fed Up (#474) will you please stop distorting my or anyone else’s words for no good reason?
I explained as good as I could to Philip Machanick that he had apparently misread my words in post #466. If Philip Machanick would have any problem with my remarks #473, I am sure that he can speak out for himself. I did not proclaim that my calculation would disprove anything IPCC said. Read my words first, and comment then if you feel it’s necessary. But not go around just shouting things out of the blue. People might start thinking that you are Completely Mixed Up.
Ray Ladbury (#475), that is an interesting idea. But doesn’t it all depend on how fast the enery would emerge again from the ocean? In my view, the more the ocean would function as a buffer with respect to excess energy, the better. And if warming occurs slower than thought, we have at least more time to prepare for changes, isn’t it?
Oops! Just as I suspected last night in bed, my posts 464 and 465 went into the wrong thread. Sorry
PS see wilt’s assertion:
“I did not proclaim that my calculation would disprove anything IPCC said.”
With his later assertions on the same post:
“and since then there have been several important new articles, for instance Susan Solomon’s recent paper in Science, suggesting that about 30% of warming during the 1990s is related to decreased water vapor in the stratosphere (see my post #383).”
And
“there is apparently a net negative feedback (compared to the generally accepted ‘pure’ effect of CO2 doubling of about 1 degree Celsius).”
CM (467), valid question. But the issue is the sensitivity from the marginal increase in CO2 starting with levels that we have not seen (upcoming future). The paleoclimatic relationships are used, in part, to justify the projection of the 20th century sensitivity into the 21st century. Since the predominance of paleoclimate change has temp leading CO2 I assumed that is the relevant question. It’s possible they only looked at the few (one??) periods where CO2 led, but they don’t say.
> Completely Mixed Up
Oh noes, that would cause far more acronym confusion than we already have.
How about “Completely Destroys Credibility” instead? That can’t be mistaken for anything els….. oh, wait …..
> Completely Fed Up says: 25 February 2010 at 7:31 AM
> “464 Rod B says:24 February 2010 at 10:57 PM
>> a 90% confidence in his result? ”
>> … “Why not 100%?”
> Why would it not being 100% be a problem?
C’mon, Completely — you’re being RodTrolled, and enjoying it.
That’s not good for you, or Rod, or anyone else, it’s just self abuse.
Rod can keep asking faux-naive questions to which he knows the answer forever, just to get your goat for his enormous herd of previously collected goats.
And you play right into this stuff when you give stupid irate answers.
It makes the two of you look like you’re a collaborative tag team here.
Eh?
Suggestion:
“RodB knows darned well what a confidence interval is, and is just playing dumb there. Of course scientists don’t claim 100 percent confidence; science is about probabilities. To claim complete confidence, you have to rely on mathematical proof”
That’s what’s wrong with 100%.
Completely Fed Up,
Thanks again for the replies. I asked William Connelly (http://scienceblogs.com/stoat/2010/02/wireless_mice_and_google_buzz.php) who let me know that my question was itself flawed, depending on which emissions scenario is involved. From the WGI Summary for Policymakers: “Warming tends to reduce land and ocean uptake of atmospheric carbon dioxide, increasing the fraction of anthropogenic emissions that remains in the atmosphere. For the A2 scenario, for example, the climate-carbon
cycle feedback increases the corresponding global average warming at 2100 by more than 1°C.”
So, it looks like your response was correct, but my question only applied certain scenarios.
“it’s just self abuse.”
If I can’t abuse myself, who can I abuse?
Tried answering wilt, but the system ate it all right up.
Hence that “PS” which was a post scriptum for a message wot went awol
Completely Fed Up (#480)
In response to a calculation by Philip Machanick (#460) I made a correction (#466), and the result of this corrected calculation was a value of 0.8 degree Celsius for a CO2 doubling. I than added:
“If that value would be correct than there is apparently a net negative feedback (compared to the generally accepted ‘pure’ effect of CO2 doubling of about 1 degree Celsius).”
Furthermore, I made the remark that science had not stopped when the IPCC report was finished, and as an example I referred to Solomon’s article. Solomon did not make the claim (and neither did I) that her article would disprove anything IPCC said. But if the conclusions of her article are right, then part of the warming during the 1990s apparently is related to a factor that was not taken into consideration before. That is not a disaster, and it is not disproving the IPCC conclusions (CO2 may still have had an important contribution to warming in recent years). It is called progress of our scientific understanding.
And with respect to understanding: I do not get the impression that your remarks contribute to understanding each other better, or are even aimed in that direction.
For those who replied, my #464 makes no sense unless in the context of its correct thread: Whatevergate
#461 Henk Hak
I originally pondered the idea that some should go to innovation. But politicians are not very good at making sure money is spent effectively, or efficiently.
The Fee & Dividend structure has best potential for success when kept simple. It also provides monetary stimulus to offset costs to those that will have trouble affording the energy cost increases. In other cases it works as an economic stimulus which will be helpful in maintaining a functioning economy. The sword of Damocles must be considered. It is critical that we maintain a functioning economy.
I think the market forces, without subsidy, should actually drive the innovation faster because the fee is progressive. When the corps realize they won’t be subsidized, then it is reasonable to assume they will rapidly develop the alternatives to protect their bottom lines. We will need to understand the best formula for the transition and that will take some in depth work.
Change the premise for motive and that should change the fundamental views on approach and execution. I do not proceed without caution.
—
The Climate Lobby
Understand the Issue
http://www.climatelobby.com/fee-and-dividend/
Sign the Petition!
http://www.climatelobby.com
“wilt says:
25 February 2010 at 1:29 PM
I than added:
“If that value would be correct than there is apparently a net negative feedback (compared to the generally accepted ‘pure’ effect of CO2 doubling of about 1 degree Celsius).””
But before that you asserted:
“your ‘simple calculation’ with respect to climate sensitivity is really far too simple.”
Why the change of heart?
You start off saying it’s no good then using it to “prove” some nebulous “negative feedback” of which you have no cause.
SM (455): It’s an absorption cross-section. The optical thickness of a mass of gas (or liquid, or solid) is
tau = k rho ds
where k is the absorption coefficient, rho the density of the absorber, and ds the path length. From unit analysis, you can see that rho (density in kilograms per cubic meter) and ds (meters) multiply together to give kg /m^2, and in fact the product can be called the “specific mass” SM or the “mass path” — mass per unit area. Since tau must be dimensionless, the units of k must be square meters per kilogram.
Rod B (463),
Try here:
http://BartonPaulLevenson.com/Lag.html
Rod B., your #463 doesn’t make sense either, as Ray also pointed out (not a reci-procal relationship). What you want to know (#481) is simply how people can calculate the warming from a doubling of CO2 based on periods when temps led CO2, isn’t it?
Hank:
“> Completely Fed Up says: 25 February 2010 at 7:31 AM
> “464 Rod B says:24 February 2010 at 10:57 PM
>> a 90% confidence in his result? ”
>> … “Why not 100%?”
> Why would it not being 100% be a problem?
C’mon, Completely — you’re being RodTrolled”
Well for those thinking legitimately that Rod B may have a point, the fact that he couldn’t answer should be answer enough for them.
I knew he wouldn’t answer.
BPL (492), thanks, but that wasn’t my argument or assertion.
CM (493), essentially, yes. Future sensitivity is partly determined/justified/estimated by looking at paleoclimate data. My question was how valid is that viz-a-viz the lag-lead thing.
CFU (494), I might answer it but only in the correct thread, Whatevergate. Sorry for the confusion.
wilt, I don’t accept your “correction” (#466). If much of the early 20th century rise was attributable to solar variation, that implies the system responds fairly rapidly to variations in TSI. That being the case, the fact that we are back to about the same TSI level today as in 1880 means that the rises attributable to solar variances should have cancelled out. In #473, you emphasise the “1919-1940 warming”. I know about that. But for that to be a significant part in today’s variance from 1880, the system would have to have a memory that the rapid variation 1919-1940 belies.
Secondly, the Solomon article (as I recall, no time to check now) claims to provide a cause for a temporary small slowdown in warming, not a reduction in climate sensitivity. If this is correct, the present post-1880 rise should be more than 0.8°C, which would give a higher sensitivity than my estimate.
Finally, my estimate is not an equilibrium figure. You need to wait for longer-term feedbacks like reduction in ice to arrive at that number.
Rod B. #496, my uneducated guess (corrections welcome) would be that lag/lead doesn’t matter to estimating climate sensitivity from past temperature changes. What matters is to account for all the significant forcings over the period in question, and that’s basically the same problem in either case.
Wilt@478, Whether having more time to prepare for warming is a boon depends on whether we can actually do anything to mitigate the effects. It is quite possible we could wind up being helpless observers and the environment degrades and is less and less able to support population levels. Consider the effect that would have on people knowing things would get worse and worse and that there was nothing you could do to improve things. Rather like the Easter Islanders after they chopped down the last tree.
Philip Machanick (#497),
I am not so sure that solar intensity is back at the level of 1880, but I don’t want to turn this into a discussion about the role of the sun. For the line of reasoning when performing the calculation that you presented initially at #460, all that matters in my view is how much of the warming during the previous century can be attributed to CO2 increase (instead of other causes). If all of the 0.8 degree temperature increase since 1880 were due to CO2 rise then you would be right in suggesting 1.9 degrees Celsius for a CO2 doubling. You will agree that most of the temperature increase in the first half of the 20th century can not be ascribed to CO2, and that is also true for a significant part of the increase during the second half of the century (even if you leave out solar effects, there were for instance contributions from black carbon, other GHG’s like methane, and aerosols). For that reason you end up much lower: approximately 0.8 degrees rather than 1.9 degrees for a CO2 doubling, in my view.
With respect to Solomon, here is the final part of the abstract of her Science article: ‘More limited data suggest that stratospheric water vapor probably increased between 1980 and 2000, which would have enhanced the decadal rate of surface warming during the 1990s by about 30% compared to estimates neglecting this change. These findings show that stratospheric water vapor represents an important driver of decadal global surface climate change.’ If she is right, the attribution to CO2 during the 1990s must be lower than previously thought and as a consequence the value for CO2 doubling decreases even further.